Sex determination of the Bosnian-Herzegovinian population based on odontometric characteristics of permanent lower canines

Introduction : Sex determination is one of ﬁ rst and most important steps in identifying disintegrated bodies and skeletal remains. During the exhumation of bodies from the mass graves and archaeological excavations, it is quite often the case that not all bones of one person are found, therefore, teeth and the scull are the only true identi ﬁ cation material. Canines are teeth most appropriate for sex determination. The aim of the research was to determine sex identity of the Bosnian-Herzegovinian population based on odontometric characteristics of permanent lower canines. Methods : The research sample included 180 patients of the Dental Of ﬁ ce, of both sexes. All patients with permanent lower right and left canines, without caries, with healthy state of gingiva and periodontium, without crown restorations were included in the research. Measurement was done directly in the patients' mouth using a digital sliding caliper. Greatest mesiodistal width of the lower right and left canine and intercuspal distance of the lower jaw were measured. Results : All parameters were higher in case of male, including Mandibular Canine Index (MCI) (p<0.01). The precision of appraising the sex identity for the Bosnian-Herzegovinian population, based on MCI on the right, amounts 68.89% and 68.54% on the left. Conclusions : The study showed that right canines are signi ﬁ cantly broader than the left ones and they are broader in case of males. Lower right canines, that is, MCI on the right, indicates greater accuracy in sex determination in relation to left lower canines. The accuracy in sex determination for all variables is higher for the female.


INTRODUCTION
Sex determination is one of fi rst and most important steps in identifying disintegrated bodies and skeletal remains. Th e past war in Bosnia and Herzegovina (1992)(1993)(1994)(1995) took a large number of human lives and many families are still searching for their relatives. According to data of the Missing Persons In-stitute and International Commission for Missing Persons (ICMP), it is believed that during the war in Bosnia and Herzegovina, about 17.000 human remains were exhumed including many those still not identifi ed. Around 9.000 persons have still not been found and identifi ed (1). Th erefore, there is a need to identify a large number of human remains exhumed from many mass graves on the territory of Bosnia and Herzegovina because it provides a discovery for survived family about the fate of their loved ones. Pelvis and scull bones are most frequently used for sex determination based on skeleton although the measurement of humerus and femur head diameter enables highly credible sex determination (2,3). Very frequently, bones of one person cannot be found during exhumations of bodies from mass graves, especially secondary and tertiary, where death remains are quite mixed, and archaeological excavations, therefore, teeth and the scull are the only real material for identifi cation (4). Th e analysis of teeth and identifi cation of discovered bodies using teeth characteristics showed as the fi rst, irreplaceable and highly important procedure in determining the identity of unknown human remains (5)(6)(7). Canines are teeth most appropriate for sex determination. Studies on permanent canines show that those are teeth that are less frequently taken out probably due to reduced caries incidence and they are the least aff ected by periodontal diseases and they are last teeth to be taken out in view of age. Moreover, those are teeth that can survive many traumas and disasters. All the aforementioned indicate that canines are teeth that can be used as key teeth for identifi cation (8)(9)(10). Sex determination using odontometric techniques is of great interest in cases of great disasters when bodies are severely damaged to the extent that identification is not possible. Th ere are many methods for studying canines' dimensions such as Fourier analysis, Moire topography, measurement of linear teeth dimension such as mesiodistal width, buccolingual width and inciso-cervical height (11)(12)(13)(14). One of them is the method according to Rao et al that is simple, credible, inexpensive, easily performed and it provides satisfactory results and it is used on greater population. Method according to Rao includes the measurement of mesiodistal width of permanent lower jaw canines as well as the measurement of intercuspal distance, that is, measurement of distance between tips of canine cusps (15). Th e success rate of sex determination based on Rao's formula is up to 89% (16). Aim of this study is to appraise the sex identity of the Bosnian-Herzegovinian population based on odontometric characteristics of lower jaw canines by applying the method according to Rao et al.

Study sample
Research sample included patients of the Dental Offi ce, of both sex, including the total of 180 patients, 90 male and 90 female patients. All patients with permanent lower right and left canines, without caries, with healthy state of gingiva and periodontium, without crown restorations were included in the research. All patients were explained the type of measurements, its method and purpose and they all signed voluntary acceptance for teeth measurement.

Methods
Research was retrospective, clinical and descriptive. It was done directly in the patients' mouth using a digital sliding caliper and values were expressed up to the hundredth part of millimeter. Parameters that were measured include: greatest mesiodistal width of the lower right and left canine and intercuspal distance of the lower jaw. Mesiodistal width of canines is measured in the manner that the greatest span between the mesial and distal approximate surface on vestibular tooth surface is measured using a digital sliding caliper. Intercuspal distance is measured in the manner that the distance between the tips of canine cusps of the right and left canine is measured Mesiodistalcrown width of permanent lower jaw canine Intercuspal distance of the lower jaw MCI = using a digital sliding caliper. On grounds of the aforementioned, using formulas developed according to Rao et al, Mandibular Canine Index (index of lower canines / MCI) and Standard Mandibular Canine Index (standard index of lover canines / Std. MCI) have been calculated (15). Standard Mandibular Canine Index (Std.MCI) is used as a key point for diff erentiating male versus female. If obtained Mandibular Canine Index (MCI) for individual is higher than the Standard Mandibular Canine Index (Std. MCI), then it is believed that it is the case of male and if it is smaller, then it is the case of a female (15).

Statistical analysis
Data were processed with application of descriptive statistics, t-tests for independent samples and chisquared test. P-value was considered statistically signifi cant if it was lower than 0.01. A statistical software IBM statistics SPSS V19.0 was used for data analysis.

RESULTS
Th e analysis of sample according to sex identity and age indicated that the group is homogenous according to age and that average age of male amounted 35.01±13.18 years, and female 35.47±13.11 years.
(Mean male MCI -SD) + (Mean female MCI + SD)   Table 2 indicates that its values were greater with male in relation to female, with statistically signifi cant diff erence according to sex of all observed parameters (p<0.01). Based on Mandibular Canine Index, 31.5% of male persons were classifi ed as females by error and 34.4% of females were classifi ed as males, which is set forth in Table 3.    (20). Th e percentage of accuracy of determininging sex of the Bosnian-Herzegovinian population based on odontometric characteristics of permanent lower canines obtained with this research is somewhat smaller in relation to presented research for most other populations. One of possible reasons is the size of sample for this study since the research was performed on the sample of only 180 patients of both sexes. Th e examination of intraobserver and extraobserver error would provide answer whether the method itself has impact on obtained results. It is also possible that there are diff erences between populations in application of the method itself. For more precise results, it is necessary to perform research on a larger sample of patients. However, the measurement of mesiodistal width of permanent lower jaw canines as well as the measurement of intercuspal distance, is simple, quick, credible, inexpensive, easily performed, noninvasive method which provides satisfactory results in sex determination of the Bosnian-Herzegovinian population, which was the overall aim of this research. Th is study shall have its practical value in sex identifi cation during anthropological processing and identifi cation of victims from the past war in Bosnia and Herzegovina, considering the fact that a large number of death remains is found in secondary or tertiary mass graves where death remains were greatly mixed or whereby only some body parts are found on the surface (25). Th erefore, it is not uncommon to fi nd only damaged scull and/or lower jaw and thereby, results of this research might provide one of methods to choose for sex determination.

CONCLUSIONS
Th e study showed that right canines are signifi cantly broader than the left ones and that they are broader for male than for female. Lower right canines, that is, Mandibular Canine Index on the right indicates greater accuracy in sex determination in relation to left lower canines. Accuracy in sex determination is higher for the female for all variables. Research established specifi c standards for sex determination, in population terms, for used sample of the Bosnian-Herzegovinian population but further research is needed for more precise values.