Five year clinical outcomes of metal ceramic and zirconia-based implant-supported dental prostheses: A retrospective study

Objectives: The implant-supported restorations can be made of all-ceramic materials. The purpose of this study was to compare five year clinical outcomes of zirconia-based and metal ceramic implant-supported fixed dental prostheses (FDPs). Methods: In this study, 114 posterior implant-supported FDPs including zirconia-based (52) or metal ceramic (62) restorations were made for 114 patients with a mean age of 59 +/- 8.4 years and evaluated in a 5 year follow up. The modified California Dental Association (CDA) guidelines were used to assess the quality of the restorations. The soft tissue status was evaluated using gingival and plaque indices, probing depth and bleeding on probing. Additionally, the bone loss around implants was assessed by parallel priapical radiographs. The visual analogue scale was used regarding patients' satisfaction. The data analysis were performed by Kaplan-Meier, log rank test, Cox regression, Mann-Whitney U and Student's t-test. (alpha = 0.05). Results: Five year Kaplan-Meier survival rate of the zirconia-based and metal ceramic FDPs were 98.1 % and 100 0 /0 respectively with no significant difference (P = 0.12). The success rates were 81.6 % for zirconia-based and 81.0 % for metal ceramic restorations (P = 0.85). The CDA rating of both studied groups was not significantly different except the marginal gap which was better in zirconia-based FDPs (P < 0.001). Fracture of veneering ceramics occurred in 2.7 % of metal ceramic and 6.4 % of zirconia-based FDPs, which were not considered as failure. Soft tissue status was not affected by the type of restorations except for plaque index which was more favorable for zirconia-based FDPs (P < 0.001). No significant difference was found between marginal bone loss of the two groups (P = 0.30 mesial, P = 0.46 distal). Conclusions: Zirconia-based and metal ceramic FDPs showed similar promising clinical performance in the 5-year follow-up. Clinical significance: Zirconia-based implant-supported FDPs might be a successful restorative method with acceptable survival rate and patient's satisfaction.