Long-Term Stability After Regenerative Treatment of Infrabony Defects: A Retrospective Case Series

Background: This study aims to evaluate long-term stability of attachment achieved in infrabony defects (IBDs) by regenerative treatment. Methods: All patients who had received regenerative treatment for at least one IBD between 2004 and 2010 were screened for this retrospective case series. If complete examinations (plaque/gingival index, probing depth [PD], vertical clinical attachment level [CAL-V]) were available for patients at baseline and 12 months after surgery, they were invited for reexamination 60 -12 months after surgery. Reexamination involved testing for interleukin (IL)-1 polymorphism and counting number of supportive periodontal treatment (SPT) visits. Forty-one patients (24 males and 17 females; age, median: 62.0 years, lower/upper quartile: 49.8/68.3 years; six smokers, and 9 IL-1 positive) were included for analysis, each contributing one IBD. Results: Regenerative therapy resulted in significant attachment gain after 1 (median: -3 mm, lower/upper quartile: -1.5/-4 mm; P <0.001) and 5 (median: -3 mm, lower/upper quartile: -1.9/4.5 mm; P <0.001) years. The study failed to detect median change of CAL-V from 1 to 5 years after surgery (median: 0 mm; lower/upper quartile: -1/1.5 mm; P = 0.84). Multiple regression analysis identified that number of SPT visits is correlated with CAL-V gain from 1 to 5 years after surgery. IL-1 polymorphism and percentage of sites with PD >6 mm at 5-year reexamination are correlated with CAL-V loss from 1 to 5 years after surgery. Conclusions: CAL-V achieved by regenerative therapy in IBDs may have retained stability over 5 years. Frequent SPT is associated with stability. IL-1 polymorphism and generalized reinfection are associated with less stability.