Zi crowns and 3-unit PFDPs fabricated using the specific CAD-CAM system show good clinical outcomes according to a recent study published in the Journal of Dentistry.
The aim of this retrospective clinical study was to evaluate the survival and the occurrence of technical and biological complications in bi-layered zirconia-based (Zi) single crown and 3-unit fixed dental prostheses (FDPs). Also, the study aimed to analyze the effects of tooth vitality (vital versus non-vital), abutment location (anterior versus posterior), and luting cement (self-adhesive resin versus resin-reinforced glass ionomer) on clinical outcomes.

A total of 147 prostheses (in 94 patients) placed by undergraduate dental students in a university dental center during the period 2015–2021 were examined clinically using modified United States Public Health Service (USPHS) and California Dental Association (CDA) criteria. The mean duration of follow-up was 37 months (range, 6 - 63 months) for the single crowns (n = 77) and 25 months (range, 6 - 68 months) for the 3-unit FDPs (n = 70). Data were descriptively analyzed to determine the types and rates of complications based on USPHS and CDA criteria. The Kaplan-Meier survival estimation method was used to determine the cumulative survival and success rates of the prostheses (α=0.05). Differences in clinical outcomes (survival or failure) according to tooth vitality, luting cement, and location were statistically analyzed using cross-tabulations and Х2 test (α=0.05).
Results
The Kaplan-Meier cumulative survival rate was estimated as 96% for the Zi 3-unit FDPs after 5.5 years, and 90% for the Zi single crowns after 4.8 years.
The 5-year estimated success rate was 68% for both 3-unit FDPs and single crowns. Seven (9.1%) 77Zi single crowns and 70 2 (2.9%) Zi 3-unit FDPs were recorded as failures with occlusal roughness being the most commonly-observed complication (crowns: 4 [5.6%]; 3-unit FDPs: 8 [11.4%]).
In terms of clinical outcomes, statistically significant differences were found between all included vital and non-vital teeth (p = .006), and cement types (p = .028).
Taking single crowns alone, significant differences in clinical outcomes according to tooth vitality were noted (p = .036), but not for PFDPs.
The location of the prostheses did not produce any significant differences in the clinical outcomes, for both prostheses types independently or combined (p > .05).
The estimated cumulative survival rates in this study for single crowns and 3-unit Zi FDPs concurred with the ranges reported in systematic reviews. Zi-based prostheses on vital teeth produced better clinical outcomes than those placed on non-vital teeth, and type of luting cement influenced the final clinical outcome.
Reference:
Reem Alfadhli, Yara Alshammari, Mirza Rustum Baig, Ridwaan Omar. Clinical outcomes of single crown and 3-unit bi-layered zirconia-based fixed dental prostheses: An upto 6- year retrospective clinical study: Clinical outcomes of zirconia FDPs, Journal of Dentistry, Volume 127, 2022, 104321, ISSN 0300-5712. https://doi.org/10.1016/j.jdent.2022.104321.
Keywords:
Reem Alfadhli, Yara Alshammari, Mirza Rustum Baig, Ridwaan Omar, Clinical, outcomes, single, crown, 3-unit, bi-layered, zirconia-based, fixed, dental, prostheses, upto 6- year, retrospective, clinical study, Clinical, outcomes, zirconia, FDPs, Journal of Dentistry