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Role of mandibular canines in establishment of gender
Egyptian Journal of Forensic Sciences (2014) 4, 71–74
H O S T E D BY
Contents lists available at ScienceDirect
Egyptian Journal of Forensic Sciences journal homepage: www.ejfs.org
ORIGINAL ARTICLE
Role of mandibular canines in establishment of gender Ch. Sai kiran *, Tanya Khaitan, P. Ramaswamy, S. Sudhakar, B. Smitha, G. Uday Department of Oral Medicine and Radiology, St. Joseph Dental College, Eluru, 534003, India Received 27 January 2014; revised 9 May 2014; accepted 13 May 2014 Available online 18 June 2014
KEYWORDS Sex dimorphism; Canine tooth; Forensic sciences; Dental models; Personal identification
Abstract Objective: The objective of this study was to determine the maximum mesiodistal width of mandibular canines for establishing their variation as a tool to determine gender and to determine the accuracy of the measurements through clinical examination and dental cast models. Study design: A total of 60 subjects (30 males and 30 females) in the age group of 15–34 years were selected for the study. The maximum mesiodistal widths of the right and left mandibular canines were first measured intraorally and then on cast models of the same patients with the help of a divider and a digital vernier caliper. The collected data were subjected to statistical analysis and sexual dimorphism was calculated. Results: The mesiodistal width of the mandibular canines as determined by clinical examination and on plaster models was statistically insignificant. The mean canine widths were found to be higher in males when compared with females. The right mandibular canine showed a greater sexual dimorphism than the left mandibular canine. Conclusion: The present study established the mandibular canine as a valuable tool for sex determination. ª 2014 Hosting by Elsevier B.V. on behalf of Forensic Medicine Authority.
1. Introduction Sex determination with the aid of skeletal remains poses a great dilemma to forensic experts, particularly when only a part of the body is endured.1 DNA analysis is considered the
* Corresponding author. Tel.: +91 9491113193. E-mail addresses: [email protected] (Ch. Sai kiran), [email protected] (T. Khaitan), drpramaswamy@ rediffmail.com (P. Ramaswamy), [email protected] (S. Sudhakar), [email protected] (B. Smitha), uday2361@ gmail.com (G. Uday). Peer review under responsibility of Forensic Medicine Authority.
most precise technique for gender determination, but lack of facilities and the cost factor hindered its use in developing countries like India. This made the teeth and their odontometric analysis as the most steadfast method. Teeth are the hardest and chemically most stable tissues in the body which exhibit the least turnover of natural structure.2 They can be selectively preserved and fossilized, thereby providing the best evidence for evolutionary change. Their resilience in the case of fire and bacterial decomposition makes them important for identification in forensic science. Of all the teeth in the human dentition, the canines are the least frequently extracted teeth because of the relatively decreased incidence of caries and periodontal disease. Furthermore, canines are reported to withstand extreme conditions and have been
http://dx.doi.org/10.1016/j.ejfs.2014.05.003 2090-536X ª 2014 Hosting by Elsevier B.V. on behalf of Forensic Medicine Authority.
72
Ch. Sai kiran et al.
recovered from human remains even in air disasters and hurricanes.3 Males possess larger tooth crowns than females in contemporary human populations, which can be attributed to the longer period of amelogenesis for both deciduous and permanent dentitions.4 Bansal et al. considered mandibular canines as the key teeth for personal identification.5 Garn et al. and Nair et al. have found the mandibular canines to exhibit the greatest sexual dimorphism among all teeth.6,7 In light of above factors this study was aimed at measuring the maximum mesiodistal width of mandibular canines to establish their variation as a tool for gender determination. The present study also intended to determine the accuracy of measurements by clinical examination and on cast models. 2. Materials and methods The study was initiated after the protocol had been approved by the institutional committee of research ethics, and written informed consents were obtained from all the subjects. A total of 60 subjects reporting to the Department of Oral Medicine and Radiology in a dental school from south India were recruited for the study. The subjects enrolled in the study were in the age group of 15–34 years (30 males and 30 females). Subjects with healthy mandibular canines and periodontium were included in the study. Subjects with dental or occlusal abnormalities (rotation, crowding, occlusal disharmony, etc.), physiologic or pathologic wear and tear (e.g., attrition, abrasion, abfraction, erosion) and deleterious oral habits (like bruxism) were excluded from the study. The maximum mesiodistal widths of right and left mandibular canines were first measured intraorally and then on cast models of the same patients with the help of divider and digital vernier caliper (Hangzhou Maxwell tools Co. Ltd, Zhejiang, China) with an accuracy of ± 0.01 mm (Figures 1 and 2) as recommended by Moorrees and Reed.8 The measurements were performed by a single examiner and each measurement was taken thrice. The average of the three values was obtained to minimize the intra-observer error. The collected data were entered in a spreadsheet (Excel 2007, Microsoft office) and were analyzed using statistical analysis software (SPSS version 16.01, SPSS. Inc., Chicago, 1989–2007). T-test was done to compare the mean width of canines in males and females. A significance was set at 0.05 level (P < 0.05). Sexual dimorphism in right and left mandib-
Figure 1
Figure 2 Figure showing the recorded measurements using the vernier calipers.
ular canines was calculated using the formula given below by Garn and Lewis.6 Sexual dimorphism ¼
Xm 100 Xf 1
where Xm = Mean value of male canine width, Xf = Mean value of female canine width. 3. Results The mesiodistal widths of mandibular canines were measured for all subjects both clinically and on the prepared cast models of the same patients. The mean mesiodistal width of right and left mandibular canines is tabulated in Table 1. The mesiodistal width of mandibular canines determined by clinical examination was found to be in accordance with the measurements on plaster models (p > 0.05). Significant differences were not obtained between the mean values of mandibular canine widths on the right and left sides (p > 0.05). Interestingly, the right and left mean canine widths in males were significantly higher than females clinically and on the plaster models (Table 2).
Figures showing measurement of mandibular canine width clinically and on dental cast model.
Role of mandibular canines in establishment of gender Table 1
Mean width of canine clinically and on cast. N
Clinical width of canine on right (cm) Clinical width of canine on left (cm) Cast width of canine on right (cm) Cast width of canine on left (cm)
Table 2
60 60 60 60
95% CI Minimum
Maximum
Mean
Std. deviation
6.17 6.37 6.02 6.27
8.40 8.28 8.31 8.24
6.96 7.02 6.98 7.04
0.45 0.41 0.41 0.41
t-Test showing the mean width of canines in males and females.
Clinical width of canine on right Clinical width of canine on left Cast width of canine on right Cast width of canine on left *
73
Gender
N
Mean
Std. deviation
P values
Males Females Males Females Males Females Males Females
30 30 30 30 30 30 30 30
7.19 6.73 7.23 6.81 7.17 6.80 7.23 6.85
0.46 0.31 0.44 0.27 0.40 0.34 0.42 0.30
0.001* 0.001* 0.001* 0.001*
Significant P < 0.05.
Table 3
Sensitivity and specificity of the test. Right side
Sensitivity Specificity Positive predictive value Negative predictive value
Left side
Percentage
95% CI
Percentage
95% CI
66.67 76.67 74.07 69.70
47.19–82.69 57.71–90.02 53.71–88.84 51.29–84.38
70 80 77.78 72.73
50.60–85.24 61.42–92.24 57.73–91.32 54.47–86.67
The cutoff point for sex determination was calculated at 7.03 mm of canine width, above which was considered to be male and below which was considered to be female. The present study revealed a high sensitivity of 70% on the left side, 66.67% on the right side and a specificity of 80% on the left side and 76.67% on the right side, for sexual dimorphism using mandibular canine widths (Table 3). Moreover, the right mandibular canine showed a greater sexual dimorphism (6.84%) than the left mandibular canine (6.17%) clinically. 4. Discussion ‘‘Sexual dimorphism’’ refers to those differences in size, stature and appearance between male and female that can be applied to dental identification, because no two mouths (dentitions) are alike.9 The sexual dimorphism of canines is not merely a coincidence, but expected to be based on functional activity.10 Eimerl postulated that canines in primates were related to the threat of aggression which later shifted to the fingers in the evolutionary process. Until this evolutionary change, canines played an important role for survival in males.11 Hashim and Murshid found the highest sexual dimorphism in canines when compared with other teeth, but failed to
obtain a significant difference in canine widths between the right and left sides.12 Similar results were obtained in the present study. These results conclude that the measurements of one side could be representative when measurements of the other side were unobtainable in forensic cases. Statistically insignificant results were obtained between the measurements of canine width clinically and on plaster models. It indicates the use of cast models of canines as a valuable source for sex determination when all the necessary human forensic evidence was lost. This study confirmed statistically significant differences between males and females in mesiodistal widths of mandibular canines, which are in agreement with other studies.10 This significant sexual dimorphism in the tooth can be attributed to the presence of relatively more dentine in males when compared with females. Agnihotri and Sikri attributed the difference of mesiodistal widths between genders to the genetics, where Y chromosome controls the size of the teeth and X chromosome controls the thickness of the enamel.13 Interestingly, studies done by Acharya and Mainali and Karen et al. revealed a reverse dimorphism in the Nepalese population and the south Indian population, respectively, where the mean widths of canines were found to be larger in females than males. This could be attributed to the evolution-
74 ary process resulting in a reduction in sexual dimorphism in modern males and females.11,14 In the present study, a higher sexual dimorphism was found in the right canines (6.84%) when compared with the left canines (6.17%), which was in accordance with the study conducted by Vishwakarma and Guha.2 Kaushal et al.11 reported a greater sexual dimorphism for left canines (8.891%) when compared with right canines (7.954%). As sexual dimorphisms in tooth size are population specific, they may vary among different ethnic groups.6 The present study confirmed a significant sexual dimorphism in the mesiodistal diameter of mandibular canines, where males had larger tooth widths than females. The right mandibular canine was found to be more dimorphic than the left mandibular canine. This study also shed light upon the use of dental casts as a valuable forensic evidence for sex determination. Funding None. Conflict of interest None declared. Informed consent Consents were obtained from all the patients who were willing to participate in the study. Ethical approval The study has been approved by the Institute’s research ethics committee board.
Ch. Sai kiran et al. References 1. Yuwanati M, Karia A, Yuwanati M. Canine tooth dimorphism: an adjunct for establishing sex identity. J Forensic Dent Sci 2012;4:80–3. 2. Vishwakarma N, Guha R. A study of sexual dimorphism in permanent mandibular canines and its implications in forensic investigations. Nepal Med Coll J 2011;13(2):96–9. 3. Boaz K, Gupta C. Dimorphism in human maxillary and mandibular canines in establishment of gender. J Forensic Dent Sci 2009;1 (1). 4. Moss ML, Moss-Salentijlign L. Analysis of developmental processes possibly related to human dental sexual dimorphism in permanent and deciduous canines. Am J Phys Anthropol 1997;46:407–13. 5. Bansal P, Saxena S, Reddy V. Mandibular canine index as a sex determinant: a study on the population of western Uttar Pradesh. J Oral Maxillofac Pathol 2008 Jul;1(12):56–9. 6. Garn SM, Lewis AB, Swindler DR, Kerewsky RS. Genetic control of sexual dimorphism in tooth size. J Dent Res 1967;46(5):963–72. 7. Nair P, Rao BB, Annigeri RG. A study of tooth size, symmetry and sexual dimorphism. J Forensic Med Toxicol 1999;16:10–3. 8. Moorrees CF, Reed RB. Correlations among crown diameters of human teeth. Arch Oral Biol 1964;9:685–97. 9. Kiesu JA. Human adult odontometrics:the study of variation in adult tooth size. Cambridge:University Press; 1990. 10. Legovic M, Novosel A, Legovic A. Regression equations for determining mesiodistal crown diameters of canines and premolars. Angle Orthodontist 2003;73:314–8. 11. Kaushal S, Patnaik VV, Agnihotri G. Mandibular canine in sex determination. J Anat Soc India 2003;52:119–24. 12. Hashim HA, Murshid ZA. Mesiodistal tooth width – a comparison between Saudi males and females. Egypt Dent J 1993;39:343–6. 13. Agnihotri G, Sikri V. Crown and cusp dimensions of the maxillary first molar: a study of sexual dimorphism in Indian Jat Sikhs. Dent Anthropol 2010;21(1):1–6. 14. Acharya A, Mainali S. Univariate sex dimorphism in the Nepalese dentition and the use of discriminant functions in gender assessment. Forensic Sci Int 2007;173:47–56.
H O S T E D BY
Contents lists available at ScienceDirect
Egyptian Journal of Forensic Sciences journal homepage: www.ejfs.org
ORIGINAL ARTICLE
Role of mandibular canines in establishment of gender Ch. Sai kiran *, Tanya Khaitan, P. Ramaswamy, S. Sudhakar, B. Smitha, G. Uday Department of Oral Medicine and Radiology, St. Joseph Dental College, Eluru, 534003, India Received 27 January 2014; revised 9 May 2014; accepted 13 May 2014 Available online 18 June 2014
KEYWORDS Sex dimorphism; Canine tooth; Forensic sciences; Dental models; Personal identification
Abstract Objective: The objective of this study was to determine the maximum mesiodistal width of mandibular canines for establishing their variation as a tool to determine gender and to determine the accuracy of the measurements through clinical examination and dental cast models. Study design: A total of 60 subjects (30 males and 30 females) in the age group of 15–34 years were selected for the study. The maximum mesiodistal widths of the right and left mandibular canines were first measured intraorally and then on cast models of the same patients with the help of a divider and a digital vernier caliper. The collected data were subjected to statistical analysis and sexual dimorphism was calculated. Results: The mesiodistal width of the mandibular canines as determined by clinical examination and on plaster models was statistically insignificant. The mean canine widths were found to be higher in males when compared with females. The right mandibular canine showed a greater sexual dimorphism than the left mandibular canine. Conclusion: The present study established the mandibular canine as a valuable tool for sex determination. ª 2014 Hosting by Elsevier B.V. on behalf of Forensic Medicine Authority.
1. Introduction Sex determination with the aid of skeletal remains poses a great dilemma to forensic experts, particularly when only a part of the body is endured.1 DNA analysis is considered the
* Corresponding author. Tel.: +91 9491113193. E-mail addresses: [email protected] (Ch. Sai kiran), [email protected] (T. Khaitan), drpramaswamy@ rediffmail.com (P. Ramaswamy), [email protected] (S. Sudhakar), [email protected] (B. Smitha), uday2361@ gmail.com (G. Uday). Peer review under responsibility of Forensic Medicine Authority.
most precise technique for gender determination, but lack of facilities and the cost factor hindered its use in developing countries like India. This made the teeth and their odontometric analysis as the most steadfast method. Teeth are the hardest and chemically most stable tissues in the body which exhibit the least turnover of natural structure.2 They can be selectively preserved and fossilized, thereby providing the best evidence for evolutionary change. Their resilience in the case of fire and bacterial decomposition makes them important for identification in forensic science. Of all the teeth in the human dentition, the canines are the least frequently extracted teeth because of the relatively decreased incidence of caries and periodontal disease. Furthermore, canines are reported to withstand extreme conditions and have been
http://dx.doi.org/10.1016/j.ejfs.2014.05.003 2090-536X ª 2014 Hosting by Elsevier B.V. on behalf of Forensic Medicine Authority.
72
Ch. Sai kiran et al.
recovered from human remains even in air disasters and hurricanes.3 Males possess larger tooth crowns than females in contemporary human populations, which can be attributed to the longer period of amelogenesis for both deciduous and permanent dentitions.4 Bansal et al. considered mandibular canines as the key teeth for personal identification.5 Garn et al. and Nair et al. have found the mandibular canines to exhibit the greatest sexual dimorphism among all teeth.6,7 In light of above factors this study was aimed at measuring the maximum mesiodistal width of mandibular canines to establish their variation as a tool for gender determination. The present study also intended to determine the accuracy of measurements by clinical examination and on cast models. 2. Materials and methods The study was initiated after the protocol had been approved by the institutional committee of research ethics, and written informed consents were obtained from all the subjects. A total of 60 subjects reporting to the Department of Oral Medicine and Radiology in a dental school from south India were recruited for the study. The subjects enrolled in the study were in the age group of 15–34 years (30 males and 30 females). Subjects with healthy mandibular canines and periodontium were included in the study. Subjects with dental or occlusal abnormalities (rotation, crowding, occlusal disharmony, etc.), physiologic or pathologic wear and tear (e.g., attrition, abrasion, abfraction, erosion) and deleterious oral habits (like bruxism) were excluded from the study. The maximum mesiodistal widths of right and left mandibular canines were first measured intraorally and then on cast models of the same patients with the help of divider and digital vernier caliper (Hangzhou Maxwell tools Co. Ltd, Zhejiang, China) with an accuracy of ± 0.01 mm (Figures 1 and 2) as recommended by Moorrees and Reed.8 The measurements were performed by a single examiner and each measurement was taken thrice. The average of the three values was obtained to minimize the intra-observer error. The collected data were entered in a spreadsheet (Excel 2007, Microsoft office) and were analyzed using statistical analysis software (SPSS version 16.01, SPSS. Inc., Chicago, 1989–2007). T-test was done to compare the mean width of canines in males and females. A significance was set at 0.05 level (P < 0.05). Sexual dimorphism in right and left mandib-
Figure 1
Figure 2 Figure showing the recorded measurements using the vernier calipers.
ular canines was calculated using the formula given below by Garn and Lewis.6 Sexual dimorphism ¼
Xm 100 Xf 1
where Xm = Mean value of male canine width, Xf = Mean value of female canine width. 3. Results The mesiodistal widths of mandibular canines were measured for all subjects both clinically and on the prepared cast models of the same patients. The mean mesiodistal width of right and left mandibular canines is tabulated in Table 1. The mesiodistal width of mandibular canines determined by clinical examination was found to be in accordance with the measurements on plaster models (p > 0.05). Significant differences were not obtained between the mean values of mandibular canine widths on the right and left sides (p > 0.05). Interestingly, the right and left mean canine widths in males were significantly higher than females clinically and on the plaster models (Table 2).
Figures showing measurement of mandibular canine width clinically and on dental cast model.
Role of mandibular canines in establishment of gender Table 1
Mean width of canine clinically and on cast. N
Clinical width of canine on right (cm) Clinical width of canine on left (cm) Cast width of canine on right (cm) Cast width of canine on left (cm)
Table 2
60 60 60 60
95% CI Minimum
Maximum
Mean
Std. deviation
6.17 6.37 6.02 6.27
8.40 8.28 8.31 8.24
6.96 7.02 6.98 7.04
0.45 0.41 0.41 0.41
t-Test showing the mean width of canines in males and females.
Clinical width of canine on right Clinical width of canine on left Cast width of canine on right Cast width of canine on left *
73
Gender
N
Mean
Std. deviation
P values
Males Females Males Females Males Females Males Females
30 30 30 30 30 30 30 30
7.19 6.73 7.23 6.81 7.17 6.80 7.23 6.85
0.46 0.31 0.44 0.27 0.40 0.34 0.42 0.30
0.001* 0.001* 0.001* 0.001*
Significant P < 0.05.
Table 3
Sensitivity and specificity of the test. Right side
Sensitivity Specificity Positive predictive value Negative predictive value
Left side
Percentage
95% CI
Percentage
95% CI
66.67 76.67 74.07 69.70
47.19–82.69 57.71–90.02 53.71–88.84 51.29–84.38
70 80 77.78 72.73
50.60–85.24 61.42–92.24 57.73–91.32 54.47–86.67
The cutoff point for sex determination was calculated at 7.03 mm of canine width, above which was considered to be male and below which was considered to be female. The present study revealed a high sensitivity of 70% on the left side, 66.67% on the right side and a specificity of 80% on the left side and 76.67% on the right side, for sexual dimorphism using mandibular canine widths (Table 3). Moreover, the right mandibular canine showed a greater sexual dimorphism (6.84%) than the left mandibular canine (6.17%) clinically. 4. Discussion ‘‘Sexual dimorphism’’ refers to those differences in size, stature and appearance between male and female that can be applied to dental identification, because no two mouths (dentitions) are alike.9 The sexual dimorphism of canines is not merely a coincidence, but expected to be based on functional activity.10 Eimerl postulated that canines in primates were related to the threat of aggression which later shifted to the fingers in the evolutionary process. Until this evolutionary change, canines played an important role for survival in males.11 Hashim and Murshid found the highest sexual dimorphism in canines when compared with other teeth, but failed to
obtain a significant difference in canine widths between the right and left sides.12 Similar results were obtained in the present study. These results conclude that the measurements of one side could be representative when measurements of the other side were unobtainable in forensic cases. Statistically insignificant results were obtained between the measurements of canine width clinically and on plaster models. It indicates the use of cast models of canines as a valuable source for sex determination when all the necessary human forensic evidence was lost. This study confirmed statistically significant differences between males and females in mesiodistal widths of mandibular canines, which are in agreement with other studies.10 This significant sexual dimorphism in the tooth can be attributed to the presence of relatively more dentine in males when compared with females. Agnihotri and Sikri attributed the difference of mesiodistal widths between genders to the genetics, where Y chromosome controls the size of the teeth and X chromosome controls the thickness of the enamel.13 Interestingly, studies done by Acharya and Mainali and Karen et al. revealed a reverse dimorphism in the Nepalese population and the south Indian population, respectively, where the mean widths of canines were found to be larger in females than males. This could be attributed to the evolution-
74 ary process resulting in a reduction in sexual dimorphism in modern males and females.11,14 In the present study, a higher sexual dimorphism was found in the right canines (6.84%) when compared with the left canines (6.17%), which was in accordance with the study conducted by Vishwakarma and Guha.2 Kaushal et al.11 reported a greater sexual dimorphism for left canines (8.891%) when compared with right canines (7.954%). As sexual dimorphisms in tooth size are population specific, they may vary among different ethnic groups.6 The present study confirmed a significant sexual dimorphism in the mesiodistal diameter of mandibular canines, where males had larger tooth widths than females. The right mandibular canine was found to be more dimorphic than the left mandibular canine. This study also shed light upon the use of dental casts as a valuable forensic evidence for sex determination. Funding None. Conflict of interest None declared. Informed consent Consents were obtained from all the patients who were willing to participate in the study. Ethical approval The study has been approved by the Institute’s research ethics committee board.
Ch. Sai kiran et al. References 1. Yuwanati M, Karia A, Yuwanati M. Canine tooth dimorphism: an adjunct for establishing sex identity. J Forensic Dent Sci 2012;4:80–3. 2. Vishwakarma N, Guha R. A study of sexual dimorphism in permanent mandibular canines and its implications in forensic investigations. Nepal Med Coll J 2011;13(2):96–9. 3. Boaz K, Gupta C. Dimorphism in human maxillary and mandibular canines in establishment of gender. J Forensic Dent Sci 2009;1 (1). 4. Moss ML, Moss-Salentijlign L. Analysis of developmental processes possibly related to human dental sexual dimorphism in permanent and deciduous canines. Am J Phys Anthropol 1997;46:407–13. 5. Bansal P, Saxena S, Reddy V. Mandibular canine index as a sex determinant: a study on the population of western Uttar Pradesh. J Oral Maxillofac Pathol 2008 Jul;1(12):56–9. 6. Garn SM, Lewis AB, Swindler DR, Kerewsky RS. Genetic control of sexual dimorphism in tooth size. J Dent Res 1967;46(5):963–72. 7. Nair P, Rao BB, Annigeri RG. A study of tooth size, symmetry and sexual dimorphism. J Forensic Med Toxicol 1999;16:10–3. 8. Moorrees CF, Reed RB. Correlations among crown diameters of human teeth. Arch Oral Biol 1964;9:685–97. 9. Kiesu JA. Human adult odontometrics:the study of variation in adult tooth size. Cambridge:University Press; 1990. 10. Legovic M, Novosel A, Legovic A. Regression equations for determining mesiodistal crown diameters of canines and premolars. Angle Orthodontist 2003;73:314–8. 11. Kaushal S, Patnaik VV, Agnihotri G. Mandibular canine in sex determination. J Anat Soc India 2003;52:119–24. 12. Hashim HA, Murshid ZA. Mesiodistal tooth width – a comparison between Saudi males and females. Egypt Dent J 1993;39:343–6. 13. Agnihotri G, Sikri V. Crown and cusp dimensions of the maxillary first molar: a study of sexual dimorphism in Indian Jat Sikhs. Dent Anthropol 2010;21(1):1–6. 14. Acharya A, Mainali S. Univariate sex dimorphism in the Nepalese dentition and the use of discriminant functions in gender assessment. Forensic Sci Int 2007;173:47–56.