This multicenter prospective case series study aimed to evaluate the outcome of periodontal regenerative therapy using a deproteinized bovine bone mineral (DBBM) in combination with a collagen barrier (CB) in the treatment of intrabony defects. A total of 36 nonsmoking patients with chronic periodontitis were recruited in five centers in Japan. All patients had at least one intrabony defect of ≥ 3 mm. The surgical procedures included access for debridement using a papilla preservation technique. Defects were filled with DBBM and covered with CB. Clinical evidence after 6 months supported the effectiveness of the combination therapy in the treatment of intrabony defects.