Association between 6-n-propylthiouracil taste phenotypes and the development of initial caries lesions during fixed...

We explored the association between the 6‑n-propylthiouracil (PROP) taste phenotypes and the incidence and severity of initial caries lesions (ICL) during fixed orthodontic treatment.

The participants were a prospective cohort of 44 fixed orthodontic patients (16 males, 28 females, 18.7 ± 5.5 years) classified as non-tasters (n = 19) and tasters (n = 25) based on their bitter taste perception of PROP. The primary outcome was the cumulative incidence (C_in) of ICL at the facial surfaces of the anterior teeth and premolars at 1, 3, 6, 9 and 12 months in treatment. The severity of ICL (Enamel Decalcification Index, EDI) was the secondary outcome. Baseline age, sex, caries status, dietary habits, oral hygiene practice, type of treatment (non-extraction/extraction), oral hygiene, and salivary flow during treatment were the confounders/covariates explored.

Non-tasters had a higher relative risk (RR) of a tooth developing ICL than tasters at 9 months (C_in = 8.6 vs 0.6%, RR = 13.4 [4.1-43.7]), and 1 year (C_in = 18 vs 7.2%, RR = 2.5 [4.1-43.7]) in univariate analysis. The EDI scores were marginally higher in non-tasters than in tasters at 6, 9, and 12 months, although the differences were not clinically significant. In the generalized linear models, the teeth in non-tasters had higher odds of developing ICL (OR = 2.8 [1.2-6.3]) than tasters, but the effect on its severity was only modest (b = 0.04).

The results suggest a possible role of the individual's taste phenotype in the development and severity of ICL during fixed orthodontic treatment.