OBJECTIVES: Interleukin (IL)-1alpha, IL-1beta and their natural specific inhibitor IL-1 receptor antagonist (IL-1ra) play a key role in the regulation of the inflammatory response in periodontal tissues. Polymorphisms in the IL-1 gene cluster have been associated with severe adult periodontitis. We aimed to investigate the IL-1 gene cluster polymorphisms in patients with peri-implantitis.

MATERIAL AND METHODS: The study included 120 North Caucasian individuals. A total of 71 patients (mean age 68 years, 76% smokers) demonstrating peri-implantitis at one or more implants as evidenced by bleeding and/or pus on probing and bone loss amounting to >3 threads on Brånemark implants and 49 controls (mean age 66 years, 45% smokers) with clinical healthy mucosa and no bone loss around the implants were recruited for the study. The titanium implants, ad modum Brånemark, had been in function for at least 2 years. Mouthwash samples were collected and used for genotyping of the bi-allelic polymorphisms IL-1A(-889), IL-1B(+3953), IL-1B(-511) and a variable number of tandem repeat IL-1RN gene polymorphisms using PCR technique.

RESULTS: Significant differences were found in the carriage rate of allele 2 in the IL-1RN gene between peri-implantitis patients and controls (56.5% vs. 33.3%, respectively; odds ratios (OR) 2.6; 95% confidence interval (CI) 1.2-5.6; P=0.015). Logistic regression analysis taking smoking, gender and age into account confirmed the association between the IL-1RN allele 2 carriers and peri-implantitis (OR 3; 95% CI 1.2-7.6; P=0.02).

CONCLUSIONS: Our results provide evidence that IL-1RN gene polymorphism is associated with peri-implantitis and may represent a risk factor for this disease.