Long-Term Performance of Bi-Layered Single Crowns Supported by Zirconia Implants - 7.5-Year Results of a Two-Center Prospective Cohort Study

Sep 29, 2026

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Objective: evaluate survival and success of veneered zirconia-based single crowns supported by zirconia implants in posterior regions, together with patient-reported outcomes, over 7.5 years. Methods: 45 patients received zirconia implant-supported posterior single crowns made from zirconia frameworks layered with a leucite-reinforced feldspathic ceramic; clinical parameters, technical complications, and PROs were assessed at follow-up using modified USPHS criteria and VAS analysis. Results: 97.5% Kaplan–Meier survival; success decreased due to chipping, occlusal roughness, marginal crevice, and over-contouring. Conclusion: high survival with stable patient expectations despite notable technical complications.

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Clinical Oral Implants Research ORIGINAL ARTICLE OPEN ACCESS Long-Term Performance ofBi-Layered Single Crowns Supported by Zirconia Implants: 7.5-Year Results of a Two-Center Prospective Cohort Study Marc Balmer1 | Benedikt C. Spies2 | Margherita G. Liguori3 | Kirstin Vach4 | Ronald E. Jung1 | Ralf-Joachim Kohal2 1Clinic of Reconstructive Dentistry, Center for Dental Medicine, University of Zurich, Zurich, Switzerland | 2Medical Center—University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Faculty of Medicine, University of Freiburg, Freiburg, Germany | 3Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy | 4Medical Center—University of Freiburg, Center for Medical Biometry and Medical Informatics, Institute for Medical Biometry and Statistics, Faculty of Medicine, University of Freiburg, Freiburg, Germany Correspondence: Marc Balmer ([marc.balmer@zzm.uzh.ch](marc.balmer@zzm.uzh.ch)) Received: 10 June 2025 | Revised: 31 August 2025 | Accepted: 18 September 2025 Funding: This work was supported by a grant from VITA Zahnfabrik H. Rauter GmbH & Co. KG, Bad Säckingen, Germany. Keywords: ceramics | clinical trials | dental crowns | dental implants | dental prosthesis | humans | implant-supported | patient satisfaction | prosthodontics | zirconium oxide ABSTRACT Objective: To evaluate the survival and success rates of veneered zirconia-based single crowns (SCs) supported by zirconia implants in posterior regions, along with patient-reported outcomes, over 7.5years. Materials and Methods: Forty-five patients received zirconia implant-supported posterior SCs (n = 45) composed of zirconia frameworks layered with a leucite-reinforced feldspathic ceramic. At 7.5years, clinical parameters and technical complications were assessed. Technical success was determined according to modified United States Public Health Service (USPHS) criteria. Patient-reported outcome measures (PROs) were evaluated using visual analog scales (VAS) . Wilcoxon matched-pairs signedrank test, mixed-effects ordered logistic regression, and linear mixed models analyzed time-dependent effects. Results: Thirty SCs (n = 30) could be evaluated at the 7.5-year follow-up (mean: 92.1 ± 3.4months) . Kaplan–Meier survival for SCs was 97.5%[95% CI: 83.6%–99.6%] . Success dropped to 79.4%[63.0%–89.2%] due to reconstructions with major chipping (n = 3), occlusal roughness (n = 7), marginal crevice (n = 1), and over-contouring (n = 2) . PROs showed significant improvements from pre-treatment to delivery (VAS scores: 93%–97%) and remained stable throughout the follow-up period. Conclusion: Veneered zirconia-based SCs supported by zirconia implants in posterior sites demonstrated high survival ratesand consistently met patients' functional and esthetic expectations. Despite these favorable outcomes, the considerable incidence of technical complications warrants further investigation through long-term clinical studies. Clinical Significance: While veneered zirconia crowns offer favorable esthetics, their susceptibility to chipping in posterior regions suggests that monolithic alternatives may be preferable. Further research is needed to optimize material selection and minimize technical complications. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2025 The Author(s). Clinical Oral Implants Research published by John Wiley & Sons Ltd. Clinical Oral Implants Research, 2026; 37:57–68 57 [https://doi.org/10.1111/clr.70051](https://doi.org/10.1111/clr.70051) 1 | Introduction The outcomes of dental implant therapy have steadily improved, with zirconia implants emerging as a reliable addendum to titanium (Pjetursson et al. 2012; Elnayef et al. 2017; Mohseni et al. 2023) . Titanium implants demonstrate high 5-year

FAQs

What is the main objective of the study?

To evaluate the survival and success rates of veneered zirconia-based single crowns supported by zirconia implants in posterior regions, including patient-reported outcomes, over 7.5 years.

How were the crowns and implants constructed and assessed?

Forty-five patients received zirconia implant-supported posterior single crowns with zirconia frameworks layered using a leucite-reinforced feldspathic ceramic. At 7.5 years, clinical parameters and technical complications were assessed using modified USPHS criteria and patient-reported outcomes via VAS.

What were the key findings regarding survival and success?

Kaplan–Meier survival for the single crowns was 97.5%, while success dropped to 79.4% due to major chipping, occlusal roughness, marginal crevice, and over-contouring.

Sep 29, 2026

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