Site-specific gingival bleeding on probing in a steady-state plaque environment: influence of polymorphisms in the interleukin-1 gene cluster.

Background: We previously reported a high prevalence of a combination of alleles 2 at positions interleukin (IL)-1A−889 and IL-1B+3954 in an Arabic population with gingivitis. In a steady state, the proportion of sites with bleeding on probing (BOP) was consistently reduced. The aim of the present study is to expand this observation by considering the site level.Methods: Fifty healthy non-smoking volunteers, 19 to 28 years of age, participated in this study. Clinical examinations included probing depth, BOP, plaque index (PI), and calculus. Examinations were repeated after 2 and 4 weeks, and subjects were advised not to change oral hygiene habits. Polymorphisms in the IL-1 gene cluster were assessed using a reverse hybridization assay.Results: Twenty-six subjects (52%) carried alleles 2 at positions IL-1A−889 and IL-1B+3954 and were designated genotype positive. In multivariate multilevel models of BOP, bleeding tendency in subjects with positive IL-1 genotype was only reduced at sites with PI 0 (odds rat...