Anatomical Proximity Between Posterior Maxillary Tooth Roots and Sinus Floor Independently Predicts Mucosal Thickening: A CBCT Study

Anatomical Proximity Between Posterior Maxillary Tooth Roots and Sinus Floor Independently Predicts Mucosal Thickening: A CBCT Study | 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 Anatomical Proximity Between Posterior Maxillary Tooth Roots and Sinus Floor Independently Predicts Mucosal Thickening: A CBCT Study Ali Altındağ, Cemile Nur Yıldırım This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8984640/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objectives This study aimed to investigate the association between anatomical proximity of posterior maxillary tooth roots to the maxillary sinus floor and both the presence and severity of maxillary sinus mucosal thickening (MT) using cone-beam computed tomography (CBCT). Materials and Methods A retrospective CBCT-based analysis was performed on 300 patients (175 females, 125 males; mean age: 27.55 ± 8.74 years). Root–sinus anatomical relationships were classified into three proximity types based on increasing root–sinus closeness. Maxillary sinus mucosal thickness was measured in millimeters, and mucosal thickening was defined using both a binary threshold (> 2 mm vs. ≤2 mm) and an ordinal severity classification (≤ 2 mm, 2–10 mm, > 10 mm). Multivariable binary logistic regression and ordinal logistic regression analyses were conducted to evaluate the independent association between proximity type and mucosal thickening, after adjustment for age, sex, diabetes, cardiovascular disease, and smoking status. Results Mucosal thickening (> 2 mm) was observed in 34.7% of patients on both sides. Proximity type was significantly associated with mucosal thickening on the right and left sides (p < 0.01). In multivariable binary logistic regression, each one-unit increase in proximity type was associated with a 2.58-fold increase in the odds of mucosal thickening on the right side (OR = 2.58; 95% CI: 1.61–4.12; p < 0.001) and a 1.93-fold increase on the left side (OR = 1.93; 95% CI: 1.23–3.03; p = 0.004). Ordinal logistic regression further demonstrated that proximity type was an independent predictor of greater mucosal thickening severity on both sides (right: OR = 2.43; left: OR = 1.90; both p < 0.01). Age showed a modest independent association, whereas systemic factors, including diabetes, cardiovascular disease, and smoking, were not significantly associated with mucosal thickening. Conclusion Anatomical proximity between posterior maxillary tooth roots and the sinus floor is a strong and independent predictor of both the presence and severity of maxillary sinus mucosal thickening. These findings emphasize the clinical importance of evaluating tooth–sinus anatomical relationships in CBCT-based diagnostic assessment and treatment planning in the posterior maxilla. Cone-beam computed tomography Maxillary sinus Molars Mucosal thickening Figures Figure 1 Introduction The maxillary sinus is the largest paranasal sinus and demonstrates close anatomical proximity to the posterior maxillary dentition, resulting in a complex structural and functional relationship between dental and sinonasal tissues [ 1 , 2 ]. The Schneiderian membrane lining the maxillary sinus is a biologically active mucosa that may undergo adaptive or pathological thickening in response to inflammatory, infectious, or mechanical stimuli. Radiographically, maxillary sinus mucosal thickening (MT) represents one of the most frequently observed incidental findings in dental imaging and is widely regarded as an indicator of sinus inflammation or subclinical mucosal response [ 3 , 4 ]. Cone-beam computed tomography (CBCT) has become the preferred imaging modality for evaluating maxillary sinus anatomy in dental practice due to its high spatial resolution and three-dimensional visualization capabilities [ 5 ]. Compared with conventional two-dimensional radiography, CBCT enables precise measurement of mucosal thickness and provides accurate assessment of the anatomical relationship between maxillary posterior tooth roots and the sinus floor [ 6 , 7 ]. This three-dimensional assessment is particularly important for identifying anatomical risk factors that may influence sinus health and treatment outcomes in the posterior maxilla. The reported prevalence of MT in CBCT-based studies ranges from 30% to 60%, even in asymptomatic populations [ 8 – 10 ]. Although a universally accepted pathological threshold has not been established, mucosal thickness exceeding 2–3 mm is commonly considered indicative of abnormal mucosal alteration [ 3 , 8 , 11 , 12 ]. Previous studies have demonstrated significant associations between odontogenic pathologies—such as periapical lesions, periodontal bone loss, and endodontic infections—and MT, supporting the concept of odontogenic influence on sinus mucosal status [ 13 – 15 ]. In addition to overt dental disease, anatomical factors have been proposed as potential contributors to sinus mucosal changes. In particular, the proximity between posterior maxillary tooth roots and the sinus floor may facilitate the transmission of inflammatory mediators or infectious processes into the sinus cavity. However, existing evidence regarding the independent role of anatomical proximity remains inconclusive. Aguori et al. [ 16 ] evaluated healthy posterior teeth and found no significant association between tooth–sinus proximity and MT. In contrast, more recent CBCT studies have demonstrated substantial anatomical variability in root–sinus relationships and have reported frequent root contact with or protrusion into the sinus cavity, especially in molar regions [ 17 – 19 ]. Despite these anatomical observations, most previous studies have focused primarily on descriptive or univariable analyses, and the independent predictive value of anatomical proximity for mucosal thickening—particularly after controlling for potential systemic confounders—remains insufficiently clarified. From a clinical perspective, identifying anatomical predictors of MT may improve risk assessment, diagnostic interpretation, and treatment planning in the posterior maxilla, particularly in implant dentistry, endodontics, and surgical interventions involving the sinus region. A better understanding of whether anatomical proximity independently influences both the occurrence and severity of mucosal thickening may also provide insight into the structural determinants of sinus mucosal response beyond traditional odontogenic or systemic risk factors. Therefore, the aim of the present study was to investigate the association between the anatomical proximity of posterior maxillary tooth roots to the sinus floor and both the presence and severity of maxillary sinus mucosal thickening using CBCT. Methods Study design and sample This retrospective cross-sectional study was conducted using cone-beam computed tomography (CBCT) images obtained from patients who attended the Department of Oral and Maxillofacial Radiology for routine diagnostic purposes. CBCT examinations had been originally performed for various clinical indications, including implant planning, assessment of impacted teeth, and evaluation of dentomaxillofacial structures. The study protocol was approved by the Local Institutional Review Board (Approval No:2024/526 – Approval Date:26.12.2024), and the study was conducted in accordance with the Declaration of Helsinki. Clinical trial number: not applicable. An a priori power analysis was performed using G*Power version 3.1.9.7 (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany) to determine the minimum required sample size. The analysis was based on the chi-square test of independence, which was considered a conservative approximation for the primary association between proximity type and mucosal thickening (>2 mm vs. ≤2 mm). Parameters were defined as follows: medium effect size (w = 0.30), significance level (α = 0.05), statistical power (1−β = 0.95), and degrees of freedom = 2. The analysis indicated that a minimum of 172 subjects was required. The final sample size of 300 patients exceeded this requirement, ensuring adequate statistical power for multivariable regression analyses. A total of 300 patients were included in the study. Inclusion criteria were: (1) availability of high-quality CBCT scans including both maxillary sinuses and posterior maxillary teeth, (2) absence of obvious maxillary sinus pathology such as cysts, tumors, or previous sinus surgery, (3) presence of at least one posterior maxillary tooth adjacent to the maxillary sinus floor. Exclusion criteria included poor image quality, motion artifacts, history of maxillary sinus surgery, and conditions that could obscure accurate evaluation of the sinus mucosa or tooth–sinus relationship. CBCT image acquisition and evaluation All CBCT examinations were performed using a 3D Accuitomo 170 system (J Morita MFG Corp., Kyoto, Japan), operating at 90 kVp and 5 mA with exposure times ranging from 15 to 18 seconds, in accordance with the manufacturer’s recommended imaging protocol. The scans were acquired using a standardized imaging protocol with a voxel size of 0.25 mm and an appropriate field of view to include both maxillary sinuses and posterior maxillary teeth. All images were evaluated using dedicated CBCT viewing software under standardized viewing conditions, including controlled ambient lighting and calibrated display monitors. Multiplanar reconstruction (MPR) images were analyzed in axial, coronal, and sagittal planes to ensure accurate anatomical assessment. The coronal plane was primarily used for evaluating the anatomical relationship between posterior tooth roots and the sinus floor and for measuring mucosal thickness. Assessment of proximity type The anatomical relationship between the roots of posterior maxillary teeth and the maxillary sinus floor was classified into three proximity types based on their spatial relationship [17-19](Figure 1): Type 1: Root apex located below the sinus floor without contact. Type 2: Root apex in direct contact with the sinus floor. Type 3: Root apex protruding into the maxillary sinus cavity. Proximity type was assessed separately for the right and left sides. When multiple posterior teeth were present, the tooth exhibiting the closest anatomical relationship to the sinus floor was used for classification, as this represents the highest potential anatomical risk condition. Measurement of maxillary sinus mucosal thickening Maxillary sinus mucosal thickness was measured as the maximum perpendicular distance from the sinus wall to the mucosal surface at the thickest location. Measurements were recorded in millimeters for both maxillary sinuses. Mucosal thickening was defined based on established radiological thresholds and categorized using both binary and ordinal classification models Primary ordinal classification (main model): Normal: ≤2 mm Moderate: >2–10 mm Severe: >10 mm Alternative ordinal classification (sensitivity analysis): Normal: ≤2 mm Moderate: >2–8 mm Severe: >8 mm For binary analyses, mucosal thickening was dichotomized as ≤2 mm and >2 mm. Observer reliability All measurements were performed independently by two experienced oral and maxillofacial radiologists (CNY and AA), who were blinded to each other’s measurements. To evaluate intra-observer reliability, repeated measurements were performed on a randomly selected subset of CBCT scans after a three-week interval. Intra-class correlation coefficients (ICC) were calculated to assess measurement reproducibility. Inter-observer agreement for proximity classification was evaluated using Cohen’s kappa coefficient. In cases of disagreement, a consensus was reached through joint re-evaluation. Statistical analysis Statistical analyses were performed using SPSS version 21 (SPSS, Chicago, Ill., USA). Descriptive statistics were calculated for demographic variables, proximity types, and mucosal thickening values. The association between proximity type and binary mucosal thickening (>2 mm) was initially evaluated using the chi-square test. Differences in continuous mucosal thickening values among proximity types were assessed using the Kruskal–Wallis test. Multivariable binary logistic regression analysis was performed to evaluate the independent effect of proximity type on the presence of mucosal thickening (>2 mm), adjusting for age and sex. Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Ordinal logistic regression models were constructed to evaluate the independent association between proximity type and mucosal thickening severity using the three-level classification (≤2 mm, 2–10 mm, >10 mm). Separate models were developed for the right and left sides. The proportional odds assumption was evaluated and confirmed before performing ordinal regression analysis. Sensitivity analyses were performed using alternative classification thresholds (≤2 mm, 2–8 mm, >8 mm) to assess the robustness of the findings. A p value < 0.05 was considered statistically significant. Results The intra-observer and inter-observer reliability for the assessment of proximity types showed excellent agreement, with Cohen’s kappa coefficients of 0.99 and 0.97, respectively. For the measurement of mucosal thickening (MT), the intra-class correlation coefficient (ICC) for intra-observer reliability was 0.95 (95% CI: 0.92–0.97), indicating a high degree of measurement reproducibility. A total of 300 patients were included. The mean age was 27.55 ± 8.74 years (range: 20–60 years). Of the participants, 175 (58.3%) were female and 125 (41.7%) were male (Table 1 ). The prevalence of diabetes, cardiovascular disease, and smoking was 4.3%, 3.0%, and 5.7%, respectively. Table 1 Demographic characteristics of the study population Gender n Mean age (years) ± SD Min Max Female 175 26.84 ± 7.82 20 58 Male 125 28.54 ± 9.84 20 60 Total 300 27.55 ± 8.74 20 60 Distribution of proximity types and prevalence of mucosal thickening Proximity Type 2 was the most frequently observed anatomical pattern on both sides. On the right side, Type 2 was observed in 187 patients (62.3%), followed by Type 3 in 88 patients (29.3%) and Type 1 in 25 patients (8.3%). Similarly, on the left side, Type 2 was present in 177 patients (59.0%), followed by Type 3 in 96 patients (32.0%) and Type 1 in 27 patients (9.0%) (Table 2 ). Table 2 Distribution of proximity types and prevalence of mucosal thickening (> 2 mm) Side Type 1 n (%) Type 2 n (%) Type 3 n (%) MT > 2 mm n (%) Right 25 (8.3%) 187 (62.3%) 88 (29.3%) 104 (34.7%) Left 27 (9.0%) 177 (59.0%) 96 (32.0%) 104 (34.7%) Mucosal thickening (> 2 mm) was observed in 104 patients (34.7%) on both the right and left sides (Table 2 ). Association between proximity type and mucosal thickening A statistically significant association was observed between proximity type and the presence of maxillary sinus mucosal thickening greater than 2 mm on both sides (Table 3 ). On the right side, the prevalence of mucosal thickening increased progressively from Type 1 (20.0%) to Type 2 (28.9%) and Type 3 (51.1%) (χ² = 15.68, p < 0.001). Table 3 The distribution of maxillary sinus mucosal thickening (MT) greater than 2 mm according to proximity type for the right and left sides Proximity type Right side MT ≤ 2 mm n (%) Right side MT > 2 mm n (%) Left side MT ≤ 2 mm n (%) Left side MT > 2 mm n (%) Type 1 20 (80.0%) 5 (20.0%) 20 (74.1%) 7 (25.9%) Type 2 133 (71.1%) 54 (28.9%) 125 (70.6%) 52 (29.4%) Type 3 43 (48.9%) 45 (51.1%) 51 (53.1%) 45 (46.9%) Chi-square (p) - 15.68 (< 0.001) - 9.41 (0.009) Similarly, on the left side, mucosal thickening was significantly more frequent in Type 3 proximity (46.9%) compared to Type 2 (29.4%) and Type 1 (25.9%) (χ² = 9.41, p = 0.009). When mucosal thickening was analyzed as a continuous variable, significant differences were also detected among proximity types on both sides. Kruskal–Wallis analysis demonstrated a statistically significant difference in MT across proximity groups on the right side (H = 15.63, p < 0.001) and on the left side (H = 10.53, p = 0.005). Multivariable binary prediction of mucosal thickening In multivariable logistic regression analysis, proximity type remained a strong and independent predictor of maxillary sinus mucosal thickening greater than 2 mm on both sides after adjustment for age, sex, diabetes, cardiovascular disease, and smoking status (Table 4 ). On the right side, each one-unit increase in proximity type was associated with a 2.58-fold increase in the odds of mucosal thickening (OR = 2.58; 95% CI: 1.61–4.12; p < 0.001). Similarly, on the left side, proximity type also demonstrated a significant association with mucosal thickening (OR = 1.93; 95% CI: 1.23–3.03; p = 0.004). Table 4 Multivariable binary logistic regression for mucosal thickening (> 2 mm) Variable Right OR (95% CI) p (Right) Left OR (95% CI) p (Left) Proximity type (per unit) 2.58 (1.61–4.12) < 0.001 1.93 (1.23–3.03) 0.004 Age (per year) 1.05 (1.01–1.08) 0.007 1.04 (1.01–1.08) 0.018 Sex (male) 1.14 (0.68–1.91) 0.607 1.85 (1.12–3.07) 0.017 Diabetes 0.98 (0.25–3.85) 0.979 1.86 (0.49–6.97) 0.359 CVD 0.13 (0.01–1.28) 0.081 0.22 (0.03–1.42) 0.111 Smoking 1.57 (0.52–4.80) 0.426 1.57 (0.53–4.66) 0.419 Age was also independently associated with mucosal thickening on both sides, with OR values of 1.05 (95% CI: 1.01–1.08; p = 0.007) on the right side and 1.04 (95% CI: 1.01–1.08; p = 0.018) on the left side. Sex was not a significant predictor in the right-side model (OR = 1.14; p = 0.607). However, male sex was significantly associated with increased odds of mucosal thickening on the left side, with males exhibiting nearly 1.9 times higher odds compared with females (OR = 1.85; 95% CI: 1.12–3.07; p = 0.017). Diabetes, cardiovascular disease, and smoking were not significantly associated with mucosal thickening in the adjusted models (all p > 0.05). Ordinal analysis of mucosal thickening severity Ordinal logistic regression analysis further demonstrated that proximity type was a significant and independent predictor of increased mucosal thickening severity on both sides after adjustment for age, sex, diabetes, cardiovascular disease, and smoking (Table 5 ). On the right side, each one-unit increase in proximity type was associated with a 2.43-fold increase in the odds of being classified into a higher mucosal thickening category (OR = 2.43; 95% CI: 1.56–3.78; p < 0.001). Similarly, on the left side, proximity type remained significantly associated with greater mucosal thickening severity (OR = 1.90; 95% CI: 1.24–2.93; p = 0.003). Table 5 Ordinal logistic regression for mucosal thickening severity (main model: ≤2 / 2–10 / >10 mm) Variable Right OR (95% CI) p (Right) Left OR (95% CI) p (Left) Proximity type (per unit) 2.43 (1.56–3.78) < 0.001 1.90 (1.24–2.93) 0.003 Age (per year) 1.04 (1.01–1.07) 0.019 1.03 (1.00–1.06) 0.084 Sex (male) 1.23 (0.75–2.02) 0.416 1.82 (1.11–2.97) 0.017 Diabetes 0.82 (0.23–2.99) 0.768 1.22 (0.39–3.77) 0.733 CVD 0.18 (0.02–1.77) 0.142 0.34 (0.06–1.95) 0.226 Smoking 1.99 (0.70–5.71) 0.199 1.47 (0.53–4.05) 0.459 Age was significantly associated with mucosal thickening severity on the right side, with each additional year increasing the odds of greater severity by approximately 4% (OR = 1.04; 95% CI: 1.01–1.07; p = 0.019). On the left side, the association between age and mucosal thickening severity showed a similar direction but did not reach statistical significance (OR = 1.03; p = 0.084). Male sex was not a significant predictor of mucosal thickening severity in the right-side model (p = 0.416). However, on the left side, male sex was significantly associated with higher mucosal thickening severity, with males showing approximately 1.8 times higher odds of being in a more severe category compared with females (OR = 1.82; 95% CI: 1.11–2.97; p = 0.017). In line with the binary models, none of the systemic variables, including diabetes, cardiovascular disease, or smoking, demonstrated a statistically significant association with mucosal thickening severity (all p > 0.05), further supporting that the relationship between proximity type and mucosal thickening severity reflects a primarily anatomical and local effect rather than a systemic one. The overall distribution pattern observed using the alternative thresholds was comparable to that of the primary ordinal classification (≤ 2 mm, 2–10 mm, > 10 mm), with approximately two-thirds of the cohort demonstrating normal mucosal thickening and around 10–14% exhibiting severe thickening on both sides. Discussion Maxillary sinus mucosal thickening (MT) has been widely recognized as a common radiographic finding in cone-beam computed tomography (CBCT) examinations, often associated with odontogenic factors such as periapical lesions, periodontal disease, or other inflammatory dental conditions. Previous observational studies and systematic reviews have demonstrated significant correlations between dental pathologies and mucosal thickening of the maxillary sinus, with periodontal bone loss and periapical lesions being among the most consistently reported risk factors [ 3 , 20 , 21 ]. These findings are supported by meta-analytic evidence indicating that the presence of odontogenic lesions increases both the likelihood of sinus mucosal thickening and the development of odontogenic maxillary sinusitis [ 20 , 22 ]. Despite the established association between dental pathology and maxillary sinus changes, the specific role of anatomical proximity between posterior maxillary tooth roots and the sinus floor in influencing both the occurrence and severity of mucosal thickening remains incompletely understood. Prior CBCT studies have primarily addressed this relationship in the context of localized pathology or morphometric descriptions without comprehensive multivariable modeling [ 21 , 23 ]. In contrast, the present study demonstrated that anatomical proximity independently predicted both the presence and severity of mucosal thickening, even after adjustment for demographic and systemic variables. This finding suggests that anatomical root–sinus relationships represent an independent structural determinant of sinus mucosal response rather than merely reflecting coexisting dental pathology. The present study was conducted in a relatively young cohort with a mean age of 27.55 ± 8.74 years and a female predominance, which should be taken into account when interpreting the findings. Nevertheless, this demographic profile is comparable to several CBCT-based studies investigating incidental maxillary sinus findings in dental populations, where young and middle-aged adults constitute the majority of examined subjects [ 24 , 25 ]. These studies suggested that incidental sinus alterations are frequently detected even in younger individuals, although the prevalence and severity of mucosal changes tend to increase with age. In contrast, Hsiao et al. [ 26 ] reported a significantly higher prevalence of maxillary sinus mucosal thickening in older age groups, indicating a possible age-related susceptibility of the Schneiderian membrane. However, the relatively modest age effect observed in the current multivariable models suggests that age alone may not be the dominant determinant of mucosal thickening. Instead, local anatomical factors and tooth–sinus relationships may play a more prominent role in shaping sinus mucosal response, which is consistent with previous CBCT-based investigations emphasizing the multifactorial nature of sinus pathology [ 27 ]. This interpretation is further supported by the large-scale CBCT study of Gu et al.[ 28 ], who demonstrated that although the distance between posterior root apices and the sinus floor increased with age, anatomical proximity patterns themselves showed limited sex and side dependency, highlighting structural relationships as relatively stable determinants across demographic strata. One of the main findings of this study is that proximity Type 2 was the most frequently encountered anatomical pattern, and that the prevalence of mucosal thickening increased progressively from Type 1 to Type 3 on both sides. This graded distribution supports the concept that closer spatial relationships between posterior maxillary tooth roots and the sinus floor are associated with a higher likelihood of mucosal alterations. Similar patterns have been reported in previous CBCT studies, which emphasized that roots located in close contact with or protruding into the sinus cavity may facilitate the spread of inflammatory mediators and odontogenic infection to the sinus mucosa [ 23 , 29 ]. In line with these findings, Gu et al. [ 28 ] reported that root apices extending into or contacting the maxillary sinus (Type IS and Type CO) were most frequently observed in palatal roots of first molars and mesiobuccal roots of second molars, anatomical sites that are also commonly implicated in odontogenic sinus pathology. Similarly, Ok et al. [ 30 ] demonstrated that posterior maxillary molars—particularly second molars—exhibit the closest proximity to the sinus floor in the Turkish population, underscoring the consistency of these anatomical risk patterns across different ethnic groups. Nair et al. [ 29 ] proposed that minimal bony separation between root apices and the sinus floor may reduce the anatomical barrier to inflammatory diffusion, thereby increasing the susceptibility of the Schneiderian membrane to thickening. Likewise, Yusufoğlu et al. [ 23 ] demonstrated that variations in tooth–sinus relationships significantly influence sinus mucosal thickening, particularly in the presence of periapical or periodontal pathology. Taken together, these findings support the biological plausibility of the present results and suggest that anatomical proximity should be considered a relevant structural risk factor for sinus mucosal alterations, independent of overt dental disease [ 13 , 31 ]. From a surgical and anatomical perspective, this concept is further reinforced by the recent three-dimensional CBCT reconstruction study of Huang et al. [ 32 ], which demonstrated that palatal roots of maxillary molars frequently exhibit root apex planes located at or above the sinus floor, thereby increasing the likelihood of sinus involvement during both endodontic microsurgery and pathological processes. Although Huang et al.[ 32 ] focused primarily on surgical access pathways, their morphometric data indirectly support the notion that palatal root proximity constitutes a critical anatomical vulnerability zone for sinus mucosal reactions. A key strength of the present study lies in the use of both binary and ordinal multivariable regression models, which allowed the assessment of anatomical proximity as an independent predictor of not only the presence but also the severity of mucosal thickening. Even after adjustment for age, sex, diabetes, cardiovascular disease, and smoking, proximity type remained a strong predictor of mucosal thickening on both sides. This indicates that the observed association is robust and not substantially confounded by systemic inflammatory or vascular conditions. These findings are in line with previous studies reporting significant associations between odontogenic conditions and sinus mucosal alterations [ 33 , 34 ]. Jouhar et al. [ 33 ] showed that periapical and periodontal pathologies exert a measurable effect on sinus mucosal thickening, particularly when dental roots are located close to the sinus floor. Similarly, Kaimal and Patil [ 34 ] reported that periapical lesions in maxillary posterior teeth were strongly associated with mucosal thickening on CBCT. The present study extends these observations by demonstrating that anatomical proximity itself exerts an independent effect, even in the absence of explicit dental pathology, highlighting the importance of structural factors in sinus health. Importantly, while most prior studies—including Gu et al.[ 28 ] and Ok et al. [ 30 ]—relied primarily on descriptive or univariable analyses, the current study contributes novel evidence by confirming this anatomical effect within a fully adjusted multivariable framework. This methodological advancement strengthens the causal inference that proximity type represents a fundamental anatomical determinant rather than merely a surrogate marker of coexisting dental pathology. Interestingly, male sex emerged as a significant predictor of mucosal thickening on the left side but not on the right. Although the clinical relevance of this asymmetry remains unclear, similar sex-related tendencies have been reported in previous studies [ 26 , 33 ]. This finding may reflect subtle differences in craniofacial morphology or sinus anatomy between sexes, as suggested in morphometric CBCT studies [ 17 , 19 ]. Gu et al. [ 28 ], however, reported minimal sex-related differences in root–sinus distance, suggesting that sex effects may be context-dependent and potentially modulated by population-specific anatomical characteristics. The use of a 2 mm threshold to define pathological mucosal thickening in the present study is consistent with widely accepted radiological criteria in the literature [ 35 , 36 ]. Terlemez et al. [ 36 ] reported substantial variability in the prevalence of mucosal thickening, ranging from 12% to over 60%, depending on population characteristics, imaging protocols, and diagnostic thresholds. This variability highlights the importance of standardized definitions when comparing results across studies. Notably, the absence of significant associations between systemic conditions such as diabetes, cardiovascular disease, and smoking and mucosal thickening in the present study suggests that local anatomical and odontogenic factors may play a more dominant role than systemic influences in determining sinus mucosal status. This observation is consistent with earlier CBCT-based studies that found limited or inconsistent effects of systemic variables on sinus pathology [ 20 , 35 , 37 ]. From a clinical perspective, these findings underscore the importance of careful radiological evaluation of tooth–sinus relationships during dental treatment planning, particularly in implant dentistry, sinus floor elevation procedures, and endodontic interventions involving posterior maxillary teeth. Limitations This study has several limitations. First, its retrospective design precludes definitive conclusions regarding causality between anatomical proximity and mucosal thickening. Second, although CBCT provides high-resolution anatomical information, the absence of clinical and endoscopic correlation limits interpretation of mucosal thickening as a purely radiological finding. Third, although major systemic factors were included in the regression models, other potential confounders such as detailed periodontal status, periapical pathology severity, or sinonasal clinical history were not systematically evaluated. Finally, the relatively young age distribution may limit generalizability to older populations with a higher prevalence of sinus pathology and systemic comorbidities. Conclusion This study demonstrates that anatomical proximity between posterior maxillary tooth roots and the maxillary sinus floor is an independent predictor of both the presence and severity of maxillary sinus mucosal thickening. Increasing proximity between tooth roots and the sinus floor was consistently associated with higher likelihood and severity of mucosal thickening, independent of demographic and systemic factors. These findings indicate that anatomical tooth–sinus relationships represent a significant structural determinant of sinus mucosal status. From a clinical perspective, CBCT-based assessment of root–sinus proximity may improve diagnostic accuracy and risk assessment in the posterior maxilla. Careful evaluation of anatomical proximity should therefore be considered during treatment planning, particularly in implant dentistry, endodontic therapy, and surgical procedures involving the maxillary sinus. Recognition of anatomical proximity as a risk factor may contribute to improved clinical decision-making and prevention of sinus-related complications. Declarations Conflict of interest : The authors declare no competing interests. Ethics Committee Approval Approval date and number The study received ethical approval from the Research Ethics Committee of the Faculty of Dentistry at Necmettin Erbakan University, and the study conducted in accordance with the Helsinki Declaration of Human Rights guidelines (Approval No:2024/526 – Approval Date:26.12.2024). Informed consents were obtained from all patients, and all data were processed anonymously. Author Contributions Concept - AA; Design - AA; Supervision - AA; Resources – AA, CNY; Data Collection and/or Processing –CNY, AA; Analysis and/or Interpretation – AA, CNY; Literature Search – AA, CNY; Writing Manuscript –AA, CNY; Critical Review – AA. Financial Disclosure None. Data availability Data is available from the corresponding author upon reasonable request. Consent to Publication Not applicable. References Dogan ME, Uluisik N, Yuvarlakbas SD. Retrospective analysis of pathological changes in the maxillary sinus with CBCT. Sci Rep. 2024;14:15529. Altindag A, Yildirim CN. Location, size, and prevalence of the maxillary sinus septa: comparison of panoramic radiography and cone-beam computed tomography. Harran Univ Fac Dent J. 2020;3:605–11. Aksoy U, Orhan K. Association between odontogenic conditions and maxillary sinus mucosal thickening: a retrospective CBCT study. Clin Oral Investig. 2019;23:123–31. Lu Y, Liu Z, Zhang L, Zhou X, Zheng Q, Duan X, Zheng G, Wang H, Huang D. 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Makris LML, Devito KL, D’Addazio PSS, Lima CO, Campos CN. Relationship of maxillary posterior roots to the maxillary sinus and cortical bone: a cone beam computed tomographic study. Gen Dent. 2020;68:e1–4. Constantino TM, Marceliano-Alves MFV, Ronquete V, da Silva Limoeiro AG, Amoroso-Silva PA, Pedano MS, Boukpessi T, Vidal F, de Carvalho Coutinho TM. The effect of age and gender on the distance between the maxillary sinus cortical bone and maxillary molars: a cone-beam tomography analysis. Sinusitis. 2025;9:9. Penarrocha-Oltra S, Soto-Penaloza D, Bagan-Debon L, Bagan-Sebastian JV, Penarrocha-Oltra D. Association between maxillary sinus pathology and odontogenic lesions in patients evaluated by cone beam computed tomography: a systematic review and meta-analysis. Med Oral Patol Oral Cir Bucal. 2019;25:e34–42. Kuligowski P, Jaron A, Preuss O, Gabrysz-Trybek E, Bladowska J, Trybek G. Association between odontogenic and maxillary sinus conditions: a retrospective cone-beam computed tomographic study. J Clin Med. 2021;10:2849. Riekki VP, Nevalainen MT, Haapea M, Sipola A, Kallio-Pulkkinen S, Bode MK. Associations between odontogenic and sinus pathologies: a low-dose CBCT study. Acta Odontol Scand. 2025;84:437–44. Yusufoglu SI, Erbasar GNH, Gulen O. Evaluation of the effect of periapical lesions and other odontogenic conditions on maxillary sinus mucosal thickness characteristics and mucosal appearance: a CBCT study. J Dent Res Dent Clin Dent Prospects. 2021;15:163–70. Pazera P, Bornstein M, Pazera A, Sendi P, Katsaros C. Incidental maxillary sinus findings in orthodontic patients: a radiographic analysis using cone-beam computed tomography. Orthod Craniofac Res. 2011;14:17–24. Allareddy V, Vincent SD, Hellstein JW, Qian F, Smoker WR, Ruprecht A. (2012) Incidental findings on cone beam computed tomography images. Int J Dent 2012:871532. Hsiao YJ, Yang J, Resnik RR, Suzuki JB. Prevalence of maxillary sinus pathology based on cone-beam computed tomography evaluation of multiethnicity dental school population. Implant Dent. 2019;28:356–66. Bornstein MM, Yeung AWK, Tanaka R, von Arx T, Jacobs R, Khong PL. Evaluation of health or pathology of bilateral maxillary sinuses in patients referred for cone beam computed tomography using a low-dose protocol. Int J Oral Maxillofac Surg. 2018;38:699–710. Gu Y, Sun C, Wu D, Zhu Q, Leng D, Zhou Y. Evaluation of the relationship between maxillary posterior teeth and the maxillary sinus floor using cone-beam computed tomography. BMC Oral Health. 2018;18:164. Nair AK, Jose M, Sreela L, Prasad TS, Mathew P. Prevalence and pattern of proximity of maxillary posterior teeth to maxillary sinus with mucosal thickening: a cone beam computed tomography based retrospective study. Acta Med Acad. 2023;22:327–32. Ok E, Gungor E, Colak M, Altunsoy M, Nur BG, Aglarci OS. Evaluation of the relationship between the maxillary posterior teeth and the sinus floor using cone-beam computed tomography. Surg Radiol Anat. 2014;36:907–14. Shanbhag S, Karnik P, Shirke P, Shanbhag V. Association between periapical lesions and maxillary sinus mucosal thickening: a retrospective cone-beam computed tomographic study. J Endod. 2013;39:853–7. Huang X, Xu J, Hou B, Wang Y. Proximity of maxillary molar palatal roots to adjacent structures for endodontic microsurgery: a cone-beam computed tomography study. BMC Oral Health. 2025;25:21. Jouhar R, Alkhames HM, Ahmed MA, Almadeh NM, Faheemuddin M, Umer MF. CBCT evaluation of periapical pathologies in maxillary posterior teeth and their relationship with maxillary sinus mucosal thickening. Healthc (Basel). 2023;11:787. Kaimal VG, Patil BJ. Evaluation of association between maxillary posterior teeth periapical pathologies and maxillary sinus mucosal changes: a cone-beam computed tomography study. Indian J Radiol Imaging. 2024;34:246–53. Janner SF, Caversaccio MD, Dubach P, Sendi P, Buser D, Bornstein MM. Characteristics and dimensions of the Schneiderian membrane: a radiographic analysis using cone beam computed tomography in patients referred for dental implant surgery in the posterior maxilla. Clin Oral Implants Res. 2011;22:1446–53. Terlemez A, Tassoker M, Kizilcakaya M, Gulec M. Comparison of cone-beam computed tomography and panoramic radiography in the evaluation of maxillary sinus pathology related to maxillary posterior teeth. Imaging Sci Dent. 2019;49:115–22. Brullmann DD, Schmidtmann I, Hornstein S, Schulze RK. Correlation of cone beam computed tomography findings in the maxillary sinus with dental diagnoses: a retrospective cross-sectional study. Clin Oral Investig. 2012;16:1023–9. Additional Declarations No competing interests reported. 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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-8984640","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":606312941,"identity":"d0a735a4-2e19-43c9-9b20-25ea15f2c5a0","order_by":0,"name":"Ali Altındağ","email":"data:image/png;base64,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","orcid":"","institution":"Necmettin Erbakan University","correspondingAuthor":true,"prefix":"","firstName":"Ali","middleName":"","lastName":"Altındağ","suffix":""},{"id":606312942,"identity":"3f9c6657-17d5-49ac-b669-7f520316313a","order_by":1,"name":"Cemile Nur Yıldırım","email":"","orcid":"","institution":"Istanbul Aydın University","correspondingAuthor":false,"prefix":"","firstName":"Cemile","middleName":"Nur","lastName":"Yıldırım","suffix":""}],"badges":[],"createdAt":"2026-02-27 07:23:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8984640/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8984640/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104874647,"identity":"f1713ff3-35ae-4808-bd22-abf873cea472","added_by":"auto","created_at":"2026-03-18 08:32:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":233388,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative CBCT images demonstrating the classification of anatomical proximity between maxillary posterior tooth roots and the sinus floor, along with mucosal thickening (MT) measurements\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(a) \u003c/strong\u003eType 1: The root apex is located below the maxillary sinus floor without any contact. \u003cstrong\u003e(b)\u003c/strong\u003e Type 2: The root apex is in direct contact with the cortical line of the maxillary sinus floor. \u003cstrong\u003e(c)\u003c/strong\u003e Type 3: The root apex protrudes into the maxillary sinus cavity. \u003cstrong\u003e(d)\u003c/strong\u003eSevere Mucosal Thickening in Type 3: An example of significant mucosal thickening (\u0026gt;10 mm) associated with a root protruding into the sinus.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8984640/v1/2f3263950d99e7307cf8be8e.png"},{"id":105996478,"identity":"52479ac7-00b9-405e-b257-35162a98eed2","added_by":"auto","created_at":"2026-04-02 09:14:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1224241,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8984640/v1/f55d41f8-2e26-4ffc-b483-f20102cb6a92.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anatomical Proximity Between Posterior Maxillary Tooth Roots and Sinus Floor Independently Predicts Mucosal Thickening: A CBCT Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe maxillary sinus is the largest paranasal sinus and demonstrates close anatomical proximity to the posterior maxillary dentition, resulting in a complex structural and functional relationship between dental and sinonasal tissues [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The Schneiderian membrane lining the maxillary sinus is a biologically active mucosa that may undergo adaptive or pathological thickening in response to inflammatory, infectious, or mechanical stimuli. Radiographically, maxillary sinus mucosal thickening (MT) represents one of the most frequently observed incidental findings in dental imaging and is widely regarded as an indicator of sinus inflammation or subclinical mucosal response [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCone-beam computed tomography (CBCT) has become the preferred imaging modality for evaluating maxillary sinus anatomy in dental practice due to its high spatial resolution and three-dimensional visualization capabilities [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Compared with conventional two-dimensional radiography, CBCT enables precise measurement of mucosal thickness and provides accurate assessment of the anatomical relationship between maxillary posterior tooth roots and the sinus floor [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. This three-dimensional assessment is particularly important for identifying anatomical risk factors that may influence sinus health and treatment outcomes in the posterior maxilla.\u003c/p\u003e \u003cp\u003eThe reported prevalence of MT in CBCT-based studies ranges from 30% to 60%, even in asymptomatic populations [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Although a universally accepted pathological threshold has not been established, mucosal thickness exceeding 2\u0026ndash;3 mm is commonly considered indicative of abnormal mucosal alteration [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Previous studies have demonstrated significant associations between odontogenic pathologies\u0026mdash;such as periapical lesions, periodontal bone loss, and endodontic infections\u0026mdash;and MT, supporting the concept of odontogenic influence on sinus mucosal status [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition to overt dental disease, anatomical factors have been proposed as potential contributors to sinus mucosal changes. In particular, the proximity between posterior maxillary tooth roots and the sinus floor may facilitate the transmission of inflammatory mediators or infectious processes into the sinus cavity. However, existing evidence regarding the independent role of anatomical proximity remains inconclusive. Aguori et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] evaluated healthy posterior teeth and found no significant association between tooth\u0026ndash;sinus proximity and MT. In contrast, more recent CBCT studies have demonstrated substantial anatomical variability in root\u0026ndash;sinus relationships and have reported frequent root contact with or protrusion into the sinus cavity, especially in molar regions [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Despite these anatomical observations, most previous studies have focused primarily on descriptive or univariable analyses, and the independent predictive value of anatomical proximity for mucosal thickening\u0026mdash;particularly after controlling for potential systemic confounders\u0026mdash;remains insufficiently clarified.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, identifying anatomical predictors of MT may improve risk assessment, diagnostic interpretation, and treatment planning in the posterior maxilla, particularly in implant dentistry, endodontics, and surgical interventions involving the sinus region. A better understanding of whether anatomical proximity independently influences both the occurrence and severity of mucosal thickening may also provide insight into the structural determinants of sinus mucosal response beyond traditional odontogenic or systemic risk factors. Therefore, the aim of the present study was to investigate the association between the anatomical proximity of posterior maxillary tooth roots to the sinus floor and both the presence and severity of maxillary sinus mucosal thickening using CBCT.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy design and sample\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective cross-sectional study was conducted using cone-beam computed tomography (CBCT) images obtained from patients who attended the Department of Oral and Maxillofacial Radiology for routine diagnostic purposes. CBCT examinations had been originally performed for various clinical indications, including implant planning, assessment of impacted teeth, and evaluation of dentomaxillofacial structures. The study protocol was approved by the Local Institutional Review Board (Approval No:2024/526 \u0026ndash; Approval Date:26.12.2024), and the study was conducted in accordance with the Declaration of Helsinki. Clinical trial number: not applicable.\u003c/p\u003e\n\u003cp\u003eAn a priori power analysis was performed using G*Power version 3.1.9.7 (Heinrich-Heine-Universit\u0026auml;t D\u0026uuml;sseldorf, D\u0026uuml;sseldorf, Germany) to determine the minimum required sample size. The analysis was based on the chi-square test of independence, which was considered a conservative approximation for the primary association between proximity type and mucosal thickening (\u0026gt;2 mm vs. \u0026le;2 mm). Parameters were defined as follows: medium effect size (w = 0.30), significance level (\u0026alpha; = 0.05), statistical power (1\u0026minus;\u0026beta; = 0.95), and degrees of freedom = 2. The analysis indicated that a minimum of 172 subjects was required. The final sample size of 300 patients exceeded this requirement, ensuring adequate statistical power for multivariable regression analyses.\u003c/p\u003e\n\u003cp\u003eA total of 300 patients were included in the study. Inclusion criteria were:\u0026nbsp;\u003cbr\u003e\u0026nbsp;(1) availability of high-quality CBCT scans including both maxillary sinuses and posterior maxillary teeth,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e(2) absence of obvious maxillary sinus pathology such as cysts, tumors, or previous sinus surgery,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e(3) presence of at least one posterior maxillary tooth adjacent to the maxillary sinus floor. Exclusion criteria included poor image quality, motion artifacts, history of maxillary sinus surgery, and conditions that could obscure accurate evaluation of the sinus mucosa or tooth\u0026ndash;sinus relationship.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCBCT image acquisition and evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll CBCT examinations were performed using a 3D Accuitomo 170 system (J Morita MFG Corp., Kyoto, Japan), operating at 90 kVp and 5 mA with exposure times ranging from 15 to 18 seconds, in accordance with the manufacturer\u0026rsquo;s recommended imaging protocol. The scans were acquired using a standardized imaging protocol with a voxel size of 0.25 mm and an appropriate field of view to include both maxillary sinuses and posterior maxillary teeth.\u003c/p\u003e\n\u003cp\u003eAll images were evaluated using dedicated CBCT viewing software under standardized viewing conditions, including controlled ambient lighting and calibrated display monitors. Multiplanar reconstruction (MPR) images were analyzed in axial, coronal, and sagittal planes to ensure accurate anatomical assessment. The coronal plane was primarily used for evaluating the anatomical relationship between posterior tooth roots and the sinus floor and for measuring mucosal thickness.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAssessment of proximity type\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe anatomical relationship between the roots of posterior maxillary teeth and the maxillary sinus floor was classified into three proximity types based on their spatial relationship [17-19](Figure 1):\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eType 1:\u003c/strong\u003e Root apex located below the sinus floor without contact.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType 2:\u003c/strong\u003e Root apex in direct contact with the sinus floor.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType 3:\u003c/strong\u003e Root apex protruding into the maxillary sinus cavity.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eProximity type was assessed separately for the right and left sides. When multiple posterior teeth were present, the tooth exhibiting the closest anatomical relationship to the sinus floor was used for classification, as this represents the highest potential anatomical risk condition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMeasurement of maxillary sinus mucosal thickening\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMaxillary sinus mucosal thickness was measured as the maximum perpendicular distance from the sinus wall to the mucosal surface at the thickest location. Measurements were recorded in millimeters for both maxillary sinuses.\u003c/p\u003e\n\u003cp\u003eMucosal thickening was defined based on established radiological thresholds and categorized using both binary and ordinal classification models\u003c/p\u003e\n\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003ePrimary ordinal classification (main model):\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eNormal: \u0026le;2 mm\u003c/li\u003e\n \u003cli\u003eModerate: \u0026gt;2\u0026ndash;10 mm\u003c/li\u003e\n \u003cli\u003eSevere: \u0026gt;10 mm\u003c/li\u003e\n\u003c/ul\u003e\n\u003col start=\"2\" type=\"1\"\u003e\n \u003cli\u003eAlternative ordinal classification (sensitivity analysis):\u003c/li\u003e\n\u003c/ol\u003e\n\u003cul\u003e\n \u003cli\u003eNormal: \u0026le;2 mm\u003c/li\u003e\n \u003cli\u003eModerate: \u0026gt;2\u0026ndash;8 mm\u003c/li\u003e\n \u003cli\u003eSevere: \u0026gt;8 mm\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eFor binary analyses, mucosal thickening was dichotomized as \u0026le;2 mm and \u0026gt;2 mm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eObserver reliability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll measurements were performed independently by two experienced oral and maxillofacial radiologists (CNY and AA), who were blinded to each other\u0026rsquo;s measurements. To evaluate intra-observer reliability, repeated measurements were performed on a randomly selected subset of CBCT scans after a three-week interval.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIntra-class correlation coefficients (ICC) were calculated to assess measurement reproducibility. Inter-observer agreement for proximity classification was evaluated using Cohen\u0026rsquo;s kappa coefficient. In cases of disagreement, a consensus was reached through joint re-evaluation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using SPSS version 21 (SPSS, Chicago, Ill., USA). Descriptive statistics were calculated for demographic variables, proximity types, and mucosal thickening values.\u003c/p\u003e\n\u003cp\u003eThe association between proximity type and binary mucosal thickening (\u0026gt;2 mm) was initially evaluated using the chi-square test. Differences in continuous mucosal thickening values among proximity types were assessed using the Kruskal\u0026ndash;Wallis test.\u003c/p\u003e\n\u003cp\u003eMultivariable binary logistic regression analysis was performed to evaluate the independent effect of proximity type on the presence of mucosal thickening (\u0026gt;2 mm), adjusting for age and sex. Odds ratios (OR) and 95% confidence intervals (CI) were calculated.\u003c/p\u003e\n\u003cp\u003eOrdinal logistic regression models were constructed to evaluate the independent association between proximity type and mucosal thickening severity using the three-level classification (\u0026le;2 mm, 2\u0026ndash;10 mm, \u0026gt;10 mm). Separate models were developed for the right and left sides. The proportional odds assumption was evaluated and confirmed before performing ordinal regression analysis.\u003c/p\u003e\n\u003cp\u003eSensitivity analyses were performed using alternative classification thresholds (\u0026le;2 mm, 2\u0026ndash;8 mm, \u0026gt;8 mm) to assess the robustness of the findings.\u003c/p\u003e\n\u003cp\u003eA p value \u0026lt; 0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e The intra-observer and inter-observer reliability for the assessment of proximity types showed excellent agreement, with Cohen\u0026rsquo;s kappa coefficients of 0.99 and 0.97, respectively. For the measurement of mucosal thickening (MT), the intra-class correlation coefficient (ICC) for intra-observer reliability was 0.95 (95% CI: 0.92\u0026ndash;0.97), indicating a high degree of measurement reproducibility.\u003c/p\u003e \u003cp\u003eA total of 300 patients were included. The mean age was 27.55\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74 years (range: 20\u0026ndash;60 years). Of the participants, 175 (58.3%) were female and 125 (41.7%) were male (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The prevalence of diabetes, cardiovascular disease, and smoking was 4.3%, 3.0%, and 5.7%, respectively.\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\u003eDemographic characteristics of the study population\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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=\"\u0026plusmn;\" 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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\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\u003eMean age (years)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMin\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMax\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e175\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e26.84\u0026thinsp;\u0026plusmn;\u0026thinsp;7.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e28.54\u0026thinsp;\u0026plusmn;\u0026thinsp;9.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e300\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e27.55\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e20\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e60\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eDistribution of proximity types and prevalence of mucosal thickening\u003c/h3\u003e\n\u003cp\u003eProximity Type 2 was the most frequently observed anatomical pattern on both sides. On the right side, Type 2 was observed in 187 patients (62.3%), followed by Type 3 in 88 patients (29.3%) and Type 1 in 25 patients (8.3%). Similarly, on the left side, Type 2 was present in 177 patients (59.0%), followed by Type 3 in 96 patients (32.0%) and Type 1 in 27 patients (9.0%) (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\u003eDistribution of proximity types and prevalence of mucosal thickening (\u0026gt;\u0026thinsp;2 mm)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSide\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eType 1\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eType 2\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eType 3\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMT\u0026thinsp;\u0026gt;\u0026thinsp;2 mm\u003c/p\u003e \u003cp\u003en (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eRight\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25\u003c/p\u003e \u003cp\u003e(8.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e187 (62.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e88\u003c/p\u003e \u003cp\u003e(29.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e104\u003c/p\u003e \u003cp\u003e(34.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLeft\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e27\u003c/p\u003e \u003cp\u003e(9.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e177 (59.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96\u003c/p\u003e \u003cp\u003e(32.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e104\u003c/p\u003e \u003cp\u003e(34.7%)\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\u003eMucosal thickening (\u0026gt;\u0026thinsp;2 mm) was observed in 104 patients (34.7%) on both the right and left sides (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eAssociation between proximity type and mucosal thickening\u003c/h2\u003e \u003cp\u003eA statistically significant association was observed between proximity type and the presence of maxillary sinus mucosal thickening greater than 2 mm on both sides (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). On the right side, the prevalence of mucosal thickening increased progressively from Type 1 (20.0%) to Type 2 (28.9%) and Type 3 (51.1%) (χ\u0026sup2; = 15.68, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\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\u003eThe distribution of maxillary sinus mucosal thickening (MT) greater than 2 mm according to proximity type for the right and left sides\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProximity\u003c/p\u003e \u003cp\u003etype\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight side MT\u0026thinsp;\u0026le;\u0026thinsp;2 mm n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRight side MT\u0026thinsp;\u0026gt;\u0026thinsp;2 mm n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLeft side MT\u0026thinsp;\u0026le;\u0026thinsp;2 mm n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLeft side MT\u0026thinsp;\u0026gt;\u0026thinsp;2 mm n (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20 (80.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5 (20.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 (74.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7 (25.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e133 (71.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e54 (28.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e125 (70.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e52 (29.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43 (48.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e45 (51.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e51 (53.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e45 (46.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChi-square (p)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e15.68 (\u0026lt;\u0026thinsp;0.001)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e9.41 (0.009)\u003c/b\u003e\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\u003eSimilarly, on the left side, mucosal thickening was significantly more frequent in Type 3 proximity (46.9%) compared to Type 2 (29.4%) and Type 1 (25.9%) (χ\u0026sup2; = 9.41, p\u0026thinsp;=\u0026thinsp;0.009).\u003c/p\u003e \u003cp\u003eWhen mucosal thickening was analyzed as a continuous variable, significant differences were also detected among proximity types on both sides. Kruskal\u0026ndash;Wallis analysis demonstrated a statistically significant difference in MT across proximity groups on the right side (H\u0026thinsp;=\u0026thinsp;15.63, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and on the left side (H\u0026thinsp;=\u0026thinsp;10.53, p\u0026thinsp;=\u0026thinsp;0.005).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eMultivariable binary prediction of mucosal thickening\u003c/h2\u003e \u003cp\u003eIn multivariable logistic regression analysis, proximity type remained a strong and independent predictor of maxillary sinus mucosal thickening greater than 2 mm on both sides after adjustment for age, sex, diabetes, cardiovascular disease, and smoking status (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). On the right side, each one-unit increase in proximity type was associated with a 2.58-fold increase in the odds of mucosal thickening (OR\u0026thinsp;=\u0026thinsp;2.58; 95% CI: 1.61\u0026ndash;4.12; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Similarly, on the left side, proximity type also demonstrated a significant association with mucosal thickening (OR\u0026thinsp;=\u0026thinsp;1.93; 95% CI: 1.23\u0026ndash;3.03; p\u0026thinsp;=\u0026thinsp;0.004).\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\u003eMultivariable binary logistic regression for mucosal thickening (\u0026gt;\u0026thinsp;2 mm)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight OR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep (Right)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLeft OR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep (Left)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eProximity type (per unit)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.58 (1.61\u0026ndash;4.12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.93 (1.23\u0026ndash;3.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (per year)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.05 (1.01\u0026ndash;1.08)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.04 (1.01\u0026ndash;1.08)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex (male)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.14 (0.68\u0026ndash;1.91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.607\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.85 (1.12\u0026ndash;3.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDiabetes\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.98 (0.25\u0026ndash;3.85)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.979\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.86 (0.49\u0026ndash;6.97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.359\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCVD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.13 (0.01\u0026ndash;1.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.081\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.22 (0.03\u0026ndash;1.42)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSmoking\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.57 (0.52\u0026ndash;4.80)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.426\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.57 (0.53\u0026ndash;4.66)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.419\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\u003eAge was also independently associated with mucosal thickening on both sides, with OR values of 1.05 (95% CI: 1.01\u0026ndash;1.08; p\u0026thinsp;=\u0026thinsp;0.007) on the right side and 1.04 (95% CI: 1.01\u0026ndash;1.08; p\u0026thinsp;=\u0026thinsp;0.018) on the left side.\u003c/p\u003e \u003cp\u003eSex was not a significant predictor in the right-side model (OR\u0026thinsp;=\u0026thinsp;1.14; p\u0026thinsp;=\u0026thinsp;0.607). However, male sex was significantly associated with increased odds of mucosal thickening on the left side, with males exhibiting nearly 1.9 times higher odds compared with females (OR\u0026thinsp;=\u0026thinsp;1.85; 95% CI: 1.12\u0026ndash;3.07; p\u0026thinsp;=\u0026thinsp;0.017).\u003c/p\u003e \u003cp\u003eDiabetes, cardiovascular disease, and smoking were not significantly associated with mucosal thickening in the adjusted models (all p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eOrdinal analysis of mucosal thickening severity\u003c/h2\u003e \u003cp\u003eOrdinal logistic regression analysis further demonstrated that proximity type was a significant and independent predictor of increased mucosal thickening severity on both sides after adjustment for age, sex, diabetes, cardiovascular disease, and smoking (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). On the right side, each one-unit increase in proximity type was associated with a 2.43-fold increase in the odds of being classified into a higher mucosal thickening category (OR\u0026thinsp;=\u0026thinsp;2.43; 95% CI: 1.56\u0026ndash;3.78; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Similarly, on the left side, proximity type remained significantly associated with greater mucosal thickening severity (OR\u0026thinsp;=\u0026thinsp;1.90; 95% CI: 1.24\u0026ndash;2.93; p\u0026thinsp;=\u0026thinsp;0.003).\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\u003eOrdinal logistic regression for mucosal thickening severity (main model: \u0026le;2 / 2\u0026ndash;10 / \u0026gt;10 mm)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight OR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ep (Right)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eLeft OR (95% CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep (Left)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eProximity type (per unit)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.43 (1.56\u0026ndash;3.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.90 (1.24\u0026ndash;2.93)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge (per year)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.04 (1.01\u0026ndash;1.07)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.03 (1.00\u0026ndash;1.06)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.084\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex (male)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.23 (0.75\u0026ndash;2.02)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.416\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.82 (1.11\u0026ndash;2.97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDiabetes\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.82 (0.23\u0026ndash;2.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.22 (0.39\u0026ndash;3.77)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.733\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCVD\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.18 (0.02\u0026ndash;1.77)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.142\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.34 (0.06\u0026ndash;1.95)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.226\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSmoking\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.99 (0.70\u0026ndash;5.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.199\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.47 (0.53\u0026ndash;4.05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.459\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\u003eAge was significantly associated with mucosal thickening severity on the right side, with each additional year increasing the odds of greater severity by approximately 4% (OR\u0026thinsp;=\u0026thinsp;1.04; 95% CI: 1.01\u0026ndash;1.07; p\u0026thinsp;=\u0026thinsp;0.019). On the left side, the association between age and mucosal thickening severity showed a similar direction but did not reach statistical significance (OR\u0026thinsp;=\u0026thinsp;1.03; p\u0026thinsp;=\u0026thinsp;0.084).\u003c/p\u003e \u003cp\u003eMale sex was not a significant predictor of mucosal thickening severity in the right-side model (p\u0026thinsp;=\u0026thinsp;0.416). However, on the left side, male sex was significantly associated with higher mucosal thickening severity, with males showing approximately 1.8 times higher odds of being in a more severe category compared with females (OR\u0026thinsp;=\u0026thinsp;1.82; 95% CI: 1.11\u0026ndash;2.97; p\u0026thinsp;=\u0026thinsp;0.017).\u003c/p\u003e \u003cp\u003eIn line with the binary models, none of the systemic variables, including diabetes, cardiovascular disease, or smoking, demonstrated a statistically significant association with mucosal thickening severity (all p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), further supporting that the relationship between proximity type and mucosal thickening severity reflects a primarily anatomical and local effect rather than a systemic one.\u003c/p\u003e \u003cp\u003eThe overall distribution pattern observed using the alternative thresholds was comparable to that of the primary ordinal classification (\u0026le;\u0026thinsp;2 mm, 2\u0026ndash;10 mm, \u0026gt;\u0026thinsp;10 mm), with approximately two-thirds of the cohort demonstrating normal mucosal thickening and around 10\u0026ndash;14% exhibiting severe thickening on both sides.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eMaxillary sinus mucosal thickening (MT) has been widely recognized as a common radiographic finding in cone-beam computed tomography (CBCT) examinations, often associated with odontogenic factors such as periapical lesions, periodontal disease, or other inflammatory dental conditions. Previous observational studies and systematic reviews have demonstrated significant correlations between dental pathologies and mucosal thickening of the maxillary sinus, with periodontal bone loss and periapical lesions being among the most consistently reported risk factors [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. These findings are supported by meta-analytic evidence indicating that the presence of odontogenic lesions increases both the likelihood of sinus mucosal thickening and the development of odontogenic maxillary sinusitis [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite the established association between dental pathology and maxillary sinus changes, the specific role of anatomical proximity between posterior maxillary tooth roots and the sinus floor in influencing both the occurrence and severity of mucosal thickening remains incompletely understood. Prior CBCT studies have primarily addressed this relationship in the context of localized pathology or morphometric descriptions without comprehensive multivariable modeling [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In contrast, the present study demonstrated that anatomical proximity independently predicted both the presence and severity of mucosal thickening, even after adjustment for demographic and systemic variables. This finding suggests that anatomical root\u0026ndash;sinus relationships represent an independent structural determinant of sinus mucosal response rather than merely reflecting coexisting dental pathology.\u003c/p\u003e \u003cp\u003eThe present study was conducted in a relatively young cohort with a mean age of 27.55\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74 years and a female predominance, which should be taken into account when interpreting the findings. Nevertheless, this demographic profile is comparable to several CBCT-based studies investigating incidental maxillary sinus findings in dental populations, where young and middle-aged adults constitute the majority of examined subjects [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. These studies suggested that incidental sinus alterations are frequently detected even in younger individuals, although the prevalence and severity of mucosal changes tend to increase with age.\u003c/p\u003e \u003cp\u003eIn contrast, Hsiao et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] reported a significantly higher prevalence of maxillary sinus mucosal thickening in older age groups, indicating a possible age-related susceptibility of the Schneiderian membrane. However, the relatively modest age effect observed in the current multivariable models suggests that age alone may not be the dominant determinant of mucosal thickening. Instead, local anatomical factors and tooth\u0026ndash;sinus relationships may play a more prominent role in shaping sinus mucosal response, which is consistent with previous CBCT-based investigations emphasizing the multifactorial nature of sinus pathology [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This interpretation is further supported by the large-scale CBCT study of Gu et al.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], who demonstrated that although the distance between posterior root apices and the sinus floor increased with age, anatomical proximity patterns themselves showed limited sex and side dependency, highlighting structural relationships as relatively stable determinants across demographic strata.\u003c/p\u003e \u003cp\u003eOne of the main findings of this study is that proximity Type 2 was the most frequently encountered anatomical pattern, and that the prevalence of mucosal thickening increased progressively from Type 1 to Type 3 on both sides. This graded distribution supports the concept that closer spatial relationships between posterior maxillary tooth roots and the sinus floor are associated with a higher likelihood of mucosal alterations. Similar patterns have been reported in previous CBCT studies, which emphasized that roots located in close contact with or protruding into the sinus cavity may facilitate the spread of inflammatory mediators and odontogenic infection to the sinus mucosa [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn line with these findings, Gu et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] reported that root apices extending into or contacting the maxillary sinus (Type IS and Type CO) were most frequently observed in palatal roots of first molars and mesiobuccal roots of second molars, anatomical sites that are also commonly implicated in odontogenic sinus pathology. Similarly, Ok et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] demonstrated that posterior maxillary molars\u0026mdash;particularly second molars\u0026mdash;exhibit the closest proximity to the sinus floor in the Turkish population, underscoring the consistency of these anatomical risk patterns across different ethnic groups.\u003c/p\u003e \u003cp\u003eNair et al. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] proposed that minimal bony separation between root apices and the sinus floor may reduce the anatomical barrier to inflammatory diffusion, thereby increasing the susceptibility of the Schneiderian membrane to thickening. Likewise, Yusufoğlu et al. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] demonstrated that variations in tooth\u0026ndash;sinus relationships significantly influence sinus mucosal thickening, particularly in the presence of periapical or periodontal pathology. Taken together, these findings support the biological plausibility of the present results and suggest that anatomical proximity should be considered a relevant structural risk factor for sinus mucosal alterations, independent of overt dental disease [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFrom a surgical and anatomical perspective, this concept is further reinforced by the recent three-dimensional CBCT reconstruction study of Huang et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], which demonstrated that palatal roots of maxillary molars frequently exhibit root apex planes located at or above the sinus floor, thereby increasing the likelihood of sinus involvement during both endodontic microsurgery and pathological processes. Although Huang et al.[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] focused primarily on surgical access pathways, their morphometric data indirectly support the notion that palatal root proximity constitutes a critical anatomical vulnerability zone for sinus mucosal reactions.\u003c/p\u003e \u003cp\u003eA key strength of the present study lies in the use of both binary and ordinal multivariable regression models, which allowed the assessment of anatomical proximity as an independent predictor of not only the presence but also the severity of mucosal thickening. Even after adjustment for age, sex, diabetes, cardiovascular disease, and smoking, proximity type remained a strong predictor of mucosal thickening on both sides. This indicates that the observed association is robust and not substantially confounded by systemic inflammatory or vascular conditions.\u003c/p\u003e \u003cp\u003eThese findings are in line with previous studies reporting significant associations between odontogenic conditions and sinus mucosal alterations [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Jouhar et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] showed that periapical and periodontal pathologies exert a measurable effect on sinus mucosal thickening, particularly when dental roots are located close to the sinus floor. Similarly, Kaimal and Patil [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] reported that periapical lesions in maxillary posterior teeth were strongly associated with mucosal thickening on CBCT. The present study extends these observations by demonstrating that anatomical proximity itself exerts an independent effect, even in the absence of explicit dental pathology, highlighting the importance of structural factors in sinus health.\u003c/p\u003e \u003cp\u003eImportantly, while most prior studies\u0026mdash;including Gu et al.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] and Ok et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u0026mdash;relied primarily on descriptive or univariable analyses, the current study contributes novel evidence by confirming this anatomical effect within a fully adjusted multivariable framework. This methodological advancement strengthens the causal inference that proximity type represents a fundamental anatomical determinant rather than merely a surrogate marker of coexisting dental pathology.\u003c/p\u003e \u003cp\u003eInterestingly, male sex emerged as a significant predictor of mucosal thickening on the left side but not on the right. Although the clinical relevance of this asymmetry remains unclear, similar sex-related tendencies have been reported in previous studies [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. This finding may reflect subtle differences in craniofacial morphology or sinus anatomy between sexes, as suggested in morphometric CBCT studies [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Gu et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], however, reported minimal sex-related differences in root\u0026ndash;sinus distance, suggesting that sex effects may be context-dependent and potentially modulated by population-specific anatomical characteristics.\u003c/p\u003e \u003cp\u003eThe use of a 2 mm threshold to define pathological mucosal thickening in the present study is consistent with widely accepted radiological criteria in the literature [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Terlemez et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] reported substantial variability in the prevalence of mucosal thickening, ranging from 12% to over 60%, depending on population characteristics, imaging protocols, and diagnostic thresholds. This variability highlights the importance of standardized definitions when comparing results across studies.\u003c/p\u003e \u003cp\u003e Notably, the absence of significant associations between systemic conditions such as diabetes, cardiovascular disease, and smoking and mucosal thickening in the present study suggests that local anatomical and odontogenic factors may play a more dominant role than systemic influences in determining sinus mucosal status. This observation is consistent with earlier CBCT-based studies that found limited or inconsistent effects of systemic variables on sinus pathology [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. From a clinical perspective, these findings underscore the importance of careful radiological evaluation of tooth\u0026ndash;sinus relationships during dental treatment planning, particularly in implant dentistry, sinus floor elevation procedures, and endodontic interventions involving posterior maxillary teeth.\u003c/p\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eThis study has several limitations. First, its retrospective design precludes definitive conclusions regarding causality between anatomical proximity and mucosal thickening. Second, although CBCT provides high-resolution anatomical information, the absence of clinical and endoscopic correlation limits interpretation of mucosal thickening as a purely radiological finding. Third, although major systemic factors were included in the regression models, other potential confounders such as detailed periodontal status, periapical pathology severity, or sinonasal clinical history were not systematically evaluated. Finally, the relatively young age distribution may limit generalizability to older populations with a higher prevalence of sinus pathology and systemic comorbidities.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study demonstrates that anatomical proximity between posterior maxillary tooth roots and the maxillary sinus floor is an independent predictor of both the presence and severity of maxillary sinus mucosal thickening. Increasing proximity between tooth roots and the sinus floor was consistently associated with higher likelihood and severity of mucosal thickening, independent of demographic and systemic factors. These findings indicate that anatomical tooth\u0026ndash;sinus relationships represent a significant structural determinant of sinus mucosal status.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, CBCT-based assessment of root\u0026ndash;sinus proximity may improve diagnostic accuracy and risk assessment in the posterior maxilla. Careful evaluation of anatomical proximity should therefore be considered during treatment planning, particularly in implant dentistry, endodontic therapy, and surgical procedures involving the maxillary sinus. Recognition of anatomical proximity as a risk factor may contribute to improved clinical decision-making and prevention of sinus-related complications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e: The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Committee Approval Approval date and number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study received ethical approval from the Research Ethics Committee of the Faculty of Dentistry at Necmettin Erbakan University, and the study conducted in accordance with the Helsinki Declaration of Human Rights guidelines (Approval No:2024/526 – Approval Date:26.12.2024). Informed consents were obtained from all patients, and all data were processed anonymously.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConcept - AA; Design - AA; Supervision - AA; Resources – AA, CNY; Data Collection and/or Processing –CNY, AA; Analysis and/or Interpretation – AA, CNY; Literature Search – AA, CNY; Writing Manuscript –AA, CNY; Critical Review – AA.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFinancial Disclosure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData is available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDogan ME, Uluisik N, Yuvarlakbas SD. 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Sinusitis. 2025;9:9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePenarrocha-Oltra S, Soto-Penaloza D, Bagan-Debon L, Bagan-Sebastian JV, Penarrocha-Oltra D. Association between maxillary sinus pathology and odontogenic lesions in patients evaluated by cone beam computed tomography: a systematic review and meta-analysis. Med Oral Patol Oral Cir Bucal. 2019;25:e34\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuligowski P, Jaron A, Preuss O, Gabrysz-Trybek E, Bladowska J, Trybek G. Association between odontogenic and maxillary sinus conditions: a retrospective cone-beam computed tomographic study. J Clin Med. 2021;10:2849.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRiekki VP, Nevalainen MT, Haapea M, Sipola A, Kallio-Pulkkinen S, Bode MK. Associations between odontogenic and sinus pathologies: a low-dose CBCT study. 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Prevalence of maxillary sinus pathology based on cone-beam computed tomography evaluation of multiethnicity dental school population. Implant Dent. 2019;28:356\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBornstein MM, Yeung AWK, Tanaka R, von Arx T, Jacobs R, Khong PL. Evaluation of health or pathology of bilateral maxillary sinuses in patients referred for cone beam computed tomography using a low-dose protocol. Int J Oral Maxillofac Surg. 2018;38:699\u0026ndash;710.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGu Y, Sun C, Wu D, Zhu Q, Leng D, Zhou Y. Evaluation of the relationship between maxillary posterior teeth and the maxillary sinus floor using cone-beam computed tomography. BMC Oral Health. 2018;18:164.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNair AK, Jose M, Sreela L, Prasad TS, Mathew P. Prevalence and pattern of proximity of maxillary posterior teeth to maxillary sinus with mucosal thickening: a cone beam computed tomography based retrospective study. Acta Med Acad. 2023;22:327\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOk E, Gungor E, Colak M, Altunsoy M, Nur BG, Aglarci OS. Evaluation of the relationship between the maxillary posterior teeth and the sinus floor using cone-beam computed tomography. Surg Radiol Anat. 2014;36:907\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShanbhag S, Karnik P, Shirke P, Shanbhag V. Association between periapical lesions and maxillary sinus mucosal thickening: a retrospective cone-beam computed tomographic study. J Endod. 2013;39:853\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang X, Xu J, Hou B, Wang Y. Proximity of maxillary molar palatal roots to adjacent structures for endodontic microsurgery: a cone-beam computed tomography study. BMC Oral Health. 2025;25:21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJouhar R, Alkhames HM, Ahmed MA, Almadeh NM, Faheemuddin M, Umer MF. CBCT evaluation of periapical pathologies in maxillary posterior teeth and their relationship with maxillary sinus mucosal thickening. Healthc (Basel). 2023;11:787.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaimal VG, Patil BJ. Evaluation of association between maxillary posterior teeth periapical pathologies and maxillary sinus mucosal changes: a cone-beam computed tomography study. Indian J Radiol Imaging. 2024;34:246\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJanner SF, Caversaccio MD, Dubach P, Sendi P, Buser D, Bornstein MM. Characteristics and dimensions of the Schneiderian membrane: a radiographic analysis using cone beam computed tomography in patients referred for dental implant surgery in the posterior maxilla. Clin Oral Implants Res. 2011;22:1446\u0026ndash;53.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTerlemez A, Tassoker M, Kizilcakaya M, Gulec M. Comparison of cone-beam computed tomography and panoramic radiography in the evaluation of maxillary sinus pathology related to maxillary posterior teeth. Imaging Sci Dent. 2019;49:115\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrullmann DD, Schmidtmann I, Hornstein S, Schulze RK. Correlation of cone beam computed tomography findings in the maxillary sinus with dental diagnoses: a retrospective cross-sectional study. Clin Oral Investig. 2012;16:1023\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Cone-beam computed tomography, Maxillary sinus, Molars, Mucosal thickening","lastPublishedDoi":"10.21203/rs.3.rs-8984640/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8984640/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eThis study aimed to investigate the association between anatomical proximity of posterior maxillary tooth roots to the maxillary sinus floor and both the presence and severity of maxillary sinus mucosal thickening (MT) using cone-beam computed tomography (CBCT).\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eA retrospective CBCT-based analysis was performed on 300 patients (175 females, 125 males; mean age: 27.55\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74 years). Root\u0026ndash;sinus anatomical relationships were classified into three proximity types based on increasing root\u0026ndash;sinus closeness. Maxillary sinus mucosal thickness was measured in millimeters, and mucosal thickening was defined using both a binary threshold (\u0026gt;\u0026thinsp;2 mm vs. \u0026le;2 mm) and an ordinal severity classification (\u0026le;\u0026thinsp;2 mm, 2\u0026ndash;10 mm, \u0026gt;\u0026thinsp;10 mm). Multivariable binary logistic regression and ordinal logistic regression analyses were conducted to evaluate the independent association between proximity type and mucosal thickening, after adjustment for age, sex, diabetes, cardiovascular disease, and smoking status.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eMucosal thickening (\u0026gt;\u0026thinsp;2 mm) was observed in 34.7% of patients on both sides. Proximity type was significantly associated with mucosal thickening on the right and left sides (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). In multivariable binary logistic regression, each one-unit increase in proximity type was associated with a 2.58-fold increase in the odds of mucosal thickening on the right side (OR\u0026thinsp;=\u0026thinsp;2.58; 95% CI: 1.61\u0026ndash;4.12; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and a 1.93-fold increase on the left side (OR\u0026thinsp;=\u0026thinsp;1.93; 95% CI: 1.23\u0026ndash;3.03; p\u0026thinsp;=\u0026thinsp;0.004). Ordinal logistic regression further demonstrated that proximity type was an independent predictor of greater mucosal thickening severity on both sides (right: OR\u0026thinsp;=\u0026thinsp;2.43; left: OR\u0026thinsp;=\u0026thinsp;1.90; both p\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Age showed a modest independent association, whereas systemic factors, including diabetes, cardiovascular disease, and smoking, were not significantly associated with mucosal thickening.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAnatomical proximity between posterior maxillary tooth roots and the sinus floor is a strong and independent predictor of both the presence and severity of maxillary sinus mucosal thickening. These findings emphasize the clinical importance of evaluating tooth\u0026ndash;sinus anatomical relationships in CBCT-based diagnostic assessment and treatment planning in the posterior maxilla.\u003c/p\u003e","manuscriptTitle":"Anatomical Proximity Between Posterior Maxillary Tooth Roots and Sinus Floor Independently Predicts Mucosal Thickening: A CBCT Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-18 08:32:15","doi":"10.21203/rs.3.rs-8984640/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a5f7caaf-2ecb-4345-a517-2f3fc09b96f6","owner":[],"postedDate":"March 18th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-02T09:13:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-18 08:32:15","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8984640","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8984640","identity":"rs-8984640","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}