Objectives: Hydroxyapatite, tricalcium phosphate, and bioactive glass are the most commonly studied alloplastic materials in periodontal regeneration. These materials have been tested alone and in combination with one another, but evaluation using all three materials in one defect has not yet been attempted. Although posttreatment histologic evaluation or reentry procedures are ideal for objectively assessing regeneration, computed tomography (CT) has become one more technique in clinicians' armories to judge the effectiveness of any such interventions. Hence, the present study was undertaken to clinically ascertain the healing of intrabony defects following treatment with a composite alloplast and complement the study with volumetric assessment using CT. Method and Materials: Twenty defects in 10 patients were treated either with open flap debridement or open flap debridement and bone graft implantation in a split-mouth study design. Clinical parameters including probing depth, clinical attachment level (CAL), and gingival margin level were recorded at baseline and at 6 months postsurgery. Plaque Index and Gingival Index were measured at baseline, 3 months, and 6 months. Hard tissue measurements were recorded using a high-resolution spiral CT scan. Results: A statistically significant (P .05) improvement in all parameters (namely probing depth, CAL, percentage defect fill, and linear bone growth) was observed in both groups of patients. However, the test group showed better clinical and radiographic outcomes when compared to the control group (P .05). Conclusion: The new composite alloplast resulted in better treatment outcomes than open flap debridement alone. Moreover, the use of CT scan in ascertaining the various defect parameters in periodontal treatment of intrabony defects appears promising. Schlagwörter: aggressive periodontitis, composite alloplast, intrabony defect, periodontal regeneration, spiral CT, volumetric analysis