Regeneration of alveolar bone defects in the experimental pig model. A systematic review and meta-analysis

Abstract Objective Pigs are emerging as a preferred experimental in vivo model for bone regeneration. The study objective was to answer the focused PEO question: in the pig model (P), what is the capacity in experimental alveolar bone defects (E) for spontaneous regeneration in terms of new bone formation (O)? Methods Following PRISMA guidelines, electronic databases were searched for studies reporting experimental bone defect- or extraction socket-healing in the maxillae or mandibles of pigs. The main inclusion criteria were presence of a control group of untreated defects/sockets and assessment of regeneration via 3D tomography [radiographic defect fill (RDF)] or 2D histomorphometry [new bone formation (NBF)]. Random effects meta-analyses were performed for the outcomes RDF and NBF. Results Overall, 45 studies were included reporting on alveolar bone defects or extraction sockets, most frequently in the mandibles of minipigs. Based on morphology, defects were broadly classified as “box-defects” (BD) or “cylinder-defects” (CD) with a wide range of healing times (10 days to 52 weeks). Meta-analyses revealed pooled estimates (with 95% confidence intervals) of 50% RDF (36.87–63.15%) and 43.74% NBF (30.47–57%) in BD, and 44% RDF (16.48–71.61%) and 39.67% NBF (31.53–47.81%) in CD, which were similar to estimates of socket-healing [48.74% RDF (40.35–57.13%) and 38.73% NBF (28.57–48.89%)]. Heterogeneity in the meta-analysis was high (I2 > 90%). Conclusion A substantial body of literature revealed a high capacity for spontaneous regeneration in experimental alveolar bone defects of (mini)pigs, which should be considered in future studies of bone regeneration in this animal model.