The Effect of Crown-to-Implant Ratio on the Clinical Outcomes of Dental Implants: A Systematic Review.

Abstract

To analyze the effect of crown-to-implant (C/I) ratio over survival rate, marginal bone loss, and prosthetic complications of dental implants. Electronic (PubMed, Ovid MEDLINE, and Cochrane Central) and manual searches for clinical trials with a minimum follow-up of 1 year were performed. Clinical and anatomical C/I ratios were obtained. Regression models were created to assess for potential correlation between C/I ratio (anatomical and clinical) and survival rate, marginal bone loss, or prosthetic complications. A subgroup analysis of 6-mm implants and a comparison of C/I ratios of > 1.5 versus ≤ 1.5 were also performed. The Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool For Randomized Controlled Trials were used to evaluate the risk of bias. An overall moderate risk of bias was assessed among the selected articles. Linear regression analysis did not reveal a significant correlation between anatomical C/I ratios and survival rate (P = .905), marginal bone loss (P = 0.33), or prosthetic complications (P = .67). Similarly, no significant correlation to survival rate and marginal bone loss (P = 0.42, P = 0.84) was observed in the articles providing the clinical C/I ratios. Increased C/I ratio does not seem to be directly related with increased marginal bone loss and does not represent a biomechanical risk factor for the stability of the prosthesis and for the survival of dental implants.