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Year : 2021  |  Volume : 39  |  Issue : 1  |  Page : 36-41

Determining caries risk susceptibility in children of Udaipur city with genetic taste sensitivity and hormonal fingerprint

Department of Paediatric Dentistry, Pacific Dental College and Hospital, Udaipur, Rajasthan, India

Date of Submission15-Dec-2020
Date of Decision03-Mar-2021
Date of Acceptance01-Apr-2021
Date of Web Publication22-Apr-2021

Correspondence Address:
Dr. Dinesh Rao
Department of Paediatric Dentistry, Pacific Dental College and Hospital, Udaipur - 313 024, Rajasthan
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jisppd.jisppd_527_20

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Background: Propylthiouracil (PROP) (a medicated tool) and hormonal fingerprint (second to fourth digits [2D:4D]) ratio can be used for detection of caries which is most prevalent oral health disease. Aim: This study aims to determine the role of genetic taste sensitivity and hormonal fingerprint (2D:4D ratio) on caries risk susceptibility. Materials and Methods: The present study was an observational and cross-sectional study. It was conducted on 570 children aged 6–12 years. PROP sensitivity test was done by PROP impregnated filter paper strips and subjects were divided accordingly into supertasters, medium-tasters, and nontasters. 2D:4D ratio was obtained by measuring length ratio of index to ring finger using Vernier caliper. Dietary preferences of the subjects were recorded. The evaluation of decayed, missing, and filled teeth/deft indices was done. Statistical Analysis: Intergroup comparisons were performed using One-way ANOVA test, independent t-test and Chi-square test at 5% significance level. Results: Positive correlation between nontasters, low digit ratio, sweet likers, and high caries index was found with a high significant difference. Conclusion: Genetic taste sensitivity and hormonal fingerprint (biological marker) can be used for detection of caries as the present research confirmed impact of hormones on taste perception.

Keywords: Dental caries risk, genetic taste sensitivity, hormonal fingerprint, propylthiouracil, second to fourth digits ratio

How to cite this article:
Dusseja SH, Rao D, Panwar S, Ameen S. Determining caries risk susceptibility in children of Udaipur city with genetic taste sensitivity and hormonal fingerprint. J Indian Soc Pedod Prev Dent 2021;39:36-41

How to cite this URL:
Dusseja SH, Rao D, Panwar S, Ameen S. Determining caries risk susceptibility in children of Udaipur city with genetic taste sensitivity and hormonal fingerprint. J Indian Soc Pedod Prev Dent [serial online] 2021 [cited 2021 Aug 2];39:36-41. Available from: https://www.jisppd.com/text.asp?2021/39/1/36/314369

   Introduction Top

Dental caries is considered to be the most prevalent oral disease worldwide and the main cause of tooth loss among the population.[1],[2] It is nothing but synergism of physical, biological, environmental, and behavioral factors associated with individual's lifestyle, including the number of cariogenic bacteria, low salivary flow, poor oral hygiene, and food consumption and also because of display to insufficient fluoride.[1]

High caries prevalence with high sugar consumption is clearly linked to the data of sugar consumption per capita with caries prevalence.[3] An important role of inherited behavior and taste thresholds is observed in the frequency of carbohydrate intake. Preference for, or rejection of some foods by children may be linked to genetic sensitivity to taste.[4] Sensitivity to the bitter taste of propylthiouracil (PROP) has an inheritance property.[5] Children, thus can be categorized into supertasters, medium tasters or nontasters as per the subject's taste threshold.[6] PROP filter paper can be used for taste research which contains only approximately 1.6 mg of PROP.[7]

Furthermore, the current research is examining the role of hormonal fingerprint (second to fourth digits [2D:4D] ratio) in taste behavior. Various psychological traits and diseases have been linked to the relative length of fingers on human hand. The ratio of lengths of 2D:4D is considered to be a sexually dimorphic trait that is lower in males than in females. According to researchers, second (index) finger is usually shorter than the fourth (ring) finger. George[8] observed that men's ring finger was relatively longer than the index finger, i.e., low digit ratio, while females show the opposite pattern, i.e., high digit ratio. This sex difference was also found in 2-year-old children, that may have developed prenatally by the 13th or 14th week postconception and thus, 2D:4D ratio could be used as a stable parameter. Testosterone-derived individuals have shorter index finger and those individuals, who are estrogen-derived have longer index finger.[9] According to the literature, fetus during intra-uterine life is exposed to prenatal androgens, and it is their concentration of exposure which dictates their taste perception, thereby affecting their oral health.[8] Thus, the current study was conducted with an aim to determine caries risk susceptibility with genetic taste sensitivity and hormonal fingerprint.

   Materials and Methods Top

Source of data

Using the data from the study by Lakshmi et al.,[10] the sample size was calculated using the formula n = 4(pq/L2), where p = prevalence of condition/health status (15), q = 100-p (when q is in percentage terms) (85), L = Allowable Error (Maximum permissible error is 20% of p giving a power of (100-L), i.e., 80% to study) (3). Thus, sample size estimated for present research was 567, which was rounded off to 570.

The study was conducted among a random sample of 570 boys and girls in the age group of 6–12 years. This age group of 6–12 years was selected due to its dynamic phase of growth representing mixed dentition period in children. This age group was also selected by Verma et al.,[11] Sharma and Hegde,[12] and Rupesh and Nayak.[13]

Ethical clearance

This present study was reviewed by the institutional ethical committee and clearance was obtained.

The children belonging to age the group of 6–12 years, children with stable mental status, with no known history of allergic reactions to PROP and those who are not under any caries preventive program were included in the study. While, children without parents' consent, with any systemic disease, whose mental condition was not stable, those on antidepressants and antibiotics, children under orthodontic therapy and with exaggerated gag reflex were excluded from the study.

Preparation of 6-n-propylthiouracil strips

Pure sample of PROP was obtained from the Sigma Pharmaceuticals, Udaipur [Figure 1]. For preparation of PROP strips, Whatman filter paper (size 1) was cut into 2 cm × 2 cm sizes and was sterilized in an autoclave at 121°C for 15 min [Figure 2]. The sterilized strips were weighed and desiccators were used for storage. The papers were pre-weighed and the values were noted. First, in a beaker, PROP (10 mg/ml) was dissolved in 5 ml of ethyl alcohol in a beaker. Ten previously sterilized Whatman filter paper strips were kept in the PROP solution for 1 h for complete absorption of the drug in filter papers [Figure 3]. The strips were removed from the solution and were air dried at room temperature. Weight of the strips postdrying was recorded. The difference of the two weights was calculated. Each strip of filter paper was saturated with approximately 1.6 mg of drug.
Figure 1: Propylthiouracil and ethyl alcohol

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Figure 2: Whatman filter paper strips cut in 2 cm × 2 cm

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Figure 3: Cut strips dissolved in solution of propylthiouracil and ethyl alcohol

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Propylthiouracil sensitivity test

For PROP sensitivity test, PROP impregnated filter paper strips were placed on the dorsal surface of the anterior two-third region of the individual's tongue for 30 s [Figure 4]. Individuals were refrained from consuming any diet for 2 h prior to PROP testing also they were advised to thoroughly clean their mouth with distilled water before the test. The individuals were asked to rate the intensity of sweetness, saltiness, or bitterness of PROP using 9-point category scales where, 1= “dislike extremely” to 9= “like extremely,” with neutrality being at point 5 (”neither like nor dislike”).[14] Individuals were then classified into groups of supertasters, medium-tasters, and nontasters.[13]
Figure 4: Filter paper kept on tongue for 30 s

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Propylthiouracil taster status

The children were subdivided as follows:

  • Supertasters: Individuals having low taste threshold to bitter and sweet substances and perceives the taste as strongest imaginable and very strong.
  • Medium-tasters: Individuals having the potential to perceive bitter and sweet substances in moderation.
  • Nontasters: Individuals having high taste threshold to bitter and sweet substances and they perceive the taste as barely detectable.

Evaluation of dietary preferences

Subjects taste quality (sweet likers/sweet dis-likers) was determined with the help of simple subjective questionnaire.

Second to fourth digits ratio

The ratio of the lengths of the index finger (2D) and ring finger (4D) was recorded using Vernier calipers and the students were categorized into high 2D:4D and low 2D:4D ratio [Figure 5].
Figure 5: Measuring second to fourth digits ratio

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Dental caries experience

The caries experience (decayed, missing, and filled teeth [DMFT]/deft index) was recorded and subjects with a total DMFT/deft score of >5 were considered to have a high caries rate.

Statistical analysis

Statistical analysis was performed using Statistical Package for Social Sciences, Version 20 software for windows (SPSS Inc., Chicago, Illinois, USA). Level of significance was kept at 5%. The demographic and clinical characteristics of individuals were evaluated using descriptive statistics. Inter-group comparisons were performed using One-way ANOVA test, independent t-test, and Chi-square test.

   Results Top

More than half of the population belonged to tasters (supertasters and medium tasters) and remaining belonged to nontasters [Graph 1]. Females belonged more to the taster group with P < 0.05 [Table 1]. The total decayed, missing and filled (DMFT/deft) value of the supertasters and the medium-tasters group was much lower than nontasters children.(P ≤ 0.05) [Table 2]. Caries active children belonged more to the nontaster group [Graph 2]. When 2D:4D ratio was measured with Vernier calipers, more than half (54.4%) had low 2D:4D ratio while remaining had 45.6% had high 2D:4D ratio [Graph 3]. Male and female distribution for digit ratio is shown [Graph 4]. Majority of the nontasters in both the genders had low 2D:4D ratio [Table 3]. After assessing dietary preferences on a whole, it was observed that, 40.7% were sweet likers and 124 out of 232 sweet likers were nontasters for PROP sensitivity which was statistically significant (P ≤ 0.05) [Table 4].
Table 1: Propylthiouracil sensitivity according to the sex

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Table 2: Comparison of caries status in different taste sensitivity groups

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Table 3: Comparison of 2D:4D ratio in different taste sensitivity groups

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Table 4: Comparison of taste preferences in different taste sensitivity groups

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When dietary preferences were compared with digit ratio 62.10% sweet likers had low 2D:4D ratio and only 37.9% had high 2D:4D ratio [Graph 5]. Nontasters have more dental caries experience with mean DMFT value 3.75 and deft value of 3 as compared to super-tasters and medium-tasters [Graph 2].

   Discussion Top

In the present study, a total of 71.2% children were found to be tasters and 28.8% were found to be nontasters. Also similar results were seen in studies done by Karmakar et al.,[15] and Lin.[7] The overall caries status (mean DMFT/dmft) was significantly much higher for nontaster children as per the results in the present study. Considering the fact that the overall increase in the consumption of sugar-rich food by nontaster children than the taster group and their preference of sweet and cariogenic food items lead to increase in caries among the nontaster children. Lin,[7] Verma et al.,[13] Sharma et al.,[12] Karmakar et al.,[15] Lakshmi et al.,[10] and Rupesh and Nayak[13] also reported similar results.

Most of the females belonged to the tasters group in the present study. Similar findings were also reported in the studies done by Karmakar et al.,[15] Duffy et al.,[16] Drewnowski et al.,[5] and Hussain et al.[17] This may be due to the fact that there is the presence of more fungiform papillae among females than males. Although contradictory results were found by Feeney and Hayes.[18]

As for the dietary preferences, only 24.4% of nontasters disliked sweets. In addition, Looy and Weingarten[19] found that participants who did not like sucrose were nearly all PROP tasters. Loper et al.[20] stated that PROP nontasters have a higher calorie intake. Females among all age groups preferred low sugar concentrations than males. Majority of the caries active children belonged to the nontaster group with the result being statistically significant. The reverse was found for caries free children. Shetty et al.,[21] Lakshmi et al.,[10] Karmakar et al.,[15] also found a similar result. Hence, one of the factors for the distribution of caries free and caries active children can be taste preference.

According to Fink et al.,[22] difference between low digit and high digit values was found to be <1. As per the study done by Verma et al.,[23] the mean ratio for men in the current study was found to be 0.94 wherein for females it was 0.95 that was below the mean value of 1. Therefore, a new median value was calculated and the population was divided into two categories, with the mean value being 0.94 and categorizing it as <0.94 and >0.94, according to population in Udaipur city. It was observed that low digit ratio group was dominated by males and high digit ratio was dominated by females, which is in accordance with studies done by George,[8] Manning et al.,[24] Fink et al.,[22] Verma et al.,[23] and Lakshmi et al.[10] In the nontaster group, the low digit ratio was found to be in higher proportion. Males had higher caries experience compared with females.[11],[13] These findings were in accordance with Lin,[7] Verma et al.[23]

If the risk factor of preferring sweets is detected early then preventive programs can be planned for such populations. PROP sensitivity test serves as an important tool to determine the inherent genetic sensitivity of a person for dietary preferences as it is a simple and cost-effective method. There was positive correlation of caries with the digit ratio in mixed dentition. Thus in mixed dentition, to predict the risk of dental caries, digit ratio can be a constant and stable anatomical marker. Early detection of dietary preferences and digit ratio may delay the onset of disease by early lifestyle interventions. Hormonal fingerprinting and PROP taste sensitivity is still a new and developing science and much remains to be discovered.

Limitations of the study

  1. Observations from certain studies reveal that sweet preferences in adults is not influenced by bitter receptor genotype[25]
  2. As hormonal fingerprint is affected by ethnicity and geographical location of individuals, the results from the current study cannot be applied to other populations
  3. Children <6 years of age were not included in the study as they are unable to comprehend the 9-point hedonic scale.

Scope of the study

  1. The association between different dental diseases and 2D:4D digit ratio can be considered in future studies
  2. Early diagnosis of the risk factors with genetic taste sensitivity and hormonal fingerprint can serve as motivational tool and encourage the parents for modifying the way of living
  3. This may also benefit and help the clinicians to spread awareness at the community level.

   Conclusion Top

Nontaster children are found to be more caries active than super-tasters and medium-tasters as they prefer more sweet foods. In addition, children having low digit ratio belonged to nontaster group and had high caries index as compared to children with high digit ratio. Thus, genetic taste sensitivity and hormonal fingerprint can act as noninvasive methods for determining caries.


The authors would like to express their gratitude to the management of Pacific Dental College and Hospital, Udaipur, Rajasthan, India, for providing all the support during the study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

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Costa SM, Martins CC, Bonfim Mde L, Zina LG, Paiva SM, Pordeus IA, et al. A systematic review of socioeconomic indicators and dental caries in adults. Int J Environ Res Public Health 2012;9:3540-74.  Back to cited text no. 2
Lehl G, Bansal K, Sekhon R. Relationship between cariogenic diet and dental caries as evaluated from a 5-day diet diary in 4-12 year-old children. J Indian Soc Pedod Prev Dent 1999;17:119-21.  Back to cited text no. 3
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Lin BP. Caries experience in children with various genetic sensitivity levels to the bitter taste of 6-n-propylthiouracil (PROP): A pilot study. Pediatr Dent 2003;25:37-42.  Back to cited text no. 7
George R. Human finger types. Anat Rec 1930;46:199-204.  Back to cited text no. 8
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3], [Table 4]


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