ABSTRACT
BACKGROUND: Clinical evidence suggests an association between preterm birth and periodontal disease. This study explores whether specific genetic polymorphisms are associated with success of periodontal therapy in pregnant women with periodontal disease and, further, whether any of these same polymorphisms are also associated with spontaneous preterm birth (sPTB). METHODS: One hundred sixty high-risk pregnant women (6 to 20 weeks of gestation) with periodontal disease (≥ 3 sites with attachment loss ≥ 4 mm) were studied. All women received scaling and root planing plus oral hygiene instruction. Periodontal examinations were performed before treatment and 20 weeks later. Participants were classified according to two study outcomes: 1) success or failure of periodontal treatment; and 2) presence or absence of sPTB. Maternal DNA samples from mucosal swabs were characterized using a 1536-SNP (single-nucleotide polymorphism) custom polymerase chain reaction chip. A probabilistic model of each dichotomous outcome, derived using a stepwise Bayesian procedure, was compared to respective null hypotheses on the basis of Monte Carlo simulations and significance estimates obtained using three measures (z-test, Welch t-test, and probability convolution). The models were further confirmed by logistic regression analyses. RESULTS: The models revealed a significant relation between a specific polymorphism of prostaglandin E receptor 3 (a gene associated with inflammatory response) and both periodontal treatment failure (odds ratio 11.09, P <0.0002) and sPTB (odds ratio 6.89, P < 0.0032). CONCLUSIONS: These results demonstrate that the risk of unsuccessful periodontal treatment is associated with tag SNPs in specific genes that regulate the inflammatory response, one of which is also associated with sPTB.