Three-dimensional analysis of the relationship between mandibular retromolar space and impacted third molars types in non-hyperdivergent adults

Three-dimensional analysis of the relationship between mandibular retromolar space and impacted third molars types in non-hyperdivergent adults | 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 Three-dimensional analysis of the relationship between mandibular retromolar space and impacted third molars types in non-hyperdivergent adults Yumei Huang, Yunjia Cheng, Yang Dan, Yingying Tang, Ya Yang, Jingfeng Xu, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1834788/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Mar, 2023 Read the published version in BMC Oral Health → Version 1 posted 8 You are reading this latest preprint version Abstract Background The anatomical position of the mandibular third molars(M3)is located in the posterior space of the molars, and many two-dimensional studies on them in the previous literature. This study evaluated the relationship between retromolar space(RS) and different impacted classifications of M3 in three‑dimensional(3D) cone‑beam computed tomography(CBCT). Methods 206 mandibular third molars from 103 patients were included and separately separated into three classifications concurring to four classification criteria which included PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP)which was fitted by the least square method and the occlusal plane(OP) as reference planes. The SPSS (version 26) was used to analyze the data. Results In all classifications of classification criteria, RS diminished steadily from the crown to the root (p < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (p < 0.05). As the degree of mesioangula impaction diminished, RS appeared an expanding trend (p 0.05). Conclusions RS were related to the impacted classifications of M3. With the increment of the impacted degree of M3 ,the retromolar space gradually diminished. In clinic, RS can be evaluated by watching the PG classification and mesial angle of M3. Retromolar space M3 Classification criteria of impaction The fitting WALA ridge plane Occlusal plane Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Background Molar distalization (MD)is a method for extending the length of dental arch[ 1 ]. Particularly in recent years, due to the popularity of invisible orthotics, the realization rate of molar distal movement has been greatly improved[ 2 , 3 ].So in the orthodontic clinic, orthodontists always relieve mild or moderate crowding and adjust the molar position relationship by MD[ 4 , 5 ]. At this time, the question arises of where the boundary of the tooth movement is The limit of MD depends on the determination of alveolar bone anatomical limit. The maxillary arch incorporates a clear posterior limit—the maxillary Tuberosity[ 6 , 7 ]. Hence ,MD is commonly utilized within the orthodontic process of the maxillary dentition. The conventional way of MD mostly uses the skeletal anchorage system, face-bow, and temporary skeletal anchorage devices, all of these can accomplish certain effect [ 8 , 9 ]. The mandible is composed of mandibular body and mandibular ramus. It is a complex structure, with masticatory muscles attached and high bone density. So the MD in mandible is difficult. With the popularity of CBCT, increasingly scholars have studied MD in mandible Kim[ 10 ]proposed that the farthest lingual cortical bone of the mandibular arch was the posterior anatomical boundary and found the RS had the minimum at the root tip. Choi et al found that RS had no statistically significant difference between class I and class III malocclusion[ 11 ]. But in previous studies, the anatomic characteristics of the mandibular angle related to MD were not considered. M3 are the distal structure of the mandibular dental arch, located at the turning point of the mandibular body and ramus. It has been reported that the impacted state of them can affect the anatomical relationship of the transition area to a certain extent[ 12 ]. The shape, position and inclination of M3 are regularly utilized to assess the difficulty of the extraction of M3 in maxillofacial surgery [ 13 ]. Be that as it may, the research between M3 and orthodontics has been simply and the relationship between distinctive impacted sorts of M3 and RS has not been thoroughly analyzed. The purpose of this study is to quantitatively measure RS of the mandible with CBCT, and find the relationship between RS and M3 impaction, so as to assist orthodontists design treatment plans. Materials And Methods sample selection This study was approved by the Research and Ethics Committee of the Affiliated Stomatology Hospital of Chongqing Medical University (2021(LSNo.045)). The sample included CBCT imagings of 103 subjects (52 males and 51 females, mean age = 28.39 years), aged from 18 to 40 years. These subjects were selected from the patients who were conceded for orthodontic treatment from 2019 to 2021 at the Department of Orthodontics, Affiliated Stomatology Hospital of Chongqing Medical University. The inclusion criteria : (1) non-vertical facial dimension (SN-MP°<32°) and Class I or Class III malocclusion, (2) normal overjet and overbite, (3) crowding of less than 4 mm in the mandibular dental arch, (4) no significant alveolar bone loss, (5) no missing teeth (including M3), (6) no noticeable facial asymmetry and deformation, (7) no tumors, fractures, cysts in mandible, (8) no diagnosed systemic disease, (9) no history of orthodontic treatment. The exclusion criteria : (1) blurred CBCT imagings ,(2) incomplete CBCT imagings ,(3) unmeasurable CBCT imagings. Construction of 3D models, reference planes and measuring lines CBCT imagings (KaVo Dental Gmb H, USA; 80 mA, 80 kVp, and 8.9-second scan time) were procured. The data was imported into Mimics 19.0 software (Materialise, Leuven, Belgium) in Digital Imaging and Communications in Medicine (DICOM) format to reconstruct the 3D hard tissue models(Fig. 1A). Connecting the left and right orbital points(Or-R, Or-L)and the right porion point(Po-R) as the Frankfort horizontal plane(FH). Connecting two mesiobuccal cusp points of the mandibular first molars(L6R-MB,L6L-MB) and the mesial contact point of the lower central incisor(LIE) as occlusal plane(OP) (Fig. 1B). We got the coordinate points of bony WALA ridge in Mimics software and imported the coordinate values into Matlab software(R2022a,MathWorks, U.S)[ 14 ] to complete the fitting of WALA ridge plane(WP), and finally imported WP into Mimics. The process was shown in Fig. 2 . To construct the reference lines. Connecting the bone marker points of the WALA ridge of the mandibular first and second molar as the WALA ridge line(WL) (Fig. 3 A).Connecting the mesial buccal cusps of the mandibular first and second molar as the occlusion line (OL) (Fig. 3 B). variables and measurements The 3D hard tissue models were imported into the Measure and Analysis Module Of Mimics for creating FH,WP, OP, WL,and OL .The angles of FH with WP, WL, OP and OL were respectively recorded as < FH-WP, <FH-WL ,<FH-OP, <FH-OL.These FH-related angulations were measured by the projection on the sagittal section (Fig. 3 A, 3 B). Recording the mesiodistal angulation(A angle: -10°~100°),labiolingual angulation(B angle) of M3 in WP-based and OP-based reference frames, separately.The detailed protocol of CBCT measurements described in Fig. 4 The RS were measured on five different level which were parallel to the horizontal plane including level 1–5 in two reference frames (Table 1 ,Fig. 5 A). Level 1–2 were at the crown level. Level 3–5 were at the root level. The distance from the distal protruding point of the crown of the mandibular second molar to the anterior wall of the mandibular canal (MC)(Fig. 5 B) was measured as RS at the crown level[ 15 ] (Fig. 5 C). The distance from the most lingual point of the distal root of the second molar to the lingual cortical bone of the mandible which parallels to the measuring line(WL P or OL P ) was measured as RS at the root level [ 10 ](Fig. 5 D). Data obtained by using WP or OP plane as reference plane were recorded as WP group and OP group respectively. Table 1 Explanation the position of five levels Level abbreviation Interpretation Level 1 L1 The level parallel to reference plane through the most distal protruding point of the crown of the second molar in mandibular Level 2 L2 The level parallel to reference plane through the cement enamel-junction of the second molar in mandibular Level 3 L3 The level parallel to reference plane through the root furcation of the second molar in mandibular Level 4 L4 The level parallel to reference plane through the distal root of the second molar in mandibular Level 5 L5 The level parallel to reference plane through the apex of the distal root of the second molar in mandibular classifications and groups of the third molars Record the impacted state and measured eruption space of M3 on CBCT- derived panoramic radiograph. According to Pell&Gregory classification(Impaction Depth: PG-A, PG-B, PG-C; Ramus Relationship: PG-I, PG-II, PG-III) (Fig. 6 ) [ 16 , 17 ]and the angles of WP-based reference frame to classify M3 (A angle:[A1:67°]; B angle :[B1: 24°]). WP-based reference system is the main reference system in this study,and OP-based reference system was used as an auxiliary system. So molars were classified according to the A and B angles of the former.We divided the A angle and B angle into the three classifications according to the trisection of a sample size to ensure the comparability between samples, individually. Additionally,all M3 also were grouped according to the patient's age, sex, and Angle malocclusion classification, respectively. Group 1 was for males, Group 2 was for females, Group 3 was for class I malocclusion, Group 4 was for class III malocclusion, Group 5 was for 18–27 year olds and Group 6 was for 28–40 year olds. Statistical Analysis The statistical analyses were performed on SPSS (version 27.0, IBM Co., Armonk, NY USA). All measurement work was measured by the same researcher in a period of time, and each measurement result was repeated 3 times, and the average value of the 3 measurement results was taken. Making statistical descriptions for measurements.All data were given as mean ± standard deviation (SD). Pearson correlation coefficient was used to analyze the correlations among the angle of line -line, line -plane..A paired t-test was performed to compare the measurement in left and right Independent t-test was performed to compare the measurement in Group1 and 2,Group3 and 4,Group5 and 6. One-way ANOVA was performed to analyze the differences of RS between different classifications under four classification criteria ,pairwise comparison between classifications was performed by LSD test. 95% confidence intervals were set for all statistical analyses (P < 0.05) Results Classification, number and Corresponding age of M3 Table 2 showed the classification and number of the third molars.The number of each classification is similar.No statistically significant differences in corresponding age among the compared classifications ,except for age in PG-I/II/III classification. The corresponding age of M3 in PG-I classification was the largest, followed by PG-II classification, and the smallest was PG-III classification (P > 0.05).(Table.2). Table 2 Basic informations of M3 classification criterion Groups Number Corresponding Age a Corresponding gender male female Impacted Depth PG-A 85 29.08 ± 0.61 44 41 PG-B 60 27.00 ± 0.76 29 32 PG-C 61 28.82 ± 0.74 30 31 P Value 0.082 Ramus Relationship PG-I 78 30.17 ± 0.65 41 37 PG-II 75 28.41 ± 0.66 40 35 PG-III 53 25.77 ± 0.70 21 32 P Value 0.000 mesiodistal angle A1 68 28.65 ± 0.67 31 37 A2 69 27.80 ± 0.76 37 32 A3 69 28.75 ± 0.68 34 35 P Value 0.573 labiolingual angle B1 71 29.79 ± 0.59 37 34 B2 70 27.96 ± 0.69 36 34 B3 65 27.35 ± 0.80 29 36 P Value 0.056 Total n = 206 206 28.40 ± 0.40 102 104 a ANOVA of Corresponding Age in each three groups under different classification criterion The significance level P < 0.05 was labeled bold The correlation of FH-related angulations For the face-face angle and the line-face angle,<FH-WP showed a strong correlation with < FH-WL(r = 0.992,p < 0.05),the corresponding standard deviation of the two were 3.73and 3.74. <FH-OP showed a weak correlation with < FH-OL(r = 0.332, p < 0.05),the corresponding standard deviation of the two were 6.99and 5.58. <FH-WP angle had strong correlations with the < FH-OP angle(r = 0.619, p < 0.05), <FH-WL angle was moderately correlated with the < FH-OL angle (r = 0.475, p < 0.05) ( Table 3 ). Table 3 Pearson correlation coefficients of FH-related angulations Reference Face-face angulations Mean ± SD(°) Line-face angulations Mean ± SD(°) r WP/WL 11.50 ± 3.73(< FH-WP) 11.53 ± 3.74(< FH-WL) 0.992 ** OP/OL 1.84 ± 6.99(< FH-OP) 10.30 ± 5.58(< FH-OL) 0.332 ** r 0.619 ** 0.475 ** Pearson correlation coefficients was labeled bold;**Significant difference at P < 0.05 Differences of different groups of RS,A angle and B angle RS decreased gradually from the crown to the root, and the minimum was at the root tip (4.39 ± 1.95 mm in WP group,3.81 ± 1.54mm in OP group). RS had statistical difference in WP and OP groups in all level (p < 0.05). In WP group ,RS of the roots part (level 3,4,5) were bigger than OP group and RS of the crown part (level 1,2) were Smaller. A,B angles had no statistical significance between two groups(Table 4 ).For all measurements ,no statistical difference existed between the right and light sides(Table 4 ).Similarly, there was also no statistical difference in sex and Angle’s classification. However, significant differences between different age groups in B angle and RS of level5 were shown (P < 0.05), the Group 6 displayed larger measurements than Group 5(Table 5). Table 4 Comparison of data between groups in different levels RS of Level 1–5(mm) Group a of different reference Group b of different sides WP groups OP groups WP VS OP Right(R) Light(L) R VS L Mean ± SD(mm) Mean ± SD(mm) p Mean ± SD(mm) Mean ± SD(mm) P L1 11.10 ± 2.30 11.49 ± 2.06 0.045 11.21 ± 2.11 11.39 ± 2.26 0.269 L2 10.62 ± 1.81 11.17 ± 1.57 0.001 10.92 ± 1.72 10.87 ± 1.72 0.704 L3 7.84 ± 1.87 7.02 ± 1.83 0.000 7.57 ± 1.86 7.24 ± 1.85 0.058 L4 6.48 ± 1.84 5.43 ± 1.69 0.000 6.03 ± 1.88 5.82 ± 1.70 0.075 L5 4.39 ± 1.95 3.81 ± 1.54 0.001 4.14 ± 1.63 3.98 ± 1.85 0.142 A angle 48.83 ± 32.57 41.85 ± 31.07 0.113 45.51 ± 32.35 43.17 ± 31.45 0.231 B angle 19.06 ± 15.07 16.63 ± 11.75 0.069 17.20 ± 14.47 18.50 ± 12.57 0.075 a Two-samples independent t-test and test for normality was significant (P < 0.05); b A paired t-test and test for normality was significant (P < 0.05); The significance level P < 0.05 was labeled bold Table 5 Comparison of Measurements at Group1 and Group2 ,Group3 and Group4,Group5 and Group6 a Measurements(the RS of level and angle) sex(N) Angle`s classification(N) Age(N) Group1(208) Mean ± SD Group2(204) Mean ± SD P Group3(332) Mean ± SD Group 4(90) Mean ± SD P Group 5 (216) Mean ± SD Group6(196) Mean ± SD P L1 11.38 ± 2.30 11.22 ± 2.07 0.465 11.31 ± 2.21 11.27 ± 2.13 0.861 10.88 ± 2.26 11.36 ± 2.33 0.723 L2 10.81 ± 1.92 10.98 ± 1.49 0.314 10.93 ± 1.72 10.76 ± 1.70 0.410 10.61 ± 1.71 10.63 ± 1.93 0.322 L3 7.73 ± 1.88 7.13 ± 1.87 0.001 7.45 ± 1.89 7.37 ± 1.93 0.743 7.74 ± 1.77 7.95 ± 1.98 0.524 L4 6.02 ± 1.76 5.89 ± 1.92 0.490 5.95 ± 1.85 5.95 ± 1.82 0.980 6.21 ± 1.81 6.78 ± 1.83 0.058 L5 3.94 ± 1.82 4.26 ± 1.73 0.066 4.06 ± 1.78 4.23 ± 1.77 0.425 3.97 ± 1.87 4.85 ± 1.95 0.000 A angle 43.61 ± 31.78 45.06 ± 32.06 0.645 44.35 ± 31.37 44.31 ± 33.88 0.990 45.72 ± 32.04 48.06 ± 33.27 0.541 B angle 17.30 ± 13.49 18.39 ± 13.62 0.418 17.96 ± 14.37 17.45 ± 10.13 0.704 16.10 ± 14.30 21.75 ± 15.31 0.000 a Independent sample T-test of measured values under different genders, different Angle,s classification, and different ages. The significance level P < 0.05 was labeled bold Differences of RS in different third molar classifications In WP group,almost all RS had statistical differences in classification criteria of PG-A/B/C,PG-I/II/III and Mesiodistal angulation (P < 0.05), except RS of level2 in PG-I/II/III. However, no statistical difference between RS and B angle. In different Pell & Gregory classifications,from PG-A to PG-C,PG-I to PG-III,RS both gradual decreased(P < 0.05).In Mesiodistal angulation, from A1 to A3, RS showed an increasing trend( P < 0.05)( Table 6 ). In OP group: the above three results were consistent with the WP group after the RS of level 2 was removed. (Table 7 ). Table 6 Comparison of RS under different classifications of M3 in WP groups a classification criterion classification The RS of Level 1–5(mm) L1 L2 L3 L4 L5 Impacted Depth PG-A 12.55 ± 1.86 10.74 ± 1.68 8.51 ± 1.67 6.94 ± 1.72 5.01 ± 1.77 PG-B 10.95 ± 1.87 11.04 ± 1.68 7.87 ± 1.63 6.11 ± 1.92 4.19 ± 2.07 PG-C 9.25 ± 1.83 10.03 ± 1.99 6.86 ± 1.96 6.19 ± 1.79 3.7 ± 1.81 P Value 0.000 0.006 0.009 0.000 0.000 Ramus Relationship PG-I, 12.51 ± 1.87 10.88 ± 1.91 8.61 ± 1.61 7.26 ± 1.73 5.22 ± 1.87 PG-II 10.83 ± 2.05 10.60 ± 1.70 7.66 ± 1.92 6.32 ± 1.81 4.28 ± 1.75 PG-III 9.44 ± 1.94 10.24 ± 1.78 6.94 ± 1.73 5.56 ± 1.57 3.33 ± 1.80 P Value 0.000 0.144 0.000 0.000 0.000 mesiodistal angle A1 9.38 ± 1.86 9.95 ± 1.68 7.51 ± 2.02 6.52 ± 1.99 4.15 ± 1.98 A2 11.03 ± 1.94 10.6 ± 1.88 7.51 ± 1.76 6.06 ± 1.79 4.09 ± 1.99 A3 12.89 ± 1.57 11.15 ± 1.65 8.49 ± 1.67 6.85 ± 1.65 4.93 ± 1.79 P Value 0.000 0.000 0.002 0.037 0.018 labiolingual angle B1 10.81 ± 2.38 10.68 ± 1.89 8.17 ± 1.71 6.95 ± 1.78 4.51 ± 2.06 B2 11.28 ± 2.39 10.61 ± 1.67 7.79 ± 1.91 6.33 ± 2.00 4.34 ± 2.15 B3 11.24 ± 2.11 10.54 ± 1.90 7.52 ± 1.87 6.12 ± 1.60 4.30 ± 1.58 P Value 0.406 0.911 0.127 0.051 0.804 a ANOVA of RS in each three groups under different classification criteria The significance level P < 0.05 was labeled bold Table 7 Comparison of RS under different classifications of M3 in OP groups a classification criterion classification The RS of Level 1–5(mm) L1 L2 L3 L4 L5 Impacted Depth PG-A 12.37 ± 1.73 11.01 ± 1.63 7.45 ± 1.75 5.87 ± 1.65 4.36 ± 1.34 PG-B 11.47 ± 1.65 11.47 ± 1.17 6.88 ± 1.79 5.03 ± 1.72 3.47 ± 1.61 PG-C 10.30 ± 2.24 11.08 ± 1.80 6.56 ± 1.86 5.19 ± 1.62 3.37 ± 1.51 P Value 0.000 0.202 0.011 0.006 0.000 Ramus Relationship PG-I, 12.28 ± 1.87 11.09 ± 1.60 7.60 ± 1.72 5.97 ± 1.62 4.39 ± 1.49 PG-II 11.06 ± 1.96 11.10 ± 1.70 6.96 ± 1.83 5.41 ± 1.67 3.67 ± 1.39 PG-III 10.96 ± 2.14 11.37 ± 1.34 6.25 ± 1.70 4.64 ± 1.54 3.16 ± 1.53 P Value 0.000 0.557 0.000 0.000 0.000 mesiodistal angle A1 10.46 ± 2.11 11.04 ± 1.60 7.03 ± 1.94 5.26 ± 1.66 3.68 ± 1.59 A2 11.37 ± 1.73 11.33 ± 1.81 6.58 ± 1.71 5.17 ± 1.59 3.57 ± 1.54 A3 12.63 ± 1.73 11.13 ± 1.27 7.45 ± 1.74 5.85 ± 1.77 4.18 ± 1.43 P Value 0.000 0.567 0.018 0.036 0.043 labiolingual angle B1 10.81 ± 2.38 10.68 ± 1.89 8.17 ± 1.71 6.95 ± 1.78 4.51 ± 2.06 B2 11.76 ± 2.00 11.17 ± 1.45 7.04 ± 1.79 5.56 ± 1.80 3.92 ± 1.63 B3 11.24 ± 1.97 10.88 ± 1.85 6.59 ± 1.86 5.11 ± 1.64 3.63 ± 1.30 P Value 0.336 0.126 0.086 0.202 0.505 a ANOVA of RS in each three groups under different classification criterion The significance level P < 0.05 was labeled bold Discussion Recent findings have shown RS is a three-dimensional spatial definition [ 10 , 11 ]. The RS was analyzed in the CBCT to avoid the error of X-ray film[ 18 ]. This study aimed to use CBCT to reconstruct 3D model and find out the relationship between M3 and RS. Patients we included were adults aged 18 to 40 years with non-vertical growth. Zhao Z et al found RS had a maximum in the hypodivergent group and was twice as large as in the hyperdivergent group[ 19 ]. Research reports the missing rate of M3 in patients with vertical skeletal craniofacial pattern was higher [ 20 ] Evidence in the literature supported our selection of patients. In the current study, we found that with the increase in average age, the M3 tends to PG-I within the classification of ramus relationship. Possibly as a result of the eruption of the M3 increases the eruption space and promotes the further growth of the mandibular angle[ 21 ]. In addition, previous studies used OP to measure the amount of tooth movement[10.11.19]. The tooth movement of malocclusion patients in orthodontic treatment is likely to influence the position of OP[ 22 ]. The findings confirmed the WALA ridge arch can represent the alveolar arch the dental arch and WALA ridge arch have high matching[ 23 , 24 ]. Hence, this study fitted the WP as a reference plane by referring to the least square method and it was also the innovation of this study[ 25 ]. We found that WP had high stability in the present study by comparing the standard deviation of < FH-WP and < FH-OP. It is suggesting that WP can be the reference plane. WL and WP were highly correlated and the result was supported by Gupta[ 24 ]. This may reflect the fact that the selected measurement datum line is also scientific. In our study, the OP was used as an auxiliary to illustrate the reliability of the results obtained by the WP. In recent years, three-dimensional digital technology with high efficiency, high accuracy, and high maneuverability can help dentists to simulate orthognathic surgery, reconstruct 3D structure of the airway, analyze organizational change in orthodontic treatment and provide effective means for personalized orthodontic treatment[ 26 ]. With the development of digital orthodontics, digital model, invisible appliance and personalized appliance have been widely used. In this study, digital technology was also used to fit the plane, which is an innovative method, hoping to help the follow-up orthodontic research work. Because of certain Angle between the reference planes, it had noticeable differences in RS which were obtained by OP and WP in this study. The consistent results with Kim were that RS on the crown side was bigger than on the root side and RS had a gradual reduction from the crown to the root tip[ 10 ]. Thus, More attention should be paid to the distal movement of roots clinically. During distal movement, the molars will tilt when the root tip touches the cortical bone. This is consistent with many previous studies[ 27 , 28 ]. Otherwise, RS had no significant difference in gender and Angle classification. In the age classification, the older group has larger RS (especially in the root tip), and B angle. The finding by Choi[ 11 ] that the available space at the posterior boundary of molars is influenced by age supports our results. From this, the influence of age on RS should be considered in orthodontics. And the influence of age on RS may be caused by periodontal disease or physiological alveolar ridge absorption.[ 29 ] The connection between M3 and RS is controversial, Previous studies[ 11 , 19 ] analyzed the RS with or without the M3 and found no notable difference. However ,many literatures reported that the existence of the third molar would increase the available space of the posterior segment of the dental arch[ 30 ]. But these scholars did not classify M3 in detail. Therefore, This study conducted an in-depth classification study and found that RS were significantly different under different classifications. In Pell-Gregory classifications, the RS presented a gradual reduction from PG-A to PG-C. Similarly, RS gradually decreased from PG-I to PG-III. With respect to angle classification ,the smaller A angle, the smaller RS. And no significant difference existed in the B-angle classification. In this study,we also confirmed that the degree of mesial impaction increased with the increase of the degree of impaction in PG-A/B/C and PG-I/II/III classification. B-angle has no significant difference in Pell-Gregory classifications. In agreement with our results, Tsai H confirmed that posterior molar space was related to the mesial angle of impacted teeth[ 31 ]. Consequently, RS was affected by the depth of impacted M3, the degree of mesioangular impaction and the distance between the anterior edge of ramus and the second molar. No matter which classification criterion, the RS decreased with the deepening of M3' s impaction degree.RS can be initially estimated by observing the depth, mesial angle, or posterior space of M3. Our findings could be used to help some primary hospitals without large dental facilities predict RS by observing panoramic or lateral radiograph, which will be beneficial to the design of orthodontic plans to push molars distally. The deficiency of this study is that the thickness of the buccolingual bone plate and the width of the Mandibular alveolar arch have not been considered and the application of digitalization is relatively superficial. Now that the digital technology has matured, people have invented the manipulator to bend the arch wire[ 32 ] .In future research, we can focus on digital technology and artificial intelligence, applying them in oral research to better help our clinical work. Conclusions Compared with occlusal plane,the fitting WALA ridge plane had higher stability ,the fitting WALA ridge plane can be used as an innovative plane for orthodontic clinical scientific research. The retromolar space of the crown levels were greater than the root levels, a minimum value was present at the root apex .Therefore ,special attention should be paid to the initial retromolar space at the apical when pushing the molar to distalization The current study found that retromolar space was significantly different in different impacted classification of the mandibular third molars,the impacted classification of M3 can be observed before orthodontics to predict the amount of molars distalization. Abbreviations 3D: Three‑dimensional; CBCT: Cone-beam computed tomography; RS: Retromolar space; M3: The mandibular third molars WP: the fitting WALA ridge plane; OP: The occlusal plane; FH: The Frankfort horizontal plane; WL: The WALA ridge line; OL: the occlusion line; MD: Molar distalization SD: Standard deviation; MC: Mandibular canal Declarations Ethics approval and consent to participate All the research work has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki). All patients involved in this study had provided the written informed consent. The study was approved by the Research and Ethics Committee of the Affiliated Stomatology Hospital of Chongqing Medical University Consent for publication Not applicable. Availability of data and materials The datasets generated or analysed during in the current study are available from the corresponding author on reasonable request.. Competing interests The authors declare no competing of interest. Funding Project Supported byChongqing Talent Program: Innovative leading talents (Medical field，CQYC20210303384) Chongqing Medical Scientific Research Project (2018ZDXM020) Authors' contributions Yumei Huang contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript. Yunjia Cheng,Yang Dan,and Yingying Tang contributed to data collection interpretation.Other authors contributed to revised the manuscript. All authors have read and approved the manuscript. Acknowledgements Not applicable References Janson G, Goizueta O E F M, Garib DG, et al. Relationship between maxillary and mandibular base lengths and dental crowding in patients with complete Class II malocclusions[J]. The Angle Orthodontist, 2011, 81(2): 217–221. Robertson L, Kaur H, Fagundes N C F, et al. Effectiveness of clear aligner therapy for orthodontic treatment: a systematic review[J]. 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Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system[J]. American journal of orthodontics and dentofacial orthopedics, 2006, 129(6): 723–733. Bayome M, Park J H, Bay C, et al. Distalization of maxillary molars using temporary skeletal anchorage devices: A systematic review and meta-analysis[J]. Orthodontics & Craniofacial Research, 2021, 24: 103–112. Ravera S, Castroflorio T, Garino F, et al. Maxillary molar distalization with aligners in adult patients: a multicenter retrospective study[J]. Progress in orthodontics, 2016, 17(1): 1–9. Kim S J, Choi T H, Baik H S, et al. Mandibular posterior anatomic limit for molar distalization[J]. Am J Orthod Dentofacial Orthop, 2014, 146(2): 190–197. Choi Y T, Kim Y J, Yang K S, et al. Bone availability for mandibular molar distalization in adults with mandibular prognathism[J]. Angle Orthod, 2018, 88(1): 52–57. Sohal K S, Moshy J R, Owibingire S S, et al. Association between impacted mandibular third molar and occurrence of mandibular angle fracture: a radiological study[J]. Journal of Oral and Maxillofacial Radiology, 2019, 7(2): 25. Susarla S M, Dodson T B. Risk factors for third molar extraction difficulty[J]. Journal of oral and maxillofacial surgery, 2004, 62(11): 1363–1371. Yumei H, Yun H, Leilei Z. A study of the correlation between the digitally fitted WALA ridge plane and the mandibular body axial plane and occlusion plane. Journal of Practical Stomatology, 2022,03:373–378. Marchiori D F, Packota G V, Boughner J C. Third-molar mineralization as a function of available retromolar space[J]. Acta Odontologica Scandinavica, 2016, 74(7): 509–517. Padhye M N, Dabir A V, Girotra C S, et al. Pattern of mandibular third molar impaction in the Indian population: a retrospective clinico-radiographic survey[J]. Oral surgery, oral medicine, oral pathology and oral radiology, 2013, 116(3): e161-e166. Zeynep Gümrükü, Balaban E, Karaba M. Is there a relationship between third-molar impaction types and the dimensional/angular measurement values of posterior mandible according to Pell & Gregory/Winter Classification?[J]. Oral Radiology, 2020, 37(1):1–7. Noffke C E E, Nzima N, Farman A G. Guidelines for the safe use of dental and maxillofacial CBCT: a review with recommendations for South Africa[J]. South African Dental Journal, 2011, 66(6): 262–266. Zhao Z, Wang Q, Yi P, et al. Quantitative evaluation of retromolar space in adults with different vertical facial types: Cone-beam computed tomography study[J]. The Angle Orthodontist, 2020, 90(6): 857–865. Huang Y, Yan Y, Cao J, et al. Obeservations on association between third molar agenesis and craniofacial morphology[J]. Journal of Orofacial Orthopedics/Fortschritte der Kieferorthopädie, 2017, 78(6): 504–510. Marchiori D F, Packota G V, Boughner J C. Initial third molar development is delayed in jaws with short distal space: An early impaction sign?[J]. Archives of oral biology, 2019, 106: 104475. Serafin M, Fastuca R, Castellani E, et al. Occlusal Plane Changes After Molar Distalization With a Pendulum Appliance in Growing Patients with Class II Malocclusion: A Retrospective Cephalometric Study[J]. Turkish Journal of Orthodontics, 2021, 34(1): 10. Glass T R, Tremont T, Martin C A, et al. A CBCT evaluation of root position in bone, long axis inclination and relationship to the WALA Ridge[C]//Seminars in Orthodontics. WB Saunders, 2019, 25(1): 24–35. Shu R, Han X, Wang Y, et al. Comparison of arch width, alveolar width and buccolingual inclination of teeth between Class II division 1 malocclusion and Class I occlusion[J]. The Angle orthodontist, 2013, 83(2): 246–252. Schomaker V, Waser J, Marsh R E, et al. To fit a plane or a line to a set of points by least squares[J]. Acta crystallographica, 1959, 12(8): 600–604. Gross D, Gross K, Wilhelmy S. Digitalization in dentistry: ethical challenges and implications[J]. Quintessence International, 2019, 50(10). Sugawara J, Kanzaki R, Takahashi I, et al. Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system[J]. American journal of orthodontics and dentofacial orthopedics, 2006, 129(6): 723–733. Kook Y A, Park J H, Bayome M, et al. Distalization of the mandibular dentition with a ramal plate for skeletal Class III malocclusion correction[J]. American Journal of Orthodontics and Dentofacial Orthopedics, 2016, 150(2): 364–377. Sapey E, Yonel Z, Edgar R, et al. The clinical and inflammatory relationships between periodontitis and chronic obstructive pulmonary disease[J]. Journal of clinical periodontology, 2020, 47(9): 1040–1052. Ghougassian S S, Ghafari J G. Association between mandibular third molar formation and retromolar space[J]. The Angle Orthodontist, 2014, 84(6): 946–950. Tsai H H. Factors associated with mandibular third molar eruption and impaction.[J]. The Journal of clinical pediatric dentistry, 2005, 30(2):109–113. Xia Z, Deng H, Weng S, et al. Development of a robotic system for orthodontic archwire bending[C]//2016 IEEE International Conference on Robotics and Automation (ICRA). IEEE, 2016: 730–735. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 10 Mar, 2023 Read the published version in BMC Oral Health → Version 1 posted Editorial decision: Major revision 15 Sep, 2022 Reviews received at journal 07 Aug, 2022 Reviewers agreed at journal 28 Jul, 2022 Reviewers invited by journal 28 Jul, 2022 Editor assigned by journal 24 Jul, 2022 Editor invited by journal 13 Jul, 2022 Submission checks completed at journal 13 Jul, 2022 First submitted to journal 07 Jul, 2022 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-1834788","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":120690684,"identity":"dc9b6f02-e24f-47f7-b1b1-1cb9ed822d0c","order_by":0,"name":"Yumei Huang","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yumei","middleName":"","lastName":"Huang","suffix":""},{"id":120690685,"identity":"6010ff67-232b-4e4e-aca0-5c3b36150b5a","order_by":1,"name":"Yunjia Cheng","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yunjia","middleName":"","lastName":"Cheng","suffix":""},{"id":120690686,"identity":"0b06416a-8151-4668-94c5-9131a07cc5ab","order_by":2,"name":"Yang Dan","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Dan","suffix":""},{"id":120690687,"identity":"21b63a11-067d-4648-bc4b-1dd233f7465b","order_by":3,"name":"Yingying Tang","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yingying","middleName":"","lastName":"Tang","suffix":""},{"id":120690688,"identity":"05b1cf58-bd21-4b5c-b28f-dc168a367436","order_by":4,"name":"Ya Yang","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ya","middleName":"","lastName":"Yang","suffix":""},{"id":120690689,"identity":"097256c9-6fe3-4e75-af7e-a91424cda57b","order_by":5,"name":"Jingfeng Xu","email":"","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jingfeng","middleName":"","lastName":"Xu","suffix":""},{"id":120690690,"identity":"b61ac3c1-364d-4285-abd2-e8fce6c4cc2c","order_by":6,"name":"Leilei Zheng","email":"data:image/png;base64,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","orcid":"","institution":"Stomatological Hospital of Chongqing Medical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Leilei","middleName":"","lastName":"Zheng","suffix":""}],"badges":[],"createdAt":"2022-07-07 10:29:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1834788/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1834788/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12903-023-02843-0","type":"published","date":"2023-03-10T19:32:56+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":24107162,"identity":"1ee9891e-bd4b-48b4-8043-8bbc5710c0bf","added_by":"auto","created_at":"2022-07-20 18:42:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":279832,"visible":true,"origin":"","legend":"\u003cp\u003eConstruction of 3D model, reference plane. A 3D 3D hard tissue model and bone marker points of mandibular WALA ridge.\u0026nbsp;B The Frankfort\u0026nbsp;horizontal\u0026nbsp;plane (FH) and the occlusal plane(OP)\u0026nbsp;\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/1130d0887edc5360fd38aeb6.png"},{"id":24107466,"identity":"1d99ceb7-8ceb-4dc7-b94a-e9e95fdec78c","added_by":"auto","created_at":"2022-07-20 18:52:16","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":262477,"visible":true,"origin":"","legend":"\u003cp\u003eThe process of complete the fitting of WP\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/fec6a22669a3294194bda99d.jpg"},{"id":24107367,"identity":"efa25dbf-8c02-4903-9805-acc3137fbb4a","added_by":"auto","created_at":"2022-07-20 18:47:16","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":70284,"visible":true,"origin":"","legend":"\u003cp\u003eThe projected schematic diagram of reference plane, line and the FH-related angulations on the sagittal plane \u003cstrong\u003eA \u003c/strong\u003eFH,WP,WL and the \u0026lt; FH-WP, \u0026lt;FH-WL.\u0026nbsp;\u003cstrong\u003eB \u003c/strong\u003eFH,OP,OL and \u0026lt;FH-OP, \u0026lt;FH-OL.\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/c39293a9726c17589ed55be7.jpg"},{"id":24107164,"identity":"23fb20ea-3520-451a-ad6b-924c7444bc67","added_by":"auto","created_at":"2022-07-20 18:42:16","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":131620,"visible":true,"origin":"","legend":"\u003cp\u003eThe detailed protocol of A,B angle measurements. Creating local 3D reference frames, the correlated planes were determined by intersected guidelines with different colors, which were red for axial planes, green for sagittal planes, and orange for coronal planes. \u003cstrong\u003eA \u003c/strong\u003eWP-based reference frame.\u003cstrong\u003e \u003c/strong\u003eTake WP as horizontal plane, Project the bony WALA ridge marks of the first and second molars on the horizontal plane, connect the two points as WL\u003csub\u003ep\u003c/sub\u003e, make the sagittal plane through WL\u003csub\u003ep\u003c/sub\u003e and perpendicular to the horizontal plane, and make the coronal plane through one mark and perpendicular to the horizontal plane and sagittal plane. \u003cstrong\u003eB\u003c/strong\u003e OP-based reference frame. The method was the same as A, and the two landmarks were replaced by the mesial buccal cusp of the first and the second molars \u003cstrong\u003eC \u003c/strong\u003eMesiodistal angle (A angle)：Find the sagittal section of the longest tooth axis of M3 and record the angle between this axis and the horizontal plane in the sagittal plane; labiolingual angle (B angle): Find the coronal or horizontal section of the longest tooth axis of M3,record the angle between this axis and the sagittal plane in the coronal or horizontal plane\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/a2338e666d6f13ab7ca370f0.jpg"},{"id":24107163,"identity":"fc3db577-7985-4066-929e-7d075f16261e","added_by":"auto","created_at":"2022-07-20 18:42:16","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":118756,"visible":true,"origin":"","legend":"\u003cp\u003elevel 1-5, mandibular canal and measurements\u0026nbsp;\u003cstrong\u003eA \u003c/strong\u003eL1 to L5\u003cstrong\u003e\u0026nbsp;B\u003c/strong\u003e the mandibular canal\u0026nbsp;\u003cstrong\u003eC\u003c/strong\u003e the measurement diagram of RS in crown level\u0026nbsp;\u003cstrong\u003eD\u003c/strong\u003e the measurement diagram of RS in the root level (The measurement method of RS on OP-based level by using OL\u003csub\u003ep\u003c/sub\u003e was consistent with this). \u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/272d4c39da2414298872401b.jpg"},{"id":24107506,"identity":"8efbdba5-51cc-4f2b-a45a-b36f3fa71c4a","added_by":"auto","created_at":"2022-07-20 18:57:16","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":127111,"visible":true,"origin":"","legend":"\u003cp\u003eThe classification criterion of Pell\u0026amp;Gregory.\u003cstrong\u003e A\u003c/strong\u003e Impaction depth of Pell-Gregory Classification: PG-A, PG-B, PG-A. \u003cstrong\u003eB\u003c/strong\u003e Ramus relationship of Pell-Gregory Classification: PG-I, PG-II , PG-III.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/58a2891d9acefef50b1923d4.png"},{"id":44721760,"identity":"6a188b44-4ddc-4fc3-92bb-be6c776a6c28","added_by":"auto","created_at":"2023-10-16 19:39:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1336493,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1834788/v1/9a26b8db-3ab6-488d-8b00-8b53a93e7512.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Three-dimensional analysis of the relationship between mandibular retromolar space and impacted third molars types in non-hyperdivergent adults","fulltext":[{"header":"Background","content":"\u003cp\u003eMolar distalization (MD)is a method for extending the length of dental arch[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Particularly in recent years, due to the popularity of invisible orthotics, the realization rate of molar distal movement has been greatly improved[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].So in the orthodontic clinic, orthodontists always relieve mild or moderate crowding and adjust the molar position relationship by MD[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. At this time, the question arises of where the boundary of the tooth movement is\u003c/p\u003e \u003cp\u003eThe limit of MD depends on the determination of alveolar bone anatomical limit. The maxillary arch incorporates a clear posterior limit\u0026mdash;the maxillary Tuberosity[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Hence ,MD is commonly utilized within the orthodontic process of the maxillary dentition. The conventional way of MD mostly uses the skeletal anchorage system, face-bow, and temporary skeletal anchorage devices, all of these can accomplish certain effect [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe mandible is composed of mandibular body and mandibular ramus. It is a complex structure, with masticatory muscles attached and high bone density. So the MD in mandible is difficult. With the popularity of CBCT, increasingly scholars have studied MD in mandible Kim[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]proposed that the farthest lingual cortical bone of the mandibular arch was the posterior anatomical boundary and found the RS had the minimum at the root tip. Choi et al found that RS had no statistically significant difference between class I and class III malocclusion[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. But in previous studies, the anatomic characteristics of the mandibular angle related to MD were not considered. M3 are the distal structure of the mandibular dental arch, located at the turning point of the mandibular body and ramus. It has been reported that the impacted state of them can affect the anatomical relationship of the transition area to a certain extent[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The shape, position and inclination of M3 are regularly utilized to assess the difficulty of the extraction of M3 in maxillofacial surgery [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBe that as it may, the research between M3 and orthodontics has been simply and the relationship between distinctive impacted sorts of M3 and RS has not been thoroughly analyzed. The purpose of this study is to quantitatively measure RS of the mandible with CBCT, and find the relationship between RS and M3 impaction, so as to assist orthodontists design treatment plans.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cdiv class=\"Section2\" id=\"Sec3\"\u003e\n \u003ch2\u003esample selection\u003c/h2\u003e\n \u003cp\u003eThis study was approved by the Research and Ethics Committee of the Affiliated Stomatology Hospital of Chongqing Medical University (2021(LSNo.045)).\u003c/p\u003e\n \u003cp\u003eThe sample included CBCT imagings of 103 subjects (52 males and 51 females, mean age\u0026thinsp;=\u0026thinsp;28.39 years), aged from 18 to 40 years. These subjects were selected from the patients who were conceded for orthodontic treatment from 2019 to 2021 at the Department of Orthodontics, Affiliated Stomatology Hospital of Chongqing Medical University.\u003c/p\u003e\n \u003cp\u003eThe inclusion criteria : (1) non-vertical facial dimension (SN-MP\u0026deg;\u0026lt;32\u0026deg;) and Class I or Class III malocclusion, (2) normal overjet and overbite, (3) crowding of less than 4 mm in the mandibular dental arch, (4) no significant alveolar bone loss, (5) no missing teeth (including M3), (6) no noticeable facial asymmetry and deformation, (7) no tumors, fractures, cysts in mandible, (8) no diagnosed systemic disease, (9) no history of orthodontic treatment.\u003c/p\u003e\n \u003cp\u003eThe exclusion criteria : (1) blurred CBCT imagings ,(2) incomplete CBCT imagings ,(3) unmeasurable CBCT imagings.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec4\"\u003e\n \u003ch2\u003eConstruction of 3D models, reference planes and measuring lines\u003c/h2\u003e\n \u003cp\u003eCBCT imagings (KaVo Dental Gmb H, USA; 80 mA, 80 kVp, and 8.9-second scan time) were procured. The data was imported into Mimics 19.0 software (Materialise, Leuven, Belgium) in Digital Imaging and Communications in Medicine (DICOM) format to reconstruct the 3D hard tissue models(Fig.\u0026nbsp;1A). Connecting the left and right orbital points(Or-R, Or-L)and the right porion point(Po-R) as the Frankfort horizontal plane(FH). Connecting two mesiobuccal cusp points of the mandibular first molars(L6R-MB,L6L-MB) and the mesial contact point of the lower central incisor(LIE) as occlusal plane(OP) (Fig.\u0026nbsp;1B).\u003c/p\u003e\n \u003cp\u003eWe got the coordinate points of bony WALA ridge in Mimics software and imported the coordinate values into Matlab software(R2022a,MathWorks, U.S)[\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e] to complete the fitting of WALA ridge plane(WP), and finally imported WP into Mimics. The process was shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003eTo construct the reference lines. Connecting the bone marker points of the WALA ridge of the mandibular first and second molar as the WALA ridge line(WL) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA).Connecting the mesial buccal cusps of the mandibular first and second molar as the occlusion line (OL) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec5\"\u003e\n \u003ch2\u003evariables and measurements\u003c/h2\u003e\n \u003cp\u003eThe 3D hard tissue models were imported into the Measure and Analysis Module Of Mimics for creating FH,WP, OP, WL,and OL .The angles of FH with WP, WL, OP and OL were respectively recorded as \u0026lt;\u0026thinsp;FH-WP, \u0026lt;FH-WL ,\u0026lt;FH-OP, \u0026lt;FH-OL.These FH-related angulations were measured by the projection on the sagittal section (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA,\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB). Recording the mesiodistal angulation(A angle: -10\u0026deg;~100\u0026deg;),labiolingual angulation(B angle) of M3 in WP-based and OP-based reference frames, separately.The detailed protocol of CBCT measurements described in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e\u003c/p\u003e\n \u003cp\u003eThe RS were measured on five different level which were parallel to the horizontal plane including level 1\u0026ndash;5 in two reference frames (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e,Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eA). Level 1\u0026ndash;2 were at the crown level. Level 3\u0026ndash;5 were at the root level. The distance from the distal protruding point of the crown of the mandibular second molar to the anterior wall of the mandibular canal (MC)(Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eB) was measured as RS at the crown level[\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e] (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eC). The distance from the most lingual point of the distal root of the second molar to the lingual cortical bone of the mandible which parallels to the measuring line(WL\u003csub\u003eP\u003c/sub\u003e or OL\u003csub\u003eP\u003c/sub\u003e) was measured as RS at the root level [\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e](Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eD). Data obtained by using WP or OP plane as reference plane were recorded as WP group and OP group respectively.\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eExplanation the position of five levels\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLevel abbreviation \u0026nbsp; Interpretation\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLevel 1 L1 \u0026nbsp; The level parallel to reference plane through the most distal protruding point of the crown of the second molar in\u003c/p\u003e\n \u003cp\u003emandibular\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLevel 2 L2 \u0026nbsp; The level parallel to reference plane through the cement enamel-junction of the second molar in mandibular\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLevel 3 L3 \u0026nbsp; The level parallel to reference plane through the root furcation of the second molar in mandibular\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLevel 4 L4 \u0026nbsp; The level parallel to reference plane through the distal root of the second molar in mandibular\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLevel 5 L5 \u0026nbsp; The level parallel to reference plane through the apex of the distal root of the second molar in mandibular\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec6\"\u003e\n \u003ch2\u003eclassifications and groups of the third molars\u003c/h2\u003e\n \u003cp\u003eRecord the impacted state and measured eruption space of M3 on CBCT- derived panoramic radiograph. According to Pell\u0026amp;Gregory classification(Impaction Depth: PG-A, PG-B, PG-C; Ramus Relationship: PG-I, PG-II, PG-III) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e) [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]and the angles of WP-based reference frame to classify M3 (A angle:[A1:\u0026lt;27\u0026deg;,A2:27\u0026thinsp;~\u0026thinsp;67\u0026deg;,A3:\u0026gt;67\u0026deg;]; B angle :[B1: \u0026lt;14\u0026deg;,B2:14\u0026thinsp;~\u0026thinsp;24\u0026deg;,B3:\u0026gt;24\u0026deg;]). WP-based reference system is the main reference system in this study,and OP-based reference system was used as an auxiliary system. So molars were classified according to the A and B angles of the former.We divided the A angle and B angle into the three classifications according to the trisection of a sample size to ensure the comparability between samples, individually. Additionally,all M3 also were grouped according to the patient\u0026apos;s age, sex, and Angle malocclusion classification, respectively. Group 1 was for males, Group 2 was for females, Group 3 was for class I malocclusion, Group 4 was for class III malocclusion, Group 5 was for 18\u0026ndash;27 year olds and Group 6 was for 28\u0026ndash;40 year olds.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec7\"\u003e\n \u003ch2\u003eStatistical Analysis\u003c/h2\u003e\n \u003cp\u003eThe statistical analyses were performed on SPSS (version 27.0, IBM Co., Armonk, NY USA). All measurement work was measured by the same researcher in a period of time, and each measurement result was repeated 3 times, and the average value of the 3 measurement results was taken.\u003c/p\u003e\n \u003cp\u003eMaking statistical descriptions for measurements.All data were given as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). Pearson correlation coefficient was used to analyze the correlations among the angle of line -line, line -plane..A paired t-test was performed to compare the measurement in left and right Independent t-test was performed to compare the measurement in Group1 and 2,Group3 and 4,Group5 and 6. One-way ANOVA was performed to analyze the differences of RS between different classifications under four classification criteria ,pairwise comparison between classifications was performed by LSD test. 95% confidence intervals were set for all statistical analyses (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05)\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cdiv class=\"Section2\" id=\"Sec9\"\u003e\n \u003ch2\u003eClassification, number and Corresponding age of M3\u003c/h2\u003e\n \u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e showed the classification and number of the third molars.The number of each classification is similar.No statistically significant differences in corresponding age among the compared classifications ,except for age in PG-I/II/III classification. The corresponding age of M3 in PG-I classification was the largest, followed by PG-II classification, and the smallest was PG-III classification (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).(Table.2).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab2\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eBasic informations of M3\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eclassification criterion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eGroups\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eNumber\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eCorresponding Age\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eCorresponding gender\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003emale\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003efemale\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eImpacted Depth\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-B\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eRamus Relationship\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e30.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003emesiodistal\u0026nbsp;angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.65\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.80\u0026thinsp;\u0026plusmn;\u0026thinsp;0.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.75\u0026thinsp;\u0026plusmn;\u0026thinsp;0.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.573\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003elabiolingual angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.79\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.35\u0026thinsp;\u0026plusmn;\u0026thinsp;0.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.056\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTotal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003en\u0026thinsp;=\u0026thinsp;206\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e206\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28.40\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e102\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e104\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\"\u003ea ANOVA of Corresponding Age in each three groups under different classification criterion\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"6\"\u003eThe significance level P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was labeled bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec10\"\u003e\n \u003ch2\u003eThe correlation of FH-related angulations\u003c/h2\u003e\n \u003cp\u003eFor the face-face angle and the line-face angle,\u0026lt;FH-WP showed a strong correlation with \u0026lt;\u0026thinsp;FH-WL(r\u0026thinsp;=\u0026thinsp;0.992,p\u0026thinsp;\u0026lt;\u0026thinsp;0.05),the corresponding standard deviation of the two were 3.73and 3.74. \u0026lt;FH-OP showed a weak correlation with \u0026lt;\u0026thinsp;FH-OL(r\u0026thinsp;=\u0026thinsp;0.332, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05),the corresponding standard deviation of the two were 6.99and 5.58. \u0026lt;FH-WP angle had strong correlations with the \u0026lt;\u0026thinsp;FH-OP angle(r\u0026thinsp;=\u0026thinsp;0.619, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), \u0026lt;FH-WL angle was moderately correlated with the \u0026lt;\u0026thinsp;FH-OL angle (r\u0026thinsp;=\u0026thinsp;0.475, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) ( Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab3\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePearson correlation coefficients of FH-related angulations\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFace-face angulations\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLine-face angulations\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003er\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWP/WL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.50\u0026thinsp;\u0026plusmn;\u0026thinsp;3.73(\u0026lt;\u0026thinsp;FH-WP)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.53\u0026thinsp;\u0026plusmn;\u0026thinsp;3.74(\u0026lt;\u0026thinsp;FH-WL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.992\u003c/strong\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOP/OL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.84\u0026thinsp;\u0026plusmn;\u0026thinsp;6.99(\u0026lt;\u0026thinsp;FH-OP)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.30\u0026thinsp;\u0026plusmn;\u0026thinsp;5.58(\u0026lt;\u0026thinsp;FH-OL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.332\u003c/strong\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003er\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.619\u003c/strong\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.475\u003c/strong\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\"\u003ePearson correlation coefficients was labeled bold;**Significant difference at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec11\"\u003e\n \u003ch2\u003eDifferences of different groups of RS,A angle and B angle\u003c/h2\u003e\n \u003cp\u003eRS decreased gradually from the crown to the root, and the minimum was at the root tip (4.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95 mm in WP group,3.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.54mm in OP group). RS had statistical difference in WP and OP groups in all level (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In WP group ,RS of the roots part (level 3,4,5) were bigger than OP group and RS of the crown part (level 1,2) were Smaller. A,B angles had no statistical significance between two groups(Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).For all measurements ,no statistical difference existed between the right and light sides(Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).Similarly, there was also no statistical difference in sex and Angle\u0026rsquo;s classification. However, significant differences between different age groups in B angle and RS of level5 were shown (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), the Group 6 displayed larger measurements than Group 5(Table\u0026nbsp;5).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab4\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of data between groups in different levels\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003eRS of\u003c/p\u003e\n \u003cp\u003eLevel 1\u0026ndash;5(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eGroup\u003csup\u003ea\u003c/sup\u003e of different reference\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eGroup\u003csup\u003eb\u003c/sup\u003eof different sides\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWP groups\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOP groups\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eWP VS OP\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eRight(R)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLight(L)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eR VS L\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.10\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.49\u0026thinsp;\u0026plusmn;\u0026thinsp;2.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.045\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.21\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.39\u0026thinsp;\u0026plusmn;\u0026thinsp;2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.269\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.62\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.92\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.87\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.704\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.84\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.02\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.24\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.48\u0026thinsp;\u0026plusmn;\u0026thinsp;1.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e5.43\u0026thinsp;\u0026plusmn;\u0026thinsp;1.69\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e6.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.82\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.075\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e3.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.001\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4.14\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.142\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA\u0026nbsp;angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48.83\u0026thinsp;\u0026plusmn;\u0026thinsp;32.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e41.85\u0026thinsp;\u0026plusmn;\u0026thinsp;31.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e45.51\u0026thinsp;\u0026plusmn;\u0026thinsp;32.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e43.17\u0026thinsp;\u0026plusmn;\u0026thinsp;31.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.231\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e19.06\u0026thinsp;\u0026plusmn;\u0026thinsp;15.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e16.63\u0026thinsp;\u0026plusmn;\u0026thinsp;11.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.069\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e17.20\u0026thinsp;\u0026plusmn;\u0026thinsp;14.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e18.50\u0026thinsp;\u0026plusmn;\u0026thinsp;12.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.075\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"11\"\u003e\u003csup\u003ea\u003c/sup\u003e Two-samples independent t-test and test for normality was significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05); \u003csup\u003eb\u003c/sup\u003e A paired t-test and test for normality was significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05);\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"11\"\u003eThe significance level P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was labeled bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Taba\"\u003e\n \u003ccaption\u003e\n \u003cp\u003eTable 5\u003c/p\u003e\n \u003cp\u003eComparison of Measurements at Group1 and Group2 ,Group3 and Group4,Group5 and Group6\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\" rowspan=\"2\"\u003e\n \u003cp\u003eMeasurements(the RS of level and angle)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"6\"\u003e\n \u003cp\u003esex(N)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eAngle`s classification(N)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"3\"\u003e\n \u003cp\u003eAge(N)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGroup1(208)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGroup2(204)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGroup3(332)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003eGroup 4(90)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGroup 5 (216)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eGroup6(196)\u003c/p\u003e\n \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.38\u0026thinsp;\u0026plusmn;\u0026thinsp;2.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.22\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.465\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.31\u0026thinsp;\u0026plusmn;\u0026thinsp;2.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e11.27\u0026thinsp;\u0026plusmn;\u0026thinsp;2.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.861\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.88\u0026thinsp;\u0026plusmn;\u0026thinsp;2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.36\u0026thinsp;\u0026plusmn;\u0026thinsp;2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.723\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.81\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.314\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e10.76\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.410\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.322\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.73\u0026thinsp;\u0026plusmn;\u0026thinsp;1.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.13\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.45\u0026thinsp;\u0026plusmn;\u0026thinsp;1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e7.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.743\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.524\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e6.02\u0026thinsp;\u0026plusmn;\u0026thinsp;1.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e5.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.490\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e5.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e5.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.980\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.21\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.78\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.058\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eL5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e3.94\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.066\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4.06\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e4.23\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.425\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e43.61\u0026thinsp;\u0026plusmn;\u0026thinsp;31.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e45.06\u0026thinsp;\u0026plusmn;\u0026thinsp;32.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.645\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e44.35\u0026thinsp;\u0026plusmn;\u0026thinsp;31.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e44.31\u0026thinsp;\u0026plusmn;\u0026thinsp;33.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.990\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.72\u0026thinsp;\u0026plusmn;\u0026thinsp;32.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48.06\u0026thinsp;\u0026plusmn;\u0026thinsp;33.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.541\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB angle\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e17.30\u0026thinsp;\u0026plusmn;\u0026thinsp;13.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e18.39\u0026thinsp;\u0026plusmn;\u0026thinsp;13.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.418\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e17.96\u0026thinsp;\u0026plusmn;\u0026thinsp;14.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e17.45\u0026thinsp;\u0026plusmn;\u0026thinsp;10.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\"\u003e\n \u003cp\u003e0.704\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16.10\u0026thinsp;\u0026plusmn;\u0026thinsp;14.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e21.75\u0026thinsp;\u0026plusmn;\u0026thinsp;15.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"16\"\u003e\u003csup\u003ea\u003c/sup\u003e Independent sample T-test of measured values under different genders, different Angle,s classification, and different ages.\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"16\"\u003eThe significance level P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was labeled bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec12\"\u003e\n \u003ch2\u003eDifferences of RS in different third molar classifications\u003c/h2\u003e\n \u003cp\u003eIn WP group,almost all RS had statistical differences in classification criteria of PG-A/B/C,PG-I/II/III and Mesiodistal angulation (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), except RS of level2 in PG-I/II/III. However, no statistical difference between RS and B angle. In different Pell \u0026amp; Gregory classifications,from PG-A to PG-C,PG-I to PG-III,RS both gradual decreased(P\u0026thinsp;\u0026lt;\u0026thinsp;0.05).In Mesiodistal angulation, from A1 to A3, RS showed an increasing trend( P\u0026thinsp;\u0026lt;\u0026thinsp;0.05)( Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). In OP group: the above three results were consistent with the WP group after the RS of level 2 was removed. (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab5\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of RS under different classifications of M3 in WP groups\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eclassification criterion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eclassification\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"5\"\u003e\n \u003cp\u003eThe RS of Level 1\u0026ndash;5(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eL2\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eL3\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eL4\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\"\u003e\n \u003cp\u003eImpacted Depth\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.55\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.94\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-B\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.04\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.87\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.19\u0026thinsp;\u0026plusmn;\u0026thinsp;2.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.25\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.19\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.006\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.009\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\"\u003e\n \u003cp\u003eRamus Relationship\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-I,\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.88\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.22\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.83\u0026thinsp;\u0026plusmn;\u0026thinsp;2.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.60\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.66\u0026thinsp;\u0026plusmn;\u0026thinsp;1.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.32\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePG-III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.44\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.24\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.94\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.56\u0026thinsp;\u0026plusmn;\u0026thinsp;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.144\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\"\u003e\n \u003cp\u003emesiodistal angle\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.38\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.51\u0026thinsp;\u0026plusmn;\u0026thinsp;2.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.52\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.51\u0026thinsp;\u0026plusmn;\u0026thinsp;1.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.06\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.09\u0026thinsp;\u0026plusmn;\u0026thinsp;1.99\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.49\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.93\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.002\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.037\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.018\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\"\u003e\n \u003cp\u003elabiolingual angle\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.81\u0026thinsp;\u0026plusmn;\u0026thinsp;2.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.51\u0026thinsp;\u0026plusmn;\u0026thinsp;2.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.28\u0026thinsp;\u0026plusmn;\u0026thinsp;2.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.61\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.79\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.33\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.34\u0026thinsp;\u0026plusmn;\u0026thinsp;2.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eB3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.24\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e7.52\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.12\u0026thinsp;\u0026plusmn;\u0026thinsp;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.30\u0026thinsp;\u0026plusmn;\u0026thinsp;1.58\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.406\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.911\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.127\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.051\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.804\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e\u003csup\u003ea\u003c/sup\u003e ANOVA of RS in each three groups under different classification criteria\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003eThe significance level P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was labeled bold\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"gridtable\"\u003e\n \u003ctable border=\"1\" id=\"Tab6\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eComparison of RS under different classifications of M3 in OP groups\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003cth align=\"left\" rowspan=\"2\" style=\"height: 70px;\"\u003e\n \u003cp\u003eclassification criterion\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003eclassification\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"5\" style=\"height: 35px;\"\u003e\n \u003cp\u003eThe RS of Level 1\u0026ndash;5(mm)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003cth align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL1\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL2\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL3\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL4\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eL5\u003c/strong\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" colspan=\"8\" style=\"height: 35px;\"\u003e\n \u003cp\u003eImpacted Depth\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" rowspan=\"3\" style=\"height: 105px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e12.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.01\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e7.45\u0026thinsp;\u0026plusmn;\u0026thinsp;1.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.87\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e4.36\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-B\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.88\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.47\u0026thinsp;\u0026plusmn;\u0026thinsp;1.61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-C\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.30\u0026thinsp;\u0026plusmn;\u0026thinsp;2.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.08\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.56\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.19\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e0.202\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.011\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.006\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" colspan=\"8\" style=\"height: 35px;\"\u003e\n \u003cp\u003eRamus Relationship\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" rowspan=\"3\" style=\"height: 105px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-I,\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e12.28\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.09\u0026thinsp;\u0026plusmn;\u0026thinsp;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e7.60\u0026thinsp;\u0026plusmn;\u0026thinsp;1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.97\u0026thinsp;\u0026plusmn;\u0026thinsp;1.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e4.39\u0026thinsp;\u0026plusmn;\u0026thinsp;1.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.06\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.10\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.41\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.67\u0026thinsp;\u0026plusmn;\u0026thinsp;1.39\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003ePG-III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.96\u0026thinsp;\u0026plusmn;\u0026thinsp;2.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.25\u0026thinsp;\u0026plusmn;\u0026thinsp;1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e4.64\u0026thinsp;\u0026plusmn;\u0026thinsp;1.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.16\u0026thinsp;\u0026plusmn;\u0026thinsp;1.53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e0.557\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" colspan=\"8\" style=\"height: 35px;\"\u003e\n \u003cp\u003emesiodistal angle\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" rowspan=\"3\" style=\"height: 105px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.46\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.04\u0026thinsp;\u0026plusmn;\u0026thinsp;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e7.03\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.26\u0026thinsp;\u0026plusmn;\u0026thinsp;1.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.37\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.58\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.54\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e12.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.13\u0026thinsp;\u0026plusmn;\u0026thinsp;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e7.45\u0026thinsp;\u0026plusmn;\u0026thinsp;1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.85\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e4.18\u0026thinsp;\u0026plusmn;\u0026thinsp;1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.000\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e0.567\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.018\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.036\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.043\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" colspan=\"8\" style=\"height: 35px;\"\u003e\n \u003cp\u003elabiolingual angle\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eB1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.81\u0026thinsp;\u0026plusmn;\u0026thinsp;2.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.68\u0026thinsp;\u0026plusmn;\u0026thinsp;1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e8.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e4.51\u0026thinsp;\u0026plusmn;\u0026thinsp;2.06\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" rowspan=\"2\" style=\"height: 70px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eB2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.76\u0026thinsp;\u0026plusmn;\u0026thinsp;2.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.17\u0026thinsp;\u0026plusmn;\u0026thinsp;1.45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e7.04\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.56\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.92\u0026thinsp;\u0026plusmn;\u0026thinsp;1.63\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003eB3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35px;\"\u003e\n \u003cp\u003e11.24\u0026thinsp;\u0026plusmn;\u0026thinsp;1.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e10.88\u0026thinsp;\u0026plusmn;\u0026thinsp;1.85\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e6.59\u0026thinsp;\u0026plusmn;\u0026thinsp;1.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e5.11\u0026thinsp;\u0026plusmn;\u0026thinsp;1.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35px;\"\u003e\n \u003cp\u003e3.63\u0026thinsp;\u0026plusmn;\u0026thinsp;1.30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 35.0938px;\"\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003eP Value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colspan=\"2\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003e0.336\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003e0.126\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003e0.086\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003e0.202\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" style=\"height: 35.0938px;\"\u003e\n \u003cp\u003e0.505\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr style=\"height: 13px;\"\u003e\n \u003ctd colspan=\"8\" style=\"height: 13px;\"\u003ea ANOVA of RS in each three groups under different classification criterion\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr style=\"height: 13px;\"\u003e\n \u003ctd colspan=\"8\" style=\"height: 13px;\"\u003eThe significance level P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was labeled bold\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eRecent findings have shown RS is a three-dimensional spatial definition [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The RS was analyzed in the CBCT to avoid the error of X-ray film[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. This study aimed to use CBCT to reconstruct 3D model and find out the relationship between M3 and RS.\u003c/p\u003e \u003cp\u003ePatients we included were adults aged 18 to 40 years with non-vertical growth. Zhao Z et al found RS had a maximum in the hypodivergent group and was twice as large as in the hyperdivergent group[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Research reports the missing rate of M3 in patients with vertical skeletal craniofacial pattern was higher [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Evidence in the literature supported our selection of patients. In the current study, we found that with the increase in average age, the M3 tends to PG-I within the classification of ramus relationship. Possibly as a result of the eruption of the M3 increases the eruption space and promotes the further growth of the mandibular angle[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition, previous studies used OP to measure the amount of tooth movement[10.11.19]. The tooth movement of malocclusion patients in orthodontic treatment is likely to influence the position of OP[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The findings confirmed the WALA ridge arch can represent the alveolar arch the dental arch and WALA ridge arch have high matching[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Hence, this study fitted the WP as a reference plane by referring to the least square method and it was also the innovation of this study[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. We found that WP had high stability in the present study by comparing the standard deviation of \u0026lt;\u0026thinsp;FH-WP and \u0026lt;\u0026thinsp;FH-OP. It is suggesting that WP can be the reference plane. WL and WP were highly correlated and the result was supported by Gupta[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This may reflect the fact that the selected measurement datum line is also scientific. In our study, the OP was used as an auxiliary to illustrate the reliability of the results obtained by the WP.\u003c/p\u003e \u003cp\u003eIn recent years, three-dimensional digital technology with high efficiency, high accuracy, and high maneuverability can help dentists to simulate orthognathic surgery, reconstruct 3D structure of the airway, analyze organizational change in orthodontic treatment and provide effective means for personalized orthodontic treatment[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. With the development of digital orthodontics, digital model, invisible appliance and personalized appliance have been widely used. In this study, digital technology was also used to fit the plane, which is an innovative method, hoping to help the follow-up orthodontic research work.\u003c/p\u003e \u003cp\u003eBecause of certain Angle between the reference planes, it had noticeable differences in RS which were obtained by OP and WP in this study. The consistent results with Kim were that RS on the crown side was bigger than on the root side and RS had a gradual reduction from the crown to the root tip[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Thus, More attention should be paid to the distal movement of roots clinically. During distal movement, the molars will tilt when the root tip touches the cortical bone. This is consistent with many previous studies[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Otherwise, RS had no significant difference in gender and Angle classification. In the age classification, the older group has larger RS (especially in the root tip), and B angle. The finding by Choi[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] that the available space at the posterior boundary of molars is influenced by age supports our results. From this, the influence of age on RS should be considered in orthodontics. And the influence of age on RS may be caused by periodontal disease or physiological alveolar ridge absorption.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe connection between M3 and RS is controversial, Previous studies[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] analyzed the RS with or without the M3 and found no notable difference. However ,many literatures reported that the existence of the third molar would increase the available space of the posterior segment of the dental arch[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. But these scholars did not classify M3 in detail. Therefore, This study conducted an in-depth classification study and found that RS were significantly different under different classifications. In Pell-Gregory classifications, the RS presented a gradual reduction from PG-A to PG-C. Similarly, RS gradually decreased from PG-I to PG-III. With respect to angle classification ,the smaller A angle, the smaller RS. And no significant difference existed in the B-angle classification. In this study,we also confirmed that the degree of mesial impaction increased with the increase of the degree of impaction in PG-A/B/C and PG-I/II/III classification. B-angle has no significant difference in Pell-Gregory classifications. In agreement with our results, Tsai H confirmed that posterior molar space was related to the mesial angle of impacted teeth[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Consequently, RS was affected by the depth of impacted M3, the degree of mesioangular impaction and the distance between the anterior edge of ramus and the second molar. No matter which classification criterion, the RS decreased with the deepening of M3' s impaction degree.RS can be initially estimated by observing the depth, mesial angle, or posterior space of M3. Our findings could be used to help some primary hospitals without large dental facilities predict RS by observing panoramic or lateral radiograph, which will be beneficial to the design of orthodontic plans to push molars distally.\u003c/p\u003e \u003cp\u003eThe deficiency of this study is that the thickness of the buccolingual bone plate and the width of the Mandibular alveolar arch have not been considered and the application of digitalization is relatively superficial. Now that the digital technology has matured, people have invented the manipulator to bend the arch wire[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] .In future research, we can focus on digital technology and artificial intelligence, applying them in oral research to better help our clinical work.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eCompared with occlusal plane,the fitting WALA ridge plane had higher stability ,the fitting WALA ridge plane can be used as an innovative plane for orthodontic clinical scientific research.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe retromolar space of the crown levels were greater than the root levels, a minimum value was present at the root apex .Therefore ,special attention should be paid to the initial retromolar space at the apical when pushing the molar to distalization\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eThe current study found that retromolar space was significantly different in different impacted classification of the mandibular third molars,the impacted classification of M3 can be observed before orthodontics to predict the amount of molars distalization.\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e3D: Three‑dimensional; CBCT: Cone-beam computed tomography; RS: Retromolar space; M3: The mandibular third molars WP: the fitting WALA ridge plane; OP: The occlusal plane; FH: The Frankfort horizontal plane; WL: The WALA ridge line; OL: the occlusion line; MD: Molar distalization SD: Standard deviation; MC: Mandibular canal\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the research work has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki). All patients involved in this study had provided the written informed consent. The study was approved by the Research and Ethics Committee of the Affiliated Stomatology Hospital of Chongqing Medical University\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated or analysed during in the current study are available from the corresponding author on reasonable request..\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eProject Supported byChongqing Talent Program: Innovative leading talents (Medical field，CQYC20210303384)\u003c/p\u003e\n\u003cp\u003eChongqing Medical Scientific Research Project (2018ZDXM020)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYumei Huang contributed to conception, design, data acquisition, analysis, and interpretation, drafted and critically revised the manuscript. Yunjia Cheng,Yang Dan,and Yingying Tang contributed to data collection interpretation.Other authors contributed to revised the manuscript. All authors have read and approved the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eJanson G, Goizueta O E F M, Garib DG, et al. Relationship between maxillary and mandibular base lengths and dental crowding in patients with complete Class II malocclusions[J]. The Angle Orthodontist, 2011, 81(2): 217\u0026ndash;221.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRobertson L, Kaur H, Fagundes N C F, et al. Effectiveness of clear aligner therapy for orthodontic treatment: a systematic review[J]. Orthodontics \u0026amp; craniofacial research, 2020, 23(2): 133\u0026ndash;142.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHong K, Kim W H, Eghan-Acquah E, et al. Efficient Design of a Clear Aligner Attachment to Induce Bodily Tooth Movement in Orthodontic Treatment Using Finite Element Analysis[J]. Materials, 2021, 14(17): 4926\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNguyen M P. Evaluation of Dental and Skeletal Changes with Sequential Distalization of Maxillary Molars Using Clear Aligners: A preliminary study[J]. 2021.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePapadimitriou A, Mousoulea S, Gkantidis N, et al. Clinical effectiveness of Invisalign\u0026reg; orthodontic treatment: a systematic review[J]. Progress in orthodontics, 2018, 19(1): 1\u0026ndash;24.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e박가영. Posterior anatomic limit for distalization of maxillary dentition[D]. Graduate School, Yonsei University, 2020.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYe J A, Tsai C Y, Lee Y H, et al. Could Cephalometric Landmarks Serve as Boundaries of Maxillary Molar Distalization? A Comparison Between Two-and Three-Dimensional Assessments[J]. Taiwanese Journal of Orthodontics, 2021, 33(3): 1.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSugawara J, Kanzaki R, Takahashi I, et al. Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system[J]. American journal of orthodontics and dentofacial orthopedics, 2006, 129(6): 723\u0026ndash;733.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBayome M, Park J H, Bay C, et al. Distalization of maxillary molars using temporary skeletal anchorage devices: A systematic review and meta-analysis[J]. Orthodontics \u0026amp; Craniofacial Research, 2021, 24: 103\u0026ndash;112.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRavera S, Castroflorio T, Garino F, et al. Maxillary molar distalization with aligners in adult patients: a multicenter retrospective study[J]. Progress in orthodontics, 2016, 17(1): 1\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim S J, Choi T H, Baik H S, et al. Mandibular posterior anatomic limit for molar distalization[J]. Am J Orthod Dentofacial Orthop, 2014, 146(2): 190\u0026ndash;197.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChoi Y T, Kim Y J, Yang K S, et al. Bone availability for mandibular molar distalization in adults with mandibular prognathism[J]. Angle Orthod, 2018, 88(1): 52\u0026ndash;57.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSohal K S, Moshy J R, Owibingire S S, et al. Association between impacted mandibular third molar and occurrence of mandibular angle fracture: a radiological study[J]. Journal of Oral and Maxillofacial Radiology, 2019, 7(2): 25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSusarla S M, Dodson T B. Risk factors for third molar extraction difficulty[J]. Journal of oral and maxillofacial surgery, 2004, 62(11): 1363\u0026ndash;1371.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYumei H, Yun H, Leilei Z. A study of the correlation between the digitally fitted WALA ridge plane and the mandibular body axial plane and occlusion plane. Journal of Practical Stomatology, 2022,03:373\u0026ndash;378.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarchiori D F, Packota G V, Boughner J C. Third-molar mineralization as a function of available retromolar space[J]. Acta Odontologica Scandinavica, 2016, 74(7): 509\u0026ndash;517.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePadhye M N, Dabir A V, Girotra C S, et al. Pattern of mandibular third molar impaction in the Indian population: a retrospective clinico-radiographic survey[J]. Oral surgery, oral medicine, oral pathology and oral radiology, 2013, 116(3): e161-e166.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZeynep G\u0026uuml;mr\u0026uuml;k\u0026uuml;, Balaban E, Karaba M. Is there a relationship between third-molar impaction types and the dimensional/angular measurement values of posterior mandible according to Pell \u0026amp; Gregory/Winter Classification?[J]. Oral Radiology, 2020, 37(1):1\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNoffke C E E, Nzima N, Farman A G. Guidelines for the safe use of dental and maxillofacial CBCT: a review with recommendations for South Africa[J]. South African Dental Journal, 2011, 66(6): 262\u0026ndash;266.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao Z, Wang Q, Yi P, et al. Quantitative evaluation of retromolar space in adults with different vertical facial types: Cone-beam computed tomography study[J]. The Angle Orthodontist, 2020, 90(6): 857\u0026ndash;865.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang Y, Yan Y, Cao J, et al. Obeservations on association between third molar agenesis and craniofacial morphology[J]. Journal of Orofacial Orthopedics/Fortschritte der Kieferorthop\u0026auml;die, 2017, 78(6): 504\u0026ndash;510.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarchiori D F, Packota G V, Boughner J C. Initial third molar development is delayed in jaws with short distal space: An early impaction sign?[J]. Archives of oral biology, 2019, 106: 104475.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSerafin M, Fastuca R, Castellani E, et al. Occlusal Plane Changes After Molar Distalization With a Pendulum Appliance in Growing Patients with Class II Malocclusion: A Retrospective Cephalometric Study[J]. Turkish Journal of Orthodontics, 2021, 34(1): 10.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGlass T R, Tremont T, Martin C A, et al. A CBCT evaluation of root position in bone, long axis inclination and relationship to the WALA Ridge[C]//Seminars in Orthodontics. WB Saunders, 2019, 25(1): 24\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShu R, Han X, Wang Y, et al. Comparison of arch width, alveolar width and buccolingual inclination of teeth between Class II division 1 malocclusion and Class I occlusion[J]. The Angle orthodontist, 2013, 83(2): 246\u0026ndash;252.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchomaker V, Waser J, Marsh R E, et al. To fit a plane or a line to a set of points by least squares[J]. 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The clinical and inflammatory relationships between periodontitis and chronic obstructive pulmonary disease[J]. Journal of clinical periodontology, 2020, 47(9): 1040\u0026ndash;1052.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGhougassian S S, Ghafari J G. Association between mandibular third molar formation and retromolar space[J]. The Angle Orthodontist, 2014, 84(6): 946\u0026ndash;950.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsai H H. Factors associated with mandibular third molar eruption and impaction.[J]. The Journal of clinical pediatric dentistry, 2005, 30(2):109\u0026ndash;113.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXia Z, Deng H, Weng S, et al. Development of a robotic system for orthodontic archwire bending[C]//2016 IEEE International Conference on Robotics and Automation (ICRA). IEEE, 2016: 730\u0026ndash;735.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Retromolar space, M3, Classification criteria of impaction, The fitting WALA ridge plane, Occlusal plane","lastPublishedDoi":"10.21203/rs.3.rs-1834788/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1834788/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe anatomical position of the mandibular third molars(M3)is located in the posterior space of the molars, and many two-dimensional studies on them in the previous literature. This study evaluated the relationship between retromolar space(RS) and different impacted classifications of M3 in three‑dimensional(3D) cone‑beam computed tomography(CBCT).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003e206 mandibular third molars from 103 patients were included and separately separated into three classifications concurring to four classification criteria which included PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP)which was fitted by the least square method and the occlusal plane(OP) as reference planes. The SPSS (version 26) was used to analyze the data.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eIn all classifications of classification criteria, RS diminished steadily from the crown to the root (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). As the degree of mesioangula impaction diminished, RS appeared an expanding trend (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). RS in classification criteria of buccolingual angle had no statistical difference(p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eRS were related to the impacted classifications of M3. With the increment of the impacted degree of M3 ,the retromolar space gradually diminished. In clinic, RS can be evaluated by watching the PG classification and mesial angle of M3.\u003c/p\u003e","manuscriptTitle":"Three-dimensional analysis of the relationship between mandibular retromolar space and impacted third molars types in non-hyperdivergent adults","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-07-20 18:42:14","doi":"10.21203/rs.3.rs-1834788/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2022-09-15T09:17:41+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-08-07T14:52:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"b00e258e-693a-4112-952e-7026ba90818a","date":"2022-07-28T15:27:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-07-28T15:06:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-07-24T05:20:39+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2022-07-13T06:09:59+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2022-07-13T06:04:15+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2022-07-07T10:21:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bf0abf5e-acf6-4f2d-a632-7af25e9e1b8e","owner":[],"postedDate":"July 20th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2023-10-16T19:35:57+00:00","versionOfRecord":{"articleIdentity":"rs-1834788","link":"https://doi.org/10.1186/s12903-023-02843-0","journal":{"identity":"bmc-oral-health","isVorOnly":false,"title":"BMC Oral Health"},"publishedOn":"2023-03-10 19:32:56","publishedOnDateReadable":"March 10th, 2023"},"versionCreatedAt":"2022-07-20 18:42:14","video":"","vorDoi":"10.1186/s12903-023-02843-0","vorDoiUrl":"https://doi.org/10.1186/s12903-023-02843-0","workflowStages":[]},"version":"v1","identity":"rs-1834788","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1834788","identity":"rs-1834788","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}