Influence of Crown/Implant Ratio on Marginal Bone Loss: A Systematic Review

Background: With the increased use of short dental implants (<10 mm), a high crown/implant (C/I) ratio has become a common finding. However, the effect of the C/I ratio on the marginal bone loss (MBL) has not yet been examined extensively. Hence, the aim of the present systematic review is to explore the influence of the C/I ratio on the success rate and MBL of dental implants. Methods: Three electronic databases (PubMed, Ovid MEDLINE, and Cochrane Central) and a manual search for human trials with a minimal follow-up of 6 months are used for the present study. A statistical analysis of the influence of the C/I ratio was performed on the peri-implant MBL while considering follow-up period, type of implants, implant connection, and technical and biologic complications. Results: One hundred ninety-six potential articles were identified on the selected databases. Only 57 articles were selected for full-text evaluation. According to the inclusion criteria, a total of 13 articles were included in this systematic review. A significant negative association between the C/I ratio and the MBL was found (P = 0.012). However, no statistically significant difference was found (P>0.15) for potential effects regarding the observation period, the type of implant connection, or between both methods of evaluating the C/I ratio. Conclusions: Within the limitations of the present study, the C/I ratio of implant-supported restorations has an effect on peri-implant marginal bone level. Within the range of 0.6/1 to 2.36/1, the higher the C/I ratio, the less the peri-implant MBL.