Xenogeneic Bone Block in Lateral Ridge Augmentation: Where Are We Now? A Systematic Review and Meta-analysis

Purpose: To investigate the clinical outcomes of xenogeneic bone blocks (XBBs) used for lateral ridge augmentation, specifically focusing on bone gain, graft survival, and implant survival. Materials and Methods: Data searches were conducted in PubMed, Embase, and ClinicalTrials.gov for randomized controlled trials (RCTs) and prospective cohort studies up to March 1, 2024. Horizontal bone gain (HBG), horizontal bone resorption (HBR), graft survival rates, and implant survival rates were analyzed. The Cochrane Risk of Bias Tool 2 (RoB2) and Newcastle-Ottawa Scale (NOS) were applied to assess the quality and risks of the included studies. Results: Four RCTs and five prospective cohort studies comprised a total of 120 bone graft sites and 141 implants that were included in the meta-analysis. A noncomparative analysis resulted in a weighted mean HBG of 4.38 mm and HBR of 0.85 mm. Comparative analysis with data from four RCTs compared XBBs with autogenous bone blocks (ABBs). The analysis resulted in a statistically significant greater HBG in XBBs, with a mean difference of 0.72 mm (95% CI = 0.067 to 1.382, P = .031, I² = 28.2%). The weighted graft survival rate for XBBs was 91.3% (95% CI = 76.6% to 97.1%, I² = 58.0 %), and the weighted implant survival rate was 84.3% (95% CI = 72.6% to 91.6%, I² = 31.6 %). Histologically, the mean percentage of mineralized vital bone in XBBs ranged from 11.6% to 29.8%, and the resorption rate ranged from 7.3% to 21%. Conclusions: The use of XBBs for lateral ridge augmentation demonstrates an acceptable survival rate and yields an adequate bone volume for subsequent implant therapy. However, the survival rate of implants placed in ridges augmented with XBBs is less favorable when compared to those augmented with ABB grafts.