IL-1 gene polymorphism and smoking, risk factors for peri-implant bone loss?

Objectives: The purpose of this study was to investigate the relation between the IL-1 polymorphism and peri-implant bone loss at osseointegrated ITI® dental implants in both smoking and non-smoking individuals. Methods: A random sample of 90 consecutively admitted patients (aged 33 - 88 years), treated with at least one ITI-implant participated in this retrospective investigation. Standardized periapical radiographs were taken on average 4.5 months after prosthetic rehabilitation and at the time of the reexamination, on average 5.5 years thereafter. The radiographs were analyzed by a masked, calibrated examiner for changes in peri-implant bone levels. The distance between the implant shoulder and the first visible bone-implant contact at the respective time points were measured using a computerized method. The absolute bone level difference during the years of service (ABL) and the annual bone loss rate (DAB) were calculated for all implants. Results: Out of the total patient sample 14 were heavy smokers (>19 cig/day), 14 moderate smokers (5-19 cig/day), 23 previous smokers (smoking cessation >5 years) and 39 non-smokers. 28 (31,1%) patients were IL-1 genotype positive. Upon stratification for smoking status a significant difference (U-Test) was found for ABL (p<0.01) and DAB (p<0.01) between non-smokers and heavy smokers, and ABL (p<0.004) and DAB (p<0.01) between former smokers and heavy smokers for the IL-1 genotype positive but not for the IL-1 genotype negative group. Conclusion: The results of this study suggest that in IL-1 genotype positive patients heavy cigarette smoking may present a high risk factor for peri-implant bone loss following prosthetic reconstruction and subsequent maintenance. On this basis, in estimating the risk for peri-implant bone loss in heavy smokers, genotyping for IL-1 polymorphism may be recommended.

Supported by the Clinical Research Foundation (CRF), University of Berne, the ITI Foundation and the “A.S.Onassis” Public Benefit Foundation