Clinical performance of tooth- or implant-supported veneered zirconia single crowns: 42-month results.

OBJECTIVES: The objective of this clinical study was to compare and assess the clinical performance of tooth-supported and implant-supported zirconia single crowns with sintered veneering caps. METHODS: In this prospective study, 118 patients with a total of 220 single crowns placed on 106 teeth (69 vital teeth, 37 endodontically treated teeth) and 114 implants in molar and premolar regions were examined during a mean observation period of 42 months. The restorations were evaluated for technical failures such as veneering porcelain fractures (chipping), surface quality, marginal fit, and the interface quality of the coping and sintered veneering. The soft tissue status was assessed using the modified Silness and Löe's plaque and gingival index (mPI) and the modified Muhlemann sulcus bleeding index (mSBI). Tooth-supported crowns were checked for secondary caries and hypersensitivity during the follow-up period. Recalls were performed every 6 months. RESULTS: The 3-year Kaplan-Meier success probability was 98.2% and 100% for implant- and tooth-supported crowns, respectively. A significant difference could be detected between the implant-supported and tooth-supported zirconia single crowns, in terms of their chipping rate (p = 0.039). Veneering material fractures were recorded on two implant-supported restorations (1.8%). No veneering fractures occurred on tooth-supported single crowns. The plaque and gingival index and sulcus bleeding index showed stable and healthy soft peri-implant and periodontal tissues. Neither loss of vitality nor secondary caries occurred on tooth-supported crowns. CONCLUSIONS: Zirconia-based single crowns with a sintered veneering cap showed promising clinical results on both tooth and implant abutments; however, the dental implants were more prone to complications. In terms of clinical significance, high-strength ceramic with a sintered veneering cap can be recommended for prosthetic treatment of both tooth- and implant-supported single crowns in molar regions. CLINICAL RELEVANCE: This study provides valuable information for further application of all-ceramic restorations.

Clinical performance of screw-retained and cemented implant-supported zirconia single crowns: 36-month results.

OBJECTIVES: The objective of this clinical study was to evaluate the clinical performance of implant-supported zirconia crowns with a sintered veneering cap. Furthermore, the influence of the type of retention (screw-retained vs cemented single crowns) was analysed. MATERIALS AND METHODS: Fifty-eight patients were accommodated with 114 implants, inserted in the molar and premolar regions. Zirconia-based crowns with a sintered veneering cap were either screw-retained (n = 53) or cemented (n = 61) on the implant. Recalls were performed every 6 months. The state of soft tissue was documented by the modified plaque and gingiva index (mPI) and sulcus bleeding index (mSBI). The restorations were evaluated for technical failures like veneering porcelain fractures, surface qualities and marginal fitting. RESULTS: Neither implant loss nor crown fractures occurred. After a mean clinical service time of 36.9 months, fractures of the veneering porcelain were registered in 1.8 % of the cases. The Kaplan-Meier survival probability regarding eventless restorations was 98.2 %. Chipping of the veneering porcelain was registered in two cemented crowns without statistical influence of the type of retention. The indices showed healthy soft periimplant tissues in both groups. CONCLUSIONS: Implant-supported zirconia crowns with a sintered veneering cap demonstrated good clinical performance. The type of retention had no influence on technical complications.