The Effect of Membrane Coverage on the Resorption of Autogenous Intraoral Block Grafts in Horizontal Ridge Augmentation: A Systematic Review of Literature and Meta-Analysis: Inevitability or an Iatrogenic Vulnerability?

BACKGROUND: Autogenous intraoral block grafting is the gold standard augmentation technique for moderate-to-severe horizontal ridge deficiency. However, the graft undergoes variable resorption during healing that might jeopardize the outcome of the procedure. Several studies hypothesized that covering the graft with a membrane decreases the amount of graft resorption, but this effect is not established in the literature. OBJECTIVE: The objective of this study is to assess the clinical value of covering intraoral block grafts with membranes in horizontal ridge augmentation regarding graft resorption (primary outcome), graft success, net bone gain, and complications (secondary outcomes). DATA SOURCES: Till August 2017, the review team conducted an electronic search including PubMed, EMBASE, Cochrane, and LILACS databases; we also identified other articles through hand searching. The search terms included alveolar ridge augmentation, bone transplantation, block graft, guided bone regeneration, membranes, resorbable membrane, and nonresorbable membrane. STUDY SELECTION: The review included human randomized controlled trials, controlled clinical trials, cohort studies, and case-control studies in English that compared membrane coverage to no membrane coverage of autogenous intraoral block grafts and reported the amount of graft resorption after > 3-month follow-up. STUDY APPRAISAL: Two authors independently assessed the risk of bias using the Cochrane risk of bias tool, and the third reviewer was the judge in case of conflict. DATA EXTRACTION: Two authors independently filled the effective practice and organization of care form for data extraction, and the third reviewer revised the data. DATA SYNTHESIS: The statistical method of choice was the generic inverse variance, and the results were pooled using random-effect models, with the effect size measure being mean difference (MD) for continuous outcomes and risk ratio (RR) for dichotomous outcomes. RESULTS: The review members screened 2266 records; we excluded 2231 records by the title and abstract and screened 35 full-text records for eligibility, from which we excluded 32 articles for certain reasons (the most common were a different comparison and excluded study design). Three randomized controlled trials were included in the quantitative and qualitative analyses of this review, providing the data for 41 participants with 49 sites. Data analysis showed a statistically significant potential benefit of membrane coverage in decreasing the amount of graft resorption of intraoral block grafts (MD: -1.20 mm, 95% confidence interval [CI]: -2.11 to -0.30, P = .009). There was no statistically significant benefit from the use of membranes regarding graft success (RR: 1.02, 95% CI: 0.89-1.17, P = .79) and net bone gain (MD: 0.46, 95% CI: -0.16 to 1.09, P = .15). The use of membranes did not show a statistically significant increase in the incidence of complications (RR: 1.80, 95% CI: 0.55-5.96, P = .33). The reviewers judged all the studies as of fair quality regarding the risk of bias. CONCLUSION: The use of membranes decreased the graft resorption, but there was no difference regarding graft success and net bone gain. The use of membranes did not increase complications. Furthermore, properly conducted studies should be used to justify the adjunctive use of barrier membranes with block grafts.