Evaluation of Ca, P, and F concentrations and cariogenic bacteria quantity in the saliva of 12-y-old children: interaction of these factors with the genetic susceptibility of the individuals

• Grant number: 12/18018-0
• Support Opportunities: Scholarships abroad - Research
• Start date: January 01, 2013
• End date: December 31, 2013
• Field of knowledge: Health Sciences - Dentistry - Pediatric Dentistry
• Principal Investigator: Raquel Fernanda Gerlach
• Grantee: Raquel Fernanda Gerlach
• Host Investigator: Alexandre Rezende Vieira
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: University of Pittsburgh (Pitt), United States

Abstract

Eventhough a marked decrease in caries prevalence has been observed worldwide, there are still groups of people with high caries prevalence. A few recent studies show associations between genetic polymorphisms and caries, and what is particularly relevant: in genes that may have a plausible biological association with dental caries. However, concentrations of Ca, P and F, and the quantification of cariogenic bacteria in saliva have not been reported in such studies so far, and these are very important factors for statistical analysis. Therefore, the aim of this study was to compare the concentrations of Ca, P and F, and the bacterial count, and analyze the associations between those variables in the light of the data already gathered for some polymorphisms in genes recognized as possibly important for the development of dental caries. Samples are saliva collected from 12-year-old school children from Curitiba, PR, stored at -800C. Bacteria quantification will be done by means of Real Time PCR employing S. mutans e S. sobrinus specific primers based on the gtfB e gtfU gene regions. To express total bacteria counts, primers based on the the 16S rRNA conserved gene sequence will be used, and the amount of cariogenic bacteria will be expressed as a ratio of the total bacteria count determined. Determination of Ca, P, and F will be done using standard analytical techniques, i.e., atomic absorption spectrometry for C, a colorimetric method for P, and an íon-specific electrode method for fluoride. Single Nucleotide Polymorphisms (SNPs) in the genes encoding enamel developmental proteins will be also analysed in this study, being those: AMELX, TUFT1 e EMGN. These SNPs will be assayed using Taqman in PCR reactions. Frequencies will be tested employing Chi-square (X-2), followed by Hardy-Weinberg equilibrium testing and case-control comparisons (using Bonferroni correction for multiple comparisons). Multilevel analyses will then follow to be able to analyze data on bacteria, SNPs and minerals in the individuals of this population. (AU)