11 August 2021

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Chipping and failure rates of implant-supported and combined tooth-implant-supported metal-ceramic and ceramic fixed dental prostheses are the same?

Giulia Palandrani

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A promising 5-year survival of 93% to 99% has been reported for implant-supported fixed dental prostheses (  FDPs ) . A review of tooth-implant-supported    FDPs reported a 5-year survival rate of 95% . Survival for    FDPs supported by teeth and implants after 10 years (77.8%) has been reported to be lower than that for solely implant-supported  FDPs

In the last 2 decades, ceramic restorations have become an esthetic alternative to metal-ceramic  FDPs . zirconia has been used as a framework material for long-span and posterior    FDPs .

A recent review stated that midterm and long-term data on the performance of monolithic zirconia implant-supported    FDPs are lacking. 

The purpose of this observational cohort study was to investigate the failure and chipping rates of ceramic    FDPs compared with those of metal-ceramic    FDPs supported by implants or by a combination of teeth and implants. Furthermore, attention was paid to the prognosis of monolithic ceramic    FDPs and to    FDPs with partial veneers restricted to the buccal surface 

Material and methods :
Four hundred thirty-four fixed dental prostheses placed in 324 patients (mean age: 60.8 years) were selected from a prospective clinical long-term study comprising 213 implant-supported fixed dental prostheses, 66 implant-supported cantilever fixed dental prostheses, and 155 tooth-implant-supported fixed dental prostheses. Metal-ceramic fixed dental prostheses (n=260) were fabricated with a high noble metal alloy (n=225) or Co-Cr base metal alloy (n=35) frameworks. Ceramic fixed dental prostheses (n=174) were all zirconia based and had monolithic (n=68), completely veneered (n=43), or partially veneered frameworks (n=63).
Most    FDPs (n=384) opposed natural dentition or fixed restorations. In 43 participants, the antagonistic jaw was restored with tooth-supported or implant-supported removable dental prostheses, and the    FDPs of 7 patients opposed a complete denture. Follow-ups were scheduled at 6-month intervals, and radiographs were made at 1-year intervals.

Results and Discussion
In a mean observation period of 4.26 years (maximum: 12.6 years), 17    FDPs failed. Reasons for failure were loss of implants (n=6), loss of abutment teeth (n=5), loosening of an abutment screw (n=1), and extended chipping of veneers (n=5). Kaplan-Meier survival analysis revealed a survival probability of 96% after 5 years and 91% after 10 years. The Kaplan-Meier curves for    FDPs with different types of support revealed similar incidences of chipping for the 3 types of support: implant-implant, tooth- implant, and implant-implant cantilever. The incidence of chipping was, however, found to differ significantly between the different framework materials and veneer types. After 5 years, the probability of chipping for complete veneers was as follows: 18% for high noble metal alloy frameworks, 35% for zirconia frameworks, and 3% for frameworks made from a Co-Cr base metal alloy. After 10 years, the incidence of chipping increased to 23% for high noble metal alloy    FDPs and to 50% for zirconia    FDPs with complete veneers. 

A low probability of chipping after 4 years was observed for zirconia    FDPs with partial veneers (3%) and for zirconia     FDPs without veneer (8%; n=2).
The Cox regression analysis revealed that the variables of age, sex, location (anterior/posterior/ combined), and support had no effect on the dependent chipping variable. A trend toward less chipping was seen in mandibular    FDPs .

Conclusions
Survival was not affected by the framework material, but zirconia was a significant risk factor for chipping with a hazard ratio of 2.76 for    FDPs with a complete veneer.
The incidence of chipping of zirconia     FDPs can be reduced by the use of monolithic zirconia or partial veneers. However, long-term performance cannot be predicted because the observation period for these types of zirconia    FDPs was restricted to a maximum of 5 years.
No differences were found among survival and chipping rates for implant-supported    FDPs , combined tooth-implant-supported    FDPs , and implant-supported cantilever    FDPs . 


Information: Long-term chipping and failure rates of implant-supported and combined tooth–implant-supported metal-ceramic and ceramic fixed dental prostheses: A cohort study.