Implant-Abutment Connections and Their Effect on Implant Survival Rates and Changes in Marginal Bone Levels (Δ): A Systematic Review and Meta-Analysis of 45,347 Oral Implants.

To quantify the cumulative oral implant survival rates and changes in radiographic bone levels based on the configuration of the implant-abutment connection type over time. An electronic literature search was conducted in four databases (PubMed/MEDLINE, Cochrane Library, Web of Science, and Embase), and records were refereed by two independent reviewers based on the inclusion criteria. Data from included articles were grouped by implant-abutment connection type into four categories ( external hex; bone level, internal, narrow cone < 45 degrees; bone level, internal wide cone ≥ 45 degrees or flat; and tissue level) and duration of follow-up (short-term 1 to 2 years, mid-term 2 to 5 years, and long-term > 5 years).