Zirconia abutments for single-tooth implant restorations: a retrospective and clinical follow-up study

Objective: To evaluate the clinical outcome of custom-made zirconia abutments for implant-supported single-tooth restorations up to 5 years after insertion. Material and methods: The study comprises two parts: (Part 1) retrospective evaluation of records of 130 patients treated with 185 single-tooth implant restorations using zirconia abutments; (Part 2) clinical examination of 25 patients with 40 restorations placed 43 years ago. Oral surgeons placed the implants. The prosthodontic treatment was provided at a prosthodontic specialist clinic. The restoration was either an all-ceramic crown for cementation or a screw-retained one-piece restoration with the veneering porcelain baked directly to the zirconia abutment. Registration of all patients' records comprised clinical and radiographic data from insertion of the restoration up to the last visit at the clinic. Results: Parts 1 and 2: The zirconia abutments performed well over the follow-up period. The rates of both technical and biological complications were low, and the patients were in general extremely satisfied with the restorations. No all-ceramic crowns fractured during the observation period. Two abutments (1%) fractured, one at insertion, the other after 2 months. Part 2: There were no significant differences for changes in any of the soft tissue registrations or the peri-implant marginal bone level between the conventional two-piece abutment-crown restoration and the one-piece restoration. The peri-implant bone level changes from placement to the clinical examination 3-5 years later were small (mean 0.29 mm, SD 0.87 mm). Conclusion: Zirconia abutments for single-implant crowns seem to demonstrate good short-term technical and biological results.