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 Table of Contents  
ORIGINAL ARTICLE
Year : 2016  |  Volume : 7  |  Issue : 2  |  Page : 99-102

Study of the relationship between taste sensation and dental caries experience among dental students


1 Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, University of Peradeniya, Peradeniya, Sri Lanka
2 Department of Basic Sciences, Faculty of Dental Sciences, University of Peradeniya, Peradeniya, Sri Lanka
3 Department of Oral Medicine and Periodontology, Faculty of Dental Sciences, University of Peradeniya, Peradeniya, Sri Lanka

Date of Submission21-Mar-2016
Date of Acceptance13-Aug-2016
Date of Web Publication16-Nov-2016

Correspondence Address:
Sumith Gunawardane
Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, University of Peradeniya, Peradeniya
Sri Lanka
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-6944.194232

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  Abstract 

Background and Aims: High sugar intake has been found to be related to high caries experience. High sugar intake is found to be prevalent among individuals who have a preference for sweet substances. Genetic sensitivity to taste has been implicated in the preference for or rejection of some foods. TAS2R38 gene appears to strongly mediate the bitter taste perception. It has also been shown that the genetic sensitivity to bitter compounds such as 6-n-propylthiouracil (PROP) is also mediated by this gene. The objective of this study was to determine the association of coronal dental caries among dental students with different genetic sensitivity levels of taste sensation as determined by the PROP.
Materials and Methods:
Coronal caries and restorations in permanent dentition were evaluated in 78 healthy 1 st year dental students aged 20-25 years. A filter paper containing PROP was used to determine the subjects' inherited ability to taste bitter and sweet taste sensation. Subjects were categorized into groups of supertasters, medium tasters, and nontasters according to the modified Green's scale. The data were analyzed using Shapiro-Wilk test and Kruskal-Wallis test.
Results: The mean decayed, missing, and filled teeth for nontasters was 1.64 ± 2.04 while 2.38 ± 3.24 for medium tasters and 1.96 ± 2.31 for supertasters.
Conclusion: Although the scientific literature suggested a significant difference in dental caries experience and inherited the ability to taste bitter taste sensation, differences in the presenting study were not statistically significant. Although this study gives negative results for the hypothesis we intended to test, the researchers expect to do the study with a large sample of Sri Lankan population in a different context.

Keywords: Dental caries, 6-n-propylthiouracil, taste sensation


How to cite this article:
Gunawardane S, Ariyasinghe S, Rajapakse S. Study of the relationship between taste sensation and dental caries experience among dental students. Indian J Oral Sci 2016;7:99-102

How to cite this URL:
Gunawardane S, Ariyasinghe S, Rajapakse S. Study of the relationship between taste sensation and dental caries experience among dental students. Indian J Oral Sci [serial online] 2016 [cited 2017 Sep 25];7:99-102. Available from: http://www.indjos.com/text.asp?2016/7/2/99/194232


  Introduction Top


The development of dental caries is dependent on critical interrelationships between susceptible host/tooth surface, specific oral bacteria, and dietary carbohydrates.[1] Therefore, higher and more frequent sugar intake may increase the risk of caries formation.[1] Several recent studies have indicated that high sugar intake has higher caries rates.[2] Szpunar et al. 1995 suggested that a higher proportion of total energy intake from sugars increased the probability of caries on all surfaces, and a higher total intake of sugars was also associated with total caries increment.[2]

It has been found that high sugar intake reflects a preference for sweet substances.[3],[4],[5] However, the physiological mechanisms that affect craving for sweet substances were not well documented. Inherited behavior and taste thresholds may play an important role in the frequency of carbohydrate intake. Genetic sensitivity to taste may be associated with a preference for or rejection of some foods.[6]

The rapid rise of dental caries supports the role of significant sweet intake in promoting caries risk. Genetic makeup which influences sweet intake may contribute to the difference of caries risk in individuals. It has been shown in studies that TAS2R38 appears to strongly mediate the bitter taste perception. It has shown that the genetic sensitivity to bitter compounds such as 6-n-propylthiouracil (PROP) is also mediated by this gene.[6],[7]

Depending on the sensitivity to PROP, population can be categorized into three subsets as supertasters (>60), medium tasters (12-60), or nontasters (<12) as determined by the subject's taste threshold on the modified Green's scale.[8],[9]

A supertaster can perceive stronger bitter and sweet tastes, as well as more burn from oral irritants, compared to those who are medium tasters and nontasters. Since supertasters can perceive taste in a lower concentration of bitter or sweet substance than nontasters, food products with strong tastes may be perceived as too strong or unpleasant for supertasters.[9] In contrast, nontasters may not be able to perceive the sweet or bitter taste in the same concentration as supertasters and, hence, require a higher concentration to perceive taste in the food products.[9] Nontasters may have a higher concentration and frequency of sugar intake compared to those who are medium tasters or supertasters and are, therefore, more susceptible to dental caries.[9] Knowledge of an individual's taste threshold facilitates the identification of those who are at high risk for developing dental caries.

Studies on taste and oral health have been conducted on adults and children in several genetically different populations. There are no such studies in the Sri Lankan dental literature with respect to the relationship between taste threshold and caries experience, and it will be useful to study the relationship between taste sensitivity and caries experience in our population.

The present pilot study was carried out to determine the prevalence of supertasters, medium tasters, and nontasters among a group of dental students and the relationship to caries experience using PROP sensitivity test. It was hypothesized that a higher prevalence of dental caries would be observed among nontaster compared to those who are medium tasters and supertasters.


  Materials and Methods Top


Ethical clearance for the study was obtained from the Ethics Review Committee, Faculty of Dental Sciences, University of Peradeniya. Participants to this study were selected from students from the Faculty of Dental Sciences, University of Peradeniya, who had not started their academic program and who were doing the Intensive English Course at the time of the study being conducted.

Inclusion criteria

  • Healthy individuals who agree to sign informed consent were included in the study.


Exclusion criteria

  • Gross oral pathology, chronic diseases, malignant disease, immunological conditions or any medical condition which have an effect on taste sensation
  • Individuals who were taking any long-term medication for chronic diseases or use of medication which has an effect of altered taste sensation within 3 months
  • History of allergy to PROP
  • Regular alcohol consumption (one drink per week)
  • Chronic smokers (one cigarette per day).


Study method

Preparation of the 6-n-propylthiouracil strips

PROP is a medication which is used in clinical practice for the treatment of Graves' disease (hyperthyroidism), and the therapeutic dosage is 150-200 mg daily for adults and 50-150 mg daily for children aged 6-10 years.[6],[7]

The pure sample of PROP was obtained from the pharmaceuticals, and the PROP strips were prepared in the Division of Microbiology, Faculty of Dental Sciences, University of Peradeniya. Whatman filter paper was cut into 2 cm × 2 cm size and sterilized in an autoclave at 121°C for 15 min. The sterilized strips were weighed and stored in the desiccator until they will be used for further preparation. 6-n-propylthiouracil (10 mg/ml) was dissolved in 5 ml of ethyl alcohol in a beaker. Ten previously cut and sterilized Whatman filter paper strips were soaked in the above solution for 1 h for the complete absorption of the drug. The strips were removed and allowed to dry at room temperature. The weight of the strips after drying was measured and recorded. The difference between the initial weight of the filter paper and the weight after the impregnation of the drug had given the actual amount of drug impregnated on each strip. An average amount of the drug impregnated on each strip was approximately 1.6 mg.

Clinical examination

A comprehensive clinical examination was performed by a trained examiner with the assistance of a recorder. The number of decayed, missing, and filled surfaces (DMFS) in the coronal portion of each tooth and the percentage of DMFS were determined according to the World health organization's guidelines. Codes for sound teeth, primary caries, secondary (recurrent) caries, preventive restorations, permanent restorations, crowns, defective or temporary restorations, and unerupted/inaccessible areas were assigned to each coronal tooth surface. The dental examination was performed in a natural lighted environment with direct visual inspection and tactile sensation with a dental explorer and mouth mirror. The participants who had found to be with dental caries or any other condition need to be treated were referred to the Dental Teaching Hospital, Peradeniya, for necessary management.

6-n-propylthiouracil sensitivity test

Following clinical examination, all subjects were classified as taster and nontaster by performing PROP sensitivity test. PROP sensitivity test was carried out by placing a filter paper containing approximately 1.6 mg of 6-npropylthiouracil on the dorsal surface of the subject's tongue for 30 s, to determine the ability to taste a bitter or sweet substance. When the bitter taste was at a maximum (30 s), each subject was asked to rate the intensity of bitterness on the modified Green's scale[8] and classified into groups of supertasters (>60), medium tasters (12-60), and nontasters (<12).

Statistical analysis

All the data were entered into a database on Microsoft Excel and analyzed with Minitab software version 16 (Minitab Inc. USA). Shapiro-Wilk test was done to assess the distribution of data. Since the data were not normally distributed, Kruskal-Wallis Test was done to find the associations between decayed, missing, and filled teeth (DMFT) and PROP sensitivity test.


  Results Top


The study sample comprised 78 healthy university students, age ranging from 21 to 25 years. Among them, 46.15% (36) were male and 53.85% (42) were female. Depending on the sensitivity to the bitter taste of PROP, 28.21% (22) of them were nontasters while 37.18% (29) were medium tasters and 34.62% (27) were super tasters. The mean DMFT for nontasters were 1.64 ± 2.04 while 2.38 ± 3.24 for medium tasters and 1.96 ± 2.31 for supertasters. Those differences were not statistically significant.


  Discussion Top


Studies have found that high sugar intake reflects a preference for sweet substances.[1],[2],[3] However, the physiological mechanisms that affect craving for sweet substances were not well documented. Inherited behavior and taste thresholds may play an important role in the frequency of carbohydrate intake. Genetic sensitivity to taste may be associated with a preference for or rejection of some foods.[1]

The present pilot study was carried out to determine the prevalence of supertasters, medium tasters, and nontasters among a group of dental students and the relationship to caries experience using PROP sensitivity test. Participants who were students belonging to the Faculty of Dental Sciences of both sexes were recruited for the study. This study determined and contrasted the prevalence of coronal caries experience among study samples who were supertasters, medium tasters, and nontasters. The majority of subjects who participated in this investigation were medium tasters (37.18%), followed by supertasters (34.62%) and nontasters (28.21%). Although it is expected to find significant differences of DMFT between taster groups, the results indicated, in general, that the overall caries experience was not significantly associated with the genetic ability to detect bitterness in this sample.

One limitation of this study was that the socioeconomic and geographic distribution of the participating subjects might not be applicable to the general Sri Lankan populations. This study sample was predominately healthy university students who have been selected from the Faculty of Dental Sciences, University of Peradeniya. Since they are in the field of dentistry, one might argue that they could have been possessed more knowledge and attitudes toward oral health care. This fact has been considered by the authors and selection of students was done from the students who have not started their dental degree program.

Another potential limitation of this study may have to do with the small sample size for all three groups of tasters. Further, there is little information on the ability of subjects to analyze complex sensitivity chemosensory stimuli in terms of the presence and magnitude of the components.


  Conclusion Top


Since there were no published studies in the Sri Lankan dental literature with respect to the relationship between taste threshold and caries experience and it was believed to be useful to study the relationship between taste sensitivity and caries experience in our population. Although this study gives negative results for the hypothesis we intended to test, the researchers expect to do the study with a large sample of Sri Lankan population in a different context.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Featherstone JD. The continuum of dental caries - Evidence for a dynamic disease process. J Dent Res 2004;83:C39-42.  Back to cited text no. 1
    
2.
Szpunar SM, Eklund SA, Burt BA. Sugar consumption and caries risk in schoolchildren with low caries experience. Community Dent Oral Epidemiol 1995;23:142-6.  Back to cited text no. 2
    
3.
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
[PUBMED]  Medknow Journal  
4.
Lingström P, van Houte J, Kashket S. Food starches and dental caries. Crit Rev Oral Biol Med 2000;11:366-80.  Back to cited text no. 4
    
5.
Touger-Decker R, van Loveren C. Sugars and dental caries. Am J Clin Nutr 2003;78:881S-92S.  Back to cited text no. 5
    
6.
Anliker JA, Bartoshuk L, Ferris AM, Hooks LD. Children′s food preferences and genetic sensitivity to the bitter taste of 6-n-propylthiouracil (PROP). Am J Clin Nutr 1991;54:316-20.  Back to cited text no. 6
    
7.
Lucchina LA, Curtis OF, Putnam P, Drewnowski A, Prutkin JM, Bartoshuk LM. Psychophysical measurement of 6-n-propylthiouracil (PROP) taste perception. Ann N Y Acad Sci 1998;855:816-9.  Back to cited text no. 7
    
8.
Green BG, Shaffer GS, Gilmore MM. A semantically labeled magnitude scale of oral sensation with apparent ratio properties. Chem Senses 1993;18:683-702.  Back to cited text no. 8
    
9.
Pidamale R, Sowmya B, Thomas A, Jose T. Genetic sensitivity to bitter taste of 6-n-propylthiouracil: A useful diagnostic aid to detect early childhood caries in pre-school children. Indian J Hum Genet 2012;18:101-5.  Back to cited text no. 9
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