Anatomical Analysis of Maxillary Third Molars with Cone-Beam Computed Tomography: Implications for Autotransplantation Operation

Anatomical Analysis of Maxillary Third Molars with Cone-Beam Computed Tomography: Implications for Autotransplantation Operation | 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 Analysis of Maxillary Third Molars with Cone-Beam Computed Tomography: Implications for Autotransplantation Operation Mingdi Xiang, yifan Sun, Siqian Hong, Yun Yan, Qifei Ge, Qinxin Wu, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7699422/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 13 Jan, 2026 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted 9 You are reading this latest preprint version Abstract Purpose Maxillary third molars (MTMs) are frequently utilized as donor teeth in autogenous tooth transplantation (ATT). This study aimed to characterize and grade MTMs’ CBCT features to inform ATT operation. Methods This retrospective CBCT analysis evaluated 800 MTMs from 537 patients regarding tooth morphology, root canal configuration, and impaction status. A CBCT-based binary complexity grading for MTM autotransplantation was established, and its clinical relevance to the operative difficulty of ATT and its adjunctive procedures (root canal treatment, RCT) was analyzed in 26 ATT cases using both a subjective five-point scale and operation time. Results Predominant characteristics of MTMs included: 1-rooted morphology (65.63%), Vertucci’s Type-I canal configuration (76.17%), root canal curvature 10°- 30° (35.44%), and non-impaction status (77.75%). Mean root length was 10.66 ± 1.56 mm, canal length 16.95 ± 1.79 mm, crown-to-root ratio 1:1.8, and maximum root cross-sectional area (CSA) 60.21 ± 13.08 mm². Significant clinical relevance (P < 0.05) was found between atraumatic tooth extraction and root number, impaction direction, and depth of MTMs; between recipient-site preparation and cervical buccolingual width, mesiodistal width, root number, and maximum root CSA; between RCT and the canal configuration and curvature; and between ATT operation time and impaction depth and root number. Conclusions MTM CBCT characteristics exhibit significant anatomical variation and are relevant to ATT complexity. The CBCT-based binary complexity grading for MTM autotransplantation predicts procedural difficulty and would facilitate comprehensive preoperative evaluation for ATT. Autogenous tooth transplantation CBCT Maxillary third molar Anatomical analysis Root canal Root morphology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Autogenous tooth transplantation (ATT)—surgical relocation of a tooth within the same individual—offers a viable solution for functional and aesthetic rehabilitation [ 1 , 2 ]. Compared to dental implants, ATT confers distinct advantages: preserved proprioception, maintained periodontal ligament viability, favorable loading characteristics, enhanced alveolar bone preservation, superior aesthetics, and intact interdental papillae [ 3 – 5 ]. ATT is a complex procedure involving multiple stages (Fig. 1 ): atraumatic donor tooth extraction, recipient site preparation, tooth transplantation/stabilization, and adjunctive procedures like postoperative root canal treatment (RCT) for teeth with complete root formation [ 5 ]. Reported ATT success rates range 60–95% (survival: 77–100%), with key prognostic factors including periodontal ligament integrity, minimally invasive techniques and optimal donor positioning, extra-alveolar time and RCT outcomes [ 6 ]. Maxillary third molars (MTMs) have gained renewed clinical significance as frequently utilized donor teeth, with the advancement of ATT techniques. Among donor teeth for ATT, MTMs are frequently selected as they are easily accessible and their removal typically has minimal functional or aesthetic consequences [ 3 ]. A retrospective study involving 614 teeth revealed that MTMs accounted for 36.8% of all donor teeth [ 4 ]. Given substantial radiographic variations in MTM anatomical morphology, root canal configuration, and impaction status, these characteristics may influence both ATT procedural complexity and clinical outcomes. Systematic morphological analysis of MTMs would therefore provide valuable clinical insights for preoperative planning, complexity assessment, and outcome prediction. Cone-beam computed tomography (CBCT) is recommended prior to ATT. Compared to traditional two-dimensional imaging, CBCT provides detailed radiographic characterization of donor tooth and offers precise information on the recipient site for ATT, thereby assisting clinicians in creating accurate preoperative designs [ 7 ]. Moreover, CBCT-based computer-aided rapid prototyping generates exact three-dimensional (3D) printed surgical guides by capturing anatomical details of donor teeth [ 8 ]. This technology enables providing visualization for preoperative planning and intraoperative guidance for alveolus preparation [ 9 ]. MTMs were previously considered non-therapeutic, resulting in limited CBCT morphological studies compared to other teeth. However, as MTMs now serve as vital donor teeth in ATT, comprehensive analysis of their CBCT characteristics has become clinically imperative. This study bridges current knowledge limitations via systematic MTM CBCT feature documentation. Furthermore, this study established a CBCT-based binary complexity grading for MTM autotransplantation; preliminary clinical validation demonstrated its significant predictability for procedural difficulty in ATT. Materials and Methods Data Resources This study analyzed CBCT scans from 537 patients (212 males and 325 females), encompassing 800 MTMs (421 right-sided and 379 left-sided). The imaging data were retrospectively collected from the Department of Medical Imaging between August and November 2024. This study has been approved by the Ethics Committee of Zhejiang Provincial Stomatological Hospital (Approval No. 2024-094). All procedures conducted in this study involving human participants adhered to ethical standards and were performed in accordance with the 1964 Helsinki Declaration. Scanning Parameters CBCT imaging was performed using a NewTom VGi system (CEFLA S.C., Italy) with the following acquisition parameters: standard-dose regular scan mode, tube voltage of 110 kV, tube current automatically adjusted by the system’s optimization, exposure time of 4.3 seconds, and a field of view of 12 × 8 cm in HiRes mode with a voxel size of 0.25 mm. CBCT Assessment CBCT datasets were imported into Mimics software (v21.0; Materialise, Leuven, Belgium). Three oral radiologists, each with over five years of specialized dental CBCT interpretation experience, underwent standardized training using 20 additional CBCT scans prior to the study. Inter-rater reliability was quantified using the intraclass correlation coefficient (ICC), demonstrating excellent agreement (ICC = 0.93; 95% CI: 0.87–0.98). During the formal study phase, quantitative measurements were averaged across observers; categorical classifications underwent consensus review to resolve discrepancies. Analyses focused on root number, tooth dimensions, root canal configuration, canal curvature, and impaction status. Classification of root number The root number was recorded as ranging from one to five. Roots were classified as single if the furcation occurred beyond the 3/4 level of the root length; those with furcation within this level were classified as multi-rooted teeth [ 10 ]. Classification of root canal configuration According to the Vertucci’s classification, root canal configuration in each root was categorized into the following eight types (Ⅰ-Ⅷ) [ 11 ]. Measurement of tooth dimension Ten measurement parameters for tooth dimensions were defined (Fig. 2 ): (1) Total tooth length: The vertical distance along the tooth’s long axis from the cusp tip to the root apex.(2) Crown length: The vertical distance along the tooth’s long axis from the cusp tip to the cementoenamel junction (CEJ).(3) Root length: The vertical distance along the tooth’s long axis from the root apex to the CEJ. (4) Root canal length: The distance along the root canal from the cusp reference point to the apical foramen. (5) Crown mesiodistal width: The maximum distance between proximal contact points perpendicular to the tooth’s long axis at the coronal third.(6) Crown buccolingual width: The maximum distance between buccal and lingual surfaces perpendicular to the tooth’s long axis at the coronal third.(7) Cervical mesiodistal width: The maximum distance at the CEJ perpendicular to the long tooth’s axis in mesiodistal orientation.(8) Cervical buccolingual width: The maximum distance at the CEJ perpendicular to the long tooth’s axis in buccolingual orientation.(9) Crown-root ratio (CRI): The ratio of crown length to root length (crown length/root length).(10) Maximum root cross-sectional area (Maximum root CSA): The maximum cross-sectional area obtained from serial sections perpendicular to the tooth’s long axis. Assessment of root canal curvature The Weine method was implemented to assess root canal curvature (Fig. 1 ) [ 12 ]. On each individual root canal, the following points were identified: coronal p1: the midpoint of the straight portion of the canal in the coronal third (approximately 2 mm below the CEJ); apical p2: the midpoint of the straight portion in the apical third (approximately 1 mm short of the radiographic apex); p3 of maximum curvature: the point where the canal deviates most abruptly from a straight line. Draw a straight line connecting p1 to p3 (coronal reference line), and another line connecting p2 to p3 (apical reference line). The angle (α) formed by the intersection of these two lines was measured and recorded as the angle of curvature. The curvature angle α of the root canal was categorized into three grades: 0° < α ≤ 10°, 10° 30° [ 13 ]. If two or more curvatures exist, it was defined as an S-shaped root canal. For each single curved canals, the location of the root canal curvature was determined by the ratio p = line p1p2/ line p2p3: coronal third (p ≤ 0.5), middle third (0.5 2) . Classification of impaction status The impaction status of MTMs was categorized into two types: impacted and non-impacted [ 14 ] According to Winter’s classification [ 15 ], impacted teeth were further categorized into six types: vertical, mesial, distal, buccal, palatal, and horizontal impaction. Based on the Pell & Gregory classification, the depth of impaction was divided into three levels: Level A, Level B, Level C [ 16 ]. CBCT-based binary complexity grading for MTM autotransplantation The complexity of ATT procedures—including recipient site preparation, atraumatic donor tooth extraction, and related procedures like post-transplantation RCT—may correlate with MTM characteristics on CBCT. No dedicated difficulty grading system exists specifically for ATT. Through comprehensive literature review on tooth morphology and extraction difficulty factors[ 15 – 19 ] combined with relevant clinical consensus (e.g., RCT difficulty consensus [ 20 ]), this study categorized MTMs’ CBCT features into low- or high-complexity grades (Table 1 ). In this proposed grading system, Level C impaction depth [ 15 ], horizontal impactions [ 17 ], and multi-rooted anatomy [ 18 ] were designated high complexity due to increased tooth/bony resistance. Since MTMs are typically transplanted to molar sites, recipient sockets must exceed donor tooth dimensions to prevent insertion trauma; thus donor teeth exceeding average molar measurements (cervical mesiodistal width > 9 mm, buccolingual width > 10 mm, or maximum root CSA > 71 mm²) were graded as high complexity [ 19 ]. Complex root canal configurations—including curvatures > 30°, S-shaped canals, apical curvature positions (p > 2), and canal lengths ≥ 30 mm—were also graded as high complexity [ 20 ]. For multi-canaled teeth, the most challenging canal determines the overall grade. Table 1 CBCT-based binary complexity grading for MTM autotransplantation Criteria Low Complexity High Complexity Root number 18,20 □1; 2 □≥ 3 Root canal configuration 20 □Type1-1; 1–2; 2 − 1; 2–2 □Other types Canal curvature angle 20 □straight canal; α ≤ 30° □α > 30°; S-shaped root canal Canal curvature position 20 □straight canal; p ≤ 2 □p > 2 Canal length 20 □≤ 30 mm □>30 mm Impaction depth 15 □Non-impacted; Level A; Level B □Level C Impaction direction 17 □Vertical; Mesial; Distal; Buccal; Palatal □Horizontal Root length 19,20 □≤ 14 mm □>14 mm Cervical mesiodistal width 19 □≤ 9 mm □>9 mm Cervical buccolingual width 19 □≤ 10 mm □>10 mm Maximum root cross-sectional area 19 □≤ 71 mm 2 □>71 mm 2 Clinical application of the complexity grading To validate the CBCT-based binary complexity grading for MTM autotransplantation, a prospective clinical study was conducted from January to July 2025. Twenty-six ATT procedures were performed by an oral surgeon with 6 years of ATT specialization. ATT protocols included recipient site preparation, atraumatic donor tooth extraction, transplantation with stabilization, and postoperative RCT at 3 weeks conducted by an endodontist with 8 years of RCT expertise. Preoperatively, MTMs’ CBCT characteristics were analyzed and complexity grading assigned. Postoperatively, the following parameters were recorded immediately: (1) total operative time (anesthesia to suture completion); (2) operative-rated difficulty of atraumatic extraction, recipient site preparation, and post-transplantation RCT (five -point Likert scale): one = Very easy; two = Easy; three = Moderate; four = Difficult; five = Very difficult. Statistical analysis Statistical analyses were performed using R software (version 4.2.1; R Foundation for Statistical Computing, Vienna, Austria). Measurement data are presented as mean ± standard deviation (mean ± SD), while count data are expressed as n (%). The chi-square test was employed for categorical variables. The Likert scale ratings (five points) for atraumatic extraction; recipient site preparation; post-transplantation RCT were analyzed using non-parametric Wilcoxon rank-sum tests, while their correlations with CBCT grading were assessed using Kendall’s Tau-b coefficient (given the limited sample size). Statistical analysis of surgical time was performed after first verifying homogeneity of variance, with intergroup comparisons conducted using independent samples t-tests and Pearson correlation employed to examine time difficulty relationships. A P -value of less than 0.05 was considered statistically significant. Results Root number The most frequent root number was 1-rooted (65.63%). There was significant gender-based differences in root number distribution (p < 0.001). Females exhibited a higher frequency of 1-rooted MTMs compared to males (Table 2 ). Representative 3D models and CBCT slices illustrating MTMs with root numbers ranging from one to five are depicted in Fig. 3 . Table 2 Classification of root number in MTMs n (%) Root number Side Gender *** Total Left (28) Right (18) Male Female 1-rooted 248 (31.00) 277 (34.63) 169 (21.13) 356 (44.50) 525 (65.63) 2-rooted 47 (5.88) 50 (6.25) 45 (5.63) 52 (6.50) 97 (12.13) 3-rooted 80 (10.00) 89 (11.13) 96 (12.00) 73 (9.13) 169 (21.13) 4-rooted 3 (0.38) 5 (0.63) 5 (0.63) 3 (0.38) 8 (1.00) 5-rooted 1 (0.13) - 1 (0.13) - 1 (0.13) Total 379 (47.38) 421 (52.63) 316 (39.50) 484 (60.50) 800 (100) *** Significant statistical differences in root number distribution between genders (χ² test, P < 0.001). Root canal configuration A total of 1263 root were detected (Table 3 ). Among them, the most frequent canal morphology was Type Ⅰ (1–1) (76.11%). One-rooted MTMs contained a rich variety of root canal types, including the seven Vertucci’s types and other atypical types, while 4-rooted and 5-rooted MTMs containing only Type Ⅰ (1–1). Representative 3D models and CBCT slices illustrating MTMs with various Vertucci’s canal morphology and 11 atypical root canal types are depicted in Fig. 4 . Table 3 The Vertucci’s classification of root canal systems in MTMs n (%) Root number Root location Type Ⅰ Type Ⅱ Type Ⅲ Type Ⅳ Type Ⅴ Type Ⅵ Type Ⅷ Atypical 1–1 2 − 1 1-2-1 2–2 1–2 2-1-2 3–3 1-rooted - 307 (24.31) 39 (3.09) 10 (0.79) 54 (4.28) 15 (1.19) 1 (0.08) 36 (2.85) 63 (4.99) 2-rooted B 57 (4.51) 11 (0.87) 4 (0.32) 11 (0.87) 7 (0.55) - 1 (0.08) 6 (0.48) P 81 (6.41) 6 (0.48) 1 (0.08) 7 (0.55) 2 (0.16) - - - 3-rooted MB 143 (11.32) 1 (0.08) 1 (0.08) 12 (0.95) 12 (0.95) - - - DB 168 (13.30) - - - 1 (0.08) - - - P 169 (13.38) - - - - - - - 4-rooted - 32 (2.53) - - - - - - - 5-rooted - 5 (0.40) - - - - - - - Total - 962 (76.17) 57 (4.51) 16 (1.27) 84 (6.65) 37 (2.93) 1 (0.08) 37 (2.93) 69(5.46) Atypical: The 69 atypical cases comprised: 5 type 2–3, 5 type 3 − 1, 11 type 3 − 2, 2 type 2-3-1, 2 type 2-3-2, 2 type 3-2-1, 1 type 3-4-3, 3 type 2-3-2-1, 1 type 2-3-2-3, 21 type C-shaped, 16 type Y(V)-shaped canals. Root abbreviations: B (buccal), P (palatal), MB (mesiobuccal), DB (distobuccal). Tooth dimension The dimensions of 800 MTMs are presented in Table 4 . The root length was 10.66 ± 1.56 mm, with 3-rooted MTMs having the longest roots at 11.22 mm and 4/5-rooted MTMs the shortest at 10.18 mm. The CRI was approximately 1:1.8, and the maximum root CSA was 60.21 ± 13.08 mm². Canal measurements revealed an average 16.95 ± 1.79 mm length. All MTMs exhibited consistent cervical constriction with nearly 1–2 mm reduction in both mesiodistal and buccolingual diameters relative to coronal dimensions. Table 4 The tooth dimension measurements (mean ± SD) in MTMs Root number Crown mesiodistal width (mm) Cervical mesiodistal width (mm) Crown buccolingual width (mm) Cervical buccolingual width (mm) Tooth length (mm) Crown length (mm) Root length (mm) Canal length (mm) Crown/Root ratio Maximum root cross-sectional area(mm 2 ) 1-rooted 8.71 ± 1.15 6.77 ± 0.91 10.08 ± 1.44 9.08 ± 1.39 16.26 ± 1.83 5.83 ± 0.73 10.44 ± 1.57 16.57 ± 1.80 1:1.81 ± 0.33 54.79 ± 11.88 2-rooted 9.28 ± 0.80 7.31 ± 0.79 10.96 ± 0.78 9.95 ± 0.75 17.00 ± 1.66 6.06 ± 0.74 10.93 ± 1.59 17.25 ± 1.63 1:1.83 ± 0.37 66.75 ± 8.20 3-rooted 9.60 ± 0.77 7.57 ± 0.72 11.77 ± 0.79 10.18 ± 0.89 17.33 ± 1.50 6.13 ± 0.81 11.22 ± 1.34 17.95 ± 1.38 1:1.84 ± 0.31 72.55 ± 7.21 4&5-rooted 9.89 ± 0.87 7.52 ± 0.67 11.70 ± 1.18 9.89 ± 0.54 16.42 ± 0.02 6.33 ± 0.96 10.18 ± 1.74 17.06 ± 2.02 1:1.66 ± 0.34 74.32 ± 5.95 Total 8.98 ± 1.11 7.01 ± 0.92 10.43 ± 1.35 9.43 ± 1.33 16.58 ± 1.80 5.92 ± 0.76 10.66 ± 1.56 16.95 ± 1.79 1:1.82 ± 0.33 60.21 ± 13.08 Root canal curvature Analysis of 1631 root canals revealed 76.33% root canal curvature (Table 5 ), predominantly single curves (73.69%). Root canal curvature α followed this distribution: Grade Ⅲ (α > 30°, 37.34%), Grade Ⅱ(10° < α ≤ 30°,35.44%), and Grade Ⅰ (0° < α ≤ 10°, 0.92%). Curvature positions were most frequent in Grade Ⅱ (57.88%; 0.5 10°) curvatures collectively represented 72.78%, with mid-root (Grade II) being the most frequent position. Table 5 The curvature of root canals in MTMs n (%) Root number Root location Straight canals Single-curved canals S-shaped canals Canal curvature angulation (α) Canal curvature position (p) Canal curvature direction 0°<α ≤ 10° 10°30° p2 Mesial Distal Palatal Buccal 1-rooted - 244 (14.96) 6 (0.37) 247 (15.14) 297 (18.21) 32 (1.96) 381 (23.36) 137 (8.40) 112 (6.87) 196 (12.02) 66 (4.05) 176 (10.80) 18 (1.10) 2-rooted B 33 (2.02) 2 (0.12) 51 (3.13) 41 (2.51) 4 (0.25) 83 (5.09) 7 (0.43) 25 (1.53) 42 (2.58) 20 (1.23) 7 (0.43) 8 (0.49) P 36 (2.21) 2 (0.12) 38 (2.33) 37 (2.27) 4 (0.25) 65 (3.99) 8 (0.49) 8 (0.49) 5 (0.31) 4 (0.25) 60 (3.68) - 3-rooted MB 12 (0.74) 1 (0.06) 67 (4.11) 106 (6.50) 13 (0.80) 160 (9.81) 1 (0.06) 3 (0.18) 161 (9.87) 5 (0.31) 5 (0.31) 9 (0.55) DB 18 (1.10) 3 (0.18) 89 (5.46) 53 (3.25) 15 (0.92) 124 (7.60) 6 (0.37) 132 (8.09) 11 (0.67) 2 (0.12) - 7 (0.43) P 33 (2.02) 1 (0.06) 76 (4.66) 58 (3.56) 4 (0.25) 109 (6.68) 22 (1.35) 3 (0.18) 1 (0.06) 2 (0.12) 129 (7.91) 1 (0.06) 4&5-rooted - 10 (0.61) - 10 (0.61) 17 (1.04) 3 (0.18) 22 (1.35) 2 (0.12) 9 (0.55) 11 (0.67) - 7 (0.43) - Total - 386 (23.67) 15 (0.92) 578 (35.44) 609 (37.34) 75 (4.60) 944 (57.88) 183 (11.22) 292 (17.90) 427 (26.18) 99 (6.07) 384 (23.54) 43 (2.64) Root abbreviations: B (buccal), P (palatal), MB (mesiobuccal), DB (distobuccal). Impaction status Among 800 MTMs, 22.25% (n = 178) were impacted, with mesial impaction being most frequent (12.38%) and horizontal impaction least frequent (0.75%). Impaction depth analysis revealed Level C predominance (82.59%) (Table 6 ). Table 6 The impaction status in MTMs n (%) Root number Non-impacted impaction direction impaction depth Vertical Mesial Distal Buccal Palatal Horizontal Level A Level B Level C 1-rooted 392 (49.00) 9 (1.13) 75 (9.34) 8 (1.00) 30 (3.75) 6 (0.75) 5 (0.63) 4 (0.50) 15 (1.88) 114 (14.25) 2-rooted 73 (9.00) 2 (0.25) 12 (1.50) 2 (0.25) 4 (0.50) 3 (0.38) 1 (0.13) 2 (0.25) 3 (0.38) 19 (2.38) 3-rooted 151 (18.88) 4 (0.50) 10 (1.25) 1 (0.13) 2 (0.25) 1 (0.13) - 1 (0.13) 5 (0.63) 12 (1.50) 4༆5-rooted 6 (0.75) - 2 (0.25) - 1 (0.13) - - - 1 (0.13) 2 (0.25) Total 622 (77.75) 15 (1.88) 99 (12.38) 11 (1.38) 37 (4.63) 10 (1.25) 6 (0.75) 7 (0.88) 24 (3.00) 147 (18.38) CBCT-based binary complexity grading for MTM autotransplantation Analysis of 800 MTMs revealed distinct CBCT difficulty grades (Fig. 5 ): For low complexity, canal length was the most frequent factor (n = 800, 100%), followed by impaction direction (n = 794, 99.25%). High complexity showed canal curvature angle being the most frequent (n = 433, 54.13%). Clinical Application of the complexity grading Correlational analysis between MTMs’ CBCT character-based binary difficulty grading and ATT procedural challenges revealed (Fig. 6 ): atraumatic tooth extraction difficulty showed significant correlations with root number, impaction direction, and impaction depth ( P < 0.01); recipient-site preparation difficulty exhibited significant correlations with high complexity in root number, cervical mesiodistal width, cervical buccolingual width, and maximum root CSA ( P < 0.01); post-transplantation RCT difficulty displayed significant correlation with root canal curvature position, curvature angle, and canal configuration ( P < 0.01); surgical duration significantly correlated with impaction depth and root number ( P < 0.001). Discussion MTMs are common donor teeth for ATT, yet their CBCT characteristics are understudied, attributable to their non-functional status and limited therapeutic relevance. Although some studies have explored the impact of clinical operative factors on ATT outcomes, the influence of MTMs’ unique anatomical features on RCT difficulty during transplantation procedures has yet to be thoroughly elucidated. Thus, this study conducted a comprehensive analysis of MTMs’ CBCT characteristics, encompassing root number, root canal configuration, root canal curvature, tooth dimensions, and impaction status. A considerable diversity of CBCT characteristics was observed. Previous CBCT analyses of MTM morphology, encompassing 116 cases from Central India and 238 cases from Moscow populations, have reported that most commonly, MTMs had three roots, three root canals and the MB, DB, and P canals most often showed Vertucci Type I [ 21 – 22 ]. This study focused on the East Asian Mongoloid population in China and revealed 1-rooted as the most prevalent configuration in MTMs, with Vertucci Type I being the dominant canal type. While root number prevalence differed from prior reports, the consistency in canal typing suggests ethnic variations may influence root numbers rather than internal canal morphology. Regarding root canal curvature, no studies in literature have investigated the characteristics of MTMs using CBCT imaging. One study of maxillary posterior teeth by X-ray film measurement, revealed that root canal curvatures were significantly more pronounced in the mesiodistal dimension compared to the buccolingual dimension [ 23 ]. In an in vitro study, more than 85% of maxillary first and second molars exhibited palatal root curvatures exceeding 10°, with buccal direction curvatures predominating [ 24 ]. This CBCT-based study revealed that 76.33% of root canals exhibited curvature, predominantly single curves (73.69%) with a small proportion of S-shaped configurations (2.64%); the curvatures were mainly oriented distally or buccally and located in the mid-root region. The findings demonstrate that MTMs display an intricate and diverse array of root canal curvatures. The dimensional parameters of MTMs reported in Wheeler's in vitro anatomical study and current this CBCT analysis demonstrate divergence [ 19 ]. The crown length demonstrated the most substantial discrepancy (6.5 mm vs 5.92 mm). The variations likely stem from methodological differences between Wheeler's caliper-based measurements on extracted teeth and digital CBCT reconstructions, accounting for potential tissue shrinkage in cadaveric specimens and the technical limitations of voxel resolution in CBCT scans. Population characteristics may also contribute to the divergence [ 25 ]. While many studies reported vertical impaction as predominant in MTMs, the data showed mesial impaction as the most frequent. This divergence likely stems from methodological variations in angular measurement protocols, where differences in reference planes significantly impact categorization [ 15 ]. Compared to the two-dimensional limitations of panoramic radiography, CBCT enables evaluation of the buccolingual impaction of MTMs. In a CBCT study on MTMs impaction, buccolingual impaction (74%) was most common, which is consistent with the research findings [ 15 ]. Several studies have indicated that Level C is the most common impaction depth for MTMs [ 26 ], a finding consistent with the research results. However, many studies also reported Level A/B as the predominant impaction depth [ 15 , 27 , 28 ], suggesting this variation may be associated with geographic location and ethnic differences. CBCT evaluation is essential for MTM extraction, particularly in ATT, where atraumatic techniques are required to avoid root damage that can cause resorption or ankylosis. Compared to mandibular third molars, MTMs are less studied in terms of extraction difficulty [ 29 ]. In this study, increased complexity in impaction direction, depth and root numbers significantly elevated surgeon-rated difficulty scores for atraumatic invasive extraction. Multiple roots (≥ 3) combined with deep impaction (Level C) prolonged total operative time [ 29 ]. Although, most MTMs exhibit low extraction complexity (1-rooted morphology, short mean root length, non-impacted), those with multi-rooted anatomy, deep impactions, or horizontal orientation require meticulous preoperative radiographic assessment. Precise recipient site preparation is critical for successful ATT to ensure optimal donor tooth accommodation. Size discrepancies incur increased trial fittings, prolonged extra-alveolar time, elevated root resorption rates, and periodontal ligament damage. In this study, the greater mesiodistal width, buccolingual width, and maximal root CSA were positively correlated with higher difficulty ratings for recipient site preparation. MTMs offer some advantages as donors due to their smaller dimensions and predominantly 1-rooted morphology. These characteristics reduce the need for bone removal when replacing unrestorable first or second molars. However, complex site preparation is required for edentulous sites with significant alveolar resorption. Additionally, a rational crown/root ratio and good relationship with adjacent teeth at the recipient site should also be considered. Radiographic evaluation plays a pivotal role in post-transplantation RCT. Mature teeth should undergo RCT within 2–4 weeks post-transplantation [ 30 ]. In this study, the complex root canal morphology, severe curvature (> 30°), and aberrant canal positions contributed to increased extraction difficulty scores. Significant morphological diversity was observed, with complex variants increasing treatment difficulty. Over 40% of root canals exhibited curvature exceeding 10°, mainly in the mid-root region with distal or buccal orientations, features that complicate instrumentation. Therefore, high-resolution CBCT imaging is necessary to accurately map 3D canal pathways. Current this study has certain limitations. Firstly, it didn’t fully analyze the anatomical structure around MTMs, such as their spatial relationships to the maxillary sinus and the second molar, retromolar space, and periodontal ligament width. Future research should include these variables in a comprehensive assessment framework. Secondly, while this study established correlations between MTM CBCT features and ATT and its adjunctive procedures difficulty, future investigations should evaluate the prognostic significance of these CBCT characteristics on postoperative outcomes. Conclusions CBCT characterization is informative for surgical planning and efficacy assessment when utilizing MTMs as donor teeth in ATT. Our analysis revealed considerable morphological diversity among MTMs, necessitating detailed preoperative assessment. The radiographic complexity of MTMs demonstrates a significant positive correlation with both surgical difficulty and operative duration through clinical validation. Declarations Acknowledgements Not applicable. Author contributions Xiang: project development, data collection and management, data analysis, manuscript writing and editing. Sun: project development, data management, data analysis, manuscript writing and editing. Hong: project development, data management, data analysis. Yan: project development, data collection and management. Ge: project development, data collection and management, data analysis. Wu: project development, data management, data analysis. Feng: project development, data collection and management, data analysis, manuscript writing and editing. All authors read and approved the final manuscript. Funding Not applicable. Data availability The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing interests. Ethics Statement This study has been approved by the Ethics Committee of Zhejiang Provincial Stomatological Hospital (Approval No. 2024-094). Consent to participate Written informed consent was obtained from all patients after a detailed explanation of the study procedures, potential risks, and benefits, in accordance with the principles of the Declaration of Helsinki. 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Cite Share Download PDF Status: Published Journal Publication published 13 Jan, 2026 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted Editorial decision: Revision requested 04 Nov, 2025 Reviews received at journal 04 Nov, 2025 Reviews received at journal 01 Nov, 2025 Reviewers agreed at journal 27 Oct, 2025 Reviewers agreed at journal 26 Oct, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 29 Sep, 2025 Submission checks completed at journal 26 Sep, 2025 First submitted to journal 24 Sep, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-7699422","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":528224068,"identity":"25b37904-9ac0-4dcf-a643-32fa7ff33055","order_by":0,"name":"Mingdi Xiang","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Mingdi","middleName":"","lastName":"Xiang","suffix":""},{"id":528224069,"identity":"f07343cc-3baf-41db-a844-7e29c5e80a35","order_by":1,"name":"yifan Sun","email":"","orcid":"","institution":"Zhejiang 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1","display":"","copyAsset":false,"role":"figure","size":1424248,"visible":true,"origin":"","legend":"\u003cp\u003eOperations of autogenous tooth transplantation: \u003cstrong\u003ea\u003c/strong\u003e Pre-operative CBCT images revealed the maxillary second molar (blue box) to be non-restorable due to periapical periodontitis. The planned solution involved transplating the maxillary third molar (red box) into the same region; \u003cstrong\u003eb\u003c/strong\u003e recipient site preparation; \u003cstrong\u003ec\u003c/strong\u003eatraumatic donor tooth extraction; \u003cstrong\u003ed\u003c/strong\u003e post-transplantation CBCT images; \u003cstrong\u003ee\u003c/strong\u003eCBCT images after root canal treatment.\u003c/p\u003e","description":"","filename":"Fig.1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/fdee8ded045c17f40d81aead.jpg"},{"id":93538826,"identity":"79657fe2-9709-4122-9c4c-3d95a6450fba","added_by":"auto","created_at":"2025-10-15 02:12:14","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":91797,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurements of CBCT characterization of MTMs on CBCT images: \u003cstrong\u003ea\u003c/strong\u003eroot canal length; \u003cstrong\u003eb\u003c/strong\u003e cervical mesiodistal width; \u003cstrong\u003ec\u003c/strong\u003e crown mesiodistal width; \u003cstrong\u003ed\u003c/strong\u003e root length; \u003cstrong\u003ee\u003c/strong\u003e crown length; \u003cstrong\u003ef\u003c/strong\u003e total tooth length; \u003cstrong\u003eg\u003c/strong\u003e cervical buccolingual width; \u003cstrong\u003eh\u003c/strong\u003e crown buccolingual width; \u003cstrong\u003eCSA\u003c/strong\u003e Maximum root cross-sectional area; \u003cstrong\u003ep1\u003c/strong\u003e the midpoint of the straight portion of the canal in the coronal third; \u003cstrong\u003ep2\u003c/strong\u003e the midpoint of the straight portion in the apical third; \u003cstrong\u003ep3\u003c/strong\u003e the point where the canal deviates most abruptly from a straight line; \u003cstrong\u003eα\u003c/strong\u003e root canal curvature angle.\u003c/p\u003e","description":"","filename":"Fig.2.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/1d27a3171c403732d15aa4ce.jpg"},{"id":93538829,"identity":"49f4e1be-39aa-4f90-a343-a8ec887cc8bb","added_by":"auto","created_at":"2025-10-15 02:12:14","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1188760,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative 3D reconstruction and CBCT images of MTMs with various root numbers: \u003cstrong\u003ea\u003c/strong\u003e 1-rooted; \u003cstrong\u003eb\u003c/strong\u003e 2-rooted; \u003cstrong\u003ec\u003c/strong\u003e 3-rooted; \u003cstrong\u003ed\u003c/strong\u003e4-rooted;\u003cstrong\u003e e\u003c/strong\u003e 5-rooted.\u003c/p\u003e","description":"","filename":"Fig.3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/e01e735a4b6bff2bb206574c.jpg"},{"id":93538831,"identity":"5987f1e8-574c-4260-8449-a95b0078850c","added_by":"auto","created_at":"2025-10-15 02:12:15","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":4537397,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative 3D reconstruction and CBCT images of MTMs with various canal types. \u003cstrong\u003ea-g \u003c/strong\u003e1-rooted maxillary third molars with type 1-1, type 2-1, type 1-2-1, type 2-2, type 1-2, type 2-1-2, type 3-3; \u003cstrong\u003eh-r\u003c/strong\u003e atypical root canal type 2-3, type 3-1, type 3-2, type 2-3-1, type 2-3-2, type 3-2-1, type 3-4-3, type 2-3-2-1, type 2-3-2-3, C-shaped and Y(V)-shaped.\u003c/p\u003e","description":"","filename":"Fig.4.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/3cf0ec8d6c2d436e84d8898b.jpg"},{"id":93539641,"identity":"5fc24d0b-d726-45ba-a9e6-54c040b1bdf9","added_by":"auto","created_at":"2025-10-15 02:20:15","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1412686,"visible":true,"origin":"","legend":"\u003cp\u003eCBCT-based binary complexity grading for MTMs in autogenous tooth transplantation (%). The related radiographic characteristics were categorized into low and high complexity grades. High complexity cases were defined by ≥ 3 roots, complex canal configuration, canal curvature \u0026gt; 30° or S-shaped, apical third curvature, canal length \u0026gt; 30 mm, Level C/horizontal impaction, root length \u0026gt; 14 mm, cervical width \u0026gt; 9 mm (mesiodistal) or \u0026gt; 10 mm (buccolingual), or maximum root cross-section \u0026gt; 71 mm². Maximum root CSA: Maximum root cross-sectional area.\u003c/p\u003e","description":"","filename":"Fig.5.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/fd818275b0505c0f0fb35baa.jpg"},{"id":93538833,"identity":"278c1eea-5eb8-40a2-8495-a0b461c49122","added_by":"auto","created_at":"2025-10-15 02:12:15","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":3185062,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation analysis between MTMs’ CBCT character-based binary difficulty grading and ATT procedural challenges. \u003cstrong\u003ea\u003c/strong\u003e Correlation analysis between the MTMs’ CBCT character-based binary difficulty grading and atraumatic tooth extraction, recipient-site preparation and post-transplantation RCT. \u003cstrong\u003eb\u003c/strong\u003e Correlation analysis between the MTMs’ CBCT character-based binary difficulty grading and operation time. \u003cstrong\u003ec\u003c/strong\u003e The heatmap of correlation analysis between the MTMs’ CBCT character-based binary difficulty grading and the ATT-related procedures. It utilizes a color gradient to visualize correlation strength, with red hues indicating positive correlations and blue hues representing negative correlations, where color intensity corresponds to correlation magnitude.\u003csup\u003e *\u003c/sup\u003e\u003cem\u003e P\u003c/em\u003e\u0026lt;0.05; \u003csup\u003e**\u003c/sup\u003e \u003cem\u003eP\u003c/em\u003e\u0026lt;0.01; \u003csup\u003e***\u003c/sup\u003e\u003cem\u003eP\u003c/em\u003e\u0026lt;0.001.\u003c/p\u003e","description":"","filename":"Fig.6.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/db0151911834b0b05c90259c.jpg"},{"id":100617511,"identity":"872946d8-9b2d-4e8f-a263-779cfc1d2b8d","added_by":"auto","created_at":"2026-01-19 17:53:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":13252127,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7699422/v1/0068f08c-8ff4-4e80-ab81-4180ddaac017.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Anatomical Analysis of Maxillary Third Molars with Cone-Beam Computed Tomography: Implications for Autotransplantation Operation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAutogenous tooth transplantation (ATT)\u0026mdash;surgical relocation of a tooth within the same individual\u0026mdash;offers a viable solution for functional and aesthetic rehabilitation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Compared to dental implants, ATT confers distinct advantages: preserved proprioception, maintained periodontal ligament viability, favorable loading characteristics, enhanced alveolar bone preservation, superior aesthetics, and intact interdental papillae [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. ATT is a complex procedure involving multiple stages (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e): atraumatic donor tooth extraction, recipient site preparation, tooth transplantation/stabilization, and adjunctive procedures like postoperative root canal treatment (RCT) for teeth with complete root formation [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Reported ATT success rates range 60\u0026ndash;95% (survival: 77\u0026ndash;100%), with key prognostic factors including periodontal ligament integrity, minimally invasive techniques and optimal donor positioning, extra-alveolar time and RCT outcomes [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eMaxillary third molars (MTMs) have gained renewed clinical significance as frequently utilized donor teeth, with the advancement of ATT techniques. Among donor teeth for ATT, MTMs are frequently selected as they are easily accessible and their removal typically has minimal functional or aesthetic consequences [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. A retrospective study involving 614 teeth revealed that MTMs accounted for 36.8% of all donor teeth [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Given substantial radiographic variations in MTM anatomical morphology, root canal configuration, and impaction status, these characteristics may influence both ATT procedural complexity and clinical outcomes. Systematic morphological analysis of MTMs would therefore provide valuable clinical insights for preoperative planning, complexity assessment, and outcome prediction.\u003c/p\u003e\u003cp\u003eCone-beam computed tomography (CBCT) is recommended prior to ATT. Compared to traditional two-dimensional imaging, CBCT provides detailed radiographic characterization of donor tooth and offers precise information on the recipient site for ATT, thereby assisting clinicians in creating accurate preoperative designs [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Moreover, CBCT-based computer-aided rapid prototyping generates exact three-dimensional (3D) printed surgical guides by capturing anatomical details of donor teeth [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. This technology enables providing visualization for preoperative planning and intraoperative guidance for alveolus preparation [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMTMs were previously considered non-therapeutic, resulting in limited CBCT morphological studies compared to other teeth. However, as MTMs now serve as vital donor teeth in ATT, comprehensive analysis of their CBCT characteristics has become clinically imperative. This study bridges current knowledge limitations via systematic MTM CBCT feature documentation. Furthermore, this study established a CBCT-based binary complexity grading for MTM autotransplantation; preliminary clinical validation demonstrated its significant predictability for procedural difficulty in ATT.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eData Resources\u003c/h2\u003e\u003cp\u003eThis study analyzed CBCT scans from 537 patients (212 males and 325 females), encompassing 800 MTMs (421 right-sided and 379 left-sided). The imaging data were retrospectively collected from the Department of Medical Imaging between August and November 2024. This study has been approved by the Ethics Committee of Zhejiang Provincial Stomatological Hospital (Approval No. 2024-094). All procedures conducted in this study involving human participants adhered to ethical standards and were performed in accordance with the 1964 Helsinki Declaration.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eScanning Parameters\u003c/h3\u003e\n\u003cp\u003eCBCT imaging was performed using a NewTom VGi system (CEFLA S.C., Italy) with the following acquisition parameters: standard-dose regular scan mode, tube voltage of 110 kV, tube current automatically adjusted by the system\u0026rsquo;s optimization, exposure time of 4.3 seconds, and a field of view of 12 \u0026times; 8 cm in HiRes mode with a voxel size of 0.25 mm.\u003c/p\u003e\n\u003ch3\u003eCBCT Assessment\u003c/h3\u003e\n\u003cp\u003eCBCT datasets were imported into Mimics software (v21.0; Materialise, Leuven, Belgium). Three oral radiologists, each with over five years of specialized dental CBCT interpretation experience, underwent standardized training using 20 additional CBCT scans prior to the study. Inter-rater reliability was quantified using the intraclass correlation coefficient (ICC), demonstrating excellent agreement (ICC\u0026thinsp;=\u0026thinsp;0.93; 95% CI: 0.87\u0026ndash;0.98). During the formal study phase, quantitative measurements were averaged across observers; categorical classifications underwent consensus review to resolve discrepancies. Analyses focused on root number, tooth dimensions, root canal configuration, canal curvature, and impaction status.\u003c/p\u003e\n\u003ch3\u003eClassification of root number\u003c/h3\u003e\n\u003cp\u003eThe root number was recorded as ranging from one to five. Roots were classified as single if the furcation occurred beyond the 3/4 level of the root length; those with furcation within this level were classified as multi-rooted teeth [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eClassification of root canal configuration\u003c/h3\u003e\n\u003cp\u003eAccording to the Vertucci\u0026rsquo;s classification, root canal configuration in each root was categorized into the following eight types (Ⅰ-Ⅷ) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eMeasurement of tooth dimension\u003c/h2\u003e\u003cp\u003eTen measurement parameters for tooth dimensions were defined (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e):\u003c/p\u003e\u003cp\u003e(1) Total tooth length: The vertical distance along the tooth\u0026rsquo;s long axis from the cusp tip to the root apex.(2) Crown length: The vertical distance along the tooth\u0026rsquo;s long axis from the cusp tip to the cementoenamel junction (CEJ).(3) Root length: The vertical distance along the tooth\u0026rsquo;s long axis from the root apex to the CEJ. (4) Root canal length: The distance along the root canal from the cusp reference point to the apical foramen. (5) Crown mesiodistal width: The maximum distance between proximal contact points perpendicular to the tooth\u0026rsquo;s long axis at the coronal third.(6) Crown buccolingual width: The maximum distance between buccal and lingual surfaces perpendicular to the tooth\u0026rsquo;s long axis at the coronal third.(7) Cervical mesiodistal width: The maximum distance at the CEJ perpendicular to the long tooth\u0026rsquo;s axis in mesiodistal orientation.(8) Cervical buccolingual width: The maximum distance at the CEJ perpendicular to the long tooth\u0026rsquo;s axis in buccolingual orientation.(9) Crown-root ratio (CRI): The ratio of crown length to root length (crown length/root length).(10) Maximum root cross-sectional area (Maximum root CSA): The maximum cross-sectional area obtained from serial sections perpendicular to the tooth\u0026rsquo;s long axis.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eAssessment of root canal curvature\u003c/h3\u003e\n\u003cp\u003eThe Weine method was implemented to assess root canal curvature (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. On each individual root canal, the following points were identified: coronal p1: the midpoint of the straight portion of the canal in the coronal third (approximately 2 mm below the CEJ); apical p2: the midpoint of the straight portion in the apical third (approximately 1 mm short of the radiographic apex); p3 of maximum curvature: the point where the canal deviates most abruptly from a straight line. Draw a straight line connecting p1 to p3 (coronal reference line), and another line connecting p2 to p3 (apical reference line). The angle (α) formed by the intersection of these two lines was measured and recorded as the angle of curvature. The curvature angle α of the root canal was categorized into three grades: 0\u0026deg; \u0026lt; α\u0026thinsp;\u0026le;\u0026thinsp;10\u0026deg;, 10\u0026deg; \u0026lt; α\u0026thinsp;\u0026le;\u0026thinsp;30\u0026deg;, α\u0026thinsp;\u0026gt;\u0026thinsp;30\u0026deg; [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. If two or more curvatures exist, it was defined as an S-shaped root canal. For each single curved canals, the location of the root canal curvature was determined by the ratio p\u0026thinsp;=\u0026thinsp;line p1p2/ line p2p3: coronal third (p\u0026thinsp;\u0026le;\u0026thinsp;0.5), middle third (0.5\u0026thinsp;\u0026lt;\u0026thinsp;p\u0026thinsp;\u0026le;\u0026thinsp;2), or apical third (p\u0026thinsp;\u0026gt;\u0026thinsp;2) \u003cb\u003e.\u003c/b\u003e\u003c/p\u003e\n\u003ch3\u003eClassification of impaction status\u003c/h3\u003e\n\u003cp\u003eThe impaction status of MTMs was categorized into two types: impacted and non-impacted [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] According to Winter\u0026rsquo;s classification [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], impacted teeth were further categorized into six types: vertical, mesial, distal, buccal, palatal, and horizontal impaction. Based on the Pell \u0026amp; Gregory classification, the depth of impaction was divided into three levels: Level A, Level B, Level C [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eCBCT-based binary complexity grading for MTM autotransplantation\u003c/h2\u003e\u003cp\u003eThe complexity of ATT procedures\u0026mdash;including recipient site preparation, atraumatic donor tooth extraction, and related procedures like post-transplantation RCT\u0026mdash;may correlate with MTM characteristics on CBCT. No dedicated difficulty grading system exists specifically for ATT. Through comprehensive literature review on tooth morphology and extraction difficulty factors[\u003cspan additionalcitationids=\"CR16 CR17 CR18\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] combined with relevant clinical consensus (e.g., RCT difficulty consensus [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]), this study categorized MTMs\u0026rsquo; CBCT features into low- or high-complexity grades (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eIn this proposed grading system, Level C impaction depth [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], horizontal impactions [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and multi-rooted anatomy [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] were designated high complexity due to increased tooth/bony resistance. Since MTMs are typically transplanted to molar sites, recipient sockets must exceed donor tooth dimensions to prevent insertion trauma; thus donor teeth exceeding average molar measurements (cervical mesiodistal width\u0026thinsp;\u0026gt;\u0026thinsp;9 mm, buccolingual width\u0026thinsp;\u0026gt;\u0026thinsp;10 mm, or maximum root CSA\u0026thinsp;\u0026gt;\u0026thinsp;71 mm\u0026sup2;) were graded as high complexity [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Complex root canal configurations\u0026mdash;including curvatures\u0026thinsp;\u0026gt;\u0026thinsp;30\u0026deg;, S-shaped canals, apical curvature positions (p\u0026thinsp;\u0026gt;\u0026thinsp;2), and canal lengths\u0026thinsp;\u0026ge;\u0026thinsp;30 mm\u0026mdash;were also graded as high complexity [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. For multi-canaled teeth, the most challenging canal determines the overall grade.\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\u003eCBCT-based binary complexity grading for MTM autotransplantation\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCriteria\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLow Complexity\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHigh Complexity\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRoot number \u003csup\u003e18,20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□1; 2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026ge; 3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRoot canal configuration \u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□Type1-1; 1\u0026ndash;2; 2\u0026thinsp;\u0026minus;\u0026thinsp;1; 2\u0026ndash;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□Other types\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCanal curvature angle \u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□straight canal; α\u0026thinsp;\u0026le;\u0026thinsp;30\u0026deg;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□α\u0026thinsp;\u0026gt;\u0026thinsp;30\u0026deg;; S-shaped root canal\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCanal curvature position \u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□straight canal; p\u0026thinsp;\u0026le;\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□p\u0026thinsp;\u0026gt;\u0026thinsp;2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCanal length \u003csup\u003e20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□\u0026le; 30 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026gt;30 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eImpaction depth \u003csup\u003e15\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□Non-impacted; Level A; Level B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□Level C\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eImpaction direction \u003csup\u003e17\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□Vertical; Mesial; Distal; Buccal; Palatal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□Horizontal\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRoot length \u003csup\u003e19,20\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□\u0026le; 14 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026gt;14 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCervical mesiodistal width \u003csup\u003e19\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□\u0026le; 9 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026gt;9 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCervical buccolingual width \u003csup\u003e19\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□\u0026le; 10 mm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026gt;10 mm\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaximum root cross-sectional area \u003csup\u003e19\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e□\u0026le; 71 mm\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e□\u0026gt;71 mm\u003csup\u003e2\u003c/sup\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\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eClinical application of the complexity grading\u003c/h2\u003e\u003cp\u003eTo validate the CBCT-based binary complexity grading for MTM autotransplantation, a prospective clinical study was conducted from January to July 2025. Twenty-six ATT procedures were performed by an oral surgeon with 6 years of ATT specialization. ATT protocols included recipient site preparation, atraumatic donor tooth extraction, transplantation with stabilization, and postoperative RCT at 3 weeks conducted by an endodontist with 8 years of RCT expertise.\u003c/p\u003e\u003cp\u003ePreoperatively, MTMs\u0026rsquo; CBCT characteristics were analyzed and complexity grading assigned. Postoperatively, the following parameters were recorded immediately: (1) total operative time (anesthesia to suture completion); (2) operative-rated difficulty of atraumatic extraction, recipient site preparation, and post-transplantation RCT (five -point Likert scale): one\u0026thinsp;=\u0026thinsp;Very easy; two\u0026thinsp;=\u0026thinsp;Easy; three\u0026thinsp;=\u0026thinsp;Moderate; four\u0026thinsp;=\u0026thinsp;Difficult; five\u0026thinsp;=\u0026thinsp;Very difficult.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eStatistical analyses were performed using R software (version 4.2.1; R Foundation for Statistical Computing, Vienna, Austria). Measurement data are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD), while count data are expressed as n (%). The chi-square test was employed for categorical variables. The Likert scale ratings (five points) for atraumatic extraction; recipient site preparation; post-transplantation RCT were analyzed using non-parametric Wilcoxon rank-sum tests, while their correlations with CBCT grading were assessed using Kendall\u0026rsquo;s Tau-b coefficient (given the limited sample size). Statistical analysis of surgical time was performed after first verifying homogeneity of variance, with intergroup comparisons conducted using independent samples t-tests and Pearson correlation employed to examine time difficulty relationships. A \u003cem\u003eP\u003c/em\u003e-value of less than 0.05 was considered statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\u003ch2\u003eRoot number\u003c/h2\u003e\u003cp\u003eThe most frequent root number was 1-rooted (65.63%). There was significant gender-based differences in root number distribution (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Females exhibited a higher frequency of 1-rooted MTMs compared to males (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Representative 3D models and CBCT slices illustrating MTMs with root numbers ranging from one to five are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\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\u003eClassification of root number in MTMs n (%)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" 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=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eRoot number\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eSide\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eGender\u003csup\u003e***\u003c/sup\u003e\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLeft (28)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRight (18)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMale\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eFemale\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e248 (31.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e277 (34.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e169 (21.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e356 (44.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e525 (65.63)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e47 (5.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e50 (6.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e45 (5.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e52 (6.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e97 (12.13)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e80 (10.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e89 (11.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e96 (12.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e73 (9.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e169 (21.13)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3 (0.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5 (0.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e5 (0.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3 (0.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8 (1.00)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e379 (47.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e421 (52.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e316 (39.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e484 (60.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e800 (100)\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\u003e\u003csup\u003e***\u003c/sup\u003eSignificant statistical differences in root number distribution between genders (χ\u0026sup2; test, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003eRoot canal configuration\u003c/h2\u003e\u003cp\u003eA total of 1263 root were detected (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Among them, the most frequent canal morphology was Type Ⅰ (1\u0026ndash;1) (76.11%). One-rooted MTMs contained a rich variety of root canal types, including the seven Vertucci\u0026rsquo;s types and other atypical types, while 4-rooted and 5-rooted MTMs containing only Type Ⅰ (1\u0026ndash;1). Representative 3D models and CBCT slices illustrating MTMs with various Vertucci\u0026rsquo;s canal morphology and 11 atypical root canal types are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe Vertucci\u0026rsquo;s classification of root canal systems in MTMs n (%)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eRoot number\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eRoot location\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eType Ⅰ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eType Ⅱ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eType Ⅲ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eType Ⅳ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eType Ⅴ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eType Ⅵ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eType Ⅷ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eAtypical\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u0026ndash;1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u0026thinsp;\u0026minus;\u0026thinsp;1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1-2-1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2\u0026ndash;2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1\u0026ndash;2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e2-1-2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e3\u0026ndash;3\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1-rooted\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\u003e307 (24.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e39 (3.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e10 (0.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e54 (4.28)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e15 (1.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e36 (2.85)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e63 (4.99)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e2-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e57 (4.51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e11 (0.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e4 (0.32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11 (0.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e7 (0.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e6 (0.48)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e81 (6.41)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6 (0.48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e7 (0.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e2 (0.16)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e3-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e143 (11.32)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e12 (0.95)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e12 (0.95)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e168 (13.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e169 (13.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4-rooted\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\u003e32 (2.53)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5-rooted\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\u003e5 (0.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\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\u003e962 (76.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e57 (4.51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e16 (1.27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e84 (6.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e37 (2.93)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (0.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e37 (2.93)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e69(5.46)\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\u003eAtypical: The 69 atypical cases comprised: 5 type 2\u0026ndash;3, 5 type 3\u0026thinsp;\u0026minus;\u0026thinsp;1, 11 type 3\u0026thinsp;\u0026minus;\u0026thinsp;2, 2 type 2-3-1, 2 type 2-3-2, 2 type 3-2-1, 1 type 3-4-3, 3 type 2-3-2-1, 1 type 2-3-2-3, 21 type C-shaped, 16 type Y(V)-shaped canals. Root abbreviations: B (buccal), P (palatal), MB (mesiobuccal), DB (distobuccal).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eTooth dimension\u003c/h2\u003e\u003cp\u003eThe dimensions of 800 MTMs are presented in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The root length was 10.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.56 mm, with 3-rooted MTMs having the longest roots at 11.22 mm and 4/5-rooted MTMs the shortest at 10.18 mm. The CRI was approximately 1:1.8, and the maximum root CSA was 60.21\u0026thinsp;\u0026plusmn;\u0026thinsp;13.08 mm\u0026sup2;. Canal measurements revealed an average 16.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79 mm length. All MTMs exhibited consistent cervical constriction with nearly 1\u0026ndash;2 mm reduction in both mesiodistal and buccolingual diameters relative to coronal dimensions.\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\u003eThe tooth dimension measurements (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD) in MTMs\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" 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=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRoot number\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCrown mesiodistal width (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eCervical mesiodistal width (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCrown buccolingual width (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eCervical buccolingual width (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eTooth length (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eCrown length (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eRoot length (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eCanal length (mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eCrown/Root ratio\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eMaximum root cross-sectional area(mm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.71\u0026thinsp;\u0026plusmn;\u0026thinsp;1.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e6.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.91\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.08\u0026thinsp;\u0026plusmn;\u0026thinsp;1.44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e9.08\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e16.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e5.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e10.44\u0026thinsp;\u0026plusmn;\u0026thinsp;1.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e16.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c10\"\u003e\u003cp\u003e1:1.81\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c11\"\u003e\u003cp\u003e54.79\u0026thinsp;\u0026plusmn;\u0026thinsp;11.88\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e9.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.31\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e9.95\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e17.00\u0026thinsp;\u0026plusmn;\u0026thinsp;1.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e6.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e10.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e17.25\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c10\"\u003e\u003cp\u003e1:1.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c11\"\u003e\u003cp\u003e66.75\u0026thinsp;\u0026plusmn;\u0026thinsp;8.20\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e9.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.57\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e11.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e10.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.89\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e17.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e6.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e11.22\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e17.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c10\"\u003e\u003cp\u003e1:1.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c11\"\u003e\u003cp\u003e72.55\u0026thinsp;\u0026plusmn;\u0026thinsp;7.21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u0026amp;5-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e9.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.52\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e11.70\u0026thinsp;\u0026plusmn;\u0026thinsp;1.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e9.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e16.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e6.33\u0026thinsp;\u0026plusmn;\u0026thinsp;0.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e10.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e17.06\u0026thinsp;\u0026plusmn;\u0026thinsp;2.02\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c10\"\u003e\u003cp\u003e1:1.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c11\"\u003e\u003cp\u003e74.32\u0026thinsp;\u0026plusmn;\u0026thinsp;5.95\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e8.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.01\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e9.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e16.58\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e5.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e10.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c9\"\u003e\u003cp\u003e16.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c10\"\u003e\u003cp\u003e1:1.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c11\"\u003e\u003cp\u003e60.21\u0026thinsp;\u0026plusmn;\u0026thinsp;13.08\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eRoot canal curvature\u003c/h2\u003e\u003cp\u003eAnalysis of 1631 root canals revealed 76.33% root canal curvature (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), predominantly single curves (73.69%). Root canal curvature α followed this distribution: Grade Ⅲ (α\u0026thinsp;\u0026gt;\u0026thinsp;30\u0026deg;, 37.34%), Grade Ⅱ(10\u0026deg; \u0026lt; α\u0026thinsp;\u0026le;\u0026thinsp;30\u0026deg;,35.44%), and Grade Ⅰ (0\u0026deg; \u0026lt; α\u0026thinsp;\u0026le;\u0026thinsp;10\u0026deg;, 0.92%). Curvature positions were most frequent in Grade Ⅱ (57.88%; 0.5\u0026thinsp;\u0026lt;\u0026thinsp;p\u0026thinsp;\u0026le;\u0026thinsp;2). Directional analysis showed distal (26.18%) and buccal (23.54%) orientations predominated. Notably, Grades Ⅱ-Ⅲ (α\u0026thinsp;\u0026gt;\u0026thinsp;10\u0026deg;) curvatures collectively represented 72.78%, with mid-root (Grade II) being the most frequent position.\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\u003eThe curvature of root canals in MTMs n (%)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\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\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eRoot number\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eRoot location\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eStraight canals\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"10\" nameend=\"c13\" namest=\"c4\"\u003e\u003cp\u003eSingle-curved canals\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c14\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eS-shaped canals\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c6\" namest=\"c4\"\u003e\u003cp\u003eCanal curvature angulation (α)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c9\" namest=\"c7\"\u003e\u003cp\u003eCanal curvature position (p)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c13\" namest=\"c10\"\u003e\u003cp\u003eCanal curvature direction\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0\u0026deg;\u0026lt;α\u0026thinsp;\u0026le;\u0026thinsp;10\u0026deg;\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e10\u0026deg;\u0026lt;α\u0026thinsp;\u0026le;\u0026thinsp;30\u0026deg;\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eα\u0026gt;30\u0026deg;\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003ep\u0026lt;0.5\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.5\u0026thinsp;\u0026le;\u0026thinsp;p\u0026thinsp;\u0026le;\u0026thinsp;2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003ep\u0026gt;2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eMesial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eDistal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003ePalatal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eBuccal\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1-rooted\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\u003e244\u003c/p\u003e\u003cp\u003e(14.96)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6\u003c/p\u003e\u003cp\u003e(0.37)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e247\u003c/p\u003e\u003cp\u003e(15.14)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e297\u003c/p\u003e\u003cp\u003e(18.21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e32\u003c/p\u003e\u003cp\u003e(1.96)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e381\u003c/p\u003e\u003cp\u003e(23.36)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e137\u003c/p\u003e\u003cp\u003e(8.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e112\u003c/p\u003e\u003cp\u003e(6.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e196\u003c/p\u003e\u003cp\u003e(12.02)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e66\u003c/p\u003e\u003cp\u003e(4.05)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e176\u003c/p\u003e\u003cp\u003e(10.80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e18\u003c/p\u003e\u003cp\u003e(1.10)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003e2-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e33\u003c/p\u003e\u003cp\u003e(2.02)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003cp\u003e(0.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e51\u003c/p\u003e\u003cp\u003e(3.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e41\u003c/p\u003e\u003cp\u003e(2.51)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4\u003c/p\u003e\u003cp\u003e(0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e83\u003c/p\u003e\u003cp\u003e(5.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e7\u003c/p\u003e\u003cp\u003e(0.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e25\u003c/p\u003e\u003cp\u003e(1.53)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e42\u003c/p\u003e\u003cp\u003e(2.58)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e20\u003c/p\u003e\u003cp\u003e(1.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e7\u003c/p\u003e\u003cp\u003e(0.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e8\u003c/p\u003e\u003cp\u003e(0.49)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e36\u003c/p\u003e\u003cp\u003e(2.21)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003cp\u003e(0.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e38\u003c/p\u003e\u003cp\u003e(2.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e37\u003c/p\u003e\u003cp\u003e(2.27)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4\u003c/p\u003e\u003cp\u003e(0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e65\u003c/p\u003e\u003cp\u003e(3.99)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e8\u003c/p\u003e\u003cp\u003e(0.49)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e8\u003c/p\u003e\u003cp\u003e(0.49)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e5\u003c/p\u003e\u003cp\u003e(0.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e4\u003c/p\u003e\u003cp\u003e(0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e60\u003c/p\u003e\u003cp\u003e(3.68)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e3-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e12\u003c/p\u003e\u003cp\u003e(0.74)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e(0.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e67\u003c/p\u003e\u003cp\u003e(4.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e106\u003c/p\u003e\u003cp\u003e(6.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e13\u003c/p\u003e\u003cp\u003e(0.80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e160\u003c/p\u003e\u003cp\u003e(9.81)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e(0.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e3\u003c/p\u003e\u003cp\u003e(0.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e161\u003c/p\u003e\u003cp\u003e(9.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e5\u003c/p\u003e\u003cp\u003e(0.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e5\u003c/p\u003e\u003cp\u003e(0.31)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e9\u003c/p\u003e\u003cp\u003e(0.55)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDB\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e18\u003c/p\u003e\u003cp\u003e(1.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3\u003c/p\u003e\u003cp\u003e(0.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e89\u003c/p\u003e\u003cp\u003e(5.46)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e53\u003c/p\u003e\u003cp\u003e(3.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e15\u003c/p\u003e\u003cp\u003e(0.92)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e124\u003c/p\u003e\u003cp\u003e(7.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e6\u003c/p\u003e\u003cp\u003e(0.37)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e132\u003c/p\u003e\u003cp\u003e(8.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e11\u003c/p\u003e\u003cp\u003e(0.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e2\u003c/p\u003e\u003cp\u003e(0.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e7\u003c/p\u003e\u003cp\u003e(0.43)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e33\u003c/p\u003e\u003cp\u003e(2.02)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e(0.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e76\u003c/p\u003e\u003cp\u003e(4.66)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e58\u003c/p\u003e\u003cp\u003e(3.56)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4\u003c/p\u003e\u003cp\u003e(0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e109\u003c/p\u003e\u003cp\u003e(6.68)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e22\u003c/p\u003e\u003cp\u003e(1.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e3\u003c/p\u003e\u003cp\u003e(0.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e(0.06)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e2\u003c/p\u003e\u003cp\u003e(0.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e129\u003c/p\u003e\u003cp\u003e(7.91)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e1\u003c/p\u003e\u003cp\u003e(0.06)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u0026amp;5-rooted\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\u003e10\u003c/p\u003e\u003cp\u003e(0.61)\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\u003e10\u003c/p\u003e\u003cp\u003e(0.61)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e17\u003c/p\u003e\u003cp\u003e(1.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3\u003c/p\u003e\u003cp\u003e(0.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e22\u003c/p\u003e\u003cp\u003e(1.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e2\u003c/p\u003e\u003cp\u003e(0.12)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e9\u003c/p\u003e\u003cp\u003e(0.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e11\u003c/p\u003e\u003cp\u003e(0.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e7\u003c/p\u003e\u003cp\u003e(0.43)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\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\u003e386\u003c/p\u003e\u003cp\u003e(23.67)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e15\u003c/p\u003e\u003cp\u003e(0.92)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e578\u003c/p\u003e\u003cp\u003e(35.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e609\u003c/p\u003e\u003cp\u003e(37.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e75\u003c/p\u003e\u003cp\u003e(4.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e944\u003c/p\u003e\u003cp\u003e(57.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e183\u003c/p\u003e\u003cp\u003e(11.22)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e292\u003c/p\u003e\u003cp\u003e(17.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e\u003cp\u003e427\u003c/p\u003e\u003cp\u003e(26.18)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c12\"\u003e\u003cp\u003e99\u003c/p\u003e\u003cp\u003e(6.07)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c13\"\u003e\u003cp\u003e384\u003c/p\u003e\u003cp\u003e(23.54)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c14\"\u003e\u003cp\u003e43\u003c/p\u003e\u003cp\u003e(2.64)\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\u003eRoot abbreviations: B (buccal), P (palatal), MB (mesiobuccal), DB (distobuccal).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003eImpaction status\u003c/h2\u003e\u003cp\u003eAmong 800 MTMs, 22.25% (n\u0026thinsp;=\u0026thinsp;178) were impacted, with mesial impaction being most frequent (12.38%) and horizontal impaction least frequent (0.75%). Impaction depth analysis revealed Level C predominance (82.59%) (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe impaction status in MTMs n (%)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"13\"\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=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eRoot number\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eNon-impacted\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"6\" nameend=\"c9\" namest=\"c4\"\u003e\u003cp\u003eimpaction direction\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c13\" namest=\"c11\"\u003e\u003cp\u003eimpaction depth\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eVertical\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eMesial\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eDistal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBuccal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003ePalatal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eHorizontal\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eLevel A\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c12\"\u003e\u003cp\u003eLevel B\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c13\"\u003e\u003cp\u003eLevel C\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e392 (49.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e9 (1.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e75 (9.34)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8 (1.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e30 (3.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6 (0.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e5 (0.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e4 (0.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e15 (1.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e114 (14.25)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e73 (9.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e12 (1.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e4 (0.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e3 (0.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e3 (0.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e19 (2.38)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e151 (18.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4 (0.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e10 (1.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e5 (0.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e12 (1.50)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4༆5-rooted\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6 (0.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\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\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e1 (0.13)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e2 (0.25)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e622 (77.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e15 (1.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e99 (12.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e11 (1.38)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e37 (4.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e10 (1.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e6 (0.75)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e7 (0.88)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e\u003cp\u003e24 (3.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c13\"\u003e\u003cp\u003e147 (18.38)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003eCBCT-based binary complexity grading for MTM autotransplantation\u003c/h2\u003e\u003cp\u003eAnalysis of 800 MTMs revealed distinct CBCT difficulty grades (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e): For low complexity, canal length was the most frequent factor (n\u0026thinsp;=\u0026thinsp;800, 100%), followed by impaction direction (n\u0026thinsp;=\u0026thinsp;794, 99.25%). High complexity showed canal curvature angle being the most frequent (n\u0026thinsp;=\u0026thinsp;433, 54.13%).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\u003ch2\u003eClinical Application of the complexity grading\u003c/h2\u003e\u003cp\u003eCorrelational analysis between MTMs\u0026rsquo; CBCT character-based binary difficulty grading and ATT procedural challenges revealed (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e): atraumatic tooth extraction difficulty showed significant correlations with root number, impaction direction, and impaction depth (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01); recipient-site preparation difficulty exhibited significant correlations with high complexity in root number, cervical mesiodistal width, cervical buccolingual width, and maximum root CSA (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01); post-transplantation RCT difficulty displayed significant correlation with root canal curvature position, curvature angle, and canal configuration (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01); surgical duration significantly correlated with impaction depth and root number (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eMTMs are common donor teeth for ATT, yet their CBCT characteristics are understudied, attributable to their non-functional status and limited therapeutic relevance. Although some studies have explored the impact of clinical operative factors on ATT outcomes, the influence of MTMs\u0026rsquo; unique anatomical features on RCT difficulty during transplantation procedures has yet to be thoroughly elucidated. Thus, this study conducted a comprehensive analysis of MTMs\u0026rsquo; CBCT characteristics, encompassing root number, root canal configuration, root canal curvature, tooth dimensions, and impaction status. A considerable diversity of CBCT characteristics was observed.\u003c/p\u003e\u003cp\u003ePrevious CBCT analyses of MTM morphology, encompassing 116 cases from Central India and 238 cases from Moscow populations, have reported that most commonly, MTMs had three roots, three root canals and the MB, DB, and P canals most often showed Vertucci Type I [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. This study focused on the East Asian Mongoloid population in China and revealed 1-rooted as the most prevalent configuration in MTMs, with Vertucci Type I being the dominant canal type. While root number prevalence differed from prior reports, the consistency in canal typing suggests ethnic variations may influence root numbers rather than internal canal morphology.\u003c/p\u003e\u003cp\u003eRegarding root canal curvature, no studies in literature have investigated the characteristics of MTMs using CBCT imaging. One study of maxillary posterior teeth by X-ray film measurement, revealed that root canal curvatures were significantly more pronounced in the mesiodistal dimension compared to the buccolingual dimension [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In an in vitro study, more than 85% of maxillary first and second molars exhibited palatal root curvatures exceeding 10\u0026deg;, with buccal direction curvatures predominating [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This CBCT-based study revealed that 76.33% of root canals exhibited curvature, predominantly single curves (73.69%) with a small proportion of S-shaped configurations (2.64%); the curvatures were mainly oriented distally or buccally and located in the mid-root region. The findings demonstrate that MTMs display an intricate and diverse array of root canal curvatures.\u003c/p\u003e\u003cp\u003eThe dimensional parameters of MTMs reported in Wheeler's in vitro anatomical study and current this CBCT analysis demonstrate divergence [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The crown length demonstrated the most substantial discrepancy (6.5 mm vs 5.92 mm). The variations likely stem from methodological differences between Wheeler's caliper-based measurements on extracted teeth and digital CBCT reconstructions, accounting for potential tissue shrinkage in cadaveric specimens and the technical limitations of voxel resolution in CBCT scans. Population characteristics may also contribute to the divergence [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eWhile many studies reported vertical impaction as predominant in MTMs, the data showed mesial impaction as the most frequent. This divergence likely stems from methodological variations in angular measurement protocols, where differences in reference planes significantly impact categorization [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Compared to the two-dimensional limitations of panoramic radiography, CBCT enables evaluation of the buccolingual impaction of MTMs. In a CBCT study on MTMs impaction, buccolingual impaction (74%) was most common, which is consistent with the research findings [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Several studies have indicated that Level C is the most common impaction depth for MTMs [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], a finding consistent with the research results. However, many studies also reported Level A/B as the predominant impaction depth [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e], suggesting this variation may be associated with geographic location and ethnic differences.\u003c/p\u003e\u003cp\u003eCBCT evaluation is essential for MTM extraction, particularly in ATT, where atraumatic techniques are required to avoid root damage that can cause resorption or ankylosis. Compared to mandibular third molars, MTMs are less studied in terms of extraction difficulty [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In this study, increased complexity in impaction direction, depth and root numbers significantly elevated surgeon-rated difficulty scores for atraumatic invasive extraction. Multiple roots (\u0026ge;\u0026thinsp;3) combined with deep impaction (Level C) prolonged total operative time [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Although, most MTMs exhibit low extraction complexity (1-rooted morphology, short mean root length, non-impacted), those with multi-rooted anatomy, deep impactions, or horizontal orientation require meticulous preoperative radiographic assessment.\u003c/p\u003e\u003cp\u003ePrecise recipient site preparation is critical for successful ATT to ensure optimal donor tooth accommodation. Size discrepancies incur increased trial fittings, prolonged extra-alveolar time, elevated root resorption rates, and periodontal ligament damage. In this study, the greater mesiodistal width, buccolingual width, and maximal root CSA were positively correlated with higher difficulty ratings for recipient site preparation. MTMs offer some advantages as donors due to their smaller dimensions and predominantly 1-rooted morphology. These characteristics reduce the need for bone removal when replacing unrestorable first or second molars. However, complex site preparation is required for edentulous sites with significant alveolar resorption. Additionally, a rational crown/root ratio and good relationship with adjacent teeth at the recipient site should also be considered.\u003c/p\u003e\u003cp\u003eRadiographic evaluation plays a pivotal role in post-transplantation RCT. Mature teeth should undergo RCT within 2\u0026ndash;4 weeks post-transplantation [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. In this study, the complex root canal morphology, severe curvature (\u0026gt;\u0026thinsp;30\u0026deg;), and aberrant canal positions contributed to increased extraction difficulty scores. Significant morphological diversity was observed, with complex variants increasing treatment difficulty. Over 40% of root canals exhibited curvature exceeding 10\u0026deg;, mainly in the mid-root region with distal or buccal orientations, features that complicate instrumentation. Therefore, high-resolution CBCT imaging is necessary to accurately map 3D canal pathways.\u003c/p\u003e\u003cp\u003eCurrent this study has certain limitations. Firstly, it didn\u0026rsquo;t fully analyze the anatomical structure around MTMs, such as their spatial relationships to the maxillary sinus and the second molar, retromolar space, and periodontal ligament width. Future research should include these variables in a comprehensive assessment framework. Secondly, while this study established correlations between MTM CBCT features and ATT and its adjunctive procedures difficulty, future investigations should evaluate the prognostic significance of these CBCT characteristics on postoperative outcomes.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eCBCT characterization is informative for surgical planning and efficacy assessment when utilizing MTMs as donor teeth in ATT. Our analysis revealed considerable morphological diversity among MTMs, necessitating detailed preoperative assessment. The radiographic complexity of MTMs demonstrates a significant positive correlation with both surgical difficulty and operative duration through clinical validation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e Xiang: project development, data collection and management, data analysis, manuscript writing and editing. Sun: project development, data management, data analysis, manuscript writing and editing. Hong: project development, data management, data analysis. Yan: project development, data collection and management. Ge: project development, data collection and management, data analysis. Wu: project development, data management, data analysis. Feng: project development, data collection and management, data analysis, manuscript writing and editing. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Statement\u0026nbsp;\u003c/strong\u003eThis study has been approved by the Ethics Committee of Zhejiang Provincial Stomatological Hospital (Approval No. 2024-094).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e Written informed consent was obtained from all patients after a detailed explanation of the study procedures, potential risks, and benefits, in accordance with the principles of the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e Written informed consent for publication of their clinical details and/or images was obtained from the patient.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTan BL, Tong HJ, Narashimhan S, Banihani A, Nazzal H, Duggal MS (2023) Tooth autotransplantation: An umbrella review. Dent Traumatol 39 Suppl 1:2-29. \u003c/li\u003e\n\u003cli\u003eJaber M, Prasad P, Akeil M, Moufti A, Al-Sammarraie A, Charaf Eddin C (2024) Long-Term Evaluation of Tooth Transplantation: An Umbrella Review. J Clin Med 13(11):3341.\u003c/li\u003e\n\u003cli\u003eYu HJ, Jia P, Lv Z, Qiu LX (2017) Autotransplantation of third molars with completely formed roots into surgically created sockets and fresh extraction sockets: a 10-year comparative study. Int J Oral Maxillofac Surg 46(4):531-538.\u003c/li\u003e\n\u003cli\u003eYoshino K, Kariya N, Namura D, et al (2012) A retrospective survey of autotransplantation of teeth in dental clinics. J Oral Rehabil 39(1):37-43.\u003c/li\u003e\n\u003cli\u003eTsukiboshi M, Tsukiboshi C, Levin L (2023) A step-by step guide for autotransplantation of teeth. Dent Traumatol 39 Suppl 1:70-80.\u003c/li\u003e\n\u003cli\u003eKafourou V, Tong HJ, Day P, Houghton N, Spencer RJ, Duggal M (2017) Outcomes and prognostic factors that influence the success of tooth autotransplantation in children and adolescents. Dent Traumatol 33(5):393-399.\u003c/li\u003e\n\u003cli\u003eLo Giudice R, Nicita F, Puleio F, Alibrandi A, Cervino G, Lizio AS, Pantaleo G (2018) Accuracy of Periapical Radiography and CBCT in Endodontic Evaluation. Int J Dent 2018(1):2514243.\u003c/li\u003e\n\u003cli\u003eAiniwaer A, Gong Z, Zuolipahaer Z, Wang L (2024) Midterm outcomes of autogenous mature third molars transplantation into surgically created sockets: A retrospective cohort study. Dent Traumatol 40(5):573-585.\u003c/li\u003e\n\u003cli\u003eShahbazian M, Jacobs R, Wyatt J, Willems G, Pattijn V, Dhoore E, VAN Lierde C, Vinckier F (2010) Accuracy and surgical feasibility of a CBCT-based stereolithographic surgical guide aiding autotransplantation of teeth: in vitro validation. J Oral Rehabil 37(11):854-859.\u003c/li\u003e\n\u003cli\u003eScott RG, Turner CG II (1997) The anthropology of modern human teeth. London: Cambridge University Press.\u003c/li\u003e\n\u003cli\u003eVertucci FJ (1984) Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 58(5):589-599.\u003c/li\u003e\n\u003cli\u003eWeine, Franklin S, Marshall H, et al (1982) Endodontic therapy. 5th ed. St. Louis (MO): Mosby.\u003c/li\u003e\n\u003cli\u003eYang Y, Wu B, Zeng J, Chen M (2020) Classification and morphology of middle mesial canals of mandibular first molars in a southern Chinese subpopulation: a cone-beam computed tomographic study. BMC Oral Health 20(1):358.\u003c/li\u003e\n\u003cli\u003eSeo MH, Sodnom-Ish B, Eo MY, Myoung H, Kim SM (2023) Radiographic evaluation before surgical extraction of impacted third molar to reduce the maxillary sinus related complication. J Korean Assoc Oral Maxillofac Surg 49(4):192-197.\u003c/li\u003e\n\u003cli\u003ede Andrade PF, Silva JNN, Sotto-Maior BS, Ribeiro CG, Devito KL, Assis NMSP (2017) Three-dimensional analysis of impacted maxillary third molars: A cone-beam computed tomographic study of the position and depth of impaction. Imaging Sci Dent 47(3):149-155.\u003c/li\u003e\n\u003cli\u003ePell GJ, Gregory BT. (1933) Impacted mandibular third molars: classification and modified techniques for removal. Dent Dig 39:330-8.\u003c/li\u003e\n\u003cli\u003eMatsuda S, Yoshimura H (2022) Maxillary third molars with horizontal impaction: A cross-sectional study using computed tomography in young Japanese patients. J Int Med Res 50(2):3000605221080281.\u003c/li\u003e\n\u003cli\u003ede Carvalho RW, de Ara\u0026uacute;jo Filho RC, do Egito Vasconcelos BC (2013) Assessment of factors associated with surgical difficulty during removal of impacted maxillary third molars. J Oral Maxillofac Surg 71(5):839-45.\u003c/li\u003e\n\u003cli\u003eWheeler RC (1974) Dental anatomy, physiology, and occlusion.\u003c/li\u003e\n\u003cli\u003eHuang D, Wang X, Liang J, et al (2024) Expert consensus on difficulty assessment of endodontic therapy. Int J Oral Sci 16(1):22.\u003c/li\u003e\n\u003cli\u003eRawtiya M, Somasundaram P, Wadhwani S, Munuga S, Agarwal M, Sethi P (2016) Retrospective study of root canal configurations of maxillary third molars in Central India population using cone beam computed tomography Part-I. Eur J Dent 10(1):97-102.\u003c/li\u003e\n\u003cli\u003eRazumova S, Brago A, Khaskhanova L, Howijieh A, Barakat H, Manvelyan A (2018) A Cone-Beam Computed Tomography Scanning of the Root Canal System of Permanent Teeth among the Moscow Population. Int J Den 2018:2615746.\u003c/li\u003e\n\u003cli\u003eQiao X, Xu T, Chen L, Yang D (2021) Analysis of Root Canal Curvature and Root Canal Morphology of Maxillary Posterior Teeth in Guizhou, China. Med Sci Monit 27: e928758.\u003c/li\u003e\n\u003cli\u003eBone J, Moule AJ (1986) The nature of curvature of palatal canals in maxillary molarm teeth. Int Endod J 19(4):178-186.\u003c/li\u003e\n\u003cli\u003eBrook AH (2009) Multilevel complex interactions between genetic, epigenetic and environmental factors in the aetiology of anomalies of dental development. Arch Oral Biol 54 (Suppl 1): S3-17.\u003c/li\u003e\n\u003cli\u003eHadziabdic N, Dzankovic A, Maktouf M, Tahmiscija I, Hasic-Brankovic L, Korac S, Haskic A (2023) The Clinical and Radiological Evaluation of Impacted Third Molar Position, Crown and Root Morphology. Acta Med Acad 52(2):77-87.\u003c/li\u003e\n\u003cli\u003eYurdabakan ZZ, Okumus O, Pekiner FN (2018) Evaluation of the maxillary third molars and maxillary sinus using cone-beam computed tomography. Niger J Clin Pract 21(8):1050-1058.\u003c/li\u003e\n\u003cli\u003eYilmaz S, Adisen MZ, Misirlioglu M, Yorubulut S (2016) Assessment of Third Molar Impaction Pattern and Associated Clinical Symptoms in a Central Anatolian Turkish Population. Med Princ Pract 25(2):169-75.\u003c/li\u003e\n\u003cli\u003eMachado HHS, Xavier CB, Damian MF (2015) Preoperative evaluation of third molar root characteristics: Correlation between clinical and radiographic findings. J. Dent. Sci 30(4):111-114.\u003c/li\u003e\n\u003cli\u003eHuang J, Gan Y, Han S, Xu HE, Yuan YI, Zhu HE, Tian X, Li N, Li D, Cai Z (2023) Outcomes of autotransplanted third molars with complete root formation: a systemic review and meta-analysis. J Evid Based Dent Pract 23(2):101842.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Autogenous tooth transplantation, CBCT, Maxillary third molar, Anatomical analysis, Root canal, Root morphology","lastPublishedDoi":"10.21203/rs.3.rs-7699422/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7699422/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eMaxillary third molars (MTMs) are frequently utilized as donor teeth in autogenous tooth transplantation (ATT). This study aimed to characterize and grade MTMs\u0026rsquo; CBCT features to inform ATT operation.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eThis retrospective CBCT analysis evaluated 800 MTMs from 537 patients regarding tooth morphology, root canal configuration, and impaction status. A CBCT-based binary complexity grading for MTM autotransplantation was established, and its clinical relevance to the operative difficulty of ATT and its adjunctive procedures (root canal treatment, RCT) was analyzed in 26 ATT cases using both a subjective five-point scale and operation time.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003ePredominant characteristics of MTMs included: 1-rooted morphology (65.63%), Vertucci\u0026rsquo;s Type-I canal configuration (76.17%), root canal curvature 10\u0026deg;- 30\u0026deg; (35.44%), and non-impaction status (77.75%). Mean root length was 10.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.56 mm, canal length 16.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79 mm, crown-to-root ratio 1:1.8, and maximum root cross-sectional area (CSA) 60.21\u0026thinsp;\u0026plusmn;\u0026thinsp;13.08 mm\u0026sup2;. Significant clinical relevance (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) was found between atraumatic tooth extraction and root number, impaction direction, and depth of MTMs; between recipient-site preparation and cervical buccolingual width, mesiodistal width, root number, and maximum root CSA; between RCT and the canal configuration and curvature; and between ATT operation time and impaction depth and root number.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eMTM CBCT characteristics exhibit significant anatomical variation and are relevant to ATT complexity. The CBCT-based binary complexity grading for MTM autotransplantation predicts procedural difficulty and would facilitate comprehensive preoperative evaluation for ATT.\u003c/p\u003e","manuscriptTitle":"Anatomical Analysis of Maxillary Third Molars with Cone-Beam Computed Tomography: Implications for Autotransplantation Operation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-15 02:12:09","doi":"10.21203/rs.3.rs-7699422/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-05T03:02:10+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-05T02:21:02+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-01T21:06:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"334836439444943584658848918513636704812","date":"2025-10-27T05:39:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"305255191488141734955567099106539972685","date":"2025-10-27T02:56:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-30T00:36:07+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-29T12:27:27+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-09-26T04:31:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2025-09-24T04:59:00+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"2d660e8a-347f-4176-a04c-389ec863e60a","owner":[],"postedDate":"October 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-19T17:24:18+00:00","versionOfRecord":{"articleIdentity":"rs-7699422","link":"https://doi.org/10.1007/s00276-025-03811-9","journal":{"identity":"surgical-and-radiologic-anatomy","isVorOnly":false,"title":"Surgical and Radiologic Anatomy"},"publishedOn":"2026-01-13 16:29:37","publishedOnDateReadable":"January 13th, 2026"},"versionCreatedAt":"2025-10-15 02:12:09","video":"","vorDoi":"10.1007/s00276-025-03811-9","vorDoiUrl":"https://doi.org/10.1007/s00276-025-03811-9","workflowStages":[]},"version":"v1","identity":"rs-7699422","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7699422","identity":"rs-7699422","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}