ObjectiveThis study was designed to evaluate, histomorphometrically, the association of platelet-rich plasma (PRP) and bioactive glass (BG) in the treatment of periodontal intrabony defects.Material and MethodsNine mongrel dogs were included in the study. Three-wall intrabony defects were surgically created at the mesial and distal aspect of first mandibular molar and exposed to plaque accumulation for 1 month. The defects were randomly assigned to the groups: control, BG, PRP, PRP+BG. Dogs were sacrificed 90 days after the surgeries. The histometric parameters evaluated were: length of sulcular and junctional epithelium, connective tissue adaptation, new cementum, new bone, defect extension and area of new bone filling the defect.ResultsA superior area of new bone was observed in PRP+BG and BG (13.80±2.32 mm2 and 15.63±2.64 mm2, respectively) when compared to the other groups (8.19±1.46 mm2 and 8.81±1.47 mm2 for control and PRP, respectively). No statistically significant differences were observed in the remaining parameters.ConclusionWithin the limits of this study, it may be concluded that PRP failed to provide statistically significant improvements in the histometric parameters.