EVALUATING GENE-ENVIRONMENT INTERACTIONS IN THE ETIOLOGY OF DENTAL CARIES IN ADULTS: THE CROSS-SECTIONAL STUDY

Objectives: Dental caries is a multifactorial disease and can be conceptualized as an interaction between genetic and environmental risk factors. The aim of this study is to examine the effects of AMELX, CA6, DEFB1 and TAS2R38 gene polymorphism and gene-environment interactions on caries etiology and risk assessment in adults.
Methods: Genomic DNA of 77 adults between 20-60 ages with ‘low caries risk group’ (DMFT≤5) and 77 adults with ‘high caries risk group’ (DMFT≥14) was extracted from the buccal mucosa. The frequency of AMELX (+522), CA6 (T55M), DEFB1 (G-20A) and TAS2R38 (A49P) single nucleotide polymorphisms (SNPs) were genotyped with the PCR-RFLP method. The environmental risk factors such as plaque amount, toothbrushing frequency, diet frequency between meals, saliva secretion rate, saliva buffer capacity, mutans streptococci counts and lactobacilli counts were examined in the study.
Results: There was no difference between the caries risk groups in relation to AMELX (+522) gene polymorphism (x² test, p>0.05). The distribution of CA6 genotype and allele frequencies in low caries risk group did not differ from high caries risk group (x² test, p>0.05). Polymorphism of DEFB1 (G-20A) was possitively and TAS2R38 (A49P) was negatively associated with caries risk (x² test, p<0.001). There were significant differences between caries susceptibility and each environmental risk factor except saliva secretion rate (Mann-Whitney U test, p<0.001). Based on stepwise multiple linear regression analyses, dental plaque amount, DEFB1 (G-20A) gene polymorphism, lactobacilli count, age, TAS2R38 (A49P) and CA6 (T55M) gene polymorphism and saliva buffer capacity explained a total of 87.8% of the variations in DMFT scores.
Conclusions: It can be concluded that variation in CA6 (T55M), DEFB1 (G-20A), TAS2R38 (A49P) may be associated with caries experience in Turkish adults when the dental plaque amount, lactobacilli count and age are high and saliva buffer capacity is low.