Modeling of Crestal Bone After Submerged vs Transmucosal Implant Placement: A Systematic Review with Meta-Analysis

Purpose: To determine differences in marginal bone changes when using submerged or transmucosal dental implants through a systematic review of the literature. Materials and Methods: PubMed, Embase, and the Cochrane Library were electronically searched for trials comparing marginal bone loss between submerged and transmucosal dental implants with a minimum follow-up of 12 months published between January 1980 and January 2016. Manual searches of the bibliographies of the included studies were also carried out. Screening of titles and abstracts, data extraction from the included studies, and quality assessment following the PRISMA statement were conducted in duplicate. Outcome measures were radiographic marginal bone level changes, implant survival, prosthesis failure, prosthetic complications, and esthetics. Results: The search strategy identified a total of 4,991 studies. Two of the authors independently screened 855 abstracts, resulting in a total of 12 studies; however, the total included in the systematic review was 11, as 2 studies were based on data from the same patients and were therefore counted as 1. A total of 998 implants (413 submerged and 585 transmucosal) were observed in 542 patients. Seven of the studies had a randomized study design and a follow-up of 12 months; therefore, they were included in the meta-analysis of bone loss and implant survival. The overall estimate of the bone loss difference was -0.01 mm (95% confidence interval [95% CI] -0.11 to 0.09 mm), and there was less bone loss in the transmucosal implants than in the submerged implants (P = .811, I2 = 63.7%). The estimated relative risk for implant loss at 12 months was 0.31 (0.09 to 1.09, P = .068, I2 = 0%) in favor of the submerged healing protocol. Augmentation procedures seemed to be successful irrespective of the implant placement modality, but owing to few clinical data no evidence could be found. Because of the lack of clinical data, esthetic outcomes could be reported only in a descriptive way. Conclusion: In the present meta-analysis, no evidence was found of differences between submerged and transmucosal implant placement protocols with regard to changes in marginal crestal bone levels or implant survival at 12 months follow-up. Therefore, it can be concluded that in many clinical situations it seems questionable whether a closed healing protocol offers an advantage over a transmucosal protocol. Keywords: bone loss, dental implants, meta-analysis, submerged, systematic review, transmucosal