Abstract: We included 38 RCTs. Twenty-two had a split-mouth design, and 16 had a parallel design. The overall evaluated data included 1402 defects. Two studies were at unclear overall risk of bias, while the remaining 36 studies had a high overall risk of bias. 1. APC + OFD versus OFD alone Twelve studies were included in this comparison, with a total of 510 infrabony defects. There is evidence of an advantage in using APC globally from split-mouth and parallel studies for all three primary outcomes: PD (mean difference (MD) 1.29 mm, 95% confidence interval (CI) 1.00 to 1.58 mm; P < 0.001; 12 studies; 510 defects; very low-quality evidence); CAL (MD 1.47 mm, 95% CI 1.11 to 1.82 mm; P < 0.001; 12 studies; 510 defects; very low-quality evidence); and RBF (MD 34.26%, 95% CI 30.07% to 38.46%; P < 0.001; 9 studies; 401 defects; very low-quality evidence). 2. APC + OFD + BG versus OFD + BG Seventeen studies were included in this comparison, with a total of 569 infrabony defects. Considering all follow-ups, as well as 3 to 6 months and 9 to 12 months, there is evidence of an advantage in using APC from both split-mouth and parallel studies for all three primary outcomes: PD (MD 0.54 mm, 95% CI 0.33 to 0.75 mm; P < 0.001; 17 studies; 569 defects; very low-quality evidence); CAL (MD 0.72 mm, 95% CI 0.43 to 1.00 mm; P < 0.001; 17 studies; 569 defects; very low-quality evidence); and RBF (MD 8.10%, 95% CI 5.26% to 10.94%; P < 0.001; 11 studies; 420 defects; very low-quality evidence). 3. APC + GTR versus GTR alone Seven studies were included in this comparison, with a total of 248 infrabony defects. Considering all follow-ups, there is probably a benefit for APC for both PD (MD 0.92 mm, 95% CI -0.02 to 1.86 mm; P = 0.05; very low-quality evidence) and CAL (MD 0.42 mm, 95% CI -0.02 to 0.86 mm; P = 0.06; very low-quality evidence). However, given the wide confidence intervals, there might be a possibility of a slight benefit for the control. When considering a 3 to 6 months and a 9 to 12 months follow-up there were no benefits evidenced, except for CAL at 3 to 6 months (MD 0.54 mm, 95% CI 0.18 to 0.89 mm; P = 0.003; 3 studies; 134 defects). No RBF data were available. 4. APC + EMD versus EMD Two studies were included in this comparison, with a total of 75 infrabony defects. There is insufficient evidence of an overall advantage of using APC for all three primary outcomes: PD (MD 0.13 mm, 95% CI -0.05 to 0.30 mm; P = 0.16; 2 studies; 75 defects; very low-quality evidence), CAL (MD 0.10 mm, 95% CI -0.13 to 0.32 mm; P = 0.40; 2 studies; 75 defects; very low-quality evidence), and RBF (MD -0.60%, 95% CI -6.21% to 5.01%; P = 0.83; 1 study; 49 defects; very low-quality evidence). All studies in all groups reported a survival rate of 100% for the treated teeth. No complete pocket closure was reported. No quantitative analysis regarding patients' quality of life was possible. There is very low-quality evidence that the adjunct of APC to OFD or OFD + BG when treating infrabony defects may improve probing pocket depth, clinical attachment level, and radiographic bone defect filling. For GTR or EMD, insufficient evidence of an advantage in using APC was observed.

Plain-language summary: Authors from Cochrane Oral Health carried out this review and the evidence is up to date to 27 February 2018. We included 38 studies and a total of 1042 infrabony defects. We considered four different types of surgical treatments and compared each technique with the same one when APC was added. Overall we considered these comparisons: open flap debridement with APC versus without APC; open flap debridement and bone graft with APC versus without APC; guided tissue regeneration with APC versus without APC; and enamel matrix derivative with APC versus without APC. There is very low-quality evidence that the addition of APC to two types of treatment: open flap debridement and open flap debridement with bone graft, may bring some advantages in the treatment of infrabony defects. However, for the other two types of treatment, guided tissue regeneration and enamel matrix derivative, there is insufficient evidence of a benefit. We judged the quality of the evidence to be very low due to problems with the design of the studies.