IL1A(-889)/IL1B(+3954) is Not Associated With Bone Levels in Middle-Aged Arabs

Objectives: Specific polymorphisms in the interleukin (IL) 1 gene cluster have been associated with chronic periodontitis in certain ethnicities. The aim of this communication was to assess alveolar bone levels in 35 to 44 year-old Arab patients and to associate them with a combination of alleles 2 of IL1A(-889) and IL1B(+3954), the so-called IL-1 genotype. Methods: Panoramic exposures of 50 patients attending a dental school in Kuwait were digitally stored and available for analysis. Thirteen patients were smokers. At each tooth, distal and mesial bone levels as expressed as % of root length were assessed to the next 5%. Results: The average bone level was located at a mean (± standard deviation) distance of 17 ± 7% of the root length apical to the cemento-enamel junction. Bone levels were significantly lower at distal as compared to mesial sites (p<0.001). Forty-four % patients were characterized by the specific combination of alleles 2, and thus regarded IL-1 genotype positive. Cumulative frequency distributions of bone levels were similar in IL-1 genotype-positive and -negative patients. Multiple linear regression of the proportion of sites with bone levels beyond a 15% or 35% threshold revealed that only smoking, but not the IL-1 genotype, was strongly associated with the extent of bone loss. The adjusted models explained 26% and 11% of the variance of extent, respectively. According to a 2-level (subject, site) logistic regression model of bone level at a threshold of 15% as response, adjusted for IL-1 genotype, gender and age, smokers had significantly higher odds of reduced bone levels at all tooth types except maxillary molars. Conclusions: While the prevalence of this particular haplotype may be high in Arabs, at least in middle-aged adults it seems not to be associated with periodontal bone loss. Supported in part by KURA Grant # DS04/02.