The Impact of Crown-to-Implant Ratio on Marginal Bone Loss: A Meta-Analysis on Human Prospective Clinical Trials

Abstract

Introduction: Multiple systematic reviews have documented the efficacy of short implants in alveolar sites with moderate vertical height atrophy. Short implants in sites with alveolar ridge atrophy are often restored with elongated restoration, leading to relatively high crown-to-implant (C/I) ratio. It is important to determine whether the increased C/I ratio has any detrimental biological effects on peri-implant bone. To that end, this systematic review sought to examine the long-term effects of C/I ratio on peri-implant marginal bone loss, as reported by prospective clinical trials. Materials and Methods: Electronic search of 3 databases and hand searching were performed to identify prospective human trials that had reported both crown/implant ratio and associated peri-implant marginal bone loss with the follow-up of at least 36 months. Random-effect meta-analysis was performed to analyze weighted mean difference (WMD) and confidence interval (CI) for recorded variables according to PRISMA guidelines. Weighted linear regression model was used to evaluate R2 value.Results: Publication search yielded 1134 records and after evaluating titles, abstracts and full-texts, 8 prospective trials were included for quantitative data synthesis. Meta-analysis for the comparison of MBL among selected studies showed a WMD of 0.01 mm, with a 95% CI= 0.08 mm to -0.07 mm (p= 0.90). Results failed to detail any significant correlation between C/I ratio and marginal bone loss. Weighted linear regression model and low (0.214) R2 ratio suggested a lack of correlation between MBL and C/I ratio. Conclusion: Basad on the available evidence, there is no relationship between C/I ratio within the range tested and marginal bone loss.