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. 2022 Feb 10;2022:8381436. doi: 10.1155/2022/8381436

Buccolingual and Mesiodistal Dimensions of the Permanent Teeth, Their Diagnostic Value for Sex Identification, and Bolton Indices

Vahid Rakhshan 1, Fataneh Ghorbanyjavadpour 2,✉, Negin Ashoori 3
PMCID: PMC8853791  PMID: 35187172

Abstract

Introduction

We aimed (1) to measure the mesiodistal and buccolingual widths of the permanent dentition in Iranian orthodontic patients, (2) to determine cut-off points for sex identification based on the mesiodistal and buccolingual diameters, and (3) to calculate Bolton indices.

Methods

The mesiodistal and buccolingual dimensions of 28 maxillary and mandibular permanent teeth in 331 Iranian nonsyndromic orthodontic patients (dental casts and radiographs) aged 12 to 35 years old with fully erupted permanent dentitions (except the third molars and some sporadic cases of a few teeth missing or excluded) were measured. The anterior, posterior, and overall Bolton ratios were calculated in cases with no missing teeth in the 6-to-6 range. Potentially associated factors (the skeletal Angle classes, crowding, sex, jaws, sides, and age), as well as the value of these measurements for sex determination and cut-off points for sex identification based on these measurements were assessed using receiver-operator characteristic (ROC) curves, analysis of variance (ANOVA), Tukey, unpaired t-test, partial and Pearson correlation coefficients, and multiple linear regression (α = 0.05).

Results

Sex dimorphism was very frequent (P ≤ 0.05 in 41 out of 56 measurements). Only the buccolingual widths of the maxillary lateral and the mandibular central and lateral differed across the Angle classes (ANOVA/Tukey, P < 0.05). Cut-off points were estimated for 38 dental measurements, which were proper for sex identification (P < 0.05), with 8 (2 maxillary and 6 mandibular) measurements being highly appropriate (having areas under ROC curves ≥ 64%, P < 0.05). Both the mandibular canines were the only teeth with all four measurements highly appropriate for this purpose. Controlling for the role of sex, aging was associated negatively with several crown dimensions (the buccolingual widths of the maxillary first and second premolar and mandibular second premolar and first molar; the mesiodistal diameters of the maxillary central, canine, first premolar, and first molar, mandibular central, lateral, first premolar, and first molar, P ≤ 0.05, partial correlation coefficient). There were significant correlations among crown sizes. All the 28 (right/left-averaged) measurements were smaller in microdontia cases (P ≤ 0.002). The anterior, posterior, and overall Bolton indices were 78.05, 105.42, and 91.87, respectively. There were correlations between the overall Bolton ratio with the other two Bolton ratios (Pearson R = 0.696, R = 0.740, P < 0.0005) but not between the anterior and posterior Bolton ratios (R = 0.045, P = 0.459). The skeletal Angle classes might not be associated with the overall and anterior Bolton ratios (ANOVA, regression, Pearson, P > 0.05). However, the posterior Bolton ratio was smaller in class II cases compared to classes I or III (Tukey, P ≤ 0.045). In the whole sample, there was no sex dimorphism in Bolton ratios (t-test, P > 0.05). However, in Angle class II patients, the anterior Bolton ratio was greater in men than in women (P = 0.014).

Conclusions

Sex dimorphism might be very common in the dentition of Iranians, with aging significantly reducing some measurements. The buccolingual widths of some incisors might differ across the skeletal Angle classes. Mandibular canines are the most appropriate teeth for sex identification. The Angle classes might not be associated with the anterior and overall Bolton ratios; nevertheless, the posterior Bolton ratio might be smaller in class II cases compared to others. In general, sex might not affect Bolton ratios; however, in class II patients, the anterior Bolton ratios might be larger in men.

1. Introduction

An important issue in dentistry is metric dental traits or mesiodistal and buccolingual crown sizes [1]. Tooth sizes are important in orthodontics, prosthodontics, restorative dentistry, anatomy, and even anthropological and forensic studies. One of the functions of orthodontists is to correct problems caused by dental size discrepancies in order to improve the mastication efficiency, the beauty of the face, and the orderliness of the dental arch [2]. Knowing the size of the teeth in populations and individuals is critical for proper diagnosis, planning an appropriate treatment, and predicting the results of orthodontic treatment [2–4]. The buccolingual dimension of the teeth is clinically important as one of the determining factors of the width of the upper and lower jaws, the width of the palate, and the space of the tongue. Therefore, the buccolingual dimensions of the teeth are related to the correct arrangement of the posterior teeth [5]. The mesiodistal dimension of the teeth has crucial orthodontic implications: to obtain an optimal occlusion, the mesiodistal measurements of the mandibular and maxillary teeth should relate to each other [6, 7]. Considerable intermaxillary mesiodistal size discrepancies—which are not uncommon—disallow aligning the teeth into an optimal occlusion [7–9]. To account for such intermaxillary relationships, Bolton [10] devised the concept of anterior and overall intermaxillary mesiodistal tooth size ratios (Bolton indices). Later, it was shown that Bolton ratios might be ethnic-specific and therefore should be assessed in different populations [6, 7, 11].

Dental crown dimensions can be used in anthropological studies, evolutionary research, and forensic sciences [3, 12–15]. Gender identification in injured bodies is an essential step and even the first step for forensic purposes [16, 17]. Determining sex through dental traits is a common practice in forensic dentistry and anthropology [18]. The most common measurements used for such purposes are mesiodistal and buccolingual widths which are convenient and reliable [19]. Numerous factors can interfere with tooth size variability, including genetic, epigenetic, or environmental factors [20]. Dental crowns might be larger in men than in women, especially in the case of the canines [13, 21–26]. Therefore, teeth are one of the desirable items for human and sex identification [24, 27, 28]. Dental sizes might also be used to estimate age [29].

Since not many studies have been done on metric dental traits especially large studies or studies in the Iranian population, we aimed to document the metric dental traits (56 mesiodistal and buccolingual crown dimensions of 28 permanent teeth) and then to determine sex dimorphism in each of the dimensions of each permanent tooth. Furthermore, the usefulness of these measurements in identifying the sex was assessed, and the cut-off point for gender determination was estimated. The associations between metric dental traits with the skeletal Angle classification and crowding were examined. Finally, we measured the Bolton intermaxillary mesiodistal tooth size ratios (Bolton indices); we also evaluated the associations between Bolton ratios with the skeletal Angle classes, sex, and age. Besides, we compared the Bolton ratios in this ethnic group with the original ratios measured by Bolton in American Caucasians [10].

2. Materials and Methods

This cross-sectional epidemiological study was performed on 662 maxillary and mandibular dental casts of 331 Iranian orthodontic patients attending the Orthodontic Department and two private orthodontic clinics in Ahvaz, Iran.

For data collection, all the available patients' records and their archival radiographs and casts were subsequently checked and approved/rejected until reaching the desired sample size. The inclusion criteria were being Iranian, 12 to 35 years old, and having a full permanent dentition except for the third molars and with no more than 2 extractions. The exclusion criteria were patients with cleft palates or lips or any systemic diseases or syndromes; patients with any history of previous prosthodontic, surgical, or orthodontic treatments; patients without a complete set of permanent teeth (except cases of hypodontia, cases of single excluded teeth, cases of one or two extracted teeth, and also except the third molars); cases with more than two extracted teeth; patients with more than two partially erupted permanent teeth; cases with poor cast quality; and cases without lateral cephalographs and panoramic radiographs. Additionally, single teeth that were not fully erupted or had (visible or a filed history of) dental caries, crown fractures, restorations, or veneers were excluded. Information on age, sex, and type of the skeletal Angle classification was recorded from the patients' files and their cephalographs. Data collection was performed from 2018 to 2020 [30, 31].

The used casts and radiographs were all archival, and thus, no harm was identified with this study. The protocol ethics were approved by the research committee of the university in accordance with the Helsinki Declaration (ethics code: U-98142).

All the used dental casts had been poured with white dental stone for orthodontic use. All the 56 dental buccolingual and mesiodistal dimensions of the 28 teeth were measured by a trained dentist at the quarter level (for each hemimaxilla or hemimandible of each patient separately): a digital caliper at an accuracy of 0.01 mm was used to measure the buccolingual distance (the largest distance between the buccal and lingual surfaces of the crown perpendicular to the mesiodistal width of that tooth, from the buccal to the lingual height of contours) and mesiodistal dimension (as the maximum distance between the mesial contact point and distal contact point, when the caliper is parallel to the buccal tooth surface); in case the proximal tooth was absent or the tooth was rotated, the anatomically normal contact points of the tooth would be detected by the observer [1, 20]. Microdontia was considered a very small size of a tooth but with a normal shape [32].

Cases with any missing teeth within the tooth range of bimaxillary first 12 teeth (bilateral centrals to the first molars) were identified and excluded. In the remaining 268 patients with no missing teeth in the bimaxillary 6–6 range, the sums of the mesiodistal diameters of the anterior 3 teeth (canine-to-canine) were calculated in the maxilla and also in the mandible. The anterior Bolton ratio was calculated as “100 × the sum of the mesiodistal widths of the 6 mandibular anterior teeth/the sum of the mesiodistal widths of the 6 maxillary anterior teeth” [7–10]. Similarly, in these 268 cases, the sums of the mesiodistal widths of the anterior 12 teeth (6–6) in the maxilla and also in the mandible were calculated. The overall Bolton ratio was computed as “100 × the sum of the mesiodistal diameters of the mandibular first 12 teeth (6–6, from the right first molar to the left first molar)/the sum of the mesiodistal dimensions of the maxillary first 12 teeth” [7–10]. The sums of the mesiodistal widths of the bimaxillary bilateral first premolar, second premolar, and first molar were calculated. The posterior Bolton ratio was calculated as “100 × the sum of the mesiodistal measurements of the mandibular premolars and first molars/the sum of the mesiodistal widths of the maxillary premolars and first molars” [33, 34].

2.1. Interexaminer Reproducibility Assessment

A second observer (FG) measured all the buccolingual and mesiodistal dimensions in all teeth of 35 randomly selected patients (4 quadrants, each). The intraclass correlation coefficient (a total of 28 Cronbach alpha values) showed excellent and high interobserver agreements between the two observers in most examinations (12 out of 28 Cronbach alpha values >0.9, 11 other Cronbach alpha values between 0.8 and 0.9, four remaining Cronbach alpha values between 0.75 and 0.8, and one last Cronbach alpha = 0.664, all P values < 0.0005).

2.2. Statistical Analyses

Statistical analysis was performed using SPSS 25 (IBM, Armonk, NY, USA). Descriptive statistics and 95% confidence intervals (CIs) were calculated. Since age might affect some crown dimensions [35], the ages of males and females were compared using an unpaired t-test. Crown dimensions were compared between men and women, using an unpaired t-test. A receiver operating characteristic (ROC) curve was used to estimate the areas under the curve (AUC) and cut-off points for the identification of individuals' sex based on dental measurements. A partial correlation coefficient, controlling for the variable sex, was used to assess correlations between age and crown measurements as well as correlations among dental measurements. In all of these analyses, the analyses for the right and left sides were conducted separately.

2.2.1. Associations between Metric Traits with the Angle Classification and Crowding

The averages were calculated for measurements on the left and right sides. Associations between these average buccolingual or average mesiodistal dimensions with the skeletal Angle classes, crowding, and microdontia were assessed using an independent-sample t-test as well as a one-way analysis of variance (ANOVA) followed by a Tukey post hoc test.

2.2.2. Bolton Anterior, Posterior, and Overall Ratios

An unpaired t-test and a one-way ANOVA followed by a Tukey test were used to compare the Bolton ratios between males and females and among the Angle classes, respectively. The effects of sex and the Angle classes on Bolton ratios were assessed using a multiple linear regression. Correlations between age and Bolton ratios were assessed using a Pearson correlation coefficient. The Bolton ratios were compared with the original ratios reported by Bolton [10] using an unpaired t-test. The level of significance was set at 0.05.

3. Results

There were 74 males and 257 females included in the study. The mean (SD) age of patients was 19.21 ± 4.87 years (range: 12–35). Mean ages of men and women were 18.29 ± 20.49 and 18.55 ± 19.76 years, respectively. The sexes were balanced in terms of age (t-test, P = 0.716). Of the patients, 182 (55.7%), 127 (38.8%), and 18 (5.5%) were classes I, II, and III, respectively (the Angle classifications of four patients were not entered). Crowding was observed in 89 out of 331 cases (26.9%).

Numerous teeth had sex dimorphism in terms of buccolingual or mesiodistal measurements (t-test, P values ≤ 0.05, Tables 1 and 2). The few measurements without sex dimorphism in the maxilla were as follows: mesiodistal dimensions of the lateral and both premolars on the right and the lateral and first premolars on the left. In the mandible, the sizes without sex dimorphism were as follows: the buccolingual widths of the central, lateral, and second premolars on the right, and the left lateral, as well as the mesiodistal measurements of the right central and premolars, and the left incisors and second premolar.

Table 1.

Descriptive statistics and 95% CIs for the mesiodistal and buccolingual widths (mm) in the right and left sides of the maxilla in males versus females (compared using the t-test).

Side Dimension Tooth Sex N Mean SD 95% CI Min Max P
Right Buccolingual 1 Female 257 7.369 0.584 7.30 7.44 5.61 9.22 0.044
Male 73 7.522 0.520 7.40 7.64 6.34 8.88
Total 330 7.403 0.573 7.34 7.47 5.61 9.22
2 Female 250 6.536 0.644 6.46 6.62 4.47 8.15 0.003
Male 72 6.812 0.816 6.62 7.00 4.22 9.91
Total 322 6.598 0.694 6.52 6.67 4.22 9.91
3 Female 253 8.178 0.647 8.10 8.26 5.65 9.65 <0.0005
Male 73 8.497 0.751 8.32 8.67 6.36 9.88
Total 326 8.250 0.683 8.18 8.32 5.65 9.88
4 Female 248 9.302 0.642 9.22 9.38 6.62 10.87 0.031
Male 72 9.488 0.624 9.34 9.63 7.79 10.85
Total 320 9.344 0.642 9.27 9.41 6.62 10.87
5 Female 254 9.450 0.644 9.37 9.53 6.16 10.94 0.047
Male 73 9.622 0.657 9.47 9.77 8.29 10.92
Total 327 9.489 0.650 9.42 9.56 6.16 10.94
6 Female 254 11.373 0.631 11.30 11.45 9.58 12.78 0.008
Male 72 11.600 0.640 11.45 11.75 10.24 13.11
Total 326 11.423 0.639 11.35 11.49 9.58 13.11
7 Female 253 11.338 0.798 11.24 11.44 8.75 13.60 0.033
Male 70 11.570 0.817 11.38 11.76 9.19 13.26
Total 323 11.388 0.806 11.30 11.48 8.75 13.60
Mesiodistal 1 Female 257 8.626 0.573 8.56 8.70 6.60 10.37 0.031
Male 73 8.789 0.556 8.66 8.92 7.62 9.98
Total 330 8.662 0.572 8.60 8.72 6.60 10.37
2 Female 250 6.759 0.708 6.67 6.85 3.90 9.69 0.560
Male 72 6.812 0.620 6.67 6.96 4.70 8.14
Total 322 6.771 0.689 6.70 6.85 3.90 9.69
3 Female 255 7.675 0.467 7.62 7.73 6.12 9.15 0.001
Male 73 7.896 0.509 7.78 8.02 6.93 8.82
Total 328 7.724 0.485 7.67 7.78 6.12 9.15
4 Female 249 6.946 0.499 6.88 7.01 5.02 9.04 0.187
Male 72 7.034 0.497 6.92 7.15 5.67 8.16
Total 321 6.966 0.499 6.91 7.02 5.02 9.04
5 Female 254 6.665 0.499 6.60 6.73 4.93 9.08 0.472
Male 73 6.713 0.513 6.59 6.83 5.78 8.05
Total 327 6.676 0.502 6.62 6.73 4.93 9.08
6 Female 254 10.050 0.723 9.96 10.14 6.54 13.16 0.018
Male 72 10.277 0.691 10.11 10.44 8.52 12.13
Total 326 10.100 0.721 10.02 10.18 6.54 13.16
7 Female 252 9.780 0.676 9.70 9.86 7.60 11.63 0.001
Male 70 10.076 0.616 9.93 10.22 8.68 11.45
Total 322 9.844 0.674 9.77 9.92 7.60 11.63
Left Buccolingual 1 Female 256 7.342 0.620 7.27 7.42 5.79 9.01 0.017
Male 74 7.536 0.591 7.40 7.67 5.78 9.57
Total 330 7.386 0.618 7.32 7.45 5.78 9.57
2 Female 252 6.547 0.627 6.47 6.62 4.62 8.41 0.013
Male 72 6.782 0.931 6.56 7.00 4.80 12.46
Total 324 6.599 0.711 6.52 6.68 4.62 12.46
3 Female 250 8.172 0.694 8.09 8.26 5.85 9.87 <0.0005
Male 73 8.500 0.727 8.33 8.67 6.20 10.05
Total 323 8.246 0.714 8.17 8.32 5.85 10.05
4 Female 250 9.297 0.633 9.22 9.38 6.19 10.91 0.026
Male 72 9.485 0.616 9.34 9.63 8.27 10.86
Total 322 9.339 0.633 9.27 9.41 6.19 10.91
5 Female 253 9.406 0.675 9.32 9.49 5.86 10.90 0.040
Male 74 9.588 0.641 9.44 9.74 8.18 11.05
Total 327 9.447 0.670 9.37 9.52 5.86 11.05
6 Female 256 11.327 0.629 11.25 11.40 9.53 12.94 0.004
Male 74 11.568 0.653 11.42 11.72 10.03 13.24
Total 330 11.381 0.641 11.31 11.45 9.53 13.24
7 Female 253 11.247 0.779 11.15 11.34 8.35 13.14 0.001
Male 71 11.602 0.727 11.43 11.77 9.61 13.62
Total 324 11.325 0.781 11.24 11.41 8.35 13.62
Mesiodistal 1 Female 256 8.659 0.607 8.58 8.73 6.46 10.61 0.017
Male 74 8.851 0.601 8.71 8.99 7.52 10.67
Total 330 8.702 0.610 8.64 8.77 6.46 10.67
2 Female 252 6.788 0.636 6.71 6.87 4.57 8.43 0.685
Male 72 6.822 0.624 6.68 6.97 4.64 7.96
Total 324 6.795 0.633 6.73 6.86 4.57 8.43
3 Female 251 7.602 0.478 7.54 7.66 5.02 9.13 0.001
Male 73 7.814 0.527 7.69 7.94 6.66 9.02
Total 324 7.650 0.496 7.60 7.70 5.02 9.13
4 Female 250 6.965 0.503 6.90 7.03 4.86 9.02 0.280
Male 72 7.039 0.543 6.91 7.17 5.49 8.38
Total 322 6.981 0.512 6.93 7.04 4.86 9.02
5 Female 253 6.642 0.575 6.57 6.71 5.01 9.73 0.037
Male 74 6.805 0.646 6.66 6.95 5.61 9.96
Total 327 6.679 0.595 6.61 6.74 5.01 9.96
6 Female 256 10.059 0.632 9.98 10.14 8.26 11.53 0.005
Male 74 10.297 0.642 10.15 10.45 8.96 11.65
Total 330 10.113 0.641 10.04 10.18 8.26 11.65
7 Female 253 9.845 0.648 9.77 9.93 8.20 11.66 0.002
Male 71 10.115 0.561 9.98 10.25 8.95 11.43
Total 324 9.904 0.639 9.83 9.97 8.20 11.66
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Tooth numbers 1 to 7 denote the most anterior (the central) to the most posterior (the second molar) teeth. SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum.

Table 2.

Descriptive statistics and 95% CIs for crown measurements (mm) in the mandible, compared between the sexes (using the t-test).

Side Dimension Tooth Sex N Mean SD 95% CI Min Max P
Right Buccolingual 1 Female 255 6.243 0.489 6.18 6.30 4.50 8.02 0.104
Male 73 6.352 0.546 6.22 6.48 4.95 7.63
Total 328 6.267 0.503 6.21 6.32 4.50 8.02
2 Female 255 6.511 0.487 6.45 6.57 5.26 8.33 0.078
Male 74 6.634 0.651 6.48 6.78 4.79 7.89
Total 329 6.539 0.530 6.48 6.60 4.79 8.33
3 Female 256 7.398 0.589 7.33 7.47 5.63 8.75 <0.0005
Male 73 7.783 0.799 7.60 7.97 5.80 9.65
Total 329 7.483 0.660 7.41 7.55 5.63 9.65
4 Female 253 7.956 0.587 7.88 8.03 6.00 9.50 <0.0005
Male 73 8.258 0.660 8.10 8.41 7.05 9.97
Total 326 8.024 0.616 7.96 8.09 6.00 9.97
5 Female 250 8.700 0.585 8.63 8.77 6.44 11.18 0.085
Male 69 8.841 0.651 8.68 9.00 7.60 9.96
Total 319 8.731 0.601 8.66 8.80 6.44 11.18
6 Female 254 10.704 0.530 10.64 10.77 8.80 12.22 0.002
Male 72 10.928 0.610 10.78 11.07 9.74 12.56
Total 326 10.753 0.556 10.69 10.81 8.80 12.56
7 Female 255 10.509 0.635 10.43 10.59 8.56 12.29 <0.0005
Male 71 10.822 0.608 10.68 10.97 9.36 12.19
Total 326 10.577 0.641 10.51 10.65 8.56 12.29
Mesiodistal 1 Female 257 5.380 0.445 5.33 5.43 4.08 6.80 0.377
Male 73 5.431 0.391 5.34 5.52 4.51 6.32
Total 330 5.391 0.433 5.34 5.44 4.08 6.80
2 Female 255 5.913 0.424 5.86 5.96 4.62 7.22 0.023
Male 74 6.041 0.430 5.94 6.14 5.33 7.18
Total 329 5.941 0.428 5.90 5.99 4.62 7.22
3 Female 257 6.599 0.476 6.54 6.66 5.17 8.78 <0.0005
Male 73 6.941 0.458 6.83 7.05 5.74 8.02
Total 330 6.674 0.493 6.62 6.73 5.17 8.78
4 Female 253 7.038 0.497 6.98 7.10 5.32 8.87 0.106
Male 73 7.144 0.482 7.03 7.26 5.73 8.26
Total 326 7.061 0.495 7.01 7.12 5.32 8.87
5 Female 250 7.051 0.550 6.98 7.12 5.86 9.40 0.078
Male 69 7.184 0.557 7.05 7.32 5.86 8.38
Total 319 7.080 0.553 7.02 7.14 5.86 9.40
6 Female 254 10.782 0.699 10.70 10.87 8.60 12.82 0.017
Male 72 11.009 0.747 10.83 11.18 9.13 13.05
Total 326 10.832 0.715 10.75 10.91 8.60 13.05
7 Female 255 10.226 0.676 10.14 10.31 8.20 12.42 <0.0005
Male 71 10.554 0.697 10.39 10.72 8.94 12.45
Total 326 10.297 0.693 10.22 10.37 8.20 12.45
Left Buccolingual 1 Female 255 6.224 0.491 6.16 6.28 4.83 7.77 0.036
Male 74 6.364 0.548 6.24 6.49 4.57 7.70
Total 329 6.256 0.507 6.20 6.31 4.57 7.77
2 Female 256 6.487 0.544 6.42 6.55 4.88 8.20 0.081
Male 74 6.611 0.501 6.49 6.73 5.29 8.04
Total 330 6.515 0.536 6.46 6.57 4.88 8.20
3 Female 257 7.424 0.604 7.35 7.50 5.53 9.10 <0.0005
Male 74 7.795 0.760 7.62 7.97 6.15 9.20
Total 331 7.507 0.659 7.44 7.58 5.53 9.20
4 Female 254 7.972 0.573 7.90 8.04 6.16 9.48 <0.0005
Male 73 8.274 0.652 8.12 8.43 6.56 9.62
Total 327 8.040 0.604 7.97 8.11 6.16 9.62
5 Female 250 8.699 0.575 8.63 8.77 6.56 10.78 0.048
Male 71 8.860 0.682 8.70 9.02 6.73 9.96
Total 321 8.735 0.603 8.67 8.80 6.56 10.78
6 Female 250 10.707 0.558 10.64 10.78 8.83 12.23 0.020
Male 73 10.887 0.643 10.74 11.04 9.74 12.67
Total 323 10.748 0.582 10.68 10.81 8.83 12.67
7 Female 255 10.492 0.625 10.41 10.57 8.56 12.05 0.004
Male 70 10.735 0.627 10.59 10.88 9.31 12.17
Total 325 10.544 0.632 10.48 10.61 8.56 12.17
Mesiodistal 1 Female 257 5.397 0.425 5.35 5.45 4.09 6.59 0.202
Male 74 5.468 0.388 5.38 5.56 4.20 6.39
Total 331 5.413 0.417 5.37 5.46 4.09 6.59
2 Female 256 5.954 0.449 5.90 6.01 4.38 7.21 0.149
Male 74 6.040 0.465 5.93 6.15 4.87 6.98
Total 330 5.973 0.454 5.92 6.02 4.38 7.21
3 Female 257 6.651 0.457 6.59 6.71 5.44 9.66 <0.0005
Male 74 6.901 0.488 6.79 7.01 5.70 7.85
Total 331 6.707 0.475 6.66 6.76 5.44 9.66
4 Female 254 7.031 0.532 6.96 7.10 5.17 8.88 0.048
Male 73 7.166 0.443 7.06 7.27 6.15 8.26
Total 327 7.061 0.516 7.00 7.12 5.17 8.88
5 Female 251 7.130 0.595 7.06 7.20 5.82 10.75 0.185
Male 72 7.234 0.559 7.10 7.37 6.22 8.96
Total 323 7.153 0.588 7.09 7.22 5.82 10.75
6 Female 250 10.795 0.704 10.71 10.88 6.84 12.65 0.009
Male 73 11.040 0.685 10.88 11.20 9.35 12.92
Total 323 10.851 0.706 10.77 10.93 6.84 12.92
7 Female 255 10.239 0.703 10.15 10.33 8.44 12.28 0.003
Male 70 10.514 0.608 10.37 10.66 9.02 11.78
Total 325 10.298 0.692 10.22 10.37 8.44 12.28
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Tooth numbers 1 to 7 indicate the most anterior to the most posterior teeth. SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum.

The t-test did not show any significant differences between the left versus right sides in any of the teeth of either the maxilla or the mandible (all P values > 0.05).

The statistically significant areas under the ROC curves indicated that numerous teeth can be used for sex determination (Figure 1, Table 3) although AUCs were not considerably large in many of the statistically significant measurements. In each measurement of each quadrant, the canine had the greatest area under the curve among all other teeth. The highest AUC belonged to the mesiodistal dimension of the mandibular canine. The measurements with AUCs ≥ 64% were as follows: the buccolingual size of the right and left maxillary canines and the buccolingual size of the right and left mandibular canines and the right and left mandibular first premolars, as well as the mesiodistal dimension of the right and left mandibular canines (Figures 1 and 2, Table 3). The cut-off points for determining the sex based on the buccolingual and mesiodistal measurements of the maxillary and mandibular permanent teeth are presented in Table 3.

Figure 1.

Figure 1

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ROC curves of all the assessed mesiodistal and buccolingual dimensions of all the teeth in the left and right sides of the maxilla.

Table 3.

The areas under ROC curves and the cut-off points for sex determination (mm).

Jaw Side Dimension Tooth Area SE P 95% CI Cut-off (mm)
Maxilla Right Buccolingual Central 0.596 0.040 0.021 0.517 0.675 7.715
Lateral 0.628 0.041 0.002 0.547 0.709 6.950
Canine 0.662 0.040 <0.0005 0.584 0.741 8.665
First premolar 0.587 0.043 0.037 0.502 0.672 9.915
Second premolar 0.590 0.045 0.031 0.502 0.677 10.175
First molar 0.589 0.041 0.032 0.509 0.670 11.715
Second molar 0.567 0.041 0.107 0.487 0.648 —
Mesiodistal Central 0.575 0.041 0.072 0.494 0.656 —
Lateral 0.526 0.041 0.527 0.446 0.606 —
Canine 0.628 0.041 0.002 0.547 0.710 7.930
First premolar 0.526 0.042 0.528 0.444 0.609 —
Second premolar 0.536 0.044 0.383 0.449 0.623 —
First molar 0.590 0.041 0.030 0.509 0.671 10.275
Second molar 0.598 0.041 0.018 0.518 0.678 10.235
Left Buccolingual Central 0.602 0.038 0.011 0.529 0.676 7.355
Lateral 0.606 0.039 0.009 0.529 0.683 6.535
Canine 0.643 0.040 <0.0005 0.566 0.721 8.780
First premolar 0.583 0.041 0.039 0.503 0.663 9.845
Second premolar 0.591 0.041 0.024 0.512 0.671 9.865
First molar 0.596 0.040 0.018 0.518 0.674 11.505
Second molar 0.616 0.037 0.004 0.543 0.690 11.235
Mesiodistal Central 0.591 0.039 0.025 0.513 0.668 8.570
Lateral 0.537 0.039 0.363 0.460 0.614 —
Canine 0.627 0.041 0.002 0.546 0.708 7.835
First premolar 0.532 0.042 0.422 0.450 0.615 —
Second premolar 0.583 0.041 0.041 0.503 0.663 7.365
First molar 0.595 0.040 0.019 0.516 0.673 10.815
Second molar 0.611 0.039 0.006 0.536 0.687 10.155
Mandible Right Buccolingual Central 0.578 0.043 0.056 0.494 0.662 —
Lateral 0.572 0.043 0.078 0.488 0.655 —
Canine 0.652 0.043 <0.0005 0.568 0.736 7.905
First premolar 0.652 0.041 <0.0005 0.572 0.732 8.285
Second premolar 0.572 0.045 0.078 0.484 0.660 —
First molar 0.594 0.042 0.021 0.512 0.677 11.455
Second molar 0.629 0.039 0.002 0.553 0.705 10.755
Mesiodistal Central 0.536 0.040 0.372 0.457 0.615 —
Lateral 0.577 0.041 0.059 0.497 0.656 —
Canine 0.720 0.036 <0.0005 0.650 0.790 6.835
First premolar 0.575 0.040 0.066 0.497 0.653 —
Second premolar 0.563 0.041 0.119 0.483 0.644 —
First molar 0.605 0.040 0.010 0.526 0.684 10.885
Second molar 0.620 0.038 0.003 0.545 0.695 10.275
Left Buccolingual Central 0.617 0.039 0.003 0.540 0.695 6.175
Lateral 0.610 0.039 0.006 0.534 0.686 6.575
Canine 0.683 0.041 <0.0005 0.604 0.763 7.765
First premolar 0.673 0.039 <0.0005 0.596 0.749 8.275
Second premolar 0.606 0.043 0.008 0.522 0.689 9.025
First molar 0.571 0.042 0.077 0.489 0.652 —
Second molar 0.603 0.040 0.010 0.526 0.681 10.610
Mesiodistal Central 0.553 0.038 0.183 0.478 0.628 —
Lateral 0.547 0.042 0.238 0.465 0.629 —
Canine 0.668 0.041 <0.0005 0.589 0.748 6.960
First premolar 0.585 0.038 0.033 0.511 0.658 6.965
Second premolar 0.554 0.041 0.172 0.473 0.635 —
First molar 0.598 0.039 0.014 0.522 0.673 10.910
Second molar 0.631 0.037 0.001 0.559 0.703 10.275
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SE: standard error; CI: confidence interval for the AUC. Measurements below the cut-off points belong to women.

Figure 2.

Figure 2

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ROC curves of all the assessed mesiodistal and buccolingual dimensions of all the teeth in the left and right sides of the mandible.

Controlling for the role of sex, age was negatively and weakly correlated with buccolingual widths of the right maxillary first premolar (r = −0.119, P = 0.045, partial correlation coefficient) and second premolar (r = −0.121, P = 0.040, Figure 3(a)), the left maxillary first premolar (r = −0.131, P = 0.025) and second premolar (r = −0.145, P = 0.013, Figure 3(b)), the right mandibular second premolar (r = −0.138, P = 0.017) and first molar (r = −0.155, P = 0.007, Figure 3(c)), and the left mandibular second premolar (r = −0.131, P = 0.023) and first molar (r = −0.135, P = 0.019, Figure 3(d), Appendix 1).

Figure 3.

Figure 3

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Scatterplots showing the significant correlations between age (the X axis, year) and the buccolingual widths (the Y axis, mm), in (a) the right maxillary teeth, (b) the left maxillary teeth, (c) the right mandibular teeth, and (d) the left mandibular teeth.

Age was also correlated negatively, significantly, and weakly with mesiodistal dimensions of the right maxillary first premolar (r = −0.124, P = 0.034) and first molar (r = −0.185, P = 0.002, Figure 4(a)); the left maxillary central (r = −0.159, P = 0.006), canine (r = −0.129, P = 0.027), first premolar (r = −0.133, P = 0.023), and first molar (r = −0.134, P = 0.022, Figure 4(b)); the right mandibular lateral (r = −0.177, P = 0.002), first premolar (r = −0.149, P = 0.010); and first molar (r = −0.159, P = 0.006, Figure 4(c)); and the left mandibular central (r = −0.163, P = 0.004), lateral (r = −0.131, P = 0.022), and first premolar (r = −0.175, P = 0.002, Figure 4(d), Appendix 1).

Figure 4.

Figure 4

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Scatterplots illustrating the significant correlations between age (the X axis, year) and the mesiodistal widths (the Y axis, mm), in (a) the right maxillary teeth, (b) the left maxillary teeth, (c) the right mandibular teeth, and (d) the left mandibular teeth.

3.1. Associations between Metric Traits with the Angle Classification

According to the ANOVA, the teeth that had different sizes in different classes were the maxillary lateral (buccolingual measurement only) and the mandibular central and lateral (buccolingual only, Table 4). According to the Tukey post hoc test, the buccolingual dimension of maxillary lateral differed only between classes I and II (P = 0.030). Similarly, the buccolingual width of the mandibular central differed only between classes I and II (P = 0.032). The buccolingual diameter of the mandibular lateral differed between classes I and II (P = 0.025, Table 4).

Table 4.

Descriptive statistics and 95% CIs for dental measurements (averages of the right and left sides, mm) in different Angle classes. The classes are compared using the one-way ANOVA.

Jaw Measurement Tooth Class N Mean SD 95% CI Min Max P
Maxilla Buccolingual 1 I 182 7.355 0.540 7.28 7.43 5.91 8.68 0.271
II 127 7.440 0.623 7.33 7.55 5.88 9.04
III 18 7.528 0.539 7.26 7.80 6.47 8.45
2 I 177 6.516 0.617 6.42 6.61 4.47 8.29 0.039
II 127 6.706 0.683 6.59 6.83 5.06 10.13
III 17 6.635 0.576 6.34 6.93 5.84 7.66
3 I 179 8.193 0.657 8.10 8.29 6.24 9.62 0.205
II 125 8.329 0.689 8.21 8.45 6.18 9.87
III 18 8.206 0.571 7.92 8.49 7.10 9.37
4 I 177 9.309 0.588 9.22 9.40 6.41 10.74 0.454
II 125 9.397 0.646 9.28 9.51 7.50 10.69
III 17 9.381 0.539 9.10 9.66 8.21 10.12
5 I 181 9.425 0.652 9.33 9.52 6.01 10.91 0.360
II 126 9.522 0.615 9.41 9.63 7.66 10.99
III 18 9.549 0.557 9.27 9.83 8.19 10.41
6 I 181 11.386 0.575 11.30 11.47 9.73 12.80 0.797
II 127 11.431 0.657 11.32 11.55 9.81 13.17
III 18 11.440 0.689 11.10 11.78 9.96 12.78
7 I 178 11.336 0.752 11.23 11.45 8.98 13.04 0.651
II 125 11.404 0.801 11.26 11.55 9.34 13.32
III 18 11.263 0.743 10.89 11.63 9.78 12.80
Mesiodistal 1 I 182 8.694 0.545 8.61 8.77 6.64 10.06 0.842
II 127 8.656 0.580 8.55 8.76 6.84 10.47
III 18 8.664 0.673 8.33 9.00 7.14 9.85
2 I 177 6.790 0.620 6.70 6.88 3.90 8.10 0.846
II 127 6.749 0.662 6.63 6.87 4.42 8.04
III 17 6.741 0.676 6.39 7.09 5.29 7.70
3 I 180 7.697 0.501 7.62 7.77 5.57 9.14 0.558
II 126 7.689 0.427 7.61 7.76 6.84 8.84
III 18 7.572 0.386 7.38 7.76 6.78 8.10
4 I 177 6.984 0.488 6.91 7.06 5.58 9.03 0.849
II 125 6.956 0.491 6.87 7.04 4.94 8.29
III 17 7.006 0.385 6.81 7.20 6.38 7.81
5 I 181 6.675 0.526 6.60 6.75 5.61 8.96 0.851
II 126 6.673 0.484 6.59 6.76 4.97 8.09
III 18 6.745 0.547 6.47 7.02 5.25 7.52
6 I 181 10.080 0.598 9.99 10.17 8.46 11.89 0.161
II 127 10.185 0.668 10.07 10.30 8.63 11.76
III 18 9.932 0.656 9.61 10.26 9.16 11.12
7 I 178 9.848 0.592 9.76 9.94 8.26 11.48 0.159
II 125 9.937 0.631 9.83 10.05 8.23 11.62
III 18 9.666 0.688 9.32 10.01 8.77 10.98
Mandible Buccolingual 1 I 182 6.209 0.457 6.14 6.28 4.78 7.55 0.042
II 125 6.348 0.491 6.26 6.43 5.20 7.82
III 18 6.273 0.477 6.04 6.51 5.25 7.01
2 I 182 6.481 0.476 6.41 6.55 5.17 7.66 0.009
II 127 6.628 0.502 6.54 6.72 5.38 7.97
III 18 6.346 0.483 6.11 6.59 5.64 7.23
3 I 182 7.442 0.626 7.35 7.53 5.89 8.92 0.235
II 127 7.565 0.621 7.46 7.67 6.07 9.43
III 18 7.480 0.638 7.16 7.80 6.42 8.75
4 I 178 8.002 0.572 7.92 8.09 6.11 9.59 0.484
II 127 8.083 0.603 7.98 8.19 6.11 9.71
III 18 8.015 0.558 7.74 8.29 7.05 8.94
5 I 180 8.729 0.569 8.65 8.81 6.56 9.95 0.766
II 124 8.747 0.596 8.64 8.85 6.56 10.18
III 18 8.642 0.465 8.41 8.87 7.52 9.29
6 I 182 10.734 0.526 10.66 10.81 9.32 12.09 0.908
II 126 10.752 0.580 10.65 10.85 8.82 12.62
III 18 10.787 0.532 10.52 11.05 9.86 11.85
7 I 181 10.560 0.616 10.47 10.65 9.26 12.04 0.934
II 125 10.546 0.612 10.44 10.65 8.56 12.04
III 18 10.600 0.546 10.33 10.87 9.56 11.62
Mesiodistal 1 I 182 5.391 0.393 5.33 5.45 4.12 6.41 0.814
II 127 5.408 0.412 5.34 5.48 4.24 6.45
III 18 5.449 0.423 5.24 5.66 4.46 6.00
2 I 182 5.962 0.407 5.90 6.02 4.97 7.22 0.554
II 127 5.959 0.434 5.88 6.04 4.50 7.11
III 18 5.850 0.441 5.63 6.07 4.94 6.51
3 I 182 6.715 0.426 6.65 6.78 5.48 8.00 0.527
II 127 6.661 0.481 6.58 6.75 5.39 7.85
III 18 6.649 0.394 6.45 6.84 5.80 7.37
4 I 178 7.081 0.462 7.01 7.15 5.98 8.30 0.711
II 127 7.035 0.494 6.95 7.12 5.44 8.26
III 18 7.051 0.559 6.77 7.33 5.72 7.57
5 I 181 7.127 0.498 7.05 7.20 6.06 8.79 0.656
II 124 7.090 0.539 6.99 7.19 5.86 8.67
III 18 7.199 0.568 6.92 7.48 6.00 8.46
6 I 182 10.853 0.676 10.75 10.95 8.95 12.65 0.255
II 126 10.769 0.723 10.64 10.90 8.17 12.99
III 18 11.031 0.514 10.77 11.29 10.14 11.84
7 I 181 10.317 0.595 10.23 10.40 8.96 12.01 0.648
II 125 10.253 0.692 10.13 10.38 8.52 12.31
III 18 10.346 0.628 10.03 10.66 9.48 11.78
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Tooth numbers 1 to 7 indicate the central to the second molar teeth. SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum.

All dental measurements were similar between cases with and without crowding (t-test, P > 0.05, Table 5).

Table 5.

Descriptive statistics and 95% CIs for dental measurements (averages of the right and left sides, mm) in crowded versus noncrowded dentitions. The groups are compared using the t-test.

Jaw Measurement Tooth Crowding N Mean SD 95% CI Min Max P
Maxilla Buccolingual 1 No 242 7.411 0.606 7.33 7.49 5.88 9.04 0.443
Yes 89 7.356 0.480 7.26 7.46 5.93 8.17
Total 331 7.396 0.575 7.33 7.46 5.88 9.04
2 No 237 6.622 0.682 6.53 6.71 4.47 10.13 0.191
Yes 88 6.515 0.569 6.39 6.64 5.27 7.60
Total 325 6.593 0.654 6.52 6.66 4.47 10.13
3 No 239 8.257 0.660 8.17 8.34 6.24 9.87 0.670
Yes 87 8.221 0.680 8.08 8.37 6.18 9.55
Total 326 8.248 0.664 8.18 8.32 6.18 9.87
4 No 239 9.349 0.617 9.27 9.43 6.41 10.74 0.805
Yes 84 9.330 0.592 9.20 9.46 8.01 10.44
Total 323 9.344 0.610 9.28 9.41 6.41 10.74
5 No 241 9.454 0.636 9.37 9.53 6.01 10.99 0.512
Yes 88 9.506 0.627 9.37 9.64 7.90 10.91
Total 329 9.468 0.633 9.40 9.54 6.01 10.99
6 No 241 11.403 0.611 11.33 11.48 9.73 13.17 0.999
Yes 89 11.403 0.632 11.27 11.54 9.81 12.76
Total 330 11.403 0.616 11.34 11.47 9.73 13.17
7 No 236 11.361 0.783 11.26 11.46 8.98 13.32 0.918
Yes 88 11.351 0.737 11.19 11.51 9.34 13.04
Total 324 11.358 0.770 11.27 11.44 8.98 13.32
Mesiodistal 1 No 242 8.687 0.602 8.61 8.76 6.64 10.47 0.771
Yes 89 8.667 0.466 8.57 8.76 7.47 10.13
Total 331 8.682 0.568 8.62 8.74 6.64 10.47
2 No 237 6.781 0.653 6.70 6.86 3.90 8.07 0.726
Yes 88 6.753 0.602 6.63 6.88 4.75 8.10
Total 325 6.773 0.639 6.70 6.84 3.90 8.10
3 No 239 7.701 0.446 7.64 7.76 6.78 9.14 0.375
Yes 89 7.649 0.521 7.54 7.76 5.57 8.84
Total 328 7.687 0.467 7.64 7.74 5.57 9.14
4 No 239 6.977 0.480 6.92 7.04 4.94 9.03 0.870
Yes 84 6.967 0.497 6.86 7.07 5.58 8.08
Total 323 6.974 0.484 6.92 7.03 4.94 9.03
5 No 241 6.670 0.507 6.61 6.73 4.97 8.96 0.660
Yes 88 6.698 0.514 6.59 6.81 5.19 8.57
Total 329 6.677 0.508 6.62 6.73 4.97 8.96
6 No 241 10.090 0.607 10.01 10.17 8.46 11.70 0.424
Yes 89 10.152 0.694 10.01 10.30 8.47 11.89
Total 330 10.106 0.631 10.04 10.17 8.46 11.89
7 No 236 9.857 0.595 9.78 9.93 8.26 11.59 0.405
Yes 88 9.921 0.668 9.78 10.06 8.23 11.62
Total 324 9.874 0.616 9.81 9.94 8.23 11.62
Mandible Buccolingual 1 No 241 6.279 0.507 6.21 6.34 4.78 7.82 0.295
Yes 88 6.216 0.401 6.13 6.30 5.19 7.04
Total 329 6.262 0.481 6.21 6.31 4.78 7.82
2 No 242 6.559 0.512 6.49 6.62 5.17 7.97 0.052
Yes 89 6.440 0.439 6.35 6.53 5.46 7.33
Total 331 6.527 0.496 6.47 6.58 5.17 7.97
3 No 242 7.499 0.632 7.42 7.58 5.89 9.43 0.754
Yes 89 7.475 0.605 7.35 7.60 6.07 8.65
Total 331 7.492 0.624 7.42 7.56 5.89 9.43
4 No 241 8.025 0.564 7.95 8.10 6.11 9.32 0.696
Yes 86 8.054 0.635 7.92 8.19 6.63 9.71
Total 327 8.033 0.583 7.97 8.10 6.11 9.71
5 No 239 8.730 0.577 8.66 8.80 6.56 9.95 0.955
Yes 87 8.726 0.574 8.60 8.85 7.33 10.18
Total 326 8.729 0.575 8.67 8.79 6.56 10.18
6 No 242 10.767 0.551 10.70 10.84 8.82 12.62 0.220
Yes 88 10.683 0.539 10.57 10.80 9.32 11.88
Total 330 10.745 0.548 10.69 10.80 8.82 12.62
7 No 238 10.565 0.625 10.48 10.64 8.56 12.04 0.824
Yes 89 10.548 0.578 10.43 10.67 9.26 11.75
Total 327 10.560 0.612 10.49 10.63 8.56 12.04
Mesiodistal 1 No 242 5.412 0.405 5.36 5.46 4.12 6.45 0.510
Yes 89 5.379 0.393 5.30 5.46 4.47 6.27
Total 331 5.403 0.402 5.36 5.45 4.12 6.45
2 No 242 5.969 0.414 5.92 6.02 4.50 7.22 0.387
Yes 89 5.924 0.430 5.83 6.01 4.75 6.98
Total 331 5.957 0.418 5.91 6.00 4.50 7.22
3 No 242 6.695 0.442 6.64 6.75 5.39 7.98 0.785
Yes 89 6.680 0.464 6.58 6.78 5.45 8.00
Total 331 6.691 0.447 6.64 6.74 5.39 8.00
4 No 241 7.067 0.462 7.01 7.13 5.44 8.30 0.703
Yes 86 7.044 0.526 6.93 7.16 5.67 8.26
Total 327 7.061 0.479 7.01 7.11 5.44 8.30
5 No 239 7.121 0.522 7.05 7.19 5.86 8.79 0.984
Yes 88 7.120 0.523 7.01 7.23 6.09 8.62
Total 327 7.121 0.521 7.06 7.18 5.86 8.79
6 No 242 10.848 0.673 10.76 10.93 8.78 12.99 0.515
Yes 88 10.792 0.733 10.64 10.95 8.17 12.65
Total 330 10.833 0.689 10.76 10.91 8.17 12.99
7 No 238 10.278 0.640 10.20 10.36 8.52 12.31 0.397
Yes 89 10.345 0.625 10.21 10.48 8.95 11.84
Total 327 10.297 0.635 10.23 10.37 8.52 12.31
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Tooth numbers 1 to 7 indicate the central to the second molar teeth. SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum.

All “left/right-averaged” buccolingual and mesiodistal measurements of all the 14 teeth (the maxillary and mandibular centrals to the second molars, regardless of their right and left sides) differed significantly between the cases with microdontia versus those without it (t-test, P ≤ 0.002, Table 6).

Table 6.

Descriptive statistics and 95% CIs for dental sizes (averages of the right and left sides, mm) in cases with and without microdontia. The groups are compared using the t-test.

Jaw Measurement Tooth Microdontia N Mean SD 95% CI Min Max P
Maxilla Buccolingual 1 No 203 7.489 0.550 7.41 7.56 5.91 9.04 <0.0005
Yes 128 7.250 0.584 7.15 7.35 5.88 8.52
Total 331 7.396 0.575 7.33 7.46 5.88 9.04
2 No 199 6.681 0.650 6.59 6.77 4.51 10.13 0.002
Yes 126 6.454 0.639 6.34 6.57 4.47 8.19
Total 325 6.593 0.654 6.52 6.66 4.47 10.13
3 No 200 8.370 0.659 8.28 8.46 6.18 9.87 <0.0005
Yes 126 8.054 0.628 7.94 8.16 6.24 9.54
Total 326 8.248 0.664 8.18 8.32 6.18 9.87
4 No 196 9.483 0.525 9.41 9.56 8.01 10.74 <0.0005
Yes 127 9.129 0.668 9.01 9.25 6.41 10.68
Total 323 9.344 0.610 9.28 9.41 6.41 10.74
5 No 202 9.663 0.508 9.59 9.73 8.36 10.99 <0.0005
Yes 127 9.156 0.689 9.04 9.28 6.01 10.78
Total 329 9.468 0.633 9.40 9.54 6.01 10.99
6 No 202 11.584 0.558 11.51 11.66 10.11 13.17 <0.0005
Yes 128 11.117 0.595 11.01 11.22 9.73 12.47
Total 330 11.403 0.616 11.34 11.47 9.73 13.17
7 No 197 11.609 0.678 11.51 11.70 9.54 13.32 <0.0005
Yes 127 10.969 0.743 10.84 11.10 8.98 12.89
Total 324 11.358 0.770 11.27 11.44 8.98 13.32
Mesiodistal 1 No 203 8.834 0.514 8.76 8.91 7.63 10.47 <0.0005
Yes 128 8.440 0.567 8.34 8.54 6.64 10.33
Total 331 8.682 0.568 8.62 8.74 6.64 10.47
2 No 199 6.977 0.513 6.91 7.05 4.74 8.10 <0.0005
Yes 126 6.451 0.685 6.33 6.57 3.90 7.70
Total 325 6.773 0.639 6.70 6.84 3.90 8.10
3 No 201 7.826 0.444 7.76 7.89 6.84 9.14 <0.0005
Yes 127 7.467 0.416 7.39 7.54 5.57 8.47
Total 328 7.687 0.467 7.64 7.74 5.57 9.14
4 No 196 7.107 0.430 7.05 7.17 5.58 8.29 <0.0005
Yes 127 6.770 0.492 6.68 6.86 4.94 9.03
Total 323 6.974 0.484 6.92 7.03 4.94 9.03
5 No 202 6.817 0.469 6.75 6.88 5.70 8.57 <0.0005
Yes 127 6.455 0.490 6.37 6.54 4.97 8.96
Total 329 6.677 0.508 6.62 6.73 4.97 8.96
6 No 202 10.318 0.588 10.24 10.40 8.74 11.89 <0.0005
Yes 128 9.773 0.549 9.68 9.87 8.46 11.12
Total 330 10.106 0.631 10.04 10.17 8.46 11.89
7 No 197 10.100 0.568 10.02 10.18 8.59 11.62 <0.0005
Yes 127 9.524 0.517 9.43 9.61 8.23 11.05
Total 324 9.874 0.616 9.81 9.94 8.23 11.62
Mandible Buccolingual 1 No 201 6.329 0.470 6.26 6.39 4.78 7.82 0.001
Yes 128 6.157 0.481 6.07 6.24 4.83 7.37
Total 329 6.262 0.481 6.21 6.31 4.78 7.82
2 No 203 6.598 0.472 6.53 6.66 5.21 7.97 0.001
Yes 128 6.414 0.513 6.32 6.50 5.17 7.53
Total 331 6.527 0.496 6.47 6.58 5.17 7.97
3 No 203 7.595 0.650 7.51 7.69 5.89 9.43 <0.0005
Yes 128 7.329 0.543 7.23 7.42 5.91 8.71
Total 331 7.492 0.624 7.42 7.56 5.89 9.43
4 No 200 8.169 0.535 8.09 8.24 6.97 9.59 <0.0005
Yes 127 7.818 0.592 7.71 7.92 6.11 9.71
Total 327 8.033 0.583 7.97 8.10 6.11 9.71
5 No 198 8.891 0.510 8.82 8.96 7.33 9.95 <0.0005
Yes 128 8.479 0.581 8.38 8.58 6.56 10.18
Total 326 8.729 0.575 8.67 8.79 6.56 10.18
6 No 202 10.914 0.501 10.84 10.98 9.82 12.62 <0.0005
Yes 128 10.477 0.515 10.39 10.57 8.82 11.60
Total 330 10.745 0.548 10.69 10.80 8.82 12.62
7 No 199 10.732 0.541 10.66 10.81 9.31 12.04 <0.0005
Yes 128 10.292 0.621 10.18 10.40 8.56 11.88
Total 327 10.560 0.612 10.49 10.63 8.56 12.04
Mesiodistal 1 No 203 5.495 0.377 5.44 5.55 4.51 6.45 <0.0005
Yes 128 5.257 0.397 5.19 5.33 4.12 6.41
Total 331 5.403 0.402 5.36 5.45 4.12 6.45
2 No 203 6.054 0.387 6.00 6.11 5.18 7.11 <0.0005
Yes 128 5.803 0.421 5.73 5.88 4.50 7.22
Total 331 5.957 0.418 5.91 6.00 4.50 7.22
3 No 203 6.811 0.424 6.75 6.87 5.74 7.98 <0.0005
Yes 128 6.502 0.418 6.43 6.58 5.39 8.00
Total 331 6.691 0.447 6.64 6.74 5.39 8.00
4 No 200 7.207 0.430 7.15 7.27 6.06 8.30 <0.0005
Yes 127 6.831 0.462 6.75 6.91 5.44 7.80
Total 327 7.061 0.479 7.01 7.11 5.44 8.30
5 No 199 7.286 0.500 7.22 7.36 6.19 8.79 <0.0005
Yes 128 6.864 0.445 6.79 6.94 5.86 8.13
Total 327 7.121 0.521 7.06 7.18 5.86 8.79
6 No 202 11.066 0.606 10.98 11.15 9.41 12.99 <0.0005
Yes 128 10.467 0.652 10.35 10.58 8.17 12.15
Total 330 10.833 0.689 10.76 10.91 8.17 12.99
7 No 199 10.508 0.567 10.43 10.59 9.18 12.31 <0.0005
Yes 128 9.968 0.597 9.86 10.07 8.52 11.84
Total 327 10.297 0.635 10.23 10.37 8.52 12.31
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Tooth numbers 1 to 7 denote the central to the second molar teeth. SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum.

There were significant positive correlations among all different crown measurements of all the assessed teeth (Appendix 1).

3.2. Bolton Indices

Between men and women, there was no significant difference in terms of Bolton ratios (t-test, Table 7). There was no significant difference among different Angle classes in terms of the overall or anterior Bolton ratios (Table 7). However, the posterior Bolton ratios differed significantly across the Angle classes (ANOVA, Table 7). The Tukey test showed that the mean posterior Bolton ratio in class II patients was smaller than those in both class I (P = 0.029) and class III patients (P = 0.045). There was no significant difference between classes I and III (P = 0.369, Tukey). The multiple regression did not detect any significant effect of sex (P ≥ 0.080) or the Angle classification (P ≥ 0.304) on any Bolton ratios.

Table 7.

The Bolton ratios in men, women, and different Angle classes.

Bolton ratio Variables N Mean SD 95% CI Min Max P
Overall Female 210 91.78 2.48 91.44 92.12 83.97 99.09 0.229
Male 58 92.22 2.42 91.58 92.85 86.32 99.87
Total 268 91.87 2.47 91.58 92.17 83.97 99.87
Anterior Female 210 77.86 3.11 77.44 78.29 69.00 89.43 0.059
Male 58 78.74 3.02 77.94 79.53 71.45 87.61
Total 268 78.05 3.11 77.68 78.43 69.00 89.43
Posterior Female 210 105.42 3.77 104.91 105.93 96.20 114.43 0.995
Male 58 105.41 3.83 104.41 106.42 97.14 115.59
Total 268 105.42 3.77 104.96 105.87 96.20 115.59
Overall Class I 142 91.96 2.43 91.56 92.37 86.32 99.09 0.083
Class II 110 91.55 2.41 91.10 92.01 83.97 99.87
Class III 13 93.03 2.50 91.52 94.54 88.94 97.73
Anterior Class I 142 77.90 2.98 77.41 78.40 71.45 86.06 0.667
Class II 110 78.16 3.30 77.54 78.79 69.00 89.43
Class III 13 78.56 2.96 76.77 80.35 74.48 85.40
Posterior Class I 142 105.80 3.64 105.19 106.40 96.78 112.49 0.008
Class II 110 104.60 3.69 103.90 105.30 96.20 115.59
Class III 13 107.19 4.16 104.67 109.70 100.42 112.31
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SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum. The P values for comparisons between men and women are calculated using the unpaired t-test. The P values for comparisons across Angle classes are calculated using the one-way ANOVA.

There was no correlation between ages with any Bolton ratios (Pearson R ≤ 0.064, P ≥ 0.297). The correlations between the overall Bolton index with the anterior Bolton index (Pearson R = 0.696, P < 0.00000005) and the posterior Bolton index (R = 0.740, P < 0.00000005) were significant. However, the was no significant correlation between the anterior and posterior Bolton ratios (R = 0.045, P = 0.459).

The unpaired t-test was used to compare the sexes within each Angle class separately (Table 8). Because of the small number of class III males, no comparisons were done for class III cases. As the only significant comparison, the anterior Bolton ratio of class II men was significantly larger than that of class II women (P = 0.014, Table 8).

Table 8.

The Bolton indices in men versus women within different Angle classes.

Angle classes Bolton ratio Sex N Mean SD 95% CI Min Max P
Class I Overall Female 115 91.91 2.48 91.45 92.37 86.40 99.09 0.586
Male 27 92.19 2.22 91.32 93.07 86.32 95.72
Anterior Female 115 77.89 2.97 77.34 78.44 72.16 86.06 0.909
Male 27 77.96 3.09 76.74 79.18 71.45 86.02
Posterior Female 115 105.69 3.72 105.00 106.38 96.78 112.37 0.472
Male 27 106.25 3.28 104.96 107.55 99.47 112.49
Class II Overall Female 82 91.35 2.35 90.83 91.86 83.97 97.67 0.121
Male 28 92.17 2.53 91.19 93.15 87.72 99.87
Anterior Female 82 77.72 3.33 76.99 78.45 69.00 89.43 0.014
Male 28 79.48 2.92 78.35 80.61 74.52 87.61
Posterior Female 82 104.64 3.60 103.85 105.43 96.20 114.43 0.841
Male 28 104.48 4.01 102.92 106.03 97.14 115.59
Class III Overall Female 11 93.46 2.48 91.79 95.13 88.94 97.73 —
Male 2 90.69 0.57 — — 90.28 91.09
Anterior Female 11 78.72 3.15 76.60 80.83 74.48 85.40 —
Male 2 77.68 2.09 — — 76.20 79.15
Posterior Female 11 107.94 4.09 105.20 110.69 100.42 112.31 —
Male 2 103.03 0.46 — — 102.71 103.36
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SD: standard deviation; CI: confidence interval; Min: minimum; Max: maximum. The P values are calculated using the unpaired t-test.

The comparison of the overall Bolton ratio of this sample (Table 7) with the original overall Bolton ratio (mean: 91.3, SD: 1.91, n = 55) [10] did not show a significant difference (unpaired t-test, P = 0.107). However, the anterior Bolton ratio of this sample was significantly greater (t-test, P = 0.0498, Table 7) than the original anterior Bolton ratio (mean: 77.2, SD: 1.65, n = 55) [10].

4. Discussion

Tooth size variation is influenced by environmental and genetic factors including race, sex, heredity, cellular changes, and bilateral asymmetry [4, 20, 36]. Environmental factors include nutrition, disease, and climate, which might affect the prenatal dental system and seem to make little change to the normal dental system [37]. The strong contribution of genetic factors to the differences in dental measurements has been shown, but the influence of environmental factors seems plausible as well. Both environmental and genetic factors play a role in the etiology of supernumerary teeth, hypodontia, megadontia, and microdontia [38]. Sizes of teeth might vary in different populations [1, 20, 39]. Sex dimorphism has been reported as ranging between 0.82% and 5.97% for all teeth [4]. An example of a sex difference is the tendency of men to have larger teeth than women, which reflects the relationship between the X chromosome and the Y chromosome. For example, men who are XXY and XYY have teeth larger than XY men [1]. Our results were in line with these suggestions.

Keiser and Julius examined mesiodistal and buccolingual tooth sizes and concluded that they could be used to determine sex [40]. Using the dental dimensions of one ethnic group might be used in other ethnicities as well [41]. One of the preferred methods is to use the canine index, which uses the mesiodistal size of the mandibular canine together with intercanine width [42–44]. But the most widely used method is the mesiodistal and buccolingual dimensions [13, 22, 23]. The mandibular canine seems to have the greatest sex dimorphism among all teeth while incisors might have the least sexual dimorphism [24–26]. A recent meta-analysis suggested that the canine might have the most sex dimorphism among all teeth, which might be due to the longer duration of amelogenesis of this tooth in men compared to women [4]. This is in agreement with our findings of the possibility of the use of mandibular canines in predicting gender. Some researchers have shown that when the mesiodistal size of the canine tooth is larger than 7.0 to 7.2 mm, there is a very high probability that the person is male [16, 24, 45], and this was in line with our results pertaining to the mandibular canine. Some authors have suggested that both the mesiodistal and buccolingual dimensions are needed together for sex determination [46]. In our study, many molar teeth could be used for sex identification. In earlier research, this tooth was sometimes useful, and in some studies, it was useful merely alongside other teeth for sex determination, indicating the role of ethnicity in sex dimorphism [47–51].

Our findings indicated that aging might reduce the mesiodistal and buccolingual dimensions of certain teeth. In archaeological studies, the pattern of increased wear appears to be age-dependent, while in modern populations, men are more prone to tooth wear than women [35]. Such wear might affect both epidemiological and clinical outcomes and should be taken into account in such examinations.

The Bolton ratios found in this study were within the range reported earlier [6, 7, 11, 33, 34]. In comparison to the original Bolton ratios, our sample's anterior Bolton ratio was larger. This should be considered when practicing on Iranian patients; still, it should be noted that such results are not definitive, and sometimes, even studies conducted within the same ethnicity and country yield different results [6, 11]. The Angle classes were not associated with the anterior and posterior Bolton ratios in this sample. This finding was similar to some previous studies [8, 52–54] but in contrast to some others [33, 55]. It was found, however, that the posterior Bolton ratio might be smaller in class II patients, compared to classes I and III. In terms of sex dimorphism in Bolton ratios, when our whole sample was assessed, no sexual dimorphism was observed in this study. This finding was in line with most previous studies as well as the conclusion of a recent meta-analysis on Bolton ratios [6, 7, 53–55]. However, when sex dimorphism was examined separately within each of the Angle classes I or II, it was found that in class II patients, the anterior Bolton ratio might be greater in men than in women. We observed a 70% positive correlation between the anterior and overall Bolton indices. This was greater than the studies of Bolton (50% correlation) [10] or White (-12% correlation) [56] but slightly smaller than a study on Sudanese people (79% correlation) [7]. The controversies might be attributable to real ethnic differences as well as methodological variations such as eligibility criteria or sample sizes. The concept of the posterior Bolton ratio is introduced and assessed in merely two studies [33, 34]. We observed a 74% correlation between the posterior and overall Bolton ratios and almost no correlation between the anterior and posterior Bolton ratios. More studies are needed on the posterior Bolton ratio.

This study was limited by some factors. The number of females was much greater than males, although both seemed to be adequate. Moreover, the sample size pertaining to the Bolton ratios of class III men was very small. Hence, we did not perform inferential statistics on this subgroup. The generalizability of some aspects of this research was limited to the target population (Iranian orthodontic patients).

5. Conclusions

Within the limitations of this study, the following key points can be summarized:

  1. Sex dimorphism existed in most dental measurements. ROC curve analyses indicated that (A) the mandibular teeth mostly seemed better than the maxillary ones for sex identification; (B) the most appropriate dental measurements for sex determination were the buccolingual dimension of the right and left maxillary canines, the buccolingual measurement of the right and left mandibular canines and the right and left mandibular first premolars, as well as (C) the mesiodistal dimension of the right and left mandibular canines

  2. Cut-off points for sex identification based on proper dental measurements were calculated for 38 teeth. In the maxilla, the buccolingual cut-off points ranged from 7.715 mm for the central to 11.715 mm for the first molar; the mesiodistal cut-offs ranged from 8.750 mm for the central to 10.815 mm for the first molar. In the mandible, the range of buccolingual cut-off points was 6.175 mm to 11.455 mm (the central to the first molar), while the range of mesiodistal cut-off points was 6.835 mm to 10.910 mm (the canine to the first molar).

  3. (A) Aging might slightly reduce the buccolingual crown dimension in a few posterior teeth: the right and left maxillary first premolar and second premolar and right and left mandibular second premolar and first molar. (B) It might also slightly reduce the mesiodistal widths of certain anterior and posterior teeth: the right maxillary first premolar and first molar, the left maxillary central, canine, first premolar, first molar, the right mandibular lateral, first premolar, and first molar, and the left mandibular central, lateral, and first premolar

  4. (A) The only measurements differing among the skeletal Angle classes were the buccolingual widths of the maxillary lateral, the mandibular central, and the mandibular lateral. These differed mainly between classes I and II. (B) Dental measurements might not differ between crowded and noncrowded dentitions. (C) All crown sizes might be smaller in microdontia cases compared to cases without this anomaly

  5. The anterior, posterior, and overall Bolton indices were 78.05, 105.42, and 91.87, respectively. The skeletal Angle classification might not be associated with the anterior and overall Bolton ratios. However, class II patients might have smaller posterior Bolton ratios compared to class I or III patients. Aging might not affect Bolton indices. In the whole sample, there was no sexual dimorphism in either of these indices. However, in class II patients, the anterior Bolton ratio was greater in men than in women. There were 69.6% and 74.0% correlations between the overall Bolton indexes with the anterior and posterior Bolton indices, respectively. The anterior and posterior Bolton indices might not be correlated. The overall Bolton ratio in this population might not differ much from the original overall Bolton ratio. Nonetheless, this population's anterior Bolton ratio might be greater than Bolton's original anterior ratio

Data Availability

The raw data are available from the authors upon reasonable request.

Ethical Approval

Protocol ethics were approved by the Research Committee of the University in accordance with the Helsinki Declaration.

Conflicts of Interest

The authors declare that they have no conflict of interest.

Authors' Contributions

Negin Ashoori collected the data and wrote the thesis. Fataneh Ghorbanyjavadpour collected the data and mentored the thesis. Vahid Rakhshan conceived the study and all the ideas and hypotheses, designed the study, validated the data and fully analyzed it, mentored the thesis, interpreted the findings, drafted and revised the manuscript, and created the Tables/Appendix/Figures.

Supplementary Materials

Supplementary Materials

Supplementary file: Appendix 1. Online supplementary spreadsheet showing partial correlation coefficients (controlling for the role of sex) across tooth sizes and between age and tooth sizes.

Click here for additional data file. (54.9KB, docx)

References

  • 1.Deepak V., Goryawala S., Reddy Y., Chhabra R. Assessment of ethnicity in Indian population using tooth crown metric dental traits. Journal of International Oral Health: JIOH . 2015;7(9):83–87. [PMC free article] [PubMed] [Google Scholar]
  • 2.Togoo R., Alqahtani W., Abdullah E., et al. Comparison of mesiodistal tooth width in individuals from three ethnic groups in southern Saudi Arabia. Nigerian Journal of Clinical Practice . 2019;22(4):p. 553. doi: 10.4103/njcp.njcp_593_18. [DOI] [PubMed] [Google Scholar]
  • 3.Shaweesh A. I. Mesiodistal and faciolingual diameters of the permanent teeth in a Jordanian population. Archives of Oral Biology . 2017;73:253–258. doi: 10.1016/j.archoralbio.2016.10.026. [DOI] [PubMed] [Google Scholar]
  • 4.da Silva P. R., Lopes M. C., Martins-Filho I. E., Biazevic M. G. H., Michel-Crosato E. Tooth crown mesiodistal measurements for the determination of sexual dimorphism across a range of populations: a systematic review and meta-analysis. The Journal of Forensic Odonto-Stomatology . 2019;37(1):2–19. [PMC free article] [PubMed] [Google Scholar]
  • 5.Agenter M. K., Harris E. F., Blair R. N. Influence of tooth crown size on malocclusion. American Journal of Orthodontics and Dentofacial Orthopedics . 2009;136:795–804. doi: 10.1016/j.ajodo.2007.12.030. [DOI] [PubMed] [Google Scholar]
  • 6.Machado V., Botelho J., Mascarenhas P., Mendes J. J., Delgado A. A systematic review and meta-analysis on Bolton's ratios: normal occlusion and malocclusion. Journal of Orthodontics . 2020;47:7–29. doi: 10.1177/1465312519886322. [DOI] [PubMed] [Google Scholar]
  • 7.AaH A. H., Eldin A.-H. M., Hashim H. A. Bolton tooth size ratio among Sudanese population sample: a preliminary study. Journal of Orthodontic Science . 2015;4(3):77–82. doi: 10.4103/2278-0203.160240. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Crosby D. R., Alexander C. G. The occurrence of tooth size discrepancies among different malocclusion groups. American Journal of Orthodontics and Dentofacial Orthopedics . 1989;95:457–461. doi: 10.1016/0889-5406(89)90408-3. [DOI] [PubMed] [Google Scholar]
  • 9.Freeman J. E., Maskeroni A. J., Lorton L. Frequency of Bolton tooth-size discrepancies among orthodontic patients. American Journal of Orthodontics and Dentofacial Orthopedics . 1996;110:24–27. doi: 10.1016/s0889-5406(96)70083-5. [DOI] [PubMed] [Google Scholar]
  • 10.Bolton W. A. Disharmony in tooth size and its relation to the analysis and treatment of malocclusion. The Angle Orthodontist . 1958;28:113–130. [Google Scholar]
  • 11.Kachoei M., Ahangar-Atashi M. H., Pourkhamneh S. Bolton's intermaxillary tooth size ratios among Iranian schoolchildren. Medicina Oral, Patología Oral y Cirugía Bucal . 2011;16:e568–e572. doi: 10.4317/medoral.16.e568. [DOI] [PubMed] [Google Scholar]
  • 12.Brown T., Margetts B., Townsend G. Comparison of mesiodistal crown diameters of the deciduous and permanent teeth in Australian Aboriginals. Australian Dental Journal . 1980;25:28–33. doi: 10.1111/j.1834-7819.1980.tb03660.x. [DOI] [PubMed] [Google Scholar]
  • 13.Moorrees C. F., Thomsen S. Ø., Jensen E., Yen P. K.-J. Mesiodistal crown diameters of the deciduous and permanent teeth in individuals. Journal of Dental Research . 1957;36:39–47. doi: 10.1177/00220345570360011501. [DOI] [PubMed] [Google Scholar]
  • 14.Yonezu T., Warren J. J., Bishara S. E., Steinbock K. L. Comparison of tooth size and dental arch widths in contemporary Japanese and American preschool children. World Journal of Orthodontics . 2001;2 [Google Scholar]
  • 15.Yoo H.-I., Yang D.-W., Lee M.-Y., Kim M.-S., Kim S.-H. Morphological analysis of the occlusal surface of maxillary molars in Koreans. Archives of Oral Biology . 2016;67:15–21. doi: 10.1016/j.archoralbio.2016.02.020. [DOI] [PubMed] [Google Scholar]
  • 16.Srivastava P. Correlation of odontometric measures in sex determination. Journal of Indian Academy of Forensic Medicine . 2010;32:56–61. [Google Scholar]
  • 17.Thapar R., Angadi P. V., Hallikerimath S., Kale A. D. Sex assessment using odontometry and cranial anthropometry: evaluation in an Indian sample. Forensic Science, Medicine, and Pathology . 2012;8:94–100. doi: 10.1007/s12024-011-9247-4. [DOI] [PubMed] [Google Scholar]
  • 18.Mackinejad S. A., Kaviani R., Rakhshan V., Khabir F. Assessment of the cut-off point of mesiodistal and buccolingual widths of permanent teeth for determination of sex. Isfahan Dental Journal . 2015;11:153–162. [Google Scholar]
  • 19.Babu S. S., Nair S. S., Gopakumar D., Kurian N., Parameswar A., Baby T. K. Linear odontometric analysis of permanent dentition as a forensic aid: a retrospective study. Journal of Clinical and Diagnostic Research: JCDR . 2016;10:p. ZC24. doi: 10.7860/JCDR/2016/18677.7741. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20.Brook A., Griffin R., Townsend G., Levisianos Y., Russell J., Smith R. Variability and patterning in permanent tooth size of four human ethnic groups. Archives of Oral Biology . 2009;54:S79–S85. doi: 10.1016/j.archoralbio.2008.12.003. [DOI] [PubMed] [Google Scholar]
  • 21.Hattab F., Al-Khateeb S., Sultan I. Mesiodistal crown diameters of permanent teeth in Jordanians. Archives of Oral Biology . 1996;41:641–645. doi: 10.1016/s0003-9969(96)00066-0. [DOI] [PubMed] [Google Scholar]
  • 22.Garn S., Lewis A., Walenga A. Maximum-confidence values for the human mesiodistal crown dimension of human teeth. Archives of Oral Biology . 1968;13:841–844. doi: 10.1016/0003-9969(68)90107-6. [DOI] [PubMed] [Google Scholar]
  • 23.Garn S. M., Cole P., Wainwright R., Guire K. Sex discriminatory effectiveness using combinations of permanent teeth. Journal of Dental Research . 1977;56(6):697–697. doi: 10.1177/00220345770560062601. [DOI] [PubMed] [Google Scholar]
  • 24.Kaushal S., Patnaik V., Agnihotri G. Mandibular canines in sex determination. Journal of the Anatomical Society of India . 2003;52:119–124. [Google Scholar]
  • 25.Garn S. M., Lewis A. B., Swindler D. R., Kerewsky R. S. Genetic control of sexual dimorphism in tooth size. Journal of Dental Research . 1967;46:963–972. doi: 10.1177/00220345670460055801. [DOI] [PubMed] [Google Scholar]
  • 26.Hsu J. W., Tsai P. L., Hsiao T. H., Chang H. P., Liu L. M., Liu K. M., et al. Ethnic dental analysis of shovel and Carabelli's traits in a Chinese population. Australian Dental Journal . 1999;44:40–45. doi: 10.1111/j.1834-7819.1999.tb00534.x. [DOI] [PubMed] [Google Scholar]
  • 27.Anderson D. L., Thompson G. W. Interrelationships and sex differences of dental and skeletal measurements. Journal of Dental Research . 1973;52:431–438. doi: 10.1177/00220345730520030701. [DOI] [PubMed] [Google Scholar]
  • 28.Petersen K., Kogon S. Dental identification in the Woodbridge disaster. Journal of the Canadian Dental Association . 1971;37:275–279. [PubMed] [Google Scholar]
  • 29.Felemban N. H., Manjunatha B. S. Prevalence of the number of cusps and occlusal groove patterns of the mandibular molars in a Saudi Arabian population. Journal of Forensic and Legal Medicine . 2017;49:54–58. doi: 10.1016/j.jflm.2017.05.013. [DOI] [PubMed] [Google Scholar]
  • 30.Baby T. K., Sunil S., Babu S. S. Nonmetric traits of permanent posterior teeth in Kerala population: a forensic overview. Journal of oral and maxillofacial pathology: JOMFP . 2017;21:p. 301. doi: 10.4103/jomfp.JOMFP_21_17. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 31.Ghorbanijavadpour F., Rakhshan V., Ashoori N. Evaluation of prevalence of hypodontia based on sex, dental and skeletal relationship in patients admitted to Ahvaz Dental School. Journal of Isfahan Dental School . 2021;17:56–63. [Google Scholar]
  • 32.Scheid R. C., Weiss G. Woelfel's dental anatomy . Jones & Bartlett Publishers; 2020. [Google Scholar]
  • 33.Fattahi H. R., Pakshir H. R., Hedayati Z. Comparison of tooth size discrepancies among different malocclusion groups. European Journal of Orthodontics . 2006;28:491–495. doi: 10.1093/ejo/cjl012. [DOI] [PubMed] [Google Scholar]
  • 34.Laino A., Quaremba G., Paduano S., Stanzione S. Prevalence of tooth-size discrepancy among different malocclusion groups. Progress in Orthodontics . 2003;4:37–44. doi: 10.1034/j.1600-9975.2002.02035.x. [DOI] [PubMed] [Google Scholar]
  • 35.Brook A., Underhill C., Foo L., Hector M. Approximal attrition and permanent tooth crown size in a Romano-British population. Dental Anthropology Journal . 2006;19:23–28. [Google Scholar]
  • 36.Bishara S. E., Jakobsen J. R., Abdallah E. M., Garcia A. F. Comparisons of mesiodistal and bnccolingnal crown dimensions of the permanent teeth in three populations from Egypt, Mexico, and the United States. American Journal of Orthodontics and Dentofacial Orthopedics . 1989;96:416–422. doi: 10.1016/0889-5406(89)90326-0. [DOI] [PubMed] [Google Scholar]
  • 37.Bailit H. Dental variation among populations. An anthropologic view. Dental Clinics of North America . 1975;19:125–139. [PubMed] [Google Scholar]
  • 38.Brook A. A unifying aetiological explanation for anomalies of human tooth number and size. Archives of Oral Biology . 1984;29:373–378. doi: 10.1016/0003-9969(84)90163-8. [DOI] [PubMed] [Google Scholar]
  • 39.Hanihara T., Ishida H. Metric dental variation of major human populations. American Journal of Physical Anthropology: The Official Publication of the American Association of Physical Anthropologists . 2005;128:287–298. doi: 10.1002/ajpa.20080. [DOI] [PubMed] [Google Scholar]
  • 40.Kieser J. A., Julius K. Human Adult Odontometrics: the Study of Variation in Adult Tooth Size . Cambridge University Press; 1990. [Google Scholar]
  • 41.Verhoeven J., Van Aken J., Van Der Weerdt G. The length of teeth: a statistical analysis of the differences in length of human teeth for radiologic purposes. Oral Surgery, Oral Medicine, Oral Pathology . 1979;47:193–199. doi: 10.1016/0030-4220(79)90180-4. [DOI] [PubMed] [Google Scholar]
  • 42.Rao N. G., Rao N. N., Pai M. L., Kotian M. S. Mandibular canine index—a clue for establishing sex identity. Forensic Science International . 1989;42:249–254. doi: 10.1016/0379-0738(89)90092-3. [DOI] [PubMed] [Google Scholar]
  • 43.Sherfudhin H., Abdullah M., Khan N. A cross-sectional study of canine dimorphism in establishing sex identity: comparison of two statistical methods. Journal of Oral Rehabilitation . 1996;23:627–631. doi: 10.1046/j.1365-2842.1996.00406.x. [DOI] [PubMed] [Google Scholar]
  • 44.Muller M., Lupi-Pegurier L., Quatrehomme G., Bolla M. Odontometrical method useful in determining gender and dental alignment. Forensic Science International . 2001;121:194–197. doi: 10.1016/s0379-0738(01)00399-1. [DOI] [PubMed] [Google Scholar]
  • 45.Rai B., Dhattarwal S., Anand S., Bhardwaj D. Mesio-distal diameter of mandibular canine as a sex and intercanine distance as the age determinant. Indian Internet Journal of Forensic Medicine & Toxicology . 2008;6:44–47. [Google Scholar]
  • 46.Acharya A. B., Mainali S. Sex discrimination potential of buccolingual and mesiodistal tooth dimensions. Journal of Forensic Sciences . 2008;53:790–792. doi: 10.1111/j.1556-4029.2008.00778.x. [DOI] [PubMed] [Google Scholar]
  • 47.Shrestha R. Measurement of mesio-distal tooth diameter of Nepalese permanent dentition. Journal of Nepal Dental Association . 2005;7:55–63. [Google Scholar]
  • 48.İşcan M. Y., Kedici P. S. Sexual variation in bucco-lingual dimensions in Turkish dentition. Forensic Science International . 2003;137:160–164. doi: 10.1016/s0379-0738(03)00349-9. [DOI] [PubMed] [Google Scholar]
  • 49.Townsend G. Tooth size characteristics of Australian Aborigines. Occasional Papers in Human Biology . 1979;1:17–38. [Google Scholar]
  • 50.Ghose L. J., Baghdady V. S. Analysis of the Iraqi dentition: mesiodistal crown diameters of permanent teeth. Journal of Dental Research . 1979;58:1047–1054. doi: 10.1177/00220345790580030301. [DOI] [PubMed] [Google Scholar]
  • 51.Harris E. F., Nweeia M. T. Tooth size of Ticuna Indians, Colombia, with phenetic comparisons to other Amerindian. American Journal of Physical Anthropology . 1980;53:81–91. doi: 10.1002/ajpa.1330530112. [DOI] [PubMed] [Google Scholar]
  • 52.Hashim H. A., Zuhair Murshid B. Mesiodistal tooth width in a Saudi population: a preliminary report. Saudi Dental Journal . 1992;5:68–72. [Google Scholar]
  • 53.Basaran G., Selek M., Hamamci O., Akkuş Z. Intermaxillary Bolton tooth size discrepancies among different malocclusion groups. The Angle Orthodontist . 2006;76:26–30. doi: 10.1043/0003-3219(2006)076[0026:IBTSDA]2.0.CO;2. [DOI] [PubMed] [Google Scholar]
  • 54.Uysal T., Sari Z., Basciftci F. A., Memili B. Intermaxillary tooth size discrepancy and malocclusion: is there a relation? The Angle Orthodontist . 2005;75:208–213. doi: 10.1043/0003-3219(2005)075<0204:ITSDAM>2.0.CO;2. [DOI] [PubMed] [Google Scholar]
  • 55.Nie Q., Lin J. Comparison of intermaxillary tooth size discrepancies among different malocclusion groups. American Journal of Orthodontics and Dentofacial Orthopedics . 1999;116:539–544. doi: 10.1016/s0889-5406(99)70186-1. [DOI] [PubMed] [Google Scholar]
  • 56.White L. W. The clinical use of occlusograms. Journal of Clinical Orthodontics . 1982;16:92–103. [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary Materials

Supplementary file: Appendix 1. Online supplementary spreadsheet showing partial correlation coefficients (controlling for the role of sex) across tooth sizes and between age and tooth sizes.

Click here for additional data file. (54.9KB, docx)

Data Availability Statement

The raw data are available from the authors upon reasonable request.

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