SEXUAL DIMORPHISM IN MAXILLARY FIRST MOLAR AMONG NEPALESE POPULATION OF EASTERN NEPAL

Sanjib Kumar Sah1*, Suman Pokhrel2, Sidarth Timsinha3 Umesh Kumar Mehta4, Raju Kumar Chaudhary5, Rajesh Kumar Shah6 Received : 04 March, 2021 Accepted : 28 July, 2021 Published : 04 November 2021 1492 ISSN: 2542-2758 (Print) 2542-2804 (Online) Birat Journal of Health Sciences Vol.6/No.2/Issue 15/May-Aug., 2021 Original Research Ar cle


Introduc on
Sexual refers to d dimorphism ifferences in size, stature and appearance between male and female. It is a known fact that tooth crown is formed to full size in childhood even before erup on into oral cavity. The shape and size of the teeth permits an interes ng dimension of study for sexual dimorphism, we aimed to delineate the sexual dimorphism by measuring the mesiodistal (MD) and buccolingual (BL) diameters of permanent maxillary first molar in Nepalese popula on of Eastern Nepal.

Objec ves
The aim of this study was to evaluate the sexual dimorphism in maxillary first molar among Nepalese popula on of eastern Nepal Methodology 100 par cipants of either sex (50 males & 50 females) aged between 17 to 25 years were enrolled in the study. A er thorough dental examina on, impression of the maxillary arch was made and MD diameter and BL diameters were measured with the help of digital vernier caliper. A P value of <0.05 was considered as sta s cally significant.

Result
Sexual dimorphism was found in MD and BL diameters of maxillary first molar in males measuring higher than females. Right mesiodistal showed the highest sexual dimorphism, whereas right buccolingual showed the least.

Conclusions
This study confirms that permanent maxillary first molar shows significant sexual dimorphism, out of which mesiodistal measurement stands out to be the best parameter in Nepalese popula on of Eastern region.

Introduc on
Teeth are an excellent ssue material in living and non-living popula on for anthropological, gene c, odontologic and 1 forensic inves ga ons . They exhibit the least turnover of natural structure and have strong resistance to decay and structural changes even long me a er death. Durability in the face of fire and bacterial decomposi on makes them 1 invaluable for iden fica on. Maxillary first molar are the first permanent teeth to erupt into the oral cavity at an average age of 6-7 years and are less likely to be impacted 1 than canines. If the postcranial skeleton is intact, sex can be 2,3 accurately determined in mature individuals. Sexual dimorphism refers to the differences in size, stature and appearance between male and female that can be applied to dental iden fica on because no two dental arrangements 4 are alike. Gender determina on of skeletal remains is part of the archaeological, anthropological and medico-legal examina ons. The only method that can give a totally accurate result is Deoxyribonucleic Acid technique but in many cases for several reasons it is quite difficult to perform 5,6 because of its cost and me consump on. The study of the shape and size of the teeth permits an interes ng dimension of study for sexual dimorphism; this is for the fact that tooth crown is formed to full size in childhood even before erup on into oral cavity. Sex in the dental indexes are differences 7,8 assessed using univariate and mul variate sta s c. This study is therefore a nobel a empt to study the sexual dimorphism in maxillary first molar teeth. This study also intends to find any changes in mesio-distal (MD) and buccolingual (BL) diameters between right and le side teeth in each gender. The result of the study could be a vital tool and may play a significant role in establishing the iden ty of an individual. was used to make impressions of the maxillary arch and casts were poured instantly in type II dental stone to minimize dimensional changes. The BL and MD diameters of the permanent maxillary first molar were measured using digital vernier caliper on the study cast as shown in Figure 1 and Figure 2. The greatest distance on the occlusal surface between the perpendicular plane of mesial and distal surfaces of the crown of the tooth was taken as MD diameter, and the greatest distance between the perpendicular plane of buccal and lingual surfaces of the crown of the tooth was taken as BL diameter. The mean value of MD and BL diameters of male and female were used in the calcula on of sexual dimorphism. Sexual dimorphisms in the right and le maxillary molar were calculated as:

METHODOLOGY
Where, Xm= mean of male tooth dimension, Xf = mean of female tooth dimension

RESULTS
On measuring MD and BL diameters for right and le first maxillary molar, it was found out that males had greater mean MD and BL diameters of first maxillary molar in comparison to females. However, the mean values of both MD and BL were not sta s cally significant (Table 1).  Our study showed that both the mesiodistal and buccolingual dimensions of right-side tooth were greater than the le side although the result was not sta s cally significant (Table 3). On correla on between le and right mesiodistal diameters of maxillary molar and buccolingual dimensions of either side maxillary molar and found out that they were strongly associated (Table 4).

DISCUSSION
Craniofacial morphology, pubis measurements, dental records, DNA analysis etc. are some of the basis for human sex determina on. Out of the known parameters, odontometrics studies being simple, inexpensive, and easy to measure, it has gained the epitome of popularity. Dental records have proved its significance in providing durable evidence even in post mortem iden fica on which makes it 9 a reliable biological feature in sex differen a on. Many studies had been carried out in different popula on and had demonstrated that sexual dimorphism can be accurately [10][11][12][13] assessed by using dental dimensions. Mesiodistal (MD) and buccolingual (BL) diameters of maxillary first molar were measured. The diameters of maxillary first molar were found to be higher in males than females which were in accordance [4][5][6]14 with other studies. Environmental factors and gene cs may have been the primary factors bringing this kind of varia on between both sexes. This change may also be due toamelogenesis which occur for longer dura on in males. The crown calcifica on finishing early in femalesrela ve to males also may subserve the varia on. However, MD and BL diameters, we observed in our study between two sexes were not sta s cally significant as it was shown on few other 15 studies. This might be due to the gene c varia on of popula on that we undertook in our study. In our present study both MD and BL parameters of right sided teeth were higher as compared to le sided teeth in both sexes. In accordance to our results, Bhavasar et al., who conducted similar kind of study in Guajara popula on of India also showed similar finding in which right sided teeth 16 parameters were higher as compared to le sided teeth. Contrarily, our results were not in accordance with the results showed by Rai B et al. who found out that right buccolingual diameters of maxillary first molars to be 7 smaller than the le ones. Another study done by Sonika V et al. on Haryana popula on of India also showed all the diameters of le teeth were significantly higher than the 17 right sided parameters. This varia on could be due to the dental asymmetry of le and right side teeth possessed by the study popula on. Also this varia on may be acquired due to the maximum use of right-side teeth during mas ca on and grinding of food. Sexual dimorphism percentage in our study was calculated by using the standard formula comprising mean diameter of teeth and found out to be 5.24% for right maxillary mesiodistal diameter, 4.29% for right maxillary buccolingual diameter, 4.46% for le maxillary mesiodistal diameter and 4.40% le maxillary buccolingual diameter, respec vely. The mesiodistal diameters of maxillary first molars in the present study were found to exhibit greater sexual dimorphism than buccolingual diameters of the same teeth. Similar findings were noted in a study conducted on Guajara popula on in where sexual dimorphism were best demonstrated by 16 mesiodistal dimension. Another study done by Manav et al. also showed and concluded that MD measurements were be er suited than BL dimensions for sex determina ons 18 when used independently. In contrast to our results, Sonika V et al., Sharma et al. and Garn et al. showed maximum sexual dimorphism on buccolingual dimensions than mesiodistal 17,19, dimensions.
Narang RS et alalso observed sexual dimorphism to be 7.4% and 6.3% for right and le bucco 20 lingual dimensions of maxillary first molars.

CONCLUSION
Odontometrics features of teeth may subserve utmost help in determina on of sex. The MD and BL dimensions of maxillary molar in male are greater than those of females and right sided dimensions are greater than the counterparts. This study confirms that permanent maxillary first molar shows significant sexual dimorphism, out of which mesiodistal measurement stand out as the best parameter in Nepalese popula on of Eastern region.

RECOMMENDATION
Prospec ve longitudinal study increasing the number of study subject is recommended. Also, such studies could be conducted in mul ple centers so that the findings can be generalized in large popula on.

LIMITATION OF STUDY
The study includes only pa ents a ending dental OPD of single ter ary care hospital. Therefore, due to small sample size the finding of the study cannot be generalized in large popula on.