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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.