Effects of High Crown-to-Implant Ratio Over Time: A Retrospective Analysis
Objectives: The aim of this study is to evaluate retrospectively the effects of high crown-to-implant (C/I) ratio on 241 short (6- to 8-mm long), delayed loading dental implants in splinted and nonsplinted implant restorations.
Methods: One expert operator performed implant surgery in 78 non-consecutive patients, successfully placing a total amount of 241 short (6- to 8-mm) implants. All implants supported fixed rehabilitations and shared a high C/I ratio (radiographically measured from 1.5 to 3.10), but 208 were splinted, while 33 retained a single crown at the end of therapy. In all cases, the final restorations were opposed to fixed prostheses or natural dentition. The sample size was investigated in terms of implant survival rate (ISR) and prosthetic success rate (PSR) after a mean observation period of at least 5 years, distinguishing between splinted (SI) and nonsplinted (NSI) short implants.
Results: In the SI group, the ISR was 97.6% because 5 implants were lost due to perimplantitis over time, while the PSR was steady at 100% since all prostheses remained functional. In the NSI group, both ISR and PSR settled at 97% because one implant was removed after 6 years of function due to perimplantitis.
Conclusions: Within the limits of this study, we could affirm that once we achieve osseointegration we should not fear a high C/I ratio. In fact, it seems to affect similarly splinted and nonsplinted short implants over a mean observation period of at least 5 years.