Interleukin-1 gene polymorphisms and long-term stability following guided tissue regeneration therapy

Background: Specific interleukin (IL)-1 gene polymorphisms are associated with an increased susceptibility to severe periodontitis, increased inflammation, and increased likelihood of tooth loss during the maintenance phase after conventional periodontal therapy. The aim of the present study was to evaluate the impact of genotype on the maintenance of gained clinical attachment obtained after guided tissue regeneration (GTR) surgical therapy in deep intrabony defects. Methods: Forty deep (≥4 mm) interproximal angular bony defects with presurgical clinical attachment loss of >8 mm were treated by GTR using a non-absorbable expanded polytetrafluoroethylene (ePTFE) membrane. Membranes were surgically removed 4 to 6 weeks after surgery. Afterwards patients were placed on monthly recall for the first year and every 3 months for the following 3 years. At the 4-year re-evaluation, a IL-1 genetic susceptibility test was performed on all patients. Results: Fourteen (35% of the 40 patients) were genotype-positive (+). At baseline no statistically significant differences were found between patients with different genotypes in full mouth plaque score (FMPS), full mouth bleeding score (FMBS), clinical attachment level (CAL), probing depth (PD), or gingival recession. At year 1 follow up visit, no statistically significant differences were noted between genotype + and genotype - patients in FMPS, FMBS, amount of CAL gain, decrease in PD, or increase in gingival recession. Sixteen patients had membrane exposure after the GTR procedures. In these patients, the amount of CAL gain (P