MORPHOLOGICAL CHARACTERISTICS OF AURICULA IN CHILDREN FROM KYUSTENDIL REGION (SOUTHWEST BULGARIA)

The shape of human auricula is characterized by specific features. The diversity of these individual characteristics can be used in forensic identification of individuals. Inter and intrapopulation variability in the shape of auricula is not thoroughly investigated neither in Bulgaria, nor worldwide. The present study was conducted in the town of Kyustendil (Southwest Bulgaria). The examined sample comprised 240 individuals of both sexes 120 school boys and 120 school girls (11 to 18 years of age). The shape of auricula and the absence/presence of tuberculum auriculae Darwini were defined by the scale of Schwalbe-Martin and Saller (1959). The most common form of both ears in the examined group is form 6 (60.00%) followed by form 3 with 20.83%. When an additional tuberculum Darwini was present, it was mostly asymmetrically positioned in both sexes. High percentage of individuals with ears positioned in a greater distance from the surface of the head was also established. Within the examined male group, 20.83% had prominent ears, the percentage was higher in comparison with the females, where the percentage was 1.66 % lower than in males.


Introduction
The construction of human auricula is characterized by specific features.The diversity of these individual characteristics gives us the possibility of using them in forensics for identification of individuals (Kapil et al., 2014).More detailed anthropological study of the morphology and size of auricula can lead to a more complete description of human population and represents a valuable source of information in aesthetic surgery (Brucker et al., 2003), especially for the removal of the consequences of traumatic injuries (Azaria et. al., 2003, Kollali 2009).In this field of medicine these qualitative and quantitative traits and their normal variations are widely used.Although studies based on the variability of the auricular dimensions have been performed during the last decades, inter-and intrapopulation variability of the descriptive auricular shape is poorly studied not only in Bulgaria, but also worldwide.On the Balkan Peninsula V. Bozic-Krstic (1991) examined students from Vojvodina and established the frequencies of different types of lobulus auriculae.Brodar, Bögel (1971) tracked down the relationships of the same traits between twins and their parents.In Bulgaria Todorov, Gavrilovič (1990) examined the Bulgarian population in connection with the presence of Darwin's tubercle (tuberculum auriculae Darwini) without specifying the study area.Although protruding ears are among the most common congenital deformities in craniofacial area, clear consensus in literature in terms of their determination is still absent (Driessen et al., 2011).
The purpose of this study was to determine the frequency of the auricular shapes and the tuberculum auriculae Darwini in teenagers from Kyustendil region.

Material and methods
The survey was performed in the area of Kyustendil town.The sample comprised 240 individuals of both genders -120 school boys and 120 school girls (11 to 18 years of age).The shape of auricula and the absence or presence of tuberculum auriculae Darwini, have been determined macroscopically according to the descriptive scale for auricular forms of Schwalbe cited by Martin, Saller (1957) (Fig. 1).Differences between the characters' occurrence frequencies have been estimated by means of Chi square and PAST software (Hammer et al., 2001).

Results
When comparing both auriculae according to their form (table 1), the percentage of forms 3 and 4 in girls is higher on the right auricle (18.33% and 9.17% respectively) in comparison with the left (15.00% and 8.33% respectively).Reverse pattern is observed in the case of males, where the percentage of these forms is higher on the left auricle (20.83% and 9.17% respectively), than the one on the right (15.83% and 6.67% respectively).In the case of form 5 gender differences are insignificant.Form 6 of the left auricula is, on average, equally present in both girls (60.8%) and boys (60.00%) while the same form of the right auricula shows different percentage with respect to gender (57.50% in girlsand 65.00% in boys).Form 1 is rarely observed, whereas form 2 is lacking.The most common form for both ears in the examined sample appears to be form 6 (60.00%), followed by form 3 (20.83%)(Fig. 2).In view of the symmetry of forms in both genders (when concrete form is present in both ears) forms 4, 5 and 6 showed small percentage in terms of differences (table 2).The greatest difference according to gender in terms of the symmetry of forms is observed in form 3 (4.16%intergender difference).Most symmetrical among the examined teenagers is form 6 (50% girls and 54.17% boys from the total sample).There have not been observed individuals with two tuberkuli on both ears.
From tables 2 and 3 it can be concluded, that the presence of an additional tuberculum Darwini, is generally characterized by an asymmetrical position in both sexes.The most common combinations of forms in both genders are 3/5 (6.67%) and 5/6 (7.92%), referred to the total studied number.All possible combinations of forms for both ears have been established, but with no significantly great gender differences.
The sample is characterized by higher percentage of symmetry of the auricular shapes in both sexes, with a higher and statistically significant rate of symmetry in boys (76.67) in comparison with girls (71.67%) (Table 3).(Chi-square value=65.2465,P value=0).
Tabela 3. Asymmetry and symmetry of auricular forms in both genders in the studied sample from Kyustendil region.The dominance of auricular non-tubercular forms (1 + 6) is well illustrated (table 4).The frequency of form 1 has an extremely low rate and only in males (table 1).Form 6 is present in the majority of the surveyed individuals.

Gender
In view to the presence of tuberculum Darwini there has been established small difference between the percentages of both genders in the examined population (table 4).Nevertheless, this difference is statistically significant, as Chi square=36.4568,p=0.Individuals with protruding auriculae have also been established (table 5)."Protruding ears" were found in 20.83% of the male representatives, the percentage was higher than the one established in the female group, where it was 1.66 lower.This difference is not significant, as Chi-square=0.18,P value=0.67136.When this feature is unilateral, the trait is more present in the left ear of both sexes (5.83% in girls, 9.17% in boys).

Discussion
Form 6 is most frequent among the established auricular forms.Intersexual differences have been noticed regarding the bilateral auricular form symmetry and presence of tuberculum auriculae Darwini only.
If we compare our data on intersexual frequencies of tuberculum Darwini with those of Todorov, Gavrilovič (1990) (men -47.44% and women -47.39% respectively), it can be concluded that we found slightly greater intersexual difference, but nevertheless significant.
Greater auricular distance from the scull ("protruding ears") is the most common congenital malformation.Moreover, many authors have reported significant intergender differences regarding this feature (Driessen et al., 2011).Our observed insignificant differences concerning this trait do not confirm this hypothesis.Furthermore, males have generally bigger ears than females (Healthcote 1995) and ear dimensions change through the process of growth (Meijerman et al., 2007), but ear form does not.In fact, according to the method of Martin-Saller descriptive auricular shape is not extensively investigated worldwide.More information has to be accumulated in order to track down a clearer tendency.During the last decades studies on the auricular shape have been performed, but they mainly concern the variability of measured dimensions (Kapil et al., 2014) or lobe conjugation, but not the auricular descriptive traits, although their frequencies also represent important characteristics for population distinction.The results obtained from the survey of high school students from Kyustendil region can greatly contribute to the population anthropology, for characterization of the studied and other populations, especially having in mind the scantiness of data on the subject.

Figure 2 .
Figure 2. Frequency of various forms of auricula dextra and sinistra in both sexes in the examined sample from Kyustendil town.

Table 1 .
Auricular forms frequencies in both ears and both genders in the studied sample from Kyustendil region.

Table 2 .
Symmetry of auricular forms in both genders in the studied sample from Kyustendil region.

Table 4 .
Occurrence frequency of tuberculum auriculae Darwini in both sexes in the studied sample from Kyustendil region.

Table 5 .
Occurrence frequency of "protruding ears" in both sexes in the studied sample from Kyustendil region.