Retrospective Evaluation of the Influence the Interleukin‐1 Genotype on Radiographic Bone Levels in Treated Periodontal Patients Over 10 Years

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Abstract
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 (cementoenamel 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 (ΔBD) 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 (ΔBC) 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. J Periodontol 2001;72:767‐773.