Residual Bone Height and Implant Survival After Lateral Sinus Floor Elevation: A Continuous-Variable Analysis With 13-Year Follow-up

Residual Bone Height and Implant Survival After Lateral Sinus Floor Elevation: A Continuous-Variable Analysis With 13-Year Follow-up | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Residual Bone Height and Implant Survival After Lateral Sinus Floor Elevation: A Continuous-Variable Analysis With 13-Year Follow-up Kagan Degerliyurt, Aria Besharati Givi, Senem Denizci Degerliyurt This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9361228/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Objectives: To evaluate the effect of residual bone height (RBH) on implant survival following lateral sinus floor elevation (LSFE), and to assess the influence of sinus membrane perforation and patient-related factors. Materials and Methods A total of 217 implants placed after LSFE were retrospectively analyzed. RBH was assessed both categorically (RBH < 2 mm, 2 ≤ RBH < 4 mm, RBH ≥ 4 mm) and as a continuous variable. Implant failure was the primary outcome. Associations were evaluated using chi-square tests, Kaplan–Meier survival analysis with log-rank testing, and Cox proportional hazards regression. Multivariable logistic regression was used to identify independent predictors, including sinus membrane perforation, smoking, age, and sex. Results: The overall implant failure rate was 8.8% (19/217). RBH was not significantly associated with implant loss when analyzed categorically (p > 0.05), and no significant differences in survival were observed among RBH groups (log-rank p = 0.258). However, when analyzed as a continuous variable, RBH showed a significant inverse association with implant failure, with each 1-mm increase reducing the odds of failure (OR = 0.62, 95% CI: 0.38–0.99, p = 0.045). Sinus membrane perforation was strongly associated with implant loss, with failure rates of 44.4% in perforated cases versus 5.5% in non-perforated cases (p < 0.001). Smoking showed a non-significant trend toward increased risk, while age and sex were not significantly associated with implant failure. Conclusions: RBH does not appear to be a significant predictor of implant loss when categorized; however, continuous analysis suggests a dose–response relationship, indicating that decreasing RBH progressively increases failure risk. Sinus membrane perforation emerged as the strongest determinant of implant failure, highlighting the critical importance of surgical technique in LSFE procedures. Residual bone height sinus floor elevation dental implants membrane perforation implant survival risk factors Figures Figure 1 Figure 2 BACKGROUND Severe bone loss and the pneumatization of the maxillary sinus can limit the treatment options for placing dental implants in posterior maxilla. 1 , 2 Among the methods used to solve these problems, sinus floor elevation with bone grafts is still one of the most reliable and cost- effective options. 3 Maxillary sinus elevation, either through a lateral or crestal approach, is a common surgical technique to increase the residual bone height in the posterior maxilla. 4 Transcrestal sinus elevation is considered less invasive than the lateral approach since it requires less operation time, causes fewer postoperative problems, and can improve primary stability by increasing bone density. 5 , 6 However, a disadvantage of the crestal technique is that it usually enables less membrane elevation compared to the lateral approach. 7 – 9 Therefore, clinicians prefer the lateral sinus augmentation technique to safely create more space for bone augmentation. 3 , 10 Severely atrophic maxilla present a significant challenge for simultaneous implant placement because very limited residual bone height (RBH) can compromise implant stability and survival. 11 In addition, this region typically exhibits lower bone density, requiring careful planning to achieve adequate primary implant stability. When RBH is below 3 mm, the remaining bone volume may be insufficient to achieve adequate primary stability, thereby restricting the feasibility of a one-stage procedure. 12 Although several studies have suggested that an RBH threshold of approximately 3 mm can support favorable long-term outcomes with simultaneous implant placement, the predictability of this approach in sites with ≤ 3 mm RBH remains uncertain. 13 , 14 Some evidence indicates that lateral sinus floor elevation (LSFE) with simultaneous implantation can still yield acceptable survival rates in such cases; however, other analyses have demonstrated a progressive increase in implant failure risk as RBH decreases. 11 , 12 Experimental and retrospective studies also report reduced bone–implant contact and lower survival rates when RBH is < 3 mm. 15 Some studies have suggested a critical threshold of 2 mm for residual bone height (RBH), below which implant survival may be adversely affected. In the present study, this proposed cutoff is also specifically evaluated alongside continuous analysis of RBH. 10 , 15 Consequently, the reliability of one-stage LSFE with simultaneous implant placement in extremely atrophic maxilla remains controversial, particularly because large-scale studies with long-term follow-up are still lacking. Therefore, the purpose of this study was to evaluate the influence of residual bone height and other variables on the long-term success of dental implants placed simultaneously with lateral sinus floor elevation. MATERIALS AND METHODS This study was designed as a retrospective cohort study and conducted in accordance with the STROBE guidelines for observational studies. A total of 217 consecutive patients who underwent 217 lateral sinus floor elevation (LSFE) along with simultaneous dental implant placement between 2012 and 2017 were recruited from the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Istanbul Aydın University. Patients in whom a single implant was placed in conjunction with lateral sinus floor elevation (LSFE) were included in the study, regardless of side. In patients with multiple implants meeting the inclusion criteria, a single implant was randomly selected using a computer-generated randomization sequence generated in R software (R Foundation for Statistical Computing, Vienna, Austria) to ensure reproducibility and to avoid clustering bias. To eliminate variability in outcomes attributable to differences between implant systems, only patients treated with Straumann® Standart Plus implants (Straumann, Basel, Switzerland) were included in the study cohort. Participants were selected based on predefined inclusion and exclusion criteria. Inclusion criteria were: patients aged 18 years or older; absence of first molar with a healing period of at least 6 months; no membrane thickening above 2 mm; simultaneous implant placement with lateral sinus floor elevation (LSFE); complete clinical and radiographic records, along with follow-up data sufficient to assess implant survival; residual bone height (RBH) ≤ 5 mm at the implant site as confirmed by Cone Beam Computed Tomography (CBCT); complete medical records; and completion of the prosthetic restoration. Exclusion criteria included the presence of uncontrolled systemic diseases, untreated periapical or periodontal infections adjacent to the maxillary sinus before surgery, anatomical variations such as septa that could influence surgical outcomes, bisphosphonate therapy, a history of head and neck radiotherapy, the requirement for additional vertical or horizontal bone augmentation procedures other than LSFE, previous LSFE in the same maxillary sinus, and the absence of follow-up records. Patients were followed clinically and radiographically after implant placement. Follow-up duration was recorded in years. For time-dependent analyses, the follow-up period was divided into early (≤ 12 months) and late (> 12 months) phases. The final follow-up evaluations of all patients were conducted in 2025. The shortest follow-up duration in this study was 8 years, and the longest was 13 years. Patients were stratified into three groups according to residual bone height (RBH): RBH< 2mm, RBH ≥ 2 and <4mm, and RBH≥ 4mm. The residual bone height was measured using cone-beam computed tomography (CBCT), by assessing the minimum vertical distance from the crest of the alveolar ridge to the base of the maxillary sinus. This retrospective study was conducted in accordance with the revised Declaration of Helsinki. In addition, the study protocol was approved by Ethics Committee of Istanbul Aydın University by the approval No. 2023 − 135. Informed consent for participation was obtained from all participants prior to surgical intervention, including explicit acknowledgment that their clinical data could be used for future scientific and research purposes. All data collection and analysis were conducted in such a manner that the patients could not be identified. Statistical Analysis Statistical analyses were performed using R 4.5.1 (R Foundation for Statistical Computing, Vienna, Austria). and IBM SPSS Statistics for Windows (Version 22.0, IBM Corp., Armonk, NY, USA), with significance set at p < 0.05. The primary exposure variable was residual bone height (RBH), measured preoperatively using radiographic imaging and analyzed both as a categorical variable (RBH <2mm, 2 ≤ RBH<4mm and RBH≥4mm) and as a continuous variable to minimize information loss associated with categorization. Categorical variables were expressed as frequencies and percentages, and continuous variables as mean ± standard deviation or median (interquartile range), as appropriate. A secondary exposure variable was sinus membrane perforation, recorded intraoperatively as a binary variable (yes/no). Additional covariates included age, sex, and smoking status. The primary outcome was implant failure, defined as implant loss occurring either during the healing phase including failures detected at re-entry for healing abutment placement or after prosthetic loading. Time-to-event was calculated from the date of implant placement to the date of failure or last follow-up. Early failures identified at re-entry were recorded as events occurring at the time of re-entry. The association between RBH and implant failure was initially evaluated using the Pearson chi-square test or Fisher–Freeman–Halton exact test, where applicable. The association between RBH category and sinus membrane perforation was assessed using the Pearson chi-square test. In addition, because RBH categories were ordinal, a Cochran–Armitage trend test was performed to evaluate a possible linear trend in perforation rates across RBH groups. Survival analysis was performed to account for varying follow-up durations. Implant survival was estimated using the Kaplan–Meier method, and differences between RBH groups were compared with the log-rank test. Early failures recorded at re-entry were assigned a minimal positive time value for analysis. The independent effect of RBH on implant failure was evaluated using Cox proportional hazards regression and multivariable logistic regression models, adjusting for sinus membrane perforation, smoking status, age, and sex. Results were expressed as hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs). To evaluate the temporal effects of RBH and sinus membrane perforation, a time-stratified (landmark) analysis was performed by dividing follow-up into early (≤ 12 months) and late (> 12 months) phases. Separate Cox regression models were constructed for each phase. In addition, interaction analyses were performed to assess whether the effect of RBH and perforation differed significantly between early and late periods. For perforation, differences in implant loss rates between groups in early and late phases were additionally assessed using Fisher’s exact test, and comparison of effect sizes across time periods was performed using a test for homogeneity of odds ratios. Potential model instability due to low event counts was considered, and adjusted models were constructed using clinically relevant covariates. All tests were two-sided. Surgical Procedure All LSFE procedures were carried out by a senior experienced surgeon following a standardized protocol. After administration of local infiltration anesthesia, midcrestal, mesial, and distal incisions were made, and a full-thickness mucoperiosteal flap was elevated to expose the lateral wall of the maxillary sinus. A round diamond bur was used to create the lateral bony window. The Schneiderian membrane was carefully elevated, and its integrity was assessed both visually and with the Valsalva maneuver. In cases of membrane perforation, repair was performed using L-PRF combined with a resorbable collagen membrane (Bio-Gide, Wolhusen, Switzerland), or by repositioning and suturing the membrane to the superior margin of the bony window, supplemented with L-PRF. An epinephrine-soaked cotton sponge was then placed within the elevated sinus cavity to control bleeding, and the implant osteotomy was prepared. After removal of the sponge, 1–2 g of deproteinized bovine bone matrix (Bio-Oss, Wolhusen, Switzerland), depending on the extent of augmentation, was grafted into the sinus space. The implant was subsequently inserted, and the lateral window was covered with a resorbable collagen membrane (Bio-Gide, Wolhusen, Switzerland) and L-PRF. Finally, the flap was repositioned and closed with 3/0 non-resorbable silk sutures (Dogsan, Trabzon, Turkey). Implants were left to heal in a submerged manner before second-stage surgery and definitive prosthetic restoration. Postoperatively, patients were prescribed Amoxicillin+Clavulanic acid 625 mg (2x1), combined analgesics (Ibuprofen 400 mg 2x1 + Paracetamol 500 mg 4x1), and Chlorhexidine/Benzydamine hydrochloride mouthwash. Postoperative instructions were provided to the patients. A follow-up appointment and suture removal was scheduled for 7 days after surgery. Six months following the surgery, healing abutments were placed, and a torque of 35 N.cm was applied using a ratchet wrench. Implants that exhibited no mobility under the applied torque were regarded as successfully osseointegrated. RESULTS A total of 217 lateral sinus floor elevation (LSFE) procedures with simultaneous implant placement were included in the study. The patients ranged in age from 19 to 75 years, with a mean age of 48.7 ± 11.4 years. Of the implants, 140 (64.5%) were placed in male patients and 77 (35.5%) in female patients. The residual bone height (RBH) ranged from 1.2 to 5.0 mm (mean: 3.47 ± 1.14 mm). RBH was categorized into three groups: <2 mm (n = 39, 18.0%), 2–<4 mm (n = 82, 37.8%), and ≥ 4 mm (n = 96, 44.2%). A total of 91 patients (41.9%) were smokers. Detailed distribution of study parameters is presented in Table 1 . Table 1 Distribution of Study Parameters RBH n % Below 2 mm 39 18 Between 2 mm and 4 mm (inclusive of 2 mm) 82 37,8 Above 4 mm (inclusive of 4 mm) 96 44,2 Sex Male Female 140 77 64.5 35.5 Smoking Yes 88 40,6 No 129 59,4 Failure Yes 19 8.8 No 198 91.2 Time of failure (n = 19) After loading (AL) 9 47,4 Before loading (BL) 10 52,6 Perforation Yes 18 8.3 No 199 91.7 During the follow-up period, 19 implants (8.8%) failed. Of these, 10 (52.6%) occurred during re-entry for healing abutment placement, and 9 (47.4%) occurred after definitive prosthetic restoration. Clinical characteristics and management of failed implants are summarized in Table 2 . Table 2 Clinical Characteristics and Post-failure Management of Failed Implants Following Lateral Sinus Floor Elevation. 1. Date of operation RBH (mm) Perforation Failure Management & Outcome February/2015 4.9 + BL Simultaneous reimplantation Uneventful at 11 years follow-up 2. September/2013 4.9 - AL (109 m) Immediate autogenous bone grafting Reimplantation after 4 months Uneventful at 3 years follow-up. 3. March/2015 4.7 - AL (74 m) Immediate reimplantation with simultaneous autogenous bone grafting Uneventful at 5 years follow-up 4. February/2016 4.7 + BL Simultaneous reimplantation Uneventful at 9 years follow-up 5. March/2013 4.7 + BL Simultaneous reimplantation Uneventful at 11 years follow-up 6. July/2014 4.6 + BL Simultaneous reimplantation Uneventful at 10 years follow-up 7. March/2014 4.2 - AL (75 m) Immediate reimplantation Uneventful at 5 years follow-up 8. March/2014 3.9 + AL (98 m) Immediate autogenous bone grafting Reimplantation after 4 months Uneventful at 2 years follow-up. 9. September/2014 2.9 + AL (21 m) Immediate reimplantation with simultaneous autogenous bone grafting Uneventful at 9 years follow-up 10. August/2016 2.8 - AL (59 m) Immediate autogenous bone grafting/Reimplantation at 4 months post regrafting/Uneventful at 4 years follow-up. 11. August/2016 2.6 + BL Immediate implantation Failed 72 months after reimplantation Immediate autogenous bone grafting Reimplantation after 4 months Uneventful at 4 years follow-up. 12. April/2014 2.1 - AL (51 m) Immediate reimplantation with simultaneous autogenous bone grafting Uneventful at 7 years follow-up 13. September/2015 2.1 + BL Immediate reimplantation Uneventful at 9 years follow-up 14. March/2016 1.5 - BL Immediate reimplantation Uneventful at 9 years follow-up 15. July/2013 1.3 + BL Immediate reimplantation Uneventful at 11 years follow-up 16. July/2015 0.8 - BL Immediate autogenous bone grafting Reimplantation after 4 months Uneventful at 9 years follow-up. 17. June/2015 0.2 - BL Immediate reimplantation Uneventful at 9 years follow-up 18. April/2013 0.2 - AL (14 m) Immediate reimplantation Uneventful at 10 years follow-up 19. September/2014 0.2 - AL (17 m) Immediate reimplantation Uneventful at 8 years follow-up RBH, residual bone height; BL, early (before loading) failure; AL, late (after loading) failure; m, months. Implant failure was observed in 6 cases (15.4%) in the RBH < 2 mm group, 6 cases (7.3%) in the 2 ≤ RBH < 4 mm group, and 7 cases (7.3%) in the RBH ≥ 4 mm group. Although the failure rate in the < 2 mm group was approximately twofold higher, no statistically significant association was found between RBH category and implant failure (Pearson chi-square, χ² = 2.615, p = 0.270; Fisher–Freeman–Halton exact test, p = 0.324). When RBH was analyzed as a continuous variable, a significant association emerged in multivariable logistic regression. Each 1-mm increase in RBH was associated with a reduced odds of implant failure (OR = 0.62, 95% CI: 0.38–0.99, p = 0.045). These findings are detailed in Table 3 . Table 3 Relationship of RBH, Smoking, and Perforation with Implant Failure RBH (categorical) Failure n (%) No Failure n (%) Effect Estimate 95% CI p-value < 2 mm 6 (15.4%) 33 (84.6%) Ref – 2–<4 mm 6 (7.3%) 76 (92.7%) – – ≥ 4 mm 7 (7.3%) 89 (92.7%) – – 0.270† RBH (continuous) per 1 mm increase – – OR = 0.62 0.38–0.99 0.045‡ Smoking Yes 11 (12.1%) 80 (87.9%) OR = 2.995 0.874–10.268 0.081‡ No 8 (6.3%) 118 (93.7%) Ref – aHR = 2.761 0.968–7.878 0.058§ Perforation Yes 8 (44.4%) 10 (55.6%) OR = 19.240 5.540–66.820 < 0.001‡ No 11 (5.5%) 188 (94.5%) Ref – Age per year – – OR = 1.033 0.981–1.087 0.213‡ aHR = 1.028 0.983–1.075 0.223§ Sex Female 7 70 OR = 2.189 0.619–7.745 0.224‡ Male 12 128 Ref – aHR = 1.753 0.601–5.109 0.304§ † Pearson chi-square or Fisher–Freeman–Halton exact test ‡ Multivariable logistic regression analysis § Multivariable Cox proportional hazards regression analysis Ref: reference category Kaplan–Meier analysis showed no significant differences in implant survival among RBH groups across the entire follow-up period (log-rank test, χ² = 2.71, p = 0.258) (Fig. 1). Survival estimates for each RBH group are presented in Table 4 , and log-rank test results are summarized in Table 5 . Table 4 Kaplan–Meier Survival Estimates by RBH Group RBH Group n Events 1-year survival (%) 5-year survival (%) 10-year survival (%) < 2 mm 39 6 89.7 84.6 84.6 2–<4 mm 82 6 97.6 93.9 92.5 ≥ 4 mm 96 7 95.8 95.8 92.4 Kaplan–Meier survival estimates were calculated based on time-to-event analysis. Table 5 Log-rank Test Results for Implant Survival Comparison χ² df p-value RBH groups (< 2, ≥ 2 < 4, ≥ 4 mm) 2.71 2 0.258 Perforation (Yes vs No) — 1 < 0.001 Log-rank test was used to compare survival distributions. χ² value for perforation not shown due to extreme separation driven by early failures. Consistently, Cox proportional hazards analysis demonstrated no significant association between RBH category and implant failure. Compared with the RBH ≥ 4 mm group, the hazard ratio was 1.03 (95% CI: 0.35–3.07, p = 0.956) for the 2 ≤ RBH < 4 mm group and 2.22 (95% CI: 0.75–6.61, p = 0.152) for the RBH < 2 mm group. Multivariable Cox regression results are presented in Table 6 . Table 6 Multivariable Cox Proportional Hazards Analysis RBH 2–<4 mm vs ≥ 4 mm Hazard Ratio (HR) 95% CI p-value 1.03 0.35–3.07 0.956 RBH < 2 mm vs ≥ 4 mm 2.22 0.75–6.61 0.152 Smoking (Yes vs No) 2.76 0.97–7.88 0.058 Age (per year) 1.03 0.98–1.08 0.223 Sex (Female vs Male) 1.75 0.60–5.11 0.304 Cox model adjusted for smoking, age, and sex. Time-stratified analysis revealed that the effect of RBH was more pronounced in the early phase (≤ 12 months), although not statistically significant (unadjusted HR = 0.669, p = 0.172; adjusted HR = 0.664, p = 0.207). In the late phase (> 12 months), no meaningful association was observed (unadjusted HR = 0.753, p = 0.355; adjusted HR = 0.747, p = 0.387). These results are summarized in Table 7 . Table 7 Time-stratified analysis of the effects of residual bone height (RBH) and sinus membrane perforation on implant survival. RBH (per 1 mm increase) Phase Model / Comparison Effect Estimate 95% CI p-value Early (≤ 12 months) Cox (unadjusted) HR = 0.669 0.375–1.192 0.172 Cox (adjusted)* HR = 0.664 0.351–1.256 0.207 Late (> 12 months) Cox (unadjusted) HR = 0.753 0.413–1.372 0.355 Cox (adjusted)* HR = 0.747 0.386–1.446 0.387 Membrane perforation Early (≤ 12 months) Failure rate comparison† 38.9% (7/18) vs 1.5% (3/199) - 12 months) Failure rate comparison† 9.1% (1/11) vs 4.1% (8/196) - 0.394 Late (> 12 months) Cox (unadjusted) HR = 2.231 0.279–17.854 0.450 Cox (adjusted)* HR = 2.226 0.272–18.246 0.456 Temporal comparison Early vs Late Homogeneity test† - - 0.021 *Adjusted for smoking, age, and sex. † p-values derived from Fisher’s exact test or homogeneity test. Abbreviations: HR, hazard ratio; CI, confidence interval. Overall, RBH was not identified as a statistically significant predictor of implant survival when analyzed categorically, despite a trend toward higher early failure rates in sites with RBH < 2 mm. Sinus membrane perforation occurred in 18 cases (8.2%). Perforation rates were comparable across RBH groups: 5.1% (2/39) in the RBH < 2 mm group, 9.8% (8/82) in the 2 ≤ RBH < 4 mm group, and 8.3% (8/96) in the RBH ≥ 4 mm group, with no statistically significant difference (Pearson chi-square, p = 0.689). No linear trend was observed across ordered RBH categories (Cochran–Armitage trend test, p = 0.674). Implant failure occurred in 44.4% (8/18) of perforated cases compared with 5.5% (11/199) in non-perforated cases. In multivariable logistic regression analysis, sinus membrane perforation was identified as a strong independent predictor of implant failure (OR = 19.240, 95% CI: 5.540–66.820, p < 0.001). (Table 2 .) Kaplan–Meier survival analysis demonstrated significantly reduced implant survival in cases with sinus membrane perforation compared to non-perforated cases (log-rank test, p < 0.001) (Fig. 2). Corresponding log-rank test results are presented in Table 5 . Time-stratified analysis showed that this effect was predominantly driven by early failures. In the early phase (≤ 12 months), implant loss occurred in 38.9% (7/18) of perforated cases, compared with 1.5% (3/199) in non-perforated cases (Fisher’s exact test, p < 0.001). In contrast, among implants surviving beyond 12 months, implant faiure rates were similar between groups (9.1% vs. 4.1%, p = 0.394). Consistently, perforation was not significantly associated with implant faiure in late-phase Cox regression analysis (HR = 2.231, 95% CI: 0.279–17.854, p = 0.450), including after adjustment for smoking, age, and sex (adjusted HR = 2.226, 95% CI: 0.272–18.246, p = 0.456). These findings are detailed in Table 7 . Smoking was associated with a higher numerical risk of implant failure, although this did not reach statistical significance in multivariable Cox regression (aHR = 2.761, 95% CI: 0.968–7.878, p = 0.058) or logistic regression (OR = 2.995, 95% CI: 0.874–10.268, p = 0.081). Age and sex were not significantly associated with implant loss. Age showed no significant effect in Cox regression (aHR = 1.028 per year, p = 0.223) or logistic regression (OR = 1.033 per year, p = 0.213). Although female patients demonstrated a higher numerical risk, this difference was not statistically significant in either Cox (p = 0.304) or logistic regression (p = 0.224) analyses. (Table 3 and Table 6 ) DISCUSSION The present study provides important insights into the role of residual bone height (RBH) in implant survival following lateral sinus floor elevation. When RBH was analyzed categorically, no statistically significant association with implant failure was observed, although a higher numerical failure rate was evident in sites with RBH < 2 mm. However, when RBH was entered into the model as a continuous variable, a significant inverse relationship emerged, indicating that decreasing RBH is associated with a progressively increasing risk of implant failure. From the opposite perspective, with each 1-mm increase in RBH reducing the odds of implant failure. This finding suggests that the effect of RBH is better understood as a dose–response relationship rather than a threshold-dependent phenomenon. Each incremental reduction in bone height contributes to increased risk, but this effect may not be detectable when RBH is arbitrarily divided into discrete categories. Similar methodological concerns have been highlighted in statistical literature, where dichotomization or categorization of continuous variables has been shown to reduce statistical power and obscure clinically relevant associations. 16 The discrepancy between categorical and continuous analyses may also help explain the inconsistencies observed in previous studies. Some authors have reported that severely reduced RBH is associated with increased implant failure 8 , 10 , 17 However, more recent randomized and controlled studies have reported no significant association between RBH and implant survival, suggesting that this relationship may be mitigated by surgical technique and appropriate case selection. 5 , 12 , 18 , 19 The present findings suggest that these conflicting results may be partly attributable to differences in analytical approaches, particularly the use of threshold-based versus continuous modeling. Historically, a residual bone height threshold of approximately 2–3 mm has been proposed as a critical determinant of implant success following sinus augmentation. 20 , 21 However, the present results challenge this concept by demonstrating that although lower RBH is associated with increased failure risk, this relationship does not appear to follow a sharp cutoff. Instead, risk appears to increase gradually as RBH decreases, supporting a more continuous biological model. Recent clinical studies have similarly demonstrated that high implant survival rates can be achieved even in sites with minimal residual bone when appropriate surgical protocols are applied. 5 , 17 , 19 Furthermore, contemporary analyses suggest that RBH may influence surgical complexity and complication risk rather than directly determining implant survival. 22 Taken together, these findings indicate that RBH should not be interpreted as a rigid decision-making threshold, but rather as a continuous anatomical parameter that modulates risk. The time-stratified analysis provides additional insight into the role of residual bone height in implant survival. Although RBH demonstrated a numerically stronger effect during the early healing phase, this difference was not statistically significant, and interaction analysis confirmed that the influence of RBH did not significantly change over time. These findings suggest that while reduced RBH may contribute to early mechanical challenges—such as limited primary stability—the overall effect of RBH on implant survival remains relatively modest when evaluated across the entire follow-up period. The absence of a significant temporal interaction further indicates that RBH does not exert a distinct phase-specific effect, but rather functions as a consistent, low-to-moderate risk modifier. Importantly, these results complement the continuous-variable analysis presented in this study. While RBH demonstrated a significant dose–response relationship when modeled continuously, the time-stratified analysis indicates that this effect is not confined to a specific postoperative phase, and does not differ significantly between early and late periods. This supports the interpretation that RBH influences implant outcomes in a gradual and continuous manner, rather than through a time-dependent or threshold-driven mechanism. From a clinical perspective, these findings reinforce the concept that although low RBH may increase technical difficulty and early risk, long-term implant survival appears to be more strongly influenced by surgical factors and complication control, particularly sinus membrane integrity. This further supports the conclusion that RBH should be considered within a broader, multifactorial risk assessment framework rather than as an isolated determinant of implant prognosis. Several recent studies and meta-analyses have demonstrated that reduced residual bone height is associated with an increased risk of sinus membrane perforation, particularly in cases with RBH below 3–4 mm. 23,24 An important observation in the present study is that RBH was not associated with sinus membrane perforation, suggesting that reduced bone height does not inherently predispose to this complication. This finding contrasts with those indicating an increased risk of perforation in cases with reduced RBH but aligns with studies emphasizing that perforation is more strongly related to membrane characteristics and surgical technique. 25 , 26 A key finding of this study is the strong and statistically significant association between sinus membrane perforation and implant failure. Implants placed in perforated sites exhibited markedly higher failure rates compared to non-perforated cases, underscoring the critical importance of membrane integrity. This observation is consistent with studies identifying perforation as a major complication affecting graft stability and osseointegration. 18 , 23 In contrast, other reports have suggested that properly managed perforations do not significantly compromise outcomes. 27 – 29 The discrepancy likely reflects differences in perforation size, repair techniques, and surgical protocols. Importantly, while RBH did not independently predict implant failure in categorical analyses, sinus membrane perforation demonstrated a strong and clinically significant association with failure, indicating that surgical factors may have a greater impact on outcomes than baseline anatomical conditions. Furthermore, the absence of an association between RBH and perforation in this study supports the notion that perforation is more strongly related to operator technique and intraoperative handling than to residual bone height itself. The time-stratified analysis demonstrated that the effect of sinus membrane perforation on implant survival is strongly phase-dependent. Perforation was associated with a marked increase in implant loss during the early healing period, whereas its effect was not statistically significant in the late phase among implants that had successfully passed the initial healing stage. This temporal pattern is biologically plausible. In the early postoperative period, sinus membrane perforation may compromise graft containment, disrupt stabilization of the augmented compartment, and impair early osseointegration. In particular, loss of membrane integrity may lead to graft displacement, impaired vascularization, and bacterial contamination, thereby increasing the risk of early implant failure. 30 Furthermore, recent evidence has identified surgical and anatomical factors related to sinus augmentation, particularly those affecting membrane integrity, as key determinants of early implant failure, supporting the role of membrane perforation as a critical early risk factor. 31 By contrast, once successful osseointegration has been established, the long-term impact of a prior perforation appears to diminish. Systematic and clinical studies have reported that implant survival rates may remain comparable between perforated and non-perforated cases when perforations are adequately managed intraoperatively. 30 , 32 This suggests that the biological consequences of perforation are primarily relevant during the early healing phase, and that their long-term influence may be mitigated following successful integration. These findings help explain the discrepancy between studies reporting no overall effect of perforation and those identifying it as a significant risk factor. The present data indicate that the impact of perforation is not constant over time but is instead concentrated in the early postoperative period, with limited influence on late implant survival. From a clinical perspective, this underscores that the primary consequence of sinus membrane perforation lies in its effect on early implant prognosis. Therefore, meticulous surgical technique, early detection of membrane tears, and appropriate repair strategies are critical to minimizing early implant loss, even if long-term outcomes may ultimately converge once initial healing has been successfully achieved. Smoking showed a higher implant failure rate compared to non-smokers; however, this association did not reach statistical significance. This contrasts with studies reporting smoking as a significant risk factor for implant failure. 10 , 33 Some studies did not observe a significant effect of smoking on implant failure aligning with our findings. 23 , 34 The lack of significance in the present study may be related to sample size limitations or variability in smoking intensity and duration. In contrast, age and sex were not associated with implant failure, indicating that demographic factors may play a limited role in determining outcomes following LSFE. This is consistent with current evidence suggesting that implant survival is largely independent of patient age and sex, provided that systemic conditions are controlled, and that local surgical factors are more decisive. 35 , 36 From a clinical perspective, the present results suggest that: RBH alone should not be considered a contraindication for implant placement although extremely low RBH (< 2 mm) may still represent a higher-risk scenario. Implant failure risk increases progressively rather than abruptly below a specific threshold, therefore, surgical factors, particularly membrane integrity, play a dominant role These findings support a shift from rigid threshold-based decision-making toward a continuous risk assessment model, in which RBH is interpreted in conjunction with surgical and patient-related factors to better predict long-term outcomes. Recent long-term and multicenter studies have further highlighted the multifactorial nature of implant survival following sinus augmentation. For instance, Bonsmann et al. 31 reported a dose-dependent relationship between reduced RBH and early implant failure, supporting the concept of a continuous risk gradient. 31 Similarly, systematic reviews have emphasized that implant outcomes are influenced by a combination of anatomical, surgical, and biological factors rather than a single parameter. 8 , 37 The present study contributes to this evolving perspective by demonstrating that the clinical relevance of RBH on long term success depends strongly on how it is analyzed, and that continuous modeling may reveal associations that are not apparent in categorical analyses. This study has several limitations that should be considered when interpreting the findings. Although multivariable analyses were performed, unmeasured factors such as bone quality, the length and the diameter of the implant, insertion torque, and prosthetic loading protocols may have influenced implant survival. The number of implant failure events was relatively low, which may have limited statistical power, particularly for detecting moderate associations and for subgroup analyses. This may partly explain why certain variables, such as smoking, demonstrated trends without reaching statistical significance. Residual bone height (RBH) was initially analyzed using categorical groupings, which may have resulted in loss of information and reduced sensitivity to detect associations. Although this limitation was partially addressed by additional continuous-variable modeling, the discrepancy between categorical and continuous analyses highlights the challenges associated with variable classification. CONCLUSION Residual bone height (RBH) was not associated with implant failure when analyzed using conventional categorical thresholds; however, continuous-variable modeling revealed a significant dose–response relationship, indicating that decreasing RBH is associated with a progressively increased risk of implant loss. These findings suggest that RBH should be interpreted as a continuous risk modifier rather than a strict clinical cutoff. Sinus membrane perforation emerged as the most critical determinant of implant failure, with a pronounced effect during the early healing phase. Its impact diminished over time among successfully integrated implants, indicating that the adverse influence of perforation is primarily confined to the initial postoperative period. From a clinical perspective, these results support a shift away from threshold-based decision-making toward a more comprehensive, risk-based approach. While low RBH may increase technical complexity, implant survival appears to be predominantly influenced by surgical factors—particularly membrane integrity and complication management—rather than baseline anatomical limitations alone. Declarations Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Istanbul Aydın University (Approval No: 2023 − 135). All procedures were performed in accordance with relevant guidelines and regulations. Due to the retrospective nature of the study and anonymization of patient data, formal informed consent was not required. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. Funding The authors received no financial support for the research, authorship, and/or publication of this article. Author Contribution KD was the attending surgeon and performed all surgical procedures and contributed to conceptualization, supervision, statistical analysis, and writing—original draft preparation.ABG contributed to writing—original draft preparation, investigation, data curation, data processing. SDD served as the second attending surgeon, assisted in all surgical procedures, and contributed to investigation, patients' follow-ups, data processing, and conceptualization. Acknowledgement The authors would like to thank the clinical and administrative staff of the Department of Oral and Maxillofacial Surgery at Istanbul Aydın University for their support in patient management and data archiving. The authors also acknowledge all patients who participated in this study and contributed to the long-term follow-up data. Data Availability The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. References Johansson LA, Isaksson S, Lindh C, Becktor JP, Sennerby L. Maxillary sinus floor augmentation and simultaneous implant placement using locally harvested autogenous bone chips and bone debris: a prospective clinical study. J Oral Maxillofac Surg. 2010;68(4):837–44. Lambert F, Lecloux G, Rompen E. One-step approach for implant placement and subantral bone regeneration using bovine hydroxyapatite: a 2- to 6-year follow-up study. Int J Oral Maxillofac Implants. 2010;25(3):598–606. Bhalla N, Dym H. Update on Maxillary Sinus Augmentation. Dent Clin North Am. 2021;65(1):197–210. Baldi D, Menini M, Pera F, Ravera G, Pera P. Sinus floor elevation using osteotomes or piezoelectric surgery. Int J Oral Maxillofac Surg. 2011;40(5):497–503. Lee D, Kim J, Kim H, et al. Clinical outcomes of maxillary sinus augmentation in atrophied posterior maxilla based on residual bone height. Maxillofac Plast Reconstr Surg. 2025;47(1):26. Gonzalez S, Tuan MC, Ahn KM, Nowzari H. Crestal approach for maxillary sinus augmentation in patients with = 4 mm of residual alveolar bone</at. Clin Implant Dent Relat Res. 2014;16(6):827–35. Qin L, Lin SX, Guo ZZ, et al. Influences of Schneiderian membrane conditions on the early outcomes of osteotome sinus floor elevation technique: a prospective cohort study in the healing period. Clin Oral Implants Res. 2017;28(9):1074–81. Pjetursson BE, Tan WC, Zwahlen M, Lang NP. A systematic review of the success of sinus floor elevation and survival of implants inserted in combination with sinus floor elevation. J Clin Periodontol. 2008;35(8 Suppl):216–40. Rosen PS, Summers R, Mellado JR, et al. The bone-added osteotome sinus floor elevation technique: multicenter retrospective report of consecutively treated patients. Int J Oral Maxillofac Implants. 1999;14(6):853–8. Wang Z, Zhang J, Li N, Pu R, Wang Y, Yang G. Survival analysis of implants placed simultaneously with lateral sinus floor elevation in severely atrophic maxilla: A 3- to 12-year retrospective cohort study. Clin Implant Dent Relat Res. 2023;25(6):1069–79. Chao YL, Chen HH, Mei CC, Tu YK, Lu HK. Meta-regression analysis of the initial bone height for predicting implant survival rates of two sinus elevation procedures. J Clin Periodontol. 2010;37(5):456–65. Park WB, Kang KL, Han JY. Factors influencing long-term survival rates of implants placed simultaneously with lateral maxillary sinus floor augmentation: A 6- to 20-year retrospective study. Clin Oral Implants Res. 2019;30(10):977–88. Peleg M, Garg AK, Mazor Z. Predictability of simultaneous implant placement in the severely atrophic posterior maxilla: A 9-year longitudinal experience study of 2132 implants placed into 731 human sinus grafts. Int J Oral Maxillofac Implants. 2006;21(1):94–102. Felice P, Pistilli R, Piattelli M, Soardi E, Barausse C, Esposito M. 1-stage versus 2-stage lateral sinus lift procedures: 1-year post-loading results of a multicentre randomised controlled trial. Eur J Oral Implantol. 2014;7(1):65–75. Fenner M, Vairaktaris E, Fischer K, Schlegel KA, Neukam FW, Nkenke E. Influence of residual alveolar bone height on osseointegration of implants in the maxilla: a pilot study. Clin Oral Implants Res. 2009;20(6):555–9. Royston P, Altman DG, Sauerbrei W. Dichotomizing continuous predictors in multiple regression: a bad idea. Stat Med. 2006;25(1):127–41. Kim HJ, Yea S, Kim KH, et al. A retrospective study of implants placed following 1-stage or 2-stage maxillary sinus floor augmentation by the lateral window technique performed on residual bone of < 4 mm: Results up to 10 years of follow-up. J Periodontol. 2020;91(2):183–93. Avila-Ortiz G, Neiva R, Galindo-Moreno P, Rudek I, Benavides E, Wang HL. Analysis of the influence of residual alveolar bone height on sinus augmentation outcomes. Clin Oral Implants Res. 2012;23(9):1082–8. Corbella S, Taschieri S, Del Fabbro M. Long-term outcomes for the treatment of atrophic posterior maxilla: a systematic review of literature. Clin Implant Dent Relat Res. 2015;17(1):120–32. Jensen OT, Shulman LB, Block MS, Iacono VJ. Report of the Sinus Consensus Conference of 1996. Int J Oral Maxillofac Implants. 1998;13 Suppl:11–45. Wallace SS, Froum SJ. Effect of maxillary sinus augmentation on the survival of endosseous dental implants. A systematic review. Ann Periodontol. 2003;8(1):328–43. Lyu M, Xu D, Zhang X, Yuan Q. Maxillary sinus floor augmentation: a review of current evidence on anatomical factors and a decision tree. Int J Oral Sci. 2023;15(1):41. Tukel HC, Tatli U. Risk factors and clinical outcomes of sinus membrane perforation during lateral window sinus lifting: analysis of 120 patients. Int J Oral Maxillofac Surg. 2018;47(9):1189–94. Ye M, Lin X, Liu W, Calatrava J, Huang W, Wang HL. Residual ridge height as a potential risk factor for membrane perforation during lateral-window sinus elevation surgery: a systematic review and meta-analysis. BMC Oral Health. 2025;25(1):1522. Lin YH, Yang YC, Wen SC, Wang HL. The influence of sinus membrane thickness upon membrane perforation during lateral window sinus augmentation. Clin Oral Implants Res. 2016;27(5):612–7. Stacchi C, Andolsek F, Berton F, Perinetti G, Navarra CO, Di Lenarda R. Intraoperative Complications During Sinus Floor Elevation with Lateral Approach: A Systematic Review. Int J Oral Maxillofac Implants. 2017;32(3):e107–18. Cha HS, Kim A, Nowzari H, Chang HS, Ahn KM. Simultaneous sinus lift and implant installation: prospective study of consecutive two hundred seventeen sinus lift and four hundred sixty-two implants. Clin Implant Dent Relat Res. 2014;16(3):337–47. Sakkas A, Konstantinidis I, Winter K, Schramm A, Wilde F. Effect of Schneiderian membrane perforation on sinus lift graft outcome using two different donor sites: a retrospective study of 105 maxillary sinus elevation procedures. GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc11. Wang X, Ma S, Lin L, Yao Q. Association between smoking and Schneiderian membrane perforation during maxillary sinus floor augmentation: A systematic review and meta-analysis. Clin Implant Dent Relat Res. 2023;25(1):166–76. Sala YM, Lu H, Chrcanovic BR. Clinical Outcomes of Maxillary Sinus Floor Perforation by Dental Implants and Sinus Membrane Perforation during Sinus Augmentation: A Systematic Review and Meta-Analysis. J Clin Med 2024;13(5). Bonsmann B, Abughalia M, von See C, Dietrich T. Risk Factors for Early Implant Failure Following Sinus Augmentation: A Multi-Centre Nested Case-Control Study. J Clin Periodontol. 2025;52(9):1306–13. Schiavo-Di Flaviano V, Egido-Moreno S, Gonzalez-Navarro B, Velasco-Ortega E, Lopez-Lopez J, Monsalve-Guil L. Influence of Schneiderian Membrane Perforation on Implant Survival Rate: Systematic Review and Meta-Analysis. J Clin Med 2024;13(13). Barbato L, Baldi N, Gonnelli A, Duvina M, Nieri M, Tonelli P. Association of Smoking Habits and Height of Residual Bone on Implant Survival and Success Rate in Lateral Sinus Lift: A Retrospective Study. J Oral Implantol. 2018;44(6):432–8. Esposito M, Felice P, Worthington HV. Interventions for replacing missing teeth: augmentation procedures of the maxillary sinus. Cochrane Database Syst Rev. 2014;2014(5):CD008397. Boboeva O, Kwon TG, Kim JW, Lee ST, Choi SY. Comparing factors affecting dental-implant loss between age groups: A retrospective cohort study. Clin Implant Dent Relat Res. 2021;23(2):208–15. Park WB, Han JY, Kang KL. Long-Term Comparison of Survival and Marginal Bone of Implants with and without Sinus Augmentation in Maxillary Molars within the Same Patients: A 5.8- to 22-Year Retrospective Study. J Clin Med 2021;10(7). Del Fabbro M, Corbella S, Weinstein T, Ceresoli V, Taschieri S. Implant survival rates after osteotome-mediated maxillary sinus augmentation: a systematic review. Clin Implant Dent Relat Res. 2012;14(Suppl 1):e159–168. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 18 May, 2026 Reviews received at journal 15 May, 2026 Reviewers agreed at journal 15 May, 2026 Reviews received at journal 15 May, 2026 Reviewers agreed at journal 15 May, 2026 Reviewers agreed at journal 13 May, 2026 Reviewers agreed at journal 10 May, 2026 Reviewers agreed at journal 08 May, 2026 Reviewers agreed at journal 08 May, 2026 Reviewers agreed at journal 06 May, 2026 Reviewers invited by journal 06 May, 2026 Editor assigned by journal 04 May, 2026 Editor invited by journal 13 Apr, 2026 Submission checks completed at journal 12 Apr, 2026 First submitted to journal 12 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9361228","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":639964218,"identity":"7501641d-0c36-4c34-83e5-7f33d085eba0","order_by":0,"name":"Kagan Degerliyurt","email":"data:image/png;base64,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","orcid":"","institution":"Istanbul Aydın University","correspondingAuthor":true,"prefix":"","firstName":"Kagan","middleName":"","lastName":"Degerliyurt","suffix":""},{"id":639964219,"identity":"fd32f1a8-9682-4dca-b0d1-17bd24f0d32f","order_by":1,"name":"Aria Besharati Givi","email":"","orcid":"","institution":"Istanbul Aydın University","correspondingAuthor":false,"prefix":"","firstName":"Aria","middleName":"Besharati","lastName":"Givi","suffix":""},{"id":639964220,"identity":"ad75a3e0-6941-4314-a340-2774f02a22b6","order_by":2,"name":"Senem Denizci Degerliyurt","email":"","orcid":"","institution":"Ministry of Health","correspondingAuthor":false,"prefix":"","firstName":"Senem","middleName":"Denizci","lastName":"Degerliyurt","suffix":""}],"badges":[],"createdAt":"2026-04-08 21:53:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9361228/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9361228/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":109278674,"identity":"abaf7cdd-6fc3-48ca-a98f-64fc304914e6","added_by":"auto","created_at":"2026-05-14 16:11:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":65318,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"OnlineFigure1.KMRBHoverallBMC.png","url":"https://assets-eu.researchsquare.com/files/rs-9361228/v1/b81294be76ff5e176b00538f.png"},{"id":109278565,"identity":"9078858c-bb6c-4bb2-8765-3bbe02d63876","added_by":"auto","created_at":"2026-05-14 16:11:16","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":116980,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"OnlineFigure2.KMperforationoverallBMC.png","url":"https://assets-eu.researchsquare.com/files/rs-9361228/v1/b0f5df9c9cffc9d66aba8329.png"},{"id":109296414,"identity":"c4cc2160-8608-415c-8b23-10a00b7a76cc","added_by":"auto","created_at":"2026-05-15 08:46:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":668003,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9361228/v1/6f32d364-9e71-44a4-b437-0b8596ad4938.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eResidual Bone Height and Implant Survival After Lateral Sinus Floor Elevation: A Continuous-Variable Analysis With 13-Year Follow-up\u003c/p\u003e","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eSevere bone loss and the pneumatization of the maxillary sinus can limit the treatment options for placing dental implants in posterior maxilla.\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e Among the methods used to solve these problems, sinus floor elevation with bone grafts is still one of the most reliable and cost- effective options.\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e Maxillary sinus elevation, either through a lateral or crestal approach, is a common surgical technique to increase the residual bone height in the posterior maxilla.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eTranscrestal sinus elevation is considered less invasive than the lateral approach since it requires less operation time, causes fewer postoperative problems, and can improve primary stability by increasing bone density.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e However, a disadvantage of the crestal technique is that it usually enables less membrane elevation compared to the lateral approach.\u003csup\u003e\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e Therefore, clinicians prefer the lateral sinus augmentation technique to safely create more space for bone augmentation.\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eSeverely atrophic maxilla present a significant challenge for simultaneous implant placement because very limited residual bone height (RBH) can compromise implant stability and survival.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e In addition, this region typically exhibits lower bone density, requiring careful planning to achieve adequate primary implant stability. When RBH is below 3 mm, the remaining bone volume may be insufficient to achieve adequate primary stability, thereby restricting the feasibility of a one-stage procedure.\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e Although several studies have suggested that an RBH threshold of approximately 3 mm can support favorable long-term outcomes with simultaneous implant placement, the predictability of this approach in sites with \u0026le;\u0026thinsp;3 mm RBH remains uncertain.\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e Some evidence indicates that lateral sinus floor elevation (LSFE) with simultaneous implantation can still yield acceptable survival rates in such cases; however, other analyses have demonstrated a progressive increase in implant failure risk as RBH decreases.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e Experimental and retrospective studies also report reduced bone\u0026ndash;implant contact and lower survival rates when RBH is \u0026lt;\u0026thinsp;3 mm.\u003csup\u003e15\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eSome studies have suggested a critical threshold of 2 mm for residual bone height (RBH), below which implant survival may be adversely affected. In the present study, this proposed cutoff is also specifically evaluated alongside continuous analysis of RBH.\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eConsequently, the reliability of one-stage LSFE with simultaneous implant placement in extremely atrophic maxilla remains controversial, particularly because large-scale studies with long-term follow-up are still lacking. Therefore, the purpose of this study was to evaluate the influence of residual bone height and other variables on the long-term success of dental implants placed simultaneously with lateral sinus floor elevation.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003e This study was designed as a retrospective cohort study and conducted in accordance with the STROBE guidelines for observational studies. A total of 217 consecutive patients who underwent 217 lateral sinus floor elevation (LSFE) along with simultaneous dental implant placement between 2012 and 2017 were recruited from the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Istanbul Aydın University. Patients in whom a single implant was placed in conjunction with lateral sinus floor elevation (LSFE) were included in the study, regardless of side. In patients with multiple implants meeting the inclusion criteria, a single implant was randomly selected using a computer-generated randomization sequence generated in R software (R Foundation for Statistical Computing, Vienna, Austria) to ensure reproducibility and to avoid clustering bias. To eliminate variability in outcomes attributable to differences between implant systems, only patients treated with Straumann\u0026reg; Standart Plus implants (Straumann, Basel, Switzerland) were included in the study cohort.\u003c/p\u003e \u003cp\u003eParticipants were selected based on predefined inclusion and exclusion criteria. Inclusion criteria were: patients aged 18 years or older; absence of first molar with a healing period of at least 6 months; no membrane thickening above 2 mm; simultaneous implant placement with lateral sinus floor elevation (LSFE); complete clinical and radiographic records, along with follow-up data sufficient to assess implant survival; residual bone height (RBH)\u0026thinsp;\u0026le;\u0026thinsp;5 mm at the implant site as confirmed by Cone Beam Computed Tomography (CBCT); complete medical records; and completion of the prosthetic restoration.\u003c/p\u003e \u003cp\u003eExclusion criteria included the presence of uncontrolled systemic diseases, untreated periapical or periodontal infections adjacent to the maxillary sinus before surgery, anatomical variations such as septa that could influence surgical outcomes, bisphosphonate therapy, a history of head and neck radiotherapy, the requirement for additional vertical or horizontal bone augmentation procedures other than LSFE, previous LSFE in the same maxillary sinus, and the absence of follow-up records.\u003c/p\u003e \u003cp\u003ePatients were followed clinically and radiographically after implant placement. Follow-up duration was recorded in years. For time-dependent analyses, the follow-up period was divided into early (\u0026le;\u0026thinsp;12 months) and late (\u0026gt;\u0026thinsp;12 months) phases. The final follow-up evaluations of all patients were conducted in 2025. The shortest follow-up duration in this study was 8 years, and the longest was 13 years.\u003c/p\u003e \u003cp\u003ePatients were stratified into three groups according to residual bone height (RBH): RBH\u0026lt; 2mm, RBH\u0026thinsp;\u0026ge;\u0026thinsp;2 and \u0026lt;4mm, and RBH\u0026ge; 4mm. The residual bone height was measured using cone-beam computed tomography (CBCT), by assessing the minimum vertical distance from the crest of the alveolar ridge to the base of the maxillary sinus.\u003c/p\u003e \u003cp\u003e This retrospective study was conducted in accordance with the revised Declaration of Helsinki. In addition, the study protocol was approved by Ethics Committee of Istanbul Aydın University by the approval No. 2023\u0026thinsp;\u0026minus;\u0026thinsp;135. Informed consent for participation was obtained from all participants prior to surgical intervention, including explicit acknowledgment that their clinical data could be used for future scientific and research purposes. All data collection and analysis were conducted in such a manner that the patients could not be identified.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using R 4.5.1 (R Foundation for Statistical Computing, Vienna, Austria). and IBM SPSS Statistics for Windows (Version 22.0, IBM Corp., Armonk, NY, USA), with significance set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eThe primary exposure variable was residual bone height (RBH), measured preoperatively using radiographic imaging and analyzed both as a categorical variable (RBH \u0026lt;2mm, 2\u0026thinsp;\u0026le;\u0026thinsp;RBH\u0026lt;4mm and RBH\u0026ge;4mm) and as a continuous variable to minimize information loss associated with categorization. Categorical variables were expressed as frequencies and percentages, and continuous variables as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or median (interquartile range), as appropriate.\u003c/p\u003e \u003cp\u003eA secondary exposure variable was sinus membrane perforation, recorded intraoperatively as a binary variable (yes/no). Additional covariates included age, sex, and smoking status.\u003c/p\u003e \u003cp\u003eThe primary outcome was implant failure, defined as implant loss occurring either during the healing phase including failures detected at re-entry for healing abutment placement or after prosthetic loading.\u003c/p\u003e \u003cp\u003eTime-to-event was calculated from the date of implant placement to the date of failure or last follow-up. Early failures identified at re-entry were recorded as events occurring at the time of re-entry.\u003c/p\u003e \u003cp\u003eThe association between RBH and implant failure was initially evaluated using the Pearson chi-square test or Fisher\u0026ndash;Freeman\u0026ndash;Halton exact test, where applicable. The association between RBH category and sinus membrane perforation was assessed using the Pearson chi-square test. In addition, because RBH categories were ordinal, a Cochran\u0026ndash;Armitage trend test was performed to evaluate a possible linear trend in perforation rates across RBH groups.\u003c/p\u003e \u003cp\u003eSurvival analysis was performed to account for varying follow-up durations. Implant survival was estimated using the Kaplan\u0026ndash;Meier method, and differences between RBH groups were compared with the log-rank test. Early failures recorded at re-entry were assigned a minimal positive time value for analysis.\u003c/p\u003e \u003cp\u003eThe independent effect of RBH on implant failure was evaluated using Cox proportional hazards regression and multivariable logistic regression models, adjusting for sinus membrane perforation, smoking status, age, and sex. Results were expressed as hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs).\u003c/p\u003e \u003cp\u003eTo evaluate the temporal effects of RBH and sinus membrane perforation, a time-stratified (landmark) analysis was performed by dividing follow-up into early (\u0026le;\u0026thinsp;12 months) and late (\u0026gt;\u0026thinsp;12 months) phases. Separate Cox regression models were constructed for each phase. In addition, interaction analyses were performed to assess whether the effect of RBH and perforation differed significantly between early and late periods.\u003c/p\u003e \u003cp\u003eFor perforation, differences in implant loss rates between groups in early and late phases were additionally assessed using Fisher\u0026rsquo;s exact test, and comparison of effect sizes across time periods was performed using a test for homogeneity of odds ratios.\u003c/p\u003e \u003cp\u003ePotential model instability due to low event counts was considered, and adjusted models were constructed using clinically relevant covariates.\u003c/p\u003e \u003cp\u003eAll tests were two-sided.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurgical Procedure\u003c/h3\u003e\n\u003cp\u003eAll LSFE procedures were carried out by a senior experienced surgeon following a standardized protocol. After administration of local infiltration anesthesia, midcrestal, mesial, and distal incisions were made, and a full-thickness mucoperiosteal flap was elevated to expose the lateral wall of the maxillary sinus. A round diamond bur was used to create the lateral bony window.\u003c/p\u003e \u003cp\u003eThe Schneiderian membrane was carefully elevated, and its integrity was assessed both visually and with the Valsalva maneuver. In cases of membrane perforation, repair was performed using L-PRF combined with a resorbable collagen membrane (Bio-Gide, Wolhusen, Switzerland), or by repositioning and suturing the membrane to the superior margin of the bony window, supplemented with L-PRF.\u003c/p\u003e \u003cp\u003eAn epinephrine-soaked cotton sponge was then placed within the elevated sinus cavity to control bleeding, and the implant osteotomy was prepared. After removal of the sponge, 1\u0026ndash;2 g of deproteinized bovine bone matrix (Bio-Oss, Wolhusen, Switzerland), depending on the extent of augmentation, was grafted into the sinus space. The implant was subsequently inserted, and the lateral window was covered with a resorbable collagen membrane (Bio-Gide, Wolhusen, Switzerland) and L-PRF.\u003c/p\u003e \u003cp\u003eFinally, the flap was repositioned and closed with 3/0 non-resorbable silk sutures (Dogsan, Trabzon, Turkey). Implants were left to heal in a submerged manner before second-stage surgery and definitive prosthetic restoration.\u003c/p\u003e \u003cp\u003ePostoperatively, patients were prescribed Amoxicillin+Clavulanic acid 625 mg (2x1), combined analgesics (Ibuprofen 400 mg 2x1\u0026thinsp;+\u0026thinsp;Paracetamol 500 mg 4x1), and Chlorhexidine/Benzydamine hydrochloride mouthwash. Postoperative instructions were provided to the patients. A follow-up appointment and suture removal was scheduled for 7 days after surgery. Six months following the surgery, healing abutments were placed, and a torque of 35 N.cm was applied using a ratchet wrench. Implants that exhibited no mobility under the applied torque were regarded as successfully osseointegrated.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 217 lateral sinus floor elevation (LSFE) procedures with simultaneous implant placement were included in the study. The patients ranged in age from 19 to 75 years, with a mean age of 48.7\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4 years. Of the implants, 140 (64.5%) were placed in male patients and 77 (35.5%) in female patients. The residual bone height (RBH) ranged from 1.2 to 5.0 mm (mean: 3.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.14 mm).\u003c/p\u003e \u003cp\u003eRBH was categorized into three groups: \u0026lt;2 mm (n\u0026thinsp;=\u0026thinsp;39, 18.0%), 2\u0026ndash;\u0026lt;4 mm (n\u0026thinsp;=\u0026thinsp;82, 37.8%), and \u0026ge;\u0026thinsp;4 mm (n\u0026thinsp;=\u0026thinsp;96, 44.2%). A total of 91 patients (41.9%) were smokers. Detailed distribution of study parameters is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDistribution of Study Parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRBH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBelow 2 mm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBetween 2 mm and 4 mm (inclusive of 2 mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e37,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbove 4 mm (inclusive of 4 mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44,2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e140\u003c/p\u003e \u003cp\u003e77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e64.5\u003c/p\u003e \u003cp\u003e35.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40,6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e129\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59,4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFailure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e198\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime of failure (n\u0026thinsp;=\u0026thinsp;19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAfter loading (AL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47,4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBefore loading (BL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52,6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e199\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eDuring the follow-up period, 19 implants (8.8%) failed. Of these, 10 (52.6%) occurred during re-entry for healing abutment placement, and 9 (47.4%) occurred after definitive prosthetic restoration. Clinical characteristics and management of failed implants are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical Characteristics and Post-failure Management of Failed Implants Following Lateral Sinus Floor Elevation.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDate of operation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRBH (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFailure\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eManagement \u0026amp; Outcome\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFebruary/2015\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.9\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSimultaneous reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 11 years follow-up\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeptember/2013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(109 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate autogenous bone grafting\u003c/p\u003e \u003cp\u003eReimplantation after 4 months\u003c/p\u003e \u003cp\u003eUneventful at 3 years follow-up.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarch/2015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(74 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation with simultaneous autogenous bone grafting Uneventful at 5 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFebruary/2016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSimultaneous reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 9 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarch/2013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSimultaneous reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 11 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJuly/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSimultaneous reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 10 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarch/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(75 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 5 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarch/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(98 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate autogenous bone grafting\u003c/p\u003e \u003cp\u003eReimplantation after 4 months\u003c/p\u003e \u003cp\u003eUneventful at 2 years follow-up.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeptember/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(21 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation with simultaneous autogenous bone grafting Uneventful at 9 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAugust/2016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(59 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate autogenous bone grafting/Reimplantation at 4 months post regrafting/Uneventful at 4 years follow-up.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAugust/2016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate implantation\u003c/p\u003e \u003cp\u003eFailed 72 months after reimplantation\u003c/p\u003e \u003cp\u003eImmediate autogenous bone grafting\u003c/p\u003e \u003cp\u003eReimplantation after 4 months\u003c/p\u003e \u003cp\u003eUneventful at 4 years follow-up.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eApril/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(51 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation with simultaneous autogenous bone grafting Uneventful at 7 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeptember/2015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 9 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMarch/2016\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 9 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJuly/2013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e+\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 11 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJuly/2015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate autogenous bone grafting\u003c/p\u003e \u003cp\u003eReimplantation after 4 months\u003c/p\u003e \u003cp\u003eUneventful at 9 years follow-up.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eJune/2015\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 9 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eApril/2013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(14 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 10 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e19.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSeptember/2014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAL\u003c/p\u003e \u003cp\u003e(17 m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eImmediate reimplantation\u003c/p\u003e \u003cp\u003eUneventful at 8 years follow-up\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eRBH, residual bone height; BL, early (before loading) failure; AL, late (after loading) failure; m, months.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eImplant failure was observed in 6 cases (15.4%) in the RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm group, 6 cases (7.3%) in the 2\u0026thinsp;\u0026le;\u0026thinsp;RBH\u0026thinsp;\u0026lt;\u0026thinsp;4 mm group, and 7 cases (7.3%) in the RBH\u0026thinsp;\u0026ge;\u0026thinsp;4 mm group. Although the failure rate in the \u0026lt;\u0026thinsp;2 mm group was approximately twofold higher, no statistically significant association was found between RBH category and implant failure (Pearson chi-square, χ\u0026sup2; = 2.615, p\u0026thinsp;=\u0026thinsp;0.270; Fisher\u0026ndash;Freeman\u0026ndash;Halton exact test, p\u0026thinsp;=\u0026thinsp;0.324).\u003c/p\u003e \u003cp\u003eWhen RBH was analyzed as a continuous variable, a significant association emerged in multivariable logistic regression. Each 1-mm increase in RBH was associated with a reduced odds of implant failure (OR\u0026thinsp;=\u0026thinsp;0.62, 95% CI: 0.38\u0026ndash;0.99, p\u0026thinsp;=\u0026thinsp;0.045). These findings are detailed in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRelationship of RBH, Smoking, and Perforation with Implant Failure\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRBH (categorical)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFailure n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo Failure n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eEffect Estimate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;2 mm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (15.4%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33 (84.6%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u0026ndash;\u0026lt;4 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (7.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e76 (92.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;4 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (7.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e89 (92.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.270\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRBH (continuous)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eper 1 mm increase\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u0026thinsp;=\u0026thinsp;0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.38\u0026ndash;0.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.045\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (12.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80 (87.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u0026thinsp;=\u0026thinsp;2.995\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.874\u0026ndash;10.268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.081\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (6.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e118 (93.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eaHR\u0026thinsp;=\u0026thinsp;2.761\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.968\u0026ndash;7.878\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.058\u0026sect;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePerforation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (44.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10 (55.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u0026thinsp;=\u0026thinsp;19.240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.540\u0026ndash;66.820\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (5.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e188 (94.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eper year\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u0026thinsp;=\u0026thinsp;1.033\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.981\u0026ndash;1.087\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.213\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eaHR\u0026thinsp;=\u0026thinsp;1.028\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.983\u0026ndash;1.075\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.223\u0026sect;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u0026thinsp;=\u0026thinsp;2.189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.619\u0026ndash;7.745\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.224\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eaHR\u0026thinsp;=\u0026thinsp;1.753\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.601\u0026ndash;5.109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.304\u0026sect;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u0026dagger; Pearson chi-square or Fisher\u0026ndash;Freeman\u0026ndash;Halton exact test\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u0026Dagger; Multivariable logistic regression analysis\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u0026sect; Multivariable Cox proportional hazards regression analysis\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eRef: reference category\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eKaplan\u0026ndash;Meier analysis showed no significant differences in implant survival among RBH groups across the entire follow-up period (log-rank test, χ\u0026sup2; = 2.71, p\u0026thinsp;=\u0026thinsp;0.258) (Fig.\u0026nbsp;1). Survival estimates for each RBH group are presented in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and log-rank test results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eKaplan\u0026ndash;Meier Survival Estimates by RBH Group\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRBH Group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEvents\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1-year survival (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5-year survival (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10-year survival (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;2 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e89.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e84.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e84.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u0026ndash;\u0026lt;4 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e93.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e92.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;4 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e95.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e95.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e92.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eKaplan\u0026ndash;Meier survival estimates were calculated based on time-to-event analysis.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLog-rank Test Results for Implant Survival\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComparison\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eχ\u0026sup2;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003edf\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRBH groups (\u0026lt;\u0026thinsp;2, \u0026ge;\u0026thinsp;2\u0026thinsp;\u0026lt;\u0026thinsp;4, \u0026ge;\u0026thinsp;4 mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.258\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePerforation (Yes vs No)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026mdash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eLog-rank test was used to compare survival distributions. χ\u0026sup2; value for perforation not shown due to extreme separation driven by early failures.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eConsistently, Cox proportional hazards analysis demonstrated no significant association between RBH category and implant failure. Compared with the RBH\u0026thinsp;\u0026ge;\u0026thinsp;4 mm group, the hazard ratio was 1.03 (95% CI: 0.35\u0026ndash;3.07, p\u0026thinsp;=\u0026thinsp;0.956) for the 2\u0026thinsp;\u0026le;\u0026thinsp;RBH\u0026thinsp;\u0026lt;\u0026thinsp;4 mm group and 2.22 (95% CI: 0.75\u0026ndash;6.61, p\u0026thinsp;=\u0026thinsp;0.152) for the RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm group. Multivariable Cox regression results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMultivariable Cox Proportional Hazards Analysis\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRBH 2\u0026ndash;\u0026lt;4 mm vs\u0026thinsp;\u0026ge;\u0026thinsp;4 mm\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHazard Ratio (HR)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.35\u0026ndash;3.07\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.956\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm vs\u0026thinsp;\u0026ge;\u0026thinsp;4 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.75\u0026ndash;6.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.152\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking (Yes vs No)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.97\u0026ndash;7.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (per year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.98\u0026ndash;1.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.223\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (Female vs Male)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.60\u0026ndash;5.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.304\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eCox model adjusted for smoking, age, and sex.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTime-stratified analysis revealed that the effect of RBH was more pronounced in the early phase (\u0026le;\u0026thinsp;12 months), although not statistically significant (unadjusted HR\u0026thinsp;=\u0026thinsp;0.669, p\u0026thinsp;=\u0026thinsp;0.172; adjusted HR\u0026thinsp;=\u0026thinsp;0.664, p\u0026thinsp;=\u0026thinsp;0.207). In the late phase (\u0026gt;\u0026thinsp;12 months), no meaningful association was observed (unadjusted HR\u0026thinsp;=\u0026thinsp;0.753, p\u0026thinsp;=\u0026thinsp;0.355; adjusted HR\u0026thinsp;=\u0026thinsp;0.747, p\u0026thinsp;=\u0026thinsp;0.387). These results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTime-stratified analysis of the effects of residual bone height (RBH) and sinus membrane perforation on implant survival.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eRBH (per 1 mm increase)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePhase\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModel / Comparison\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEffect Estimate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e95% CI\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEarly (\u0026le;\u0026thinsp;12 months)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (unadjusted)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;0.669\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.375\u0026ndash;1.192\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.172\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (adjusted)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;0.664\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.351\u0026ndash;1.256\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.207\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLate (\u0026gt;\u0026thinsp;12 months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (unadjusted)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;0.753\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.413\u0026ndash;1.372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.355\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (adjusted)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;0.747\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.386\u0026ndash;1.446\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.387\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMembrane perforation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEarly (\u0026le;\u0026thinsp;12 months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFailure rate comparison\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38.9% (7/18) vs 1.5% (3/199)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLate (\u0026gt;\u0026thinsp;12 months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFailure rate comparison\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.1% (1/11) vs 4.1% (8/196)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.394\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLate (\u0026gt;\u0026thinsp;12 months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (unadjusted)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;2.231\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.279\u0026ndash;17.854\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.450\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCox (adjusted)*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHR\u0026thinsp;=\u0026thinsp;2.226\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.272\u0026ndash;18.246\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.456\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTemporal comparison\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEarly vs Late\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHomogeneity test\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.021\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e*Adjusted for smoking, age, and sex.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u0026dagger; p-values derived from Fisher\u0026rsquo;s exact test or homogeneity test.\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviations: HR, hazard ratio; CI, confidence interval.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eOverall, RBH was not identified as a statistically significant predictor of implant survival when analyzed categorically, despite a trend toward higher early failure rates in sites with RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm.\u003c/p\u003e \u003cp\u003eSinus membrane perforation occurred in 18 cases (8.2%). Perforation rates were comparable across RBH groups: 5.1% (2/39) in the RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm group, 9.8% (8/82) in the 2\u0026thinsp;\u0026le;\u0026thinsp;RBH\u0026thinsp;\u0026lt;\u0026thinsp;4 mm group, and 8.3% (8/96) in the RBH\u0026thinsp;\u0026ge;\u0026thinsp;4 mm group, with no statistically significant difference (Pearson chi-square, p\u0026thinsp;=\u0026thinsp;0.689). No linear trend was observed across ordered RBH categories (Cochran\u0026ndash;Armitage trend test, p\u0026thinsp;=\u0026thinsp;0.674).\u003c/p\u003e \u003cp\u003eImplant failure occurred in 44.4% (8/18) of perforated cases compared with 5.5% (11/199) in non-perforated cases. In multivariable logistic regression analysis, sinus membrane perforation was identified as a strong independent predictor of implant failure (OR\u0026thinsp;=\u0026thinsp;19.240, 95% CI: 5.540\u0026ndash;66.820, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.)\u003c/p\u003e \u003cp\u003eKaplan\u0026ndash;Meier survival analysis demonstrated significantly reduced implant survival in cases with sinus membrane perforation compared to non-perforated cases (log-rank test, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Fig.\u0026nbsp;2). Corresponding log-rank test results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eTime-stratified analysis showed that this effect was predominantly driven by early failures. In the early phase (\u0026le;\u0026thinsp;12 months), implant loss occurred in 38.9% (7/18) of perforated cases, compared with 1.5% (3/199) in non-perforated cases (Fisher\u0026rsquo;s exact test, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In contrast, among implants surviving beyond 12 months, implant faiure rates were similar between groups (9.1% vs. 4.1%, p\u0026thinsp;=\u0026thinsp;0.394). Consistently, perforation was not significantly associated with implant faiure in late-phase Cox regression analysis (HR\u0026thinsp;=\u0026thinsp;2.231, 95% CI: 0.279\u0026ndash;17.854, p\u0026thinsp;=\u0026thinsp;0.450), including after adjustment for smoking, age, and sex (adjusted HR\u0026thinsp;=\u0026thinsp;2.226, 95% CI: 0.272\u0026ndash;18.246, p\u0026thinsp;=\u0026thinsp;0.456). These findings are detailed in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e .\u003c/p\u003e \u003cp\u003eSmoking was associated with a higher numerical risk of implant failure, although this did not reach statistical significance in multivariable Cox regression (aHR\u0026thinsp;=\u0026thinsp;2.761, 95% CI: 0.968\u0026ndash;7.878, p\u0026thinsp;=\u0026thinsp;0.058) or logistic regression (OR\u0026thinsp;=\u0026thinsp;2.995, 95% CI: 0.874\u0026ndash;10.268, p\u0026thinsp;=\u0026thinsp;0.081).\u003c/p\u003e \u003cp\u003eAge and sex were not significantly associated with implant loss. Age showed no significant effect in Cox regression (aHR\u0026thinsp;=\u0026thinsp;1.028 per year, p\u0026thinsp;=\u0026thinsp;0.223) or logistic regression (OR\u0026thinsp;=\u0026thinsp;1.033 per year, p\u0026thinsp;=\u0026thinsp;0.213). Although female patients demonstrated a higher numerical risk, this difference was not statistically significant in either Cox (p\u0026thinsp;=\u0026thinsp;0.304) or logistic regression (p\u0026thinsp;=\u0026thinsp;0.224) analyses. (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe present study provides important insights into the role of residual bone height (RBH) in implant survival following lateral sinus floor elevation. When RBH was analyzed categorically, no statistically significant association with implant failure was observed, although a higher numerical failure rate was evident in sites with RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm. However, when RBH was entered into the model as a continuous variable, a significant inverse relationship emerged, indicating that decreasing RBH is associated with a progressively increasing risk of implant failure. From the opposite perspective, with each 1-mm increase in RBH reducing the odds of implant failure.\u003c/p\u003e \u003cp\u003eThis finding suggests that the effect of RBH is better understood as a dose\u0026ndash;response relationship rather than a threshold-dependent phenomenon. Each incremental reduction in bone height contributes to increased risk, but this effect may not be detectable when RBH is arbitrarily divided into discrete categories. Similar methodological concerns have been highlighted in statistical literature, where dichotomization or categorization of continuous variables has been shown to reduce statistical power and obscure clinically relevant associations.\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe discrepancy between categorical and continuous analyses may also help explain the inconsistencies observed in previous studies. Some authors have reported that severely reduced RBH is associated with increased implant failure\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e However, more recent randomized and controlled studies have reported no significant association between RBH and implant survival, suggesting that this relationship may be mitigated by surgical technique and appropriate case selection.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e The present findings suggest that these conflicting results may be partly attributable to differences in analytical approaches, particularly the use of threshold-based versus continuous modeling.\u003c/p\u003e \u003cp\u003eHistorically, a residual bone height threshold of approximately 2\u0026ndash;3 mm has been proposed as a critical determinant of implant success following sinus augmentation.\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e However, the present results challenge this concept by demonstrating that although lower RBH is associated with increased failure risk, this relationship does not appear to follow a sharp cutoff. Instead, risk appears to increase gradually as RBH decreases, supporting a more continuous biological model.\u003c/p\u003e \u003cp\u003eRecent clinical studies have similarly demonstrated that high implant survival rates can be achieved even in sites with minimal residual bone when appropriate surgical protocols are applied.\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e Furthermore, contemporary analyses suggest that RBH may influence surgical complexity and complication risk rather than directly determining implant survival.\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eTaken together, these findings indicate that RBH should not be interpreted as a rigid decision-making threshold, but rather as a continuous anatomical parameter that modulates risk.\u003c/p\u003e \u003cp\u003eThe time-stratified analysis provides additional insight into the role of residual bone height in implant survival. Although RBH demonstrated a numerically stronger effect during the early healing phase, this difference was not statistically significant, and interaction analysis confirmed that the influence of RBH did not significantly change over time.\u003c/p\u003e \u003cp\u003eThese findings suggest that while reduced RBH may contribute to early mechanical challenges\u0026mdash;such as limited primary stability\u0026mdash;the overall effect of RBH on implant survival remains relatively modest when evaluated across the entire follow-up period. The absence of a significant temporal interaction further indicates that RBH does not exert a distinct phase-specific effect, but rather functions as a consistent, low-to-moderate risk modifier.\u003c/p\u003e \u003cp\u003eImportantly, these results complement the continuous-variable analysis presented in this study. While RBH demonstrated a significant dose\u0026ndash;response relationship when modeled continuously, the time-stratified analysis indicates that this effect is not confined to a specific postoperative phase, and does not differ significantly between early and late periods. This supports the interpretation that RBH influences implant outcomes in a gradual and continuous manner, rather than through a time-dependent or threshold-driven mechanism.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, these findings reinforce the concept that although low RBH may increase technical difficulty and early risk, long-term implant survival appears to be more strongly influenced by surgical factors and complication control, particularly sinus membrane integrity. This further supports the conclusion that RBH should be considered within a broader, multifactorial risk assessment framework rather than as an isolated determinant of implant prognosis.\u003c/p\u003e \u003cp\u003eSeveral recent studies and meta-analyses have demonstrated that reduced residual bone height is associated with an increased risk of sinus membrane perforation, particularly in cases with RBH below 3\u0026ndash;4 mm.\u003csup\u003e23,24\u003c/sup\u003e An important observation in the present study is that RBH was not associated with sinus membrane perforation, suggesting that reduced bone height does not inherently predispose to this complication. This finding contrasts with those indicating an increased risk of perforation in cases with reduced RBH but aligns with studies emphasizing that perforation is more strongly related to membrane characteristics and surgical technique.\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eA key finding of this study is the strong and statistically significant association between sinus membrane perforation and implant failure. Implants placed in perforated sites exhibited markedly higher failure rates compared to non-perforated cases, underscoring the critical importance of membrane integrity.\u003c/p\u003e \u003cp\u003eThis observation is consistent with studies identifying perforation as a major complication affecting graft stability and osseointegration.\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e In contrast, other reports have suggested that properly managed perforations do not significantly compromise outcomes.\u003csup\u003e\u003cspan additionalcitationids=\"CR28\" citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e The discrepancy likely reflects differences in perforation size, repair techniques, and surgical protocols.\u003c/p\u003e \u003cp\u003eImportantly, while RBH did not independently predict implant failure in categorical analyses, sinus membrane perforation demonstrated a strong and clinically significant association with failure, indicating that surgical factors may have a greater impact on outcomes than baseline anatomical conditions. Furthermore, the absence of an association between RBH and perforation in this study supports the notion that perforation is more strongly related to operator technique and intraoperative handling than to residual bone height itself.\u003c/p\u003e \u003cp\u003eThe time-stratified analysis demonstrated that the effect of sinus membrane perforation on implant survival is strongly phase-dependent. Perforation was associated with a marked increase in implant loss during the early healing period, whereas its effect was not statistically significant in the late phase among implants that had successfully passed the initial healing stage.\u003c/p\u003e \u003cp\u003eThis temporal pattern is biologically plausible. In the early postoperative period, sinus membrane perforation may compromise graft containment, disrupt stabilization of the augmented compartment, and impair early osseointegration. In particular, loss of membrane integrity may lead to graft displacement, impaired vascularization, and bacterial contamination, thereby increasing the risk of early implant failure.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e Furthermore, recent evidence has identified surgical and anatomical factors related to sinus augmentation, particularly those affecting membrane integrity, as key determinants of early implant failure, supporting the role of membrane perforation as a critical early risk factor.\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eBy contrast, once successful osseointegration has been established, the long-term impact of a prior perforation appears to diminish. Systematic and clinical studies have reported that implant survival rates may remain comparable between perforated and non-perforated cases when perforations are adequately managed intraoperatively.\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e This suggests that the biological consequences of perforation are primarily relevant during the early healing phase, and that their long-term influence may be mitigated following successful integration.\u003c/p\u003e \u003cp\u003eThese findings help explain the discrepancy between studies reporting no overall effect of perforation and those identifying it as a significant risk factor. The present data indicate that the impact of perforation is not constant over time but is instead concentrated in the early postoperative period, with limited influence on late implant survival.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, this underscores that the primary consequence of sinus membrane perforation lies in its effect on early implant prognosis. Therefore, meticulous surgical technique, early detection of membrane tears, and appropriate repair strategies are critical to minimizing early implant loss, even if long-term outcomes may ultimately converge once initial healing has been successfully achieved.\u003c/p\u003e \u003cp\u003eSmoking showed a higher implant failure rate compared to non-smokers; however, this association did not reach statistical significance. This contrasts with studies reporting smoking as a significant risk factor for implant failure.\u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e Some studies did not observe a significant effect of smoking on implant failure aligning with our findings.\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e The lack of significance in the present study may be related to sample size limitations or variability in smoking intensity and duration.\u003c/p\u003e \u003cp\u003eIn contrast, age and sex were not associated with implant failure, indicating that demographic factors may play a limited role in determining outcomes following LSFE. This is consistent with current evidence suggesting that implant survival is largely independent of patient age and sex, provided that systemic conditions are controlled, and that local surgical factors are more decisive.\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e,\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, the present results suggest that: RBH alone should not be considered a contraindication for implant placement although extremely low RBH (\u0026lt;\u0026thinsp;2 mm) may still represent a higher-risk scenario. Implant failure risk increases progressively rather than abruptly below a specific threshold, therefore, surgical factors, particularly membrane integrity, play a dominant role\u003c/p\u003e \u003cp\u003eThese findings support a shift from rigid threshold-based decision-making toward a continuous risk assessment model, in which RBH is interpreted in conjunction with surgical and patient-related factors to better predict long-term outcomes.\u003c/p\u003e \u003cp\u003eRecent long-term and multicenter studies have further highlighted the multifactorial nature of implant survival following sinus augmentation. For instance, Bonsmann et al.\u003csup\u003e31\u003c/sup\u003e reported a dose-dependent relationship between reduced RBH and early implant failure, supporting the concept of a continuous risk gradient.\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e Similarly, systematic reviews have emphasized that implant outcomes are influenced by a combination of anatomical, surgical, and biological factors rather than a single parameter.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e,\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eThe present study contributes to this evolving perspective by demonstrating that the clinical relevance of RBH on long term success depends strongly on how it is analyzed, and that continuous modeling may reveal associations that are not apparent in categorical analyses.\u003c/p\u003e \u003cp\u003eThis study has several limitations that should be considered when interpreting the findings. Although multivariable analyses were performed, unmeasured factors such as bone quality, the length and the diameter of the implant, insertion torque, and prosthetic loading protocols may have influenced implant survival.\u003c/p\u003e \u003cp\u003eThe number of implant failure events was relatively low, which may have limited statistical power, particularly for detecting moderate associations and for subgroup analyses. This may partly explain why certain variables, such as smoking, demonstrated trends without reaching statistical significance.\u003c/p\u003e \u003cp\u003eResidual bone height (RBH) was initially analyzed using categorical groupings, which may have resulted in loss of information and reduced sensitivity to detect associations. Although this limitation was partially addressed by additional continuous-variable modeling, the discrepancy between categorical and continuous analyses highlights the challenges associated with variable classification.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eResidual bone height (RBH) was not associated with implant failure when analyzed using conventional categorical thresholds; however, continuous-variable modeling revealed a significant dose\u0026ndash;response relationship, indicating that decreasing RBH is associated with a progressively increased risk of implant loss. These findings suggest that RBH should be interpreted as a continuous risk modifier rather than a strict clinical cutoff.\u003c/p\u003e \u003cp\u003eSinus membrane perforation emerged as the most critical determinant of implant failure, with a pronounced effect during the early healing phase. Its impact diminished over time among successfully integrated implants, indicating that the adverse influence of perforation is primarily confined to the initial postoperative period.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, these results support a shift away from threshold-based decision-making toward a more comprehensive, risk-based approach. While low RBH may increase technical complexity, implant survival appears to be predominantly influenced by surgical factors\u0026mdash;particularly membrane integrity and complication management\u0026mdash;rather than baseline anatomical limitations alone.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Istanbul Aydın University (Approval No: 2023\u0026thinsp;\u0026minus;\u0026thinsp;135). All procedures were performed in accordance with relevant guidelines and regulations. Due to the retrospective nature of the study and anonymization of patient data, formal informed consent was not required.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors received no financial support for the research, authorship, and/or publication of this article.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eKD was the attending surgeon and performed all surgical procedures and contributed to conceptualization, supervision, statistical analysis, and writing\u0026mdash;original draft preparation.ABG contributed to writing\u0026mdash;original draft preparation, investigation, data curation, data processing. SDD served as the second attending surgeon, assisted in all surgical procedures, and contributed to investigation, patients' follow-ups, data processing, and conceptualization.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003e The authors would like to thank the clinical and administrative staff of the Department of Oral and Maxillofacial Surgery at Istanbul Aydın University for their support in patient management and data archiving. The authors also acknowledge all patients who participated in this study and contributed to the long-term follow-up data.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eJohansson LA, Isaksson S, Lindh C, Becktor JP, Sennerby L. Maxillary sinus floor augmentation and simultaneous implant placement using locally harvested autogenous bone chips and bone debris: a prospective clinical study. J Oral Maxillofac Surg. 2010;68(4):837\u0026ndash;44.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLambert F, Lecloux G, Rompen E. One-step approach for implant placement and subantral bone regeneration using bovine hydroxyapatite: a 2- to 6-year follow-up study. Int J Oral Maxillofac Implants. 2010;25(3):598\u0026ndash;606.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBhalla N, Dym H. Update on Maxillary Sinus Augmentation. Dent Clin North Am. 2021;65(1):197\u0026ndash;210.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaldi D, Menini M, Pera F, Ravera G, Pera P. Sinus floor elevation using osteotomes or piezoelectric surgery. Int J Oral Maxillofac Surg. 2011;40(5):497\u0026ndash;503.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee D, Kim J, Kim H, et al. Clinical outcomes of maxillary sinus augmentation in atrophied posterior maxilla based on residual bone height. Maxillofac Plast Reconstr Surg. 2025;47(1):26.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGonzalez S, Tuan MC, Ahn KM, Nowzari H. Crestal approach for maxillary sinus augmentation in patients with = 4 mm of residual alveolar bone\u0026lt;/at. Clin Implant Dent Relat Res. 2014;16(6):827\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQin L, Lin SX, Guo ZZ, et al. Influences of Schneiderian membrane conditions on the early outcomes of osteotome sinus floor elevation technique: a prospective cohort study in the healing period. Clin Oral Implants Res. 2017;28(9):1074\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePjetursson BE, Tan WC, Zwahlen M, Lang NP. A systematic review of the success of sinus floor elevation and survival of implants inserted in combination with sinus floor elevation. J Clin Periodontol. 2008;35(8 Suppl):216\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosen PS, Summers R, Mellado JR, et al. The bone-added osteotome sinus floor elevation technique: multicenter retrospective report of consecutively treated patients. Int J Oral Maxillofac Implants. 1999;14(6):853\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Z, Zhang J, Li N, Pu R, Wang Y, Yang G. Survival analysis of implants placed simultaneously with lateral sinus floor elevation in severely atrophic maxilla: A 3- to 12-year retrospective cohort study. Clin Implant Dent Relat Res. 2023;25(6):1069\u0026ndash;79.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChao YL, Chen HH, Mei CC, Tu YK, Lu HK. Meta-regression analysis of the initial bone height for predicting implant survival rates of two sinus elevation procedures. J Clin Periodontol. 2010;37(5):456\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark WB, Kang KL, Han JY. Factors influencing long-term survival rates of implants placed simultaneously with lateral maxillary sinus floor augmentation: A 6- to 20-year retrospective study. Clin Oral Implants Res. 2019;30(10):977\u0026ndash;88.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeleg M, Garg AK, Mazor Z. Predictability of simultaneous implant placement in the severely atrophic posterior maxilla: A 9-year longitudinal experience study of 2132 implants placed into 731 human sinus grafts. Int J Oral Maxillofac Implants. 2006;21(1):94\u0026ndash;102.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFelice P, Pistilli R, Piattelli M, Soardi E, Barausse C, Esposito M. 1-stage versus 2-stage lateral sinus lift procedures: 1-year post-loading results of a multicentre randomised controlled trial. Eur J Oral Implantol. 2014;7(1):65\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFenner M, Vairaktaris E, Fischer K, Schlegel KA, Neukam FW, Nkenke E. Influence of residual alveolar bone height on osseointegration of implants in the maxilla: a pilot study. Clin Oral Implants Res. 2009;20(6):555\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoyston P, Altman DG, Sauerbrei W. Dichotomizing continuous predictors in multiple regression: a bad idea. Stat Med. 2006;25(1):127\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim HJ, Yea S, Kim KH, et al. A retrospective study of implants placed following 1-stage or 2-stage maxillary sinus floor augmentation by the lateral window technique performed on residual bone of \u0026lt;\u0026thinsp;4 mm: Results up to 10 years of follow-up. J Periodontol. 2020;91(2):183\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAvila-Ortiz G, Neiva R, Galindo-Moreno P, Rudek I, Benavides E, Wang HL. Analysis of the influence of residual alveolar bone height on sinus augmentation outcomes. Clin Oral Implants Res. 2012;23(9):1082\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCorbella S, Taschieri S, Del Fabbro M. Long-term outcomes for the treatment of atrophic posterior maxilla: a systematic review of literature. Clin Implant Dent Relat Res. 2015;17(1):120\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJensen OT, Shulman LB, Block MS, Iacono VJ. Report of the Sinus Consensus Conference of 1996. \u003cem\u003eInt J Oral Maxillofac Implants.\u003c/em\u003e 1998;13 Suppl:11\u0026ndash;45.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWallace SS, Froum SJ. Effect of maxillary sinus augmentation on the survival of endosseous dental implants. A systematic review. Ann Periodontol. 2003;8(1):328\u0026ndash;43.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLyu M, Xu D, Zhang X, Yuan Q. Maxillary sinus floor augmentation: a review of current evidence on anatomical factors and a decision tree. Int J Oral Sci. 2023;15(1):41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTukel HC, Tatli U. Risk factors and clinical outcomes of sinus membrane perforation during lateral window sinus lifting: analysis of 120 patients. Int J Oral Maxillofac Surg. 2018;47(9):1189\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe M, Lin X, Liu W, Calatrava J, Huang W, Wang HL. Residual ridge height as a potential risk factor for membrane perforation during lateral-window sinus elevation surgery: a systematic review and meta-analysis. BMC Oral Health. 2025;25(1):1522.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin YH, Yang YC, Wen SC, Wang HL. The influence of sinus membrane thickness upon membrane perforation during lateral window sinus augmentation. Clin Oral Implants Res. 2016;27(5):612\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStacchi C, Andolsek F, Berton F, Perinetti G, Navarra CO, Di Lenarda R. Intraoperative Complications During Sinus Floor Elevation with Lateral Approach: A Systematic Review. Int J Oral Maxillofac Implants. 2017;32(3):e107\u0026ndash;18.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCha HS, Kim A, Nowzari H, Chang HS, Ahn KM. Simultaneous sinus lift and implant installation: prospective study of consecutive two hundred seventeen sinus lift and four hundred sixty-two implants. Clin Implant Dent Relat Res. 2014;16(3):337\u0026ndash;47.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSakkas A, Konstantinidis I, Winter K, Schramm A, Wilde F. Effect of Schneiderian membrane perforation on sinus lift graft outcome using two different donor sites: a retrospective study of 105 maxillary sinus elevation procedures. GMS Interdiscip Plast Reconstr Surg DGPW. 2016;5:Doc11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Ma S, Lin L, Yao Q. Association between smoking and Schneiderian membrane perforation during maxillary sinus floor augmentation: A systematic review and meta-analysis. Clin Implant Dent Relat Res. 2023;25(1):166\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSala YM, Lu H, Chrcanovic BR. Clinical Outcomes of Maxillary Sinus Floor Perforation by Dental Implants and Sinus Membrane Perforation during Sinus Augmentation: A Systematic Review and Meta-Analysis. J Clin Med 2024;13(5).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBonsmann B, Abughalia M, von See C, Dietrich T. Risk Factors for Early Implant Failure Following Sinus Augmentation: A Multi-Centre Nested Case-Control Study. J Clin Periodontol. 2025;52(9):1306\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchiavo-Di Flaviano V, Egido-Moreno S, Gonzalez-Navarro B, Velasco-Ortega E, Lopez-Lopez J, Monsalve-Guil L. Influence of Schneiderian Membrane Perforation on Implant Survival Rate: Systematic Review and Meta-Analysis. J Clin Med 2024;13(13).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBarbato L, Baldi N, Gonnelli A, Duvina M, Nieri M, Tonelli P. Association of Smoking Habits and Height of Residual Bone on Implant Survival and Success Rate in Lateral Sinus Lift: A Retrospective Study. J Oral Implantol. 2018;44(6):432\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEsposito M, Felice P, Worthington HV. Interventions for replacing missing teeth: augmentation procedures of the maxillary sinus. Cochrane Database Syst Rev. 2014;2014(5):CD008397.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoboeva O, Kwon TG, Kim JW, Lee ST, Choi SY. Comparing factors affecting dental-implant loss between age groups: A retrospective cohort study. Clin Implant Dent Relat Res. 2021;23(2):208\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark WB, Han JY, Kang KL. Long-Term Comparison of Survival and Marginal Bone of Implants with and without Sinus Augmentation in Maxillary Molars within the Same Patients: A 5.8- to 22-Year Retrospective Study. J Clin Med 2021;10(7).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDel Fabbro M, Corbella S, Weinstein T, Ceresoli V, Taschieri S. Implant survival rates after osteotome-mediated maxillary sinus augmentation: a systematic review. Clin Implant Dent Relat Res. 2012;14(Suppl 1):e159\u0026ndash;168.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Residual bone height, sinus floor elevation, dental implants, membrane perforation, implant survival, risk factors","lastPublishedDoi":"10.21203/rs.3.rs-9361228/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9361228/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives:\u003c/h2\u003e \u003cp\u003eTo evaluate the effect of residual bone height (RBH) on implant survival following lateral sinus floor elevation (LSFE), and to assess the influence of sinus membrane perforation and patient-related factors.\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eA total of 217 implants placed after LSFE were retrospectively analyzed. RBH was assessed both categorically (RBH\u0026thinsp;\u0026lt;\u0026thinsp;2 mm, 2\u0026thinsp;\u0026le;\u0026thinsp;RBH\u0026thinsp;\u0026lt;\u0026thinsp;4 mm, RBH\u0026thinsp;\u0026ge;\u0026thinsp;4 mm) and as a continuous variable. Implant failure was the primary outcome. Associations were evaluated using chi-square tests, Kaplan\u0026ndash;Meier survival analysis with log-rank testing, and Cox proportional hazards regression. Multivariable logistic regression was used to identify independent predictors, including sinus membrane perforation, smoking, age, and sex.\u003c/p\u003e\u003ch2\u003eResults:\u003c/h2\u003e \u003cp\u003eThe overall implant failure rate was 8.8% (19/217). RBH was not significantly associated with implant loss when analyzed categorically (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), and no significant differences in survival were observed among RBH groups (log-rank p\u0026thinsp;=\u0026thinsp;0.258). However, when analyzed as a continuous variable, RBH showed a significant inverse association with implant failure, with each 1-mm increase reducing the odds of failure (OR\u0026thinsp;=\u0026thinsp;0.62, 95% CI: 0.38\u0026ndash;0.99, p\u0026thinsp;=\u0026thinsp;0.045). Sinus membrane perforation was strongly associated with implant loss, with failure rates of 44.4% in perforated cases versus 5.5% in non-perforated cases (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Smoking showed a non-significant trend toward increased risk, while age and sex were not significantly associated with implant failure.\u003c/p\u003e\u003ch2\u003eConclusions:\u003c/h2\u003e \u003cp\u003eRBH does not appear to be a significant predictor of implant loss when categorized; however, continuous analysis suggests a dose\u0026ndash;response relationship, indicating that decreasing RBH progressively increases failure risk. Sinus membrane perforation emerged as the strongest determinant of implant failure, highlighting the critical importance of surgical technique in LSFE procedures.\u003c/p\u003e","manuscriptTitle":"Residual Bone Height and Implant Survival After Lateral Sinus Floor Elevation: A Continuous-Variable Analysis With 13-Year Follow-up","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-14 16:11:12","doi":"10.21203/rs.3.rs-9361228/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-19T01:41:01+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-16T03:46:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323300885725864433072965973746407533619","date":"2026-05-15T20:14:39+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T18:52:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"102529288786478055231140594630410421373","date":"2026-05-15T08:08:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"168290101156623406325831289634438938920","date":"2026-05-13T23:01:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"281048273437668757600088855340788683979","date":"2026-05-10T20:59:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"63112971509483813893844937263590677239","date":"2026-05-08T06:57:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"320750166865255727440338472401330958541","date":"2026-05-08T06:29:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"212120634275221593930633824784490659858","date":"2026-05-06T06:48:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-05-06T06:30:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-04T11:32:23+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-13T09:48:54+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-12T11:32:26+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2026-04-12T11:27:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2fb300e0-db12-407f-a01f-db9a217b9e90","owner":[],"postedDate":"May 14th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-19T01:41:01+00:00","index":70,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-16T03:46:41+00:00","index":67,"fulltext":""},{"type":"reviewerAgreed","content":"323300885725864433072965973746407533619","date":"2026-05-15T20:14:39+00:00","index":66,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-15T18:52:53+00:00","index":65,"fulltext":""},{"type":"reviewerAgreed","content":"102529288786478055231140594630410421373","date":"2026-05-15T08:08:00+00:00","index":63,"fulltext":""},{"type":"reviewerAgreed","content":"168290101156623406325831289634438938920","date":"2026-05-13T23:01:17+00:00","index":62,"fulltext":""},{"type":"reviewerAgreed","content":"281048273437668757600088855340788683979","date":"2026-05-10T20:59:26+00:00","index":46,"fulltext":""},{"type":"reviewerAgreed","content":"63112971509483813893844937263590677239","date":"2026-05-08T06:57:32+00:00","index":44,"fulltext":""},{"type":"reviewerAgreed","content":"320750166865255727440338472401330958541","date":"2026-05-08T06:29:09+00:00","index":43,"fulltext":""},{"type":"reviewerAgreed","content":"212120634275221593930633824784490659858","date":"2026-05-06T06:48:58+00:00","index":41,"fulltext":""},{"type":"reviewersInvited","content":"30","date":"2026-05-06T06:30:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-05-04T11:32:23+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T16:11:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-14 16:11:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9361228","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9361228","identity":"rs-9361228","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}