Original Article |
Corresponding author: Zdravka Harizanova ( zarahar@abv.bg ) © 2023 Zdravka Harizanova, Atanas Baltadjiev.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Harizanova Z, Baltadjiev A (2023) Anthropological study of dental indices in Bulgarian population. Folia Medica 65(4): 659-663. https://doi.org/10.3897/folmed.65.e84820
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Introduction: A number of derived quantities (called dental indices) that characterize the shape and size of the teeth are calculated between the absolute dimensions of the teeth (mesiodistal, vestibulo-oral, and height of the dental crown).
Aim: The aim of the present study was to explore the degree of sexual dimorphism in dental indices in the Bulgarian population.
Materials and methods: The study included 232 Bulgarians aged 20–40. The vestibulo-oral and mesiodistal dimensions of the teeth were measured. The crown module and crown index were calculated.
Results: We found that male Bulgarians had a significantly greater crown module of the upper canines, first premolars, molars, and second molars than females. The crown module of the lower molars was found to be similar in this respect. The crown module of the lower lateral incisors also revealed statistically significant differences, although in females it had higher values. Only the upper and lower canines and upper molars displayed sexual dimorphism according to the crown index, and women’s mean values were higher than men’s were.
Conclusions: Our results suggest that some of the dental indices in the Bulgarian population were sexually dimorphic, which may contribute to defining sex.
Bulgarians, crown index, crown module, teeth
Odontometry and its application in anthropology originated in the last century.[
An option that may be useful is the calculation of so-called dental indices. They are obtained from mathematical combinations between the linear dimensions of dental crowns.
The aim of the present study was to explore the degree of sexual dimorphism of dental indices in Bulgarian population.
The present study included 121 males and 111 females of Bulgarian origin in the age group of 20-40 years. Patients were included based on the following criteria:
1. Presence of a complete set of fully erupted and periodontally healthy teeth
2. No periodontal disease
3. No spacing and crowding in anterior teeth
4. No history of orthodontic treatments
Mesiodistal and vestibulo-oral dimensions of the teeth were measured by Dentistry Sliding Vernier Caliper. We used the technique of direct anthropometry, modified by Prof. Y. Yordanov.[
The crown module (CM) is calculated as half of the sum of the mesiodistal (MD) and vestibulo-oral (VO) size. It characterizes the total mass of the crown. For each group of teeth, for each jaw separately, the average module for the group can be calculated by summing the modules of the teeth included in it and dividing the result by their number: it is 4 for incisors, 2 for premolars, and 3 for molars. In odontology, it is accepted that the average module for the crowns of the upper molars gives the best general characteristic of the absolute dimensions of the dentition. We calculated the crown module using the following formula:
CM=(MD+VО)/2
The mean crown module of the upper molars for the Bulgarian population was calculated using this formula:
(CM16+CM17+CM26+CM27)/4.
The crown index (CI) is the ratio of the vestibulo-oral size to the mesiodistal size. It characterizes the shape of the crown. The crown index for the upper molars is always greater than 100, and for the lower ones - always below 100. The average value of the index for the upper molars is about 120.[
CI=(VO/MD)×100
and the mean crown index of the lower molars for the Bulgarian population:
(CI36+CI37+CI46+CI47)/4.
Ethical approval was granted to this study by the Ethics Committee of the Medical University of Plovdiv. Informed consents were obtained from all patients involved in the study. All methods were performed in accordance with the relevant guidelines and regulations.
The measurements were analyzed using SPSS v. 23.0 using the Student’s t-test. The level of statistical significance was set at p<0.05. The degree of significance was considered weak (p<0.05), moderate (0.01>p>0.001) or high (p<0.001).
1. The crown module of the upper canines and the first molars shows differences of high degree of significance between men and women of the Bulgarian population. Similar results were found for the first premolars as well as the second molars but with low degree of significance. The mean values of women were lower than those of men (Table
2. The crown module of the lower lateral incisors showed statistically significant differences with low degree of significance, with the mean values being higher in women than in men. We found that the crown module of the lower molars showed differences with high degree of significance, but the mean values in males were significantly higher than in females (Table
3. The crown index for the upper canines showed statistically significant differences of high degree, for the upper molars the differences were of low significance. The mean values of women were higher than those of men (Table
4. The crown index of the lower canines showed statistically significant differences with low degree of significance. The mean values of Bulgarian women were higher than those of men (Tables
Comparison of the crown module of the upper teeth between Bulgarian men and women
CM | Males | CM | Females | P | ||||||
N | Mean | SD | SE | N | Mean | SD | SE | |||
CM13 | 121 | 8.37 | 0.62 | 0.09 | CM13 | 111 | 7.97 | 0.49 | 0.08 | 0.001 |
CM14 | 121 | 8.07 | 0.46 | 0.07 | CM14 | 111 | 7.86 | 0.44 | 0.07 | 0.034 |
CM16 | 121 | 10.77 | 0.44 | 0.07 | CM16 | 111 | 10.24 | 0.44 | 0.07 | <0.001 |
CM17 | 121 | 10.23 | 0.43 | 0.07 | CM17 | 111 | 9.90 | 0.43 | 0.07 | 0.016 |
Comparison of the crown module of the lower teeth between Bulgarian men and women
CM | Males | CM | Females | P | ||||||
N | Mean | SD | SE | N | Mean | SD | SE | |||
CM32 | 121 | 5.55 | 0.47 | 0.07 | CM32 | 111 | 5.73 | 0.37 | 0.06 | 0.045 |
CM36 | 121 | 10.72 | 0.49 | 0.07 | CM36 | 111 | 10.23 | 0.49 | 0.08 | <0.001 |
Comparison of the crown index of the upper teeth between Bulgarian men and women
CI | Males | CI | Females | P | ||||||
N | Mean | SD | SE | N | Mean | SD | SE | |||
CI13 | 121 | 92.23 | 10.14 | 1.55 | CI13 | 111 | 101.1 | 14.37 | 2.19 | 0.001 |
CI16 | 121 | 101.69 | 8.09 | 1.23 | CI16 | 111 | 106.16 | 7.82 | 1.19 | 0.011 |
Application of dental indices for sex determination in forensic medicine has not yet been fully studied. Townsend and Brown[
In odontology, it is accepted that the mean crown module of the upper molars gives the best general characteristic of the absolute size of the dentition.[
The following rubrication has been introduced for the crown index of the lower molars:
In our study, we calculated the crown module and crown index for the patients we examined, divided them into upper and lower jaws, as well as into men and women. The results we obtained were summarized in four tables. The results on sexual dimorphism for the crown module were similar to the linear measurements of the same teeth, i.e. again canines and molars showed the greatest sexual dimorphism.[
When calculating the crown index, we found even less statistically significant differences between the two sexes. We found such differences only in the upper and lower canines and upper molars, which is unique in our study, given the fact that the lower molars are also teeth with high sexual dimorphism. These findings call into question the use of the crown index in sex determination. According to Kondo and Townsend, this index expresses the percentage of one linear size to another, i.e. the fact that men usually have higher linear dimensions does not mean that this will be the case when we take them in combination.[
Acharya and Mainali obtained similar results for the group of Nepalese they studied. They thought that since the crown index expressed the percentage ratio between two linear sizes, it was influenced by the difference between them.[
This is in accordance with the opinion of Goose, who also claimed that the crown index was an expression of the shape of the tooth rather than the size of the tooth.[
According to many authors, dental indices can be used to determine the biological relationships between populations, as they are an expression of historical, cultural and biological macro and micro-evolutionary processes, which would help to fully understand the origin, formation, contacts, and migration of the population.[
According to these studies, there are differences in the sizes of dental crowns between the different populations and according to the module of the upper molars, they are divided into three main groups: microdonts, mesodonts, and macrodonts. In general, microdonts are the southern branches of the European race, the most macrodontic are the representatives of the Negroid race, and the Mongoloids and the northern branches of the European race are most often mesodonts. According to Hanihara, Australian aborigines are closer to Caucasians and white Americans than to Mongoloids.[
We found that the crown module of upper canines, first premolars and molars were significantly higher in Bulgarian males than females. Similar results were found for the crown module of the lower molars. Crown module of lower lateral incisors also showed statistically significant differences but females showed higher values. The crown index showed sexual dimorphism only in upper and lower canines and upper molars and the mean values of women were higher than in men. According to both indicators (crown module and crown index), the Bulgarian population belongs to the mesodontic teeth group. We believe that crown module can successfully help defining sex while crown index is not so reliable.
The authors declare that there is no conflict of interest.
Z.H. and A.B. performed the research and drafted the manuscript, worked on the tables and English translation. All authors have seen and approved the manuscript and have contributed significantly for the paper.
This study was granted approval by the Ethics Committee of the Medical University of Plovdiv. Informed consents were obtained from all patients involved in the study.
This research has not received any specific grant from any funding agency in the public, commercial, or not-for-profit sector.