Objectives: The purpose of this study was to determine the relative impact of various predictors responsible for the variability in treatment outcome after guided tissue regeneration (GTR) in intraosseous periodontal defects.
Patients and methods: 30 patients with chronic periodontitis and at least one intraosseous periodontal lesion (> or =4 mm) were enrolled. Following full-mouth scaling, GTR using polylactic acid membranes was performed at one site in each patient. Main periodontal pathogens, defect morphology, membrane exposure and smoking habit were assessed as predictor variables. Alveolar bone level change served as the primary outcome variable in a multiple regression analysis.
Results: After 12 months, the 29 patients completing the study showed alveolar bone changes ranging from 4 mm bone gain to 1 mm bone loss (mean: 1.6+/-0.4 mm gain). Active smoking (beta-weight:-0.49, P=0.003) and persistence of subgingival infection with P. gingivalis (P.g.) (beta-weight:-0.25, P=0.11) were associated with poor treatment outcome. Deep initial intraosseous defects (beta-weight: 0.32, P=0.045) were associated with favorable treatment outcome, and membrane exposure had no impact on bone gain.
Conclusion: Active smoking was the strongest predictor variable negatively affecting alveolar bone gain following GTR in the treatment of periodontal defects. It was followed by a positive influence of a deeper intraosseous defect and by a negative effect by persistent subgingival infection of P. gingivalis. The relative impact of these factors may be useful in assessing the prognosis of GTR in intraosseous periodontal defects.