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The aim of the present study is to compare the color stability between hybrid ceramics (Vita Enamic®) and oxide ceramic (Zirconia). Twenty-four square-shaped specimens were cut using a precision saw machine. 0.8mm thick specimens of 10mm diameter were prepared with high-translucent CAD/CAM blocks by slicing them with a water-cooled diamond disk at low speed (150 rpm). The 0M1 color for Enamic® and zirconia specimens was chosen according to the Vita Easy shade guide (Vita Zahnfabrik, Germany). Each group of Zirconia and Enamic® was subdivided into three subgroups, four samples each, immersed in coffee, Pepsi®, and Perio Lacer mouthwash. Then, underwent shade measurement specimens using Vita Easy Shade. Data was collected and statistically analyzed using SPSS version 18.0 (SPSS Inc., Chicago IL, USA). Zirconia showed no difference in color in a specimen immersed in both coffee and Pepsi®. A slight difference in color after immersion in Perio Lacer mouthwash was observed. Regarding Enamic®, there was a change in the color of the specimens when placed in coffee, Pepsi®, and Perio Lacer mouthwash with the highest color change seen in the Perio Lacer mouthwash group. Color changes were mainly found in the Enamic® subgroups. Regarding the Zirconia specimen, changes were found only in the Perio Lacer mouthwash subgroup. [ABSTRACT FROM AUTHOR]

This prospective clinical trial aimed at evaluating the clinical performance of three-unit posterior zirconia fixed dental prostheses (FDPs) after 5 years of clinical function. Thirty-seven patients received 48 three-unit zirconia-based FDPs. The restorations replaced either a premolar or a molar. Specific inclusion criteria were needed. Tooth preparation was standardized. Computer-aided design/computer-assisted manufacturing frameworks with a 9-mm cross section of the connector and a 0.6-mm minimum thickness of the retainer were made. The restorations were luted with resin cement. The patients were recalled after 1, 6, 12, 24, 36, 48, and 60 months. The survival and success of the ceramics and zirconia were evaluated. The technical and aesthetic outcomes were examined using the United States Public Health Service criteria. The biologic outcomes were analyzed at abutment and contralateral teeth. Descriptive statistics were performed. All FDPs completed the study, resulting in 100% cumulative survival rate and 91.9% and 95.4% cumulative success rates for patients wearing one and two FDPs, respectively. No losses of retention were recorded. Forty-two restorations were rated alpha in all measured parameters. A minor chipping of the ceramics was detected in three restorations. No significant differences between the periodontal parameters of the test and control teeth were observed. Five-year clinical results proved that three-unit posterior zirconia-based FDPs were successful in the medium term for both function and aesthetic. Zirconia can be considered a promising substitute of metal frameworks for the fabrication of short-span posterior prostheses. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To compare the reliability of the disto-facial (DF) and mesio-lingual (ML) cusps of an anatomically correct zirconia (Y-TZP) crown system. The research hypotheses tested were: (1) fatigue reliability and failure mode are similar for the ML and DF cusps; (2) failure mode of one cusp does not affect the failure of the other. Methods: The average dimensions of a mandibular first molar crown were imported into CAD software; a tooth preparation was modelled by 1.5mm marginal high reduction of proximal walls and occlusal surface by 2.0mm. The CAD-based tooth preparation was milled and used as a die to fabricate crowns (n =14) with porcelain veneer on a 0.5mm Y-TZP core. Crowns were cemented on composite reproductions of the tooth preparation. The crowns were step-stress mouth motion fatigued with sliding (0.7mm) a tungsten-carbide indenter of 6.25mm diameter down on the inclines of either the DF or ML cusps. Use level probability Weibull curve with use stress of 200N and the reliability for completion of a mission of 50,000 cycles at 200N load were calculated. Results: Reliability for a 200N at 50,000 cycles mission was not different between tested cusps. SEM imaging showed large cohesive failures within the veneer for the ML and smaller for the DF. Fractures originated from the contact area regardless of the cusp loaded. Conclusion: No significant difference on fatigue reliability was observed between the DF compared to the ML cusp. Fracture of one cusp did not affect the other. [ABSTRACT FROM AUTHOR]

Article Title and Bibliographic Information: Effect of cement type on the clinical performance and complications of zirconia and lithium disilicate tooth-supported crowns: A systematic review. Report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics. Maroulakos G, Thompson GA, Kontogiorgos ED. J Prosthet Dent 2019;121:754-65., Source of Funding: Unknown., Type of Study/design: Systematic review., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Aim/Purpose: The primary aim of this study was to examine the clinical performance of posterior monolithic single crowns in terms of failure or complications and the secondary aim was to assess the quality of these restorations according to the United States Public Health Service (USPHS) criteria. Methods: Ιn a private dental clinic, 65 patients with need of posterior crowns were restored with monolithic zirconia crowns. All the restorations were evaluated 6 and 12 months after their cementation. The modified United States Public Health Service (USPHS) criteria and periodontal parameters were applied for the clinical evaluation of the crowns. Restorations with Alpha or Bravo rating were considered a success. Results: Descriptive statistics and nonparametric tests were used for statistical analysis. Sixty-five patients (mean age: 49.52) were restored with 65 monolithic zirconia crowns. No fracture of the restorations was recorded. The overall success rate was 98.5%. The clinical quality of all crowns was acceptable except for the marginal discoloration of one crown at the 6- and 12-month follow-up examination. Conclusions: In this study, no fracture of single-tooth monolithic crowns occurred and the success rate was high. Monolithic zirconia restorations fabricated is a viable option for the restoration of single posterior teeth.