Impact of Concave/Convergent vs Parallel/Divergent Implant Transmucosal Profiles on Hard and Soft Peri-implant Tissues: A Systematic Review with Meta-Analyses

Purpose: To systematically review the literature comparing marginal bone loss (MBL) and pink esthetic scores of implants with convergent or concave transmucosal profiles vs divergent or parallel profiles. Materials and Methods: A PICO question was defined, and an electronic search was carried out in the MEDLINE/PubMed and Cochrane Oral Health Group databases. Studies documenting type of transmucosal profile (either tissue-level profiles or abutments) and soft and/or hard tissue outcomes of implants were considered eligible. Studies were selected on the basis of the inclusion criteria and quality assessments. A meta-analysis with subgroup analyses was performed. Results: Five papers fulfilled the inclusion criteria, and four were eligible for metaanalysis. Significantly less MBL was found in concave/convergent groups, with a mean difference of 0.772 (95% confidence interval [CI]: 0.450 to 1.095; P < .001). In the subgroup analyses for platform-switching and platform-matching connections, a significant effect in favor of concave/convergent was detected, with a standardized difference in means of 1.135 (95% CI: 0.688 to 1.583, P < .001) when platform switching was considered. No significant effects were found for platform-matching connections. Conclusion: Within the limitations of this review, it is suggested that concave/convergent implant transmucosal profiles result in less MBL. No statistically significant results were obtained for soft tissue-related outcomes or for the platform-matching connection subgroup.