Clinical performance of two-piece zirconia implants in the posterior mandible and maxilla: a prospective cohort study over 2 years.

OBJECTIVES: To assess the clinical performance of two-piece zirconium implants over a period of up to 2 years.

MATERIAL & METHODS: A total of 52 patients with single-tooth gaps in the posterior mandible or maxilla received the same type of a two-piece zirconium implant system with customized heights of the transmucosal aspect. Fibreglass abutments were cemented and restored with fixed all-ceramic single crowns using a conventional loading protocol. The cumulative survival rate (primary outcome) was calculated according to the life table method, and Kaplan-Meier survival curves were used to estimate the survival function. Covariates (gender, implant position, implant diameter/length, oral surgeon) were tested using log-rank tests.

RESULTS: A total of two target implants in 2 patients were lost after a functioning time of 8 months. The cumulative survival rate was 95.8%, and the mean survival time amounted to 32.9 months. Log-rank tests revealed a significant association for the covariate "oral surgeon" (P = 0.047). The Kaplan-Meier estimates of mechanical/technical and biological complications amounted to 2.1% and 37.5%, respectively. All implant sites revealed a marked increase of the vestibular mucosal level and gain of keratinized tissue at 24 months.

CONCLUSION: Within the limitations of a prospective cohort study, it was concluded that this two-piece zirconium implant/fibreglass abutment system can be successfully used in the clinical indication investigated.