The present study was a retrospective type of study which was conducted on a group of 300 children of 10-15 years age group from both sexes who had attended the outpatient Department of Pedodontics and Preventive Dentistry, St. Joseph Dental College and Hospital, Eluru with good general health and no systemic illness or hospitalization. The study was conducted for a time period of six months. The Guardian/the Parents of the participants signed individual informed consent forms containing information about the aim of the study and the study procedures. The study was approved by the Ethical Committee of the Institution. Children with no systemic illness, healthy normal children with no physical or mental disability, children of age group–10 to15 years were included in the study and children with injuries or deformities of the hands, children with long-standing systemic illness, children who were on any medication within the past two months, children with physical or mental disability, children whose parents did not give consent were excluded from the study.

[Table/Fig-1]:

Illustration of three possible 2D:4D ratio outcomes [7].

[Table/Fig-2]:

Measurement of 2D:4D ratio.

The length of the Index (2D) and Ring (4D) fingers were measured for all the children from the ventral proximal crease of the digit to the tip. In the case there were multiple creases at the base of the digit, measurement taken from the most proximal of these creases with the help of digital Vernier’s caliper.

Calculation of Body Mass Index: Height and weight were measured for all those who are enrolled in the study. The weight of each child was measured in standing posture with equal distribution of mass between feet, to the nearest 0.1 kg using a Krups Imperial analogue weighing scale which was calibrated before use. Each child was instructed to stand still, with mass equally distributed between feet, until the scale reading stabilized. The reading was then recorded. Height was measured to the nearest 0.1cm using a stature meter attached to the wall in the department. For the calculation of BMI, the following formula was used.

BMI = Weight in kg/ height in m²

From the values obtained children were categorized as,

Underweight = <18.5

Normal weight = 18.5–24.9

Overweight = 25–29.9

Obesity = BMI of 30 or greater

Clinical Examination: Caries status (deft and DMFT) was recorded based on WHO standard criteria mentioned in the WHO oral health proforma, 1997 [8]. Two trained and calibrated examiners performed comprehensive clinical examination with the assistance of one recorder. The values of one investigator were cross examined by other investigator. Children were made to sit on the dental chair and examination was conducted under light attached to the dental chair. Sterile mouth mirrors, Community Periodontal Index (CPI) ballpoint probes. Caries was recorded as present when a lesion in a pit and a fissure or on a smooth surface had cavity with undermined enamel or smooth surface which may be arrested or active lesion. Recordings of the data were noted by a trained assistant. The occlusal characteristics including molar relation, anterior and posterior cross bite, open bite, deep bite, lower anterior crowding were also recorded.

All the data were tabulated and subjected to statistical analysis. Pearson’s correlation test, t-test and Chi-Square test were used for analysing the data in SPSS software.

The entire study population was divided into children with 2D:4D ratio less than 1 and ≥1 based on the calculations of 2D:4D. Out of 300 children 78.6% were males and 71.2% were females with 2D:4D less than 1, 21.4% males and 28.8% females were having 2D:4D ≥1. Male population showed higher prevalence in the low 2D:4D ratio [Table/Fig-3].

The Pearson’s correlation test and chi-square test showed 2D:4D has significant positive correlation with occlusal status of the individual (p=0.0001) suggesting that higher the 2D:4D higher will be the occurrence of malocclusion [Table/Fig-4]. Children having Angles Class II, Class III molar relation, anterior and posterior cross bite and anterior crowding were considered as children with malocclusion. Either one or more of the above mentioned characteristics were considered under malocclusion. Among 300 children 147(49%) of them were identified with malocclusal characteristics. With increasing values of 2D:4D ratios children were identified with more number of malocclusal characteristics.

• A significant negative correlation between 2D:4D ratio and BMI (p=0.0372) indicating higher BMI value associated with lower the 2D:4D [Table/Fig-5].

• BMI of the individual had significant negative correlation with occlusal status (p=0.041) reflecting malocclusal condition with lesser BMI [Table/Fig-6].

• Higher caries experience seen with deviated occlusal condition with significant p value (p=0.027*) [Table/Fig-7].

As predicted, male mean 2D:4D was lower than female mean 2D:4D across nations and the effected size was greatest for the right hand. This indicates that men may have experienced higher levels of prenatal testosterone and lower levels of prenatal oestrogen than women. 2D: 4D ratio has been found as a reliable marker for prenatal testosterone which causes prolongation of 4th digit relative to the 2^nd digit [1].

2D:4D ratio is sexually dimorphic. Our findings suggest that 2D:4D ratio was lower in males than females, which was in accordance with the Manning et al., [4]. The sexual dimorphism in 2D:4D ratio was also reported by Brown et al., [9]. The sexual dimorphism in digit ratio was explained by Lutchmaya et al., [10] who studied the relationships between 2D:4D ratios and Fetal Testosterone (FT) and Fetal Estrogen (FE) from amniotic fluid in a sample of 33 children. They reported significant negative associations between right 2D:4D ratio and FT/FE ratio – independent of sex – such that low 2D:4D was associated with higher levels of FT relative to FE, and high 2D:4D correlated with low FT relative to FE. They concluded that there is association between low 2D:4D and high levels of FT relative to FE, and high 2D:4D with low FT relative to FE [4,9,10].

The value of 2D:4D is lower in men and within each sex lower 2D:4D ratio points to the higher intrauterine androgen levels. Men with high sensitivity to the androgen receptors have lower (more masculine) 2D:4D ratio. 2D:4D ratio is stable and fixed in early life. There is no evidence that 2D:4D ratio changes with age [4]. Low 2D:4D digit ratio has been associated with high levels of androgens, whereas higher ratio is associated with high estrogen levels. The mean 2D:4D in the present study was 0.96 which was supported by Kangassalo et al., who concluded that the mean 2D:4D ratios of South Indian population was ranged between 0.96 -0.97, and they also noted the mean 2D:4D ratios of (Poland, Spain and England), (Zulus, Finns and Jamaican) populations as 0.99 to 1.00 and 0.93 to 0.96 respectively [11]. The 2D:4D ratio has been much spoken and discussed in the medical scenario, but not much information is available as far as dentistry is concerned [5]. The impact of human hormones (2D:4D ratio) on taste perception was explained by Verma et al., [5]. Thereby they explained the influence of 2D:4D ratio on caries index of the individuals with prevalence of more sweet likers in the low digit ratio category [5]. Lower 2D:4D ratio was associated with less malocclusion and higher dental caries was associated with more deviated occlusal characteristics according to the current study. Hence, it can be assumed that the individuals with higher 2D:4D ratio tends to have greater caries experience. Elangovan A reported that caries prevalence was more in obese children and caries scores were increasing with increased BMI for age. But the relation was not statistically significant [12] Begum MZ conducted a survey to evaluate the relation between BMI and dental caries and concluded that there was no relation between them [13]. According to Hooley et al., the higher caries incidence was associated with both high and low BMI values and stated that dental caries and BMI are related in a nonlinear fashion with more dental caries occurring in individuals with either higher or lower BMI [6]. Gupta P, Gupta N, Singh HP evaluated the prevalence of dental caries in relation to BMI in 12 year old school going children and the results showed that there was no significant correlation between them which was in accordance with the present study [14]. Malocclusion and BMI were inversely related in the present study which was supported by Stefan Van Dongen who reported that there is inverse relation between them [15]. Prevalence of malocclusion in the current study was 49% and a slightly higher value of 53.7% reported by Kumar P and co-workers [16]. However, further research to explore the impact of 2D:4D ratio and BMI on malocclusion as they are multifactorial in origin and necessitate exploration with larger sample size are necessary to confirm their practical applicability in paediatric dentistry.

The hormonal finger prints are new biological markers which can be used as predictors for the incidence of malocclusion as high 2D:4D ratio associated with high malocclusion and Lower BMI values. The present study confirms the impact of hormones on incidence of malocclusion, BMI which in turn influence the caries index and could be used as an early predictor for malocclusion and dental caries in children.