Effect of implant neck design on peri-implant tissue conditions: a narrative review

PURPOSE: The neck design of dental implants, which is crucial for the long-term health of the surrounding periodontal tissue, affects both the marginal bone preservation and soft tissue integration. This narrative review investigates various approaches for implant neck design, including macroscopic contour profiles (straight, divergent, convergent, scalloped, sloped, and triangular), surface texture modifications (microthreaded, roughened, and machined collars), and platform switching. METHODS: A narrative literature search was conducted in PubMed, Scopus, and Web of Science up to July 2025. Studies examining implant neck geometry, surface characteristics, or their mechanical and biological relevance were included. Evidence from finite element analyses, preclinical studies, clinical investigations, and systematic reviews or meta-analyses was qualitatively synthesized for comparing the implant neck designs. RESULTS: Finite-element analyses and clinical trials have indicated that divergent and convergent necks exhibit better biomechanics than traditional straight-neck designs. Sloped and triangular designs can adapt to the ridge shape, thus improving soft tissue appearance. Microthreaded and roughened collars may optimize stress distribution and promote osseointegration; however, certain concerns, such as the risk of bacterial colonization, exist. Platform switching has demonstrated consistent benefits in reducing crestal bone loss, particularly in the esthetic zones and immediate placement protocols. However, the overall evidence remains heterogeneous across studies. CONCLUSIONS: This review highlights the need to shift from a design-centric to an indication-oriented strategy. Instead of relying solely on the manufacturer's claims, neck designs should be altered based on specific factors such as tissue morphology, esthetic considerations, hygiene accessibility, and load protocols.