Synthetic Blocks for Bone Regeneration: A Systematic Review and Meta-Analysis

Abstract

This systematic review is aimed at evaluating the effectiveness of synthetic block materials for bone augmentation in preclinical in vivo studies. An electronic search was performed on Pubmed, Scopus, EMBASE. Articles selected underwent risk-of-bias assessment. The outcomes were: new bone formation and residual graft with histomorphometry, radiographic bone density, soft tissue parameters, complications. Meta-analysis was performed to compare new bone formation in test (synthetic blocks) vs. control group (autogenous blocks or spontaneous healing). The search yielded 214 articles. After screening, 39 studies were included, all performed on animal models: rabbits (n = 18 studies), dogs (n = 4), rats (n = 7), minipigs (n = 4), goats (n = 4), and sheep (n = 2). The meta-analysis on rabbit studies showed significantly higher new bone formation for synthetic blocks with respect to autogenous blocks both at four-week (mean difference (MD): 5.91%, 95% confidence intervals (CI): 1.04, 10.79%, p = 0.02) and at eight-week healing (MD: 4.44%, 95% CI: 0.71, 8.17%, p = 0.02). Other animal models evidenced a trend for better outcomes with synthetic blocks, though only based on qualitative analysis. Synthetic blocks may represent a viable resource in bone regenerative surgery for achieving new bone formation. Differences in the animal models, the design of included studies, and the bone defects treated should be considered when generalizing the results. Clinical studies are needed to confirm the effectiveness of synthetic blocks in bone augmentation procedures.

Keywords: animal models; biomaterials; block graft; bone graft; bone regeneration; bone substitutes; histological analysis; synthetic biomaterials; systematic review.

Figure 1

Flowchart of the study selection process (adapted from PRISMA guidelines [24]).

Figure 2

Risk-of-bias graph: review authors’ judgments about each risk-of-bias item presented as percentages across all included studies. + = yes (the criteria was met, green circle); − = no (the criteria was not met, red circle); ? =unclear if the criteria was met or not (yellow circle). The figure was created using RevMan Version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, 2014).

Figure 3

Risk-of-bias summary: review authors’ judgments about each risk-of-bias item for each included study. The colors have the same meaning as in Figure 2. The figure was created using RevMan Version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, 2014).

Figure 4

Forest plot showing the meta-analysis of the comparative studies performed in rabbits, with a follow-up of four and eight weeks. The results demonstrate evidence for a significantly higher new bone formation in the group using synthetic blocks. The figure was created using RevMan Version 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, 2014).