Effect of guided bone regeneration on immediately placed implants: Meta-analyses with at least 12 months follow-up after functional loading

Background Immediate implant placement (IIP) into fresh extraction socket is a favorable treatment option. If successfully managed, it reduces the overall treatment time, and increases patient's satisfaction. Surgical and restorative factors affect IIP success rates. In this systematic review we evaluate the effect of guided bone regeneration (GBR) at the time of IIP on crestal bone level (CBL) changes after at least 12-months of functional loading. Methods Reviewers conducted an independent search of the National Center for Biotechnology Information PubMed, Medline, and the Cochrane Collaboration Library from 1966 to January 2017 following the inclusion criteria. A hand search of bibliographies of reviews and clinical trials related to IIP was also performed. This study looked into CBL changes around IIP primarily and further extracted the data to conduct three meta-analysis of "IIP using GBR versus IIP without GBR", "IIP using bone graft alone versus IIP using bone graft with membrane" and "IIP using GBR versus conventional implant placement" which were further subdivided to provide more detailed information for each. Four reviewers independently assessed the study data and methodologic quality using data extraction and assessment forms. Results The electronic search identified 714 potential studies and the hand search retrieved 55 studies. Crestal bone level (CBL) changes were determined in three meta-analyses. The results revealed a mean difference in CBL changes of 0.175 +/- 0.180 mm in favor of IIP without GBR when compared with implant with GBR. However, IIP with bone graft and membrane showed better results when compared with IIP with bone graft alone [CBL changes of 0.532 +/- 0.572 mm]. CBL preservation was noted in IIP with GBR versus conventional implant placement [CBL changes of - 0.001 +/- 0.049 mm]. Conclusions Meta-analyses showed minimal difference in CBL around IIP with bone graft versus without bone graft and with IIP with GBR compared with conventional implant placement. However, IIP with bone graft and membrane reported better CBL preservation compared with IIP with bone graft alone. Nonetheless, these results should be interpreted with caution because of moderate heterogeneity between studies.