Randomized clinical trial comparing monolithic and veneered zirconia three-unit posterior fixed partial dentures in a complete digital flow: three-year follow-up

Abstract

Objectives To evaluate and to compare the clinical performance and survival rate of posterior monolithic and veneered zirconia fixed partial dentures (FPDs). Material and methods Sixty 3-unit posterior FPDs were included in the study. The patients were randomly distributed into two groups (n = 30 each) to receive either a monolithic (Zenostar T, Wieland Dental) or veneered zirconia (IPS e.max ZirCAD, Ivoclar Vivadent) FPD. Each patient received only 1 FPD. Tooth preparations were scanned (Trios 3, 3Shape), designed (Dental System 2016, 3 Shape), milled (Zenotec CAM 3.2, Wieland Dental), and cemented with a resin cement. Technical and biological outcomes and periodontal parameters were assessed. Data analysis was made using the Friedman and the Wilcoxon signed-rank tests with the Bonferroni correction and the Mann-Whitney U test. ResultsThe survival rate at 3 years was 100% for veneered and 90% for monolithic zirconia restorations. Three monolithic zirconia FPDs were lost because of biologic complications. The main complication in the veneered zirconia FPDs was the fracture of the veneering ceramic in 4 of the veneered zirconia FPDs. No fracture of the frameworks was observed in any of the groups. All restorations were assessed as satisfactory after 3 years. No differences in periodontal parameters were observed between the groups. Conclusions The results of this study suggest that monolithic zirconia and complete digital flow could be a viable alternative to veneered zirconia in the posterior regions. Clinical relevance The monolithic zirconia restorations with a digital workflow can be a viable alternative in posterior fixed partial dentures, with good periodontal outcomes. Clinical trial registration number ClinicalTrials.gov (Identifier NCT 04,879,498).

Digital workflow for monolithic and veneered zirconia and metal-ceramic posterior fixed partial dentures: A five-year prospective randomized clinical trial

“…Periodontal parameters were assessed by assigning a score of 0 to 3 (PI and GI) or 1 to 4 (MI and pocket depth). [6,10,29,36] The level of significance was set at α = 0.05. Statistical analysis was conducted with a statistical software (IBM SPSS Statistics 22.0, IBM Corp, Armonk, NY, USA).…”

“…The presence of probable bruxism was recorded based on positive clinical inspection. [37] The sample size was determined based on previous studies [6,10,13,21,29,38], and a preliminary sample size calculation was conducted using a software program (G*Power 3.1.9.4). The calculation revealed a total sample size of 82, with an effect size of 0.3 at 0.8 power and a significance level of 0.05.…”

“…The fabrication of zirconia restorations has been described in detail in a previous publication. [29] In brief, the FPDs were milled from pre-sintered zirconia blanks (Wieland Zenotec, Wieland Dental) and sintered in a furnace at 1,450ºC for MZ restorations and at 1,500ºC for VZ restorations. The MZ FPDs were carefully polished, characterized, and glazed according to the manufacturer´s instructions.…”

“…A lower assessment score was recorded in the event of discrepancies. The restorations were evaluated using the California Dental Association (CDA) criteria [6,8,10,28,29,36], and periodontal evaluation was performed using the plaque index (PI), gingival index (GI), pocket depth, and margin stability or margin index (MI) of the abutment and control teeth. [6,10,29,36] Mechanical or biological complications were also recorded (framework fracture, loss of retention, veneer chipping, secondary caries, or abutment tooth fracture).…”

“…[8,9,10,27,28] However, owing to the recent introduction of MZ, limited evidence is available to support its recommendation for routine use. [29]…”