Decementation Rates and the Peri-Implant Tissue Status of Implant-Supported Fixed Restorations Retained via Zinc Oxide Cement: A Retrospective 10-23-Year Study

Background: Long-term data on clinical outcomes of restorations attached to implants via zinc oxide (ZnO) cement have been sparse.

Purpose: The purpose of this study was to retrospectively investigate decementation rates and peri-implant tissue status of implant-supported fixed restorations retained by ZnO cement.

Materials and methods: Between 1989 and 2003, 63 partially edentulous patients received 93 implants. Of these, 27 patients received 36 screwed single crowns (SC) and served as a control (C group). The other 36 patients had their restorations cemented using ZnO cement. They were subdivided into a SC group and a fixed dental prosthesis (FDP) group. After between 10 and 23 years (mean: 13.22 ± 3.21), all decementation events and peri-implant soft tissue status were evaluated using patient records.

Results: Decementation was assessed in 57 implants supporting 30 SCs and 16 FDPs. Five cases of decementation (8.77%) were recorded after a mean of 9.27 ± 7.05 years (range: 4.81-21.79). In the control group of vertically screwed SCs, five events of screw loosening (13.89%) were recorded in five patients (18.52%) after a mean of 5.84 ± 5.96 years (range: 0.56-15.05) within a 14.30 year observation period. No cases of peri-implantitis were observed in any group. The mean values of periodontal probing depths and bleeding on probing (BOP+) were 3.74 mm and 31.58%, respectively, for ZnO-cemented restorations, versus 3.76 mm and 25%, respectively, for the C group. No significant correlations regarding technical/biologic complications between the groups were detected.

Conclusions: Within the limitations of this study, we conclude that the use of ZnO cement provides sufficient retention of implant-supported fixed restorations over long periods without biologic complications in form of peri-implantitis.