Implant Survival in the Posterior Partially Edentulous Arch-30 Years of Experience. Part IV: A Retro-Prospective Multivariable Regression Analysis on Implant Failures Related to Arch and Implant Surface

Purpose: To report implant failures in partially edentulous patients over a long-term period, focusing on differences in treatment outcomes between maxillary vs mandibular arches and different implant surfaces. Materials and Methods: Altogether, 2,453 patients were consecutively treated with 9,167 implants in 2,915 partially edentulous arches (Kennedy Class I or II) between 1986 and 2015 at one referral clinic. Implant failures were recorded on a routine basis at the clinic during follow-up, and the failures were analyzed with a focus on associations with treated arch and implant surface by means of a multivariable regression analysis. Results: Cumulative survival rates (CSRs) for arches provided with turned surface implants were 92.2%, 90.6%, 89.7%, and 88.3% after 5, 10, 15, and 25 years, respectively. Corresponding CSRs for arches provided with moderately rough surface implants were 95.7% and 95.2% after 5 and 10 years, respectively. Two individual surgeons and prosthetic treatment outside the referral clinic showed strong associations with early implant failure (P .05). Implants with a turned surface showed an increased risk for failure early after surgery ( 1 year), but a comparable pattern of a reduced risk by time was present during the late period of follow-up (> 1 year) for both surface types. Variables associated with the number of implants per operation were associated with increased risk of implant failure for both implant surface types (P .05). Conclusion: Individual surgeons seem to have an important impact on early risk of implant failure in combination with implant surface, number of placed implants, wide-platform implants, and treatment in the mandible. Observed differences in survival between different implant surfaces seem to be established early after surgery, but the risk during the following long-term period is reduced by time, and risk seems to be comparable for both surface types in both the maxilla and the mandible during maintenance.