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

Background: A difference in genetic susceptibility to plaque accumulation has been advocated to explain different responses to periodontal therapy. The purpose of this study is to assess the role of the interleukin-1 (IL-1) polymorphism 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) with moderate to severe periodontitis, treated and maintained for over 10 years were selected. At baseline (T0), 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 received scaling and root planing; 36 patients then underwent surgical therapy. Subsequently, all patients were enrolled in a periodontal maintenance program with recall visits every 3.4 +/- 1.0 months for at least 10 years. At the latest recall visit (T2) the same radiographic measurements evaluated at baseline were taken and a DNA sample for IL-1 genetic susceptibility testing was collected and sent for analysis.
Results: Twenty-three of the 60 patients (38.3%) were IL-1 genotype positive. A total of 52 teeth (3.3%) out of 1,566 were lost due to periodontitis between T0 and T2; 28 of 957 (2.9%) in the IL-1 genotype negative group and 24 of 609 (3.9%) in IL-1 genotype positive group. The mean variation in bone defect level (DeltaBD) averaged -0.04 mm in IL-1 genotype negative patients and 0.01 mm in IL-1 genotype positive patients. The mean variation in bone crest level (DeltaBC) averaged -0.24 mm in IL-1 genotype negative patients and -0.28 mm in IL-1 genotype positive patients. However, a few patients showed significant differences in response to therapy based on initial bone levels and genotype. IL-1 negative patients who showed minimal initial bone loss responded to the therapy better than the IL-1 positive patients. IL-1 positive patients with severe initial bone loss showed a better response to the therapy than IL-1 negative patients.
Conclusions: On average, there were no significant differences related to IL-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.