Influence of the interimplant horizontal distance on the clinical outcomes of patients rehabilitated with two adjacent implants: A systematic review and meta-analysis

Statement of problem: The effect of the interimplant distance on bone stability, soft tissue health, and esthetic outcomes remains controversial. Closer implants may lead to greater bone loss and esthetic complications, highlighting the importance of an optimal implant placement for long-term success and patient satisfaction. Purpose: The purpose of this systematic review was to evaluate the impact of reduced interimplant distance (<3 mm) versus increased interimplant distance (≥3 mm) on marginal bone level changes as the primary outcome. The implant survival was assessed as a secondary outcome. Material and methods: The review, registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42024622404), followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search of PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, SCOPUS, and Web of Science was conducted, involving studies published up to January 2024. Results: The initial search has identified 2065 studies. After removing duplicates, 1885 studies were assessed, and 1840 were excluded based on title and abstract review. A total of 45 full-text articles were retrieved and evaluated. Five studies met the inclusion criteria: 1 randomized controlled trial (RCT), 3 prospective observational studies, and 1 retrospective study. Following the risk of bias evaluation, no studies were excluded, though many were classified as medium or high risk. Conclusions: An interimplant distance of at least 3 mm is essential for the preservation of marginal bone levels and the support of soft tissue health, emphasizing its relevance in implant planning for optimal clinical outcomes.