Effect of cross-linked vs non-cross-linked collagen membranes on bone: A systematic review.

The aim of this study was to conduct a systematic review to compare the clinical outcomes of two different resorbable collagen membranes in terms of regenerated bone volume, postoperative complications and membrane degradation during bone regeneration procedures. Randomized controlled trials (RCT) or controlled trials (CT) that compared both techniques were reviewed on four electronic databases up to December 2015, a manual search was performed on the bibliography of the collected articles and the authors were contacted for additional references if undetected on the electronic and manual search. Membrane exposure was evaluated as a dichotomous outcome and the statistical unit was the membrane. The results were presented as relative risk (RR) with a 95% confidence interval. Eight RCTs and one CT were included in this study. The majority of the studies depicted a bone augmentation area, which ranged from 46.15% to 94.6% for the non-cross-link membranes and from 44% to 92.6% for the cross-link membranes at the 4-6 month re-entry surgery. From a total of 289 patients, a forest plot concerning the membrane exposure was constructed using the obtained RR of the included studies. The overall RR was 1.43 (95% CI: 0.85-2.39) with no statistically significant differences between the two groups, although with a marginal tendency towards higher exposure in the cross-link membrane group. This systematic review suggests the different membranes present themselves as appropriate for bone regeneration procedures, although cross-link membranes present higher rates of postoperative complications. However, more RCT with higher sample sizes are needed to evaluate the different membranes. The suggested lack of clinical differences between the compared membranes suggest that further cost-benefit ratio, tissue integration and postoperative complication oriented studies should be performed so that clinicians can take a patient-centred, evidence-based decision.

Quality assessment of systematic reviews on vertical bone regeneration.

The aim of this study was to evaluate and compare the quality of systematic reviews of vertical bone regeneration techniques, using two quality-assessment tools (AMSTAR and ROBIS). An electronic literature search was conducted to identify systematic reviews or meta-analyses that would evaluate at least one of the following outcomes: implant survival, success rates, complications or bone gain after vertical ridge augmentation. Methodological quality assessment was performed by two independent evaluators. Results were compared between reviewers, and reliability measures were calculated using the Holsti's method® and Cohen's kappa. Seventeen systematic reviews were included, of which seven presented meta-analysis. Mean ±95% confidence interval AMSTAR score was 6.35 [4.74;7.97], with higher scores being correlated with a smaller risk of bias (Pearson's correlation coefficient=-0.84; P<0.01). Cohen's inter-examiner kappa showed substantial agreement for both checklists. From the available evidence, we ascertained that, regardless of the technique used, it is possible to obtain vertical bone gains. Implant success in regenerated areas was similar to implants placed in pristine bone with results equating between 61.5% and 100% with guided bone regeneration being considered the most predictable technique regarding bone stability, while distraction osteogenesis achieved the biggest bone gains with the highest risk of possible complications.