Efficacy of lateral bone augmentation prior to implant placement: A systematic review and meta-analysis

Aim The aim of the current systematic review was to critically appraise evidence from randomized and prospective non-randomized comparative clinical trials about the efficacy of lateral bone augmentation prior to implant placement and their outcome regarding bone width gain. Materials and Methods Eight databases were searched until May 2018 for randomized and prospective non-randomized comparative trials on lateral bone augmentation prior to implant placement. After elimination of duplicate studies, data extraction and risk-of-bias assessment according to the Cochrane guidelines, random-effects meta-analyses of mean differences (MD) or relative risks (RR) and their 95% CIs were performed, followed by subgroup, meta-regression and sensitivity analyses. Results Overall, 25 trials (16 randomized/9 non-randomized) were identified, which included a total of 553 patients (42.2% male; mean age of 43.9 years). In these included studies and populations, various modalities for primary lateral bone augmentation rendered implant placement feasible. Small discrepancies were found between overall clinical and radiographic gain (pooled gains of 3.45 +/- 1.18 mm versus 2.90 +/- 0.83 mm, respectively), but were not statistically significant. Bone width gain was significantly inversely associated with baseline bone width (pooled effect: -0.35 mm/mm; 95% CI: -0.63 to -0.07 mm; p = 0.01). Additionally, % graft resorption was associated with patient age (36%/year, 95% CI: -0.62 to -0.11 mm; p = 0.01). The presence of xenograft added to autologous graft led to less resorption compared to autologous graft alone (MD: 1.06 mm; 95% CI: 0.21 to 1.92 mm; p = 0.01). Barrier membrane did not yield significant difference in terms of bone width gain (MD: -0.33 mm; 95% CI: -2.24 to 1.58 mm; p > 0.05) and graft resorption (MD: 0.84 mm; 95% CI: -1.42 to 3.09 mm; p > 0.05). However, the quality of evidence ranged from very low to moderate due to bias and imprecision. Conclusions Initially smaller bone dimensions are associated with favours larger bone width gain, which indicates that a severe lateral bone deficiency can be effectively augmented applying primary lateral bone augmentation. Both Patients' age and recipient site (maxilla or mandible) seem to influence graft resorption. The addition of a xenograft can be helpful in reducing graft resorption. Existing evidence from randomized and prospective non-randomized trials on humans indicates that lateral bone augmentation prior to implant placement can successfully increase bone width. There are some indications that patient-related, site-related, and technique-related characteristics might influence the amount of gained bone width, but the quality of evidence is for the most part hampered by the small number of existing studies and methodological limitations that might lead to bias.