Zirconia dental implants; the relationship between design and clinical outcome: A systematic review

Objective: To evaluate the clinical outcome of different designs of zirconia dental implants. Data: This systematic review adhered to the PRISMA checklist and followed the PICO framework. The protocol is registered in PROSPERO (CRD42022337228). Sources: The search was conducted in March 2023 through four databases (PubMed, Web of Science, Cochrane Library, and Google Scholar) along with a search of references in the related reviews. Three authors reviewed on title, and abstract level and analysed the risk of bias, and all authors reviewed on a full-text level. Study selection: Clinical studies excluding case reports for patients treated with different designs of zirconia dental implants were included. From a total of 2728 titles, 71 full-text studies were screened, and 27 studies were included to assess the risk of bias (ROBINS-I tool) and data extraction. After quality assessment, four studies were included, and the remaining 23 excluded studies were narratively described. Result: The included prospective studies with moderate risk of bias reported success and survival rates of onepiece implants that ranged between 95 and 98.4 % with no difference between different lengths and diameters. The acid-etched roughened surface showed higher clinical outcomes compared to other surface roughness designs. Conclusion: Promising 5-year clinical outcomes were found for one-piece zirconia implants with no difference between different diameters and lengths. Concerning surface roughness, better outcomes were found when using the acid-etched implant surface. However, due to the limited available studies, further high-quality clinical studies comparing zirconia one-piece and two-piece implants with different diameters, lengths, and surface roughness are needed. Clinical Significance: Based on this systematic review, under suitable clinical situations, the one-piece zirconia implants with diameters of 4.0 mm, 4.5 mm, or 5.5 mm and lengths of 8 mm, 10 mm, 12 mm, or 14 mm have similar promising clinical outcomes. Additionally, the acid-etched roughened implant surface may be preferable.