Efficacy of Horizontal Alveolar Ridge Expansion Through the Alveolar Ridge Split Procedure: A Systematic Review and Meta-Analysis

Purpose: Alveolar ridge split (ARS) is ridge augmentation to mitigate ridge width loss that typically follows tooth extraction. This study aimed to determine the efficacy of ARS on alveolar ridge horizontal dimensional changes and the survival rates of implants placed into the same sites. Materials and Methods: An electronic and manual search was conducted for English articles published up to January 1, 2021. The PICO (problem, intervention, comparison, outcome) model for quantitative studies was established to address the following two focused questions: (1) What are the effects of the ARS technique on increasing alveolar width and implant survival?; and (2) what are the factors that influence the efficacy of the ARS technique? The outcome measures in this systematic review and meta-analysis were mean alveolar ridge gain-horizontal (buccolingual) in millimeters from baseline (initial presentation) to final assessment (minimum of 12 weeks after ARS), implant survival rate, and patient-reported complication rate. The risk of bias was evaluated using the ROBINS-I assessment tool for non-randomized interventional studies. Weighted means were calculated, and pooled effects and 95% confidence intervals (95% CI) were depicted on forest plots. Publication bias was assessed by funnel plot and Rosenthal Statistics. A sensitivity analysis was undertaken to assess the primary outcome. Results: Overall, 35 studies met the inclusion criteria and were included in the systematic review. The mean alveolar ridge gain for ARS was 3.06 mm (95% CI: 3.01 to 3.12 mm). A mean gain of 2.99 mm (95% CI: 2.93 to 3.04 mm) was found after sensitivity analysis, excluding one article with a high risk of bias. There were no significant differences in ridge width in the group with bone graft (mean difference [95% CI] of 2.97 mm [2.91 to 3.03 mm]) and in the group without bone graft (mean difference [95% CI] of 3.06 mm [2.92 to 3.20 mm]). The ARS technique demonstrated a 98.17% implant survival rate in 4,446 implants, 4,103 of which were placed at the time of ARS with a 97.72% implant survival rate, and 343 placed in a delayed approach with a 99.14% implant survival rate. The risk of bias was low in 14.2%, low to moderate in 68.5%, moderate in 11.4%, and severe/moderate in 5.7% of the included studies. Conclusions: ARS shows a high implant survival rate in narrow alveolar ridges, adequate horizontal alveolar ridge dimensional gain regardless of adding grafting material, and minimal patient-reported complications.