10.59987/ads/2015.2.43-46
Context. Assessment of sex has significant contribution in construction of a physical profile of the decedent along with other parameters like race, stature and age. Sex determination with aid of skeletal remains is difficult procedure when, only a part of the body is obtainable. To solve this difficulty, tooth size standards based on odontometric data can be used in age and sex determination. The present study was undertaken with the objective to evaluate the reliability of sex determination using discriminant canine index (DCI).
Methods. A total of 120 subjects, with healthy periodontium and between the age groups of 15 to 40 years were selected randomly. Subjects with hard tissue abnormalities were excluded from the study. The maximum mesiodistal widths of left mandibular canines were measured intraorally with the help of divider and digital vernier caliper. Data was collected and analyzed statistically.
Results. A significant increase in the mesiodistal width of canines in males (7.21 ± 0.45 mm) when compared to females (6.77 ± 0.29 mm) was observed. The discriminant canine index (DCI) has identified 68.3% of males and 76.7% of females correctly with an overall accuracy rate of 72.5%. Conclusion. The present study indicated that the DCI can produce reliable results and can be used as an alternative for mandibular canine index (MCI), for sex determination.
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Annali di stomatologia
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Discriminant canine index – a novel approach in sex determination
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Discriminant canine index – a novel approach in sex determination
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                                                                                                   Original article



    Discriminant canine index – a novel approach in sex
    determination




                                                                                                     i
                                                                                                   al
                                                                                                on
    Chennoju Sai Kiran, MDS                                  Introduction
    Pachigolla Ramaswamy, MDS
    Erva Swathi, MDS                                         The four leading features of biological identity are
    Balla Smitha, MDS                                        sex, age, stature, and ancestry background. The
    Shankaran Sudhakar, MDS                                  forensic anthropologists wish to authenticate these




                                                                                       zi
                                                             traits for an individual from their skeletal remains. As-
    Department of Oral medicine and Radiology, St.           sessment of sex has significant contribution in con-
    Joseph Dental College, Eluru, India                      struction of a physical profile of the decedent along




                                                                          na
                                                             with other parameters like race, stature and age.
                                                             Sex can be assessed with high precision using pelvic
    Corresponding author:                                    and cranial bones. But the demerit of using these
    Chennoju Sai Kiran                                       bones is that they easily get fragmented which may be
    Department of Oral medicine and Radiology, St.




                                                               er
                                                             major hindrance for assessment of sex. The dentition is
    Joseph Dental College                                    considered as an useful adjunct in skeletal sex estima-
    Duggirala                                                tion, particularly since teeth are resistant to postmortem
    534001 Eluru, India                                      destruction and fragmentation (1). Teeth are the first-
    E-mail: iamchennojukiran@gmail.com


                                                       t     rate material for genetic and forensic investigations.
                                                    In       Teeth show signs of changes in morphology and they
                                                             are easily accessible for examination. It is the hardest
    Summary                                                  and chemically most stable structure in the body. They
                                                             are selectively preserved and fossilized, thereby provid-
    Context. Assessment of sex has significant contri-       ing the best proof for evolutionary alteration. Their re-
                                                 ni
    bution in construction of a physical profile of the      silience in the case of fire and bacterial decomposition
    decedent along with other parameters like race,          makes them important for identification in forensic sci-
    stature and age. Sex determination with aid of           ence. Sex determination with aid of skeletal remains is
                                    io

    skeletal remains is difficult procedure when, only       difficult procedure when, only a part of the body is ob-
    a part of the body is obtainable. To solve this diffi-   tainable. To solve this difficulty, tooth size standards
    culty, tooth size standards based on odontometric        based on odontometric data can be used in age and
    data can be used in age and sex determination.           sex determination (2).
                           iz



    The present study was undertaken with the objec-         “Sexual Dimorphism” refers to differences in size and
    tive to evaluate the reliability of sex determination    form between males and females that can be applied
    using discriminant canine index (DCI).                   to dental identification. In contemporary human popu-
          Ed




    Methods. A total of 120 subjects, with healthy peri-     lations, males have larger tooth crowns than females.
    odontium and between the age groups of 15 to 40          Consequently, tooth size standards based on odonto-
    years were selected randomly. Subjects with hard         metric investigations could be a reliable method in
    tissue abnormalities were excluded from the study.       sex determination when limited skeletal remnants are
    The maximum mesiodistal widths of left mandibular        recovered (3).
    canines were measured intraorally with the help of       Sex determination using dental features is primarily
IC




    divider and digital vernier caliper. Data was collect-   based upon the comparison of tooth dimensions in
    ed and analyzed statistically.                           males and females, or upon the comparison of fre-
    Results. A significant increase in the mesiodistal       quencies of nonmetric dental traits, like Carabelli’s
    width of canines in males (7.21 ± 0.45 mm) when          trait of upper molars. Mesiodistal and buccolingual di-
C




    compared to females (6.77 ± 0.29 mm) was ob-             ameters of the permanent tooth crown are the two
    served. The discriminant canine index (DCI) has          most commonly used and studied features in deter-
    identified 68.3% of males and 76.7% of females           mining sex on the basis of dental measurements (4).
    correctly with an overall accuracy rate of 72.5%.        Tooth sexual dimorphism is often related to body
    Conclusion. The present study indicated that the
©




                                                             size. In living people today, body size dimorphism av-
    DCI can produce reliable results and can be used         erages 10%. Human dental dimorphism is on the or-
    as an alternative for mandibular canine index            der of 2-6%. Canines vary from other teeth with re-
    (MCI), for sex determination.                            spect to survival and sex dichotomy (1). Of all the
                                                             teeth in the human dentition, canines are the least
    Key words: canine tooth, forensic sciences, sex di-      frequently extracted teeth (possibly because of the
    morphism, personal identification, gender identity.      relatively decreased incidence of caries and peri-

    Annali di Stomatologia 2015; VI (2): 43-46                                                                      43
    Chennoju Sai Kiran et al.


    odontal disease). Mandibular canines are considered              ±0.01 mm (Fig. 1). The measurements were per-
    to be the key teeth for sexual dimorphism. Also, ca-             formed by a single experienced examiner after nec-
    nines are reported to withstand extreme conditions               essary training. 30 patients were re-evaluated and
    and have been recovered from human remains even                  the measurements were repeated to determine the
    in air disasters and hurricanes (5).                             intraobserver error. The collected data was entered in




                                                                                                                i
    Many studies were reported in the literature where               a spreadsheet (Excel 2007, Microsoft office) and was




                                                                                                              al
    mandibular canine index (MCI) was used for sex de-               analyzed using statistical analysis software (SPSS
    termination. But very few studies were reported                  version 16.01, SPSS.inc, Chicago, 1989-2007). Sig-
    where discriminant analysis was used for gender dif-             nificance was set at 0.05 level (P<0.05). The mean




                                                                                                           on
    ferentiation. Hence the present study was undertaken             mesiodistal widths of canine were compared in males
    with the objective to evaluate the reliability of sex de-        and females using t-test. Discriminant equation was
    termination using discriminant canine index (DCI).               derived with gender as a classifying variable and
                                                                     mesiodistal widths as independent variables.




                                                                                                 zi
    Materials and methods
                                                                     Results
    A cross sectional study was planned after the proto-




                                                                                   na
    col was approved by the institutional committee of re-           A total of 120 individuals were studied (60 males and
    search ethics. A total of 120 living subjects were ran-          60 females) with an age range of 15 to 36 years. The
    domly selected comprising of 60 males and 60 fe-                 measurements were made by an experienced oral
    males between the age groups of 15 to 40 years.                  physician with necessary training. The reproducibility




                                                                       er
    Subjects with healthy periodontium with no evidence              of the measurements was tested by re-evaluating a
    of previous orthodontic treatment were included for              subset of 30 patients after a period of 3 weeks. The
    the study. Subjects with dental or occlusal abnormali-           Cohen’s kappa value obtained from the analysis was
    ties (rotation, crowding, occlusal disharmony, etc.),            0.87 which was interpreted to be in almost perfect
    physiologic or pathologic wear and tear (e.g. attrition,


                                                            t        agreement with the previous measurements.
    abrasion, abfraction, erosion) and deleterious oral
    habits (like bruxism) were excluded for the study.
                                                         In          Measurements included the mesiodistal widths of the
                                                                     left canines at their maximum diameter. The t-test re-
    The maximum mesiodistal widths of left mandibular                vealed a significant increase in the mesiodistal width
    canines were measured intraorally with the help of di-           of canines in males (7.21 ± 0.45 mm) when compared
    vider and digital vernier caliper (Hangzhou Maxwell              to females (6.77 ± 0.29 mm). The Wilks’ lambda val-
                                            ni
    tools Co. Ltd, Zhejiang, China) with an accuracy of              ue obtained in the study was 0.74 (Tab. 1).
                                                                     The given data were subjected to discriminant analy-
                                                                     sis using gender as a grouping variable and width of
                                  io

                                                                     left mandibular canine as an independent variable.
                                                                     The final equation obtained was: DCI = (-18.656) +
                                                                     (2.668 X D), where DCI is discriminant canine index
                                                                     and “D” is mesiodistal width of mandibular canine. A
                        iz



                                                                     greater DCI value (DCI > 0) indicates male gender,
                                                                     while a lesser DCI value (DCI < 0) indicates the prob-
                                                                     ability of female gender. In the present study the dis-
         Ed




    Figure 1. Figure showing measurement of left mandibular          criminant canine index (DCI) has identified 68.3% of
    canine width clinically. The armamentarium includes di-          males and 76.7% of females correctly with an overall
    vider and vernier callipers.                                     accuracy rate of 72.5% (Tab. 2).


    Table 1. Mean measurements of canine in males and females.
IC




                                  Gender             N        Mean        Std.           Std.              Wilks’         p-value
                                  of the patient                          Deviation      Error Mean        Lambda
    Clinical measurement          Males              60       7.21        0.45           0.06              0.74           0.001
C




    of canine
                                  Females            60       6.77        0.29           0.04


    Table 2. Measurement of accuracy of the study.
©




                                                                                   Gender of the patient
    Percentage of accurate prediction                    Females                 Males                Total
                                                         76.7%                   68.3%                72.5%
    Function at group centroids                          -0.588                  0.588                Classified as male if D >0
                                                                                                      Classified as female if D <0


    44                                                                                    Annali di Stomatologia 2015; VI (2): 43-46
    Discriminant canine index – a novel approach in sex determination


    Discussion                                                    canine index, when compared to the present study
                                                                  (12, 13). But our results strictly support the use of
    Teeth are the finest human remains that can be pre-           DCI over MCI for better and reliable results. This can
    served for a longer period of time. Although many ac-         be attributed to the fact that MCI is a relative value
    curate techniques (DNA analysis) are available for            obtained from the ratio of mesiodistal width of canine




                                                                                                               i
    sex determination, lack of facilities and cost factor be-     and inter - canine arch width, while DCI is an ab-




                                                                                                             al
    come sabotage for their usage in developing coun-             solute measurement. Acharya et al. has explained
    tries like India. In such conditions teeth provide an         this with an excellent example in his article, where he
    excellent source, as they are easily available, robust        considered a male canine with 8 mm of mesiodistal




                                                                                                          on
    in extreme environments and the procedure of sex              width and 32 mm of inter-canine arch width, and a fe-
    determination is simple and economical.                       male canine with 6 mm of mesiodistal width and 24
    Odontometrics is the study of tooth measurements              mm of inter-canine arch width. Though the male di-
    which play a crucial role in anthropology as they were        mensions were 33.33% larger than the female, MCI
                                                                  was interestingly the same in both the genders (8/32




                                                                                                zi
    known to show significant dimorphism in gender. Ca-
    nines were observed to show higher sexual dimor-              = 6/24 =0.25) (10). Hence the degree of dimorphism
    phism among all teeth. This can be attributed to many         also depends on the influence of parameters
                                                                  (mesiodistal width and inter canine arch width) over




                                                                                na
    factors which include:
    a) Influence of environmental factors and eating              one another in MCI. Therefore DCI has a definite ad-
        habits (6).                                               vantage over MCI in sex determination.
    b) Evolutionary differences in the size of canines in         The degree of sexual dimorphism in a given population
        males and females where the size of canines were          varies according to their evolutionary change, genetic




                                                                    er
        related to threat of aggression in primates (7).          factors and ethnic background (1). Schield et al. ob-
    c) Genetic influence of Y chromosome in determina-            served higher sexual dimorphism in Ohio Caucasians
        tion of size of the canine (8).                           and Australian aborigines than pima Indians and tris-
    d) Influence of steroid hormones on tooth size and            tanite populations (14). Interestingly Acharya et al.
        shape (9).

                                                          t       found reverse sexual dimorphism (females showed
    Khangura has conducted a study among 100 dental
                                                       In         larger teeth compared to males) in Nepalese population
    students (50 males and 50 females). He found signifi-         (15). These results conclude that individual discriminant
    cant difference in the mesiodistal diameters of left and      analysis should be done based on the ethnic origin and
    right canines in males. He also found higher sexual di-       separate discriminant equations must be derived for
    morphism in left side canines than right side (4). Simi-      better and accurate sex determination.
                                                 ni
    lar results were also reported by Ayoub et al. and            Forensic odontology is an emerging field in countries
    Kapila et al. (3, 5). Hence we included only left             like India. Hence a comprehensive database must be
    mandibular canines in order to eliminate discrepancy          established using all the possible morphometric
                                    io


    of canine measurements based on sides and to obtain           measurements of tooth and their accuracy or varia-
    the highest sexual dimorphism possible in the study.          tions in degree of sex determination must be ana-
    Mandibular canine index (MCI) is a regularly used             lyzed. The present study indicated that the DCI can
                           iz



    method for determining sex using canine teeth. But            produce reliable results and can be used as an ad-
    Acharya et al. suggested that MCI has insignificant           junct tool along with other accepted procedures for
    use in sex determination and its application has to be        sex determination.
          Ed




    restricted or discontinued in forensic and anthropo-
    logical sex predictions (10). Sherfudhin et al. com-
    pared MCI with DCI in his study, and concluded, DCI           References
    to be a better indicator for sex determination (11).
    Hence we confined our study to discriminant analysis           1. Hosmani JV, Nayak RS, Kotrashetti VS, Pradeep S, Babji
                                                                      D. Reliability of Mandibular Canines as Indicators for Sex-
    for obtaining better results.
                                                                      ual Dichotomy. J Int Oral Health. 2013 Feb;5(1):1-7.
IC




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                                                                   2. Yuwanati M, Karia A, Yuwanati M. Canine tooth dimorphism:
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                                                                                                                   on
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          (1):e1-4.                                                              Nepalese dentition and the use of discriminant functions in
    11.   Sherfudhin H, Abdullah MA, Khan N. A cross-sectional study             gender assessment. Forensic Sci Int. 2007;173:47-56.




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