Retrospective evaluation of the influence of the interleukin-1 genotype onradiographic bone levels in treated periodontal patients over 10 years

Background: A difference in genetic susceptibility to plaque accumulation h as been advocated to explain different responses to periodontal therapy. Th e purpose of this study is to assess the role of the interleukin-1(IL-l) po lymorphism on the rate of bone and tooth loss in non-smoking periodontally treated patients during maintenance. Methods: Sixty consecutive non-smoking patients (mean age 46.8 +/- 5.0) wit h moderate to severe periodontitis, treated and maintained for over 10 year s were selected. At baseline (TO), radiographic evaluation (cemento-enamel junction [CEJ]-root apex, CEJ-bottom of defect mesial and distal, CEJ-bone crest mesial and distal, crown-root ratio) was performed. All patients rece ived scaling and root planing; 36 patients then underwent surgical therapy. Subsequently, all patients were enrolled in a periodontal maintenance prog ram with recall visits every 3.4 +/- 1.0 months for at least 10 years. At t he latest recall visit (T2) the same radiographic measurements evaluated at baseline were taken and a DNA sample for IL-1 genetic susceptibility testi ng was collected and sent for analysis. Results: Twenty-three of the 60 patients (38.3%) were IL-1 genotype positiv e. A total of 52 teeth (3.3%) out of 1,566 were lost due to periodontitis b etween T0 and T2; 28 of 957 (2.9%) in the IL-l genotype negative group and 24 of 609 (3.9%) in IL-1 genotype positive group. The mean variation in bon e defect level (Delta BD) averaged -0.04 mm in IL-1 genotype negative patie nts and 0.01 mm in IL-1 genotype positive patients. The mean variation in b one crest level (Delta BC) averaged -0.24 mm in IL-1 genotype negative pati ents and -0.28 mm in IL-1 genotype positive patients. However, a few patien ts showed significant differences in response to therapy based on initial b one levels and genotype. IL-1 negative patients who showed minimal initial bone loss responded to the therapy better than the IL-I positive patients. IL-1 positive patients with severe initial bone loss showed a better respon se to the therapy than IL-1 negative patients. Conclusions: On average, there were no significant differences related to I L-1 genotype in tooth loss after 10 years in a non-smoking, well-maintained periodontal population. On an individual patient basis, the IL-1 genotype, in combination with the initial bone level, seems useful at the beginning of therapy for predicting bone level variation.