Vertical Ridge Augmentation in the Atrophic Mandible: A Systematic Review and Meta-Analysis

Purpose: To systematically appraise the effectiveness/reliability of vertical ridge augmentation (VRA) in the atrophic mandible. Articles that addressed any one of the following four areas were included in this study: amount of VRA, implant survival (ISR) and success rates (SSR) in the area of newly regenerated bone, complication rate during the bone augmentation procedure, and bone resorption. Materials and Methods: An electronic literature search was conducted by two independent reviewers in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases for articles reporting VRA in the atrophic mandible via distraction osteogenesis (DO), inlay block grafting (IBG), onlay block grafting (OBG), and guided bone regeneration (GBR). For meta-analysis, two primary (VRA and ISR [%]) and two secondary outcomes were studied (SSR [%] and vertical bone resorption [VBR] [%]). Additionally, for qualitative assessment, complications (i.e, causes of failure) were further extracted and comprehensively described. Results: Overall, 73 full-text papers were evaluated. Of these, 52 articles fulfilled the inclusion criteria. The weight mean (WM) of VRA (+/- SD) was 4.49 +/- 0.33 mm (95% CI: 3.85 to 5.14 mm). It was most notable that DO involved greater VRA than IBG, and thus, significantly higher than GBR and OBG. The technique significantly influenced the mean VRA obtained (P < .001). Nonetheless, no technique showed superiority in terms of ISR or SSR. VBR and complications were shown to be minimized for GBR. Conclusion: If similar to 4 mm of VRA is needed, any technique in optimum local and systemic conditions should be equally reliable in the atrophic mandible. However, when greater VRA is needed, DO and IBG have demonstrated accuracy. By means of complication and VBR rates, GBR was shown to have the lowest. For ISR and SSR, no statistical differences existed among all techniques. Controlled studies are needed to examine the long-term peri-implant bone fate and the frequency of biologic complications in each technique applied for the vertical augmentation of the atrophied mandible.