Comparison of Success Rate and Radiological Bone Loss in Patients with Mini-Implant versus Conventional-Sized Implant Removable Prostheses: A Meta-Analysis

Background: The objective of this meta-analysis was to assess whether mini-implants have added benefit in terms of implants success rate and average bone loss over conventional-sized implants after one year of follow-up. Methods: An electronic search of randomized clinical trials was conducted in MEDLINE (via PubMed), Cochrane Central Register of Clinical Trials (CENTRAL) and Web of Science for studies including complete or partial edentulous patients requiring two or four mini-implants or conventional/ standard-sized implants in the maxilla or mandible for implant-supported removable prostheses who completed 12 months of follow-up. Results: The search provided 194 unique articles which were screened for title and abstract. Screening generated 12 articles which went through full-text analysis using eligibility criteria, and 4 articles were included for meta-analysis. Meta-analysis of these studies indicated a non-significant difference in the success rate between the two interventions (OR = 1.69 [0.74, 3.85;p = 0.21]). Bone loss estimates resulted in a significant bone reduction (Mean Difference = -0.74 [-0.95, -0.53;p < 0.05]) in favor of two mini-implants when compared with two conventional-sized implants, but when compared four mini- with two conventional-sized implants, the estimates were non-significant (Mean Difference = -0.24 [-0.69, 0.20;p = 0.29]). Conclusion: The current evidence does not provide solid evidence of the benefits of one intervention over the other. More studies with follow-up times of 10 and more years are needed as current studies have described the short-term outcomes.