Purpose To evaluate the clinical performance and survival rate of posterior monolithic zirconia fixed partial dentures over a 2‐year period. Material and Methods A total of 20 patients, requiring 20 posterior fixed partial dentures were included in the study. Tooth preparations were scanned, and restorations were milled and cemented with a resin cement. The restorations were assessed for the quality of the surface and the color, anatomical form and marginal integrity. Periodontal status was assessed by determining the plaque index, gingival index, pocket depth, and margin index of the abutment teeth. Data were statistically analyzed using the Friedman and the Wilcoxon signed‐rank tests with the Bonferroni correction. Results The survival rate at 2 years was 100%, and no biological or technical complications were observed. All restorations were assessed as satisfactory. The results obtained for gingival index and plaque index were better at 2 years follow‐up, than at baseline. The margin index remained stable throughout the follow‐up period. No differences in periodontal parameters were observed between abutment and control teeth. Conclusions The high survival rate after 2 years suggest that monolithic zirconia may be an acceptable alternative to metal‐ceramic and veneered zirconia restorations in the posterior region. Additional long‐term, controlled studies are necessary to confirm the results.

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).

Biologically oriented preparation technique (BOPT) is a vertical preparation technique without a finish line to create a new anatomic crown with a prosthetic emergence profile. This case report describe the protocol realized digitally in a patient who required a new fixed partial denture (FPD) in the anterior esthetic zone. After time of temporary restoration, definitive conventional (CI) (double-cord retraction and vinyl polysiloxane material), and digital impression (DI) with three different intraoral scanner (IOS) (Trios®, True Definition® and iTero®) were taken. All digital impression were obtained through three different scans: temporary restoration in the mouth after healing period, prepared teeth, and temporary restoration out of the mouth. To establish which of the IOS was the most accurate, it was necessary to compare the STL files obtained from each of the IOS with the STL file of the conventional impression, which was digitized with a laboratory scanner (3Shape D800). All these STL were imported to a software (ExoCAD 2.4 Plovdiv®), and they were superimposed. To establish the difference in trueness with SC, 6 points were chosen, 3 points in teeth, and another 3 points in soft tissue. The mean measurement in terms of trueness in teeth were: STS (0,039 mm), SI (0,054 mm), STD (0,067 mm); and in soft tissue were: STS (0,051 mm), SI (0,09 mm), STD [0,236 mm]. The IOSs showed differences between them in terms of trueness, being the Trios the most accuracy IOS. Final restoration was fabricated and cemented. The patient was examined at 3, 6 and 12 months, without any type of biological or mechanical complications. Digital impression with an IOS seems to be a viable alternative to perform zirconia FPD in the BOPT tecbique. Key words: Intraoral scanners, accuracy, vertical preparation, precision, CAD-CAM, prosthodontics.

Ceramic materials have evolved rapidly in recent years owing to a high esthetic demand in dental treatment. However, despite the wide range of available ceramic materials, the most suitable option, there is no clear option for clinicians, especially for posterior restorations, remains unclear. [1] Zirconia has been introduced as an alternative for metal-free restorations and is the strongest material among all ceramics. [2,3] However, owing to its high opacity, the framework must be veneered with feldspathic ceramics. [2,4] The main disadvantage of veneered zirconia (VZ) is porcelain chipping, [5-10] and monolithic zirconia (MZ) has been introduced as an alternative to VZ. [1,11,12] MZ comprises second-generation zirconia with higher translucency than that of conventional zirconia, which is obtained by reducing the concentration of alumina and the porosity and grain size by increasing the sintering temperature. [2,13] Nevertheless, MZ is not without its drawbacks because the hardness and wear of the opposing tooth can be a concern. It has been reported that restoration surface treatment methods play an important role and that polished surfaces are less abrasive and more favorable considering the wear of the opposing tooth. [14-17] The enamel wear due to MZ crowns is greater than that due to natural teeth [1,17,18] but less than that caused by veneer restorations. [16,[18][19][20][21][22][23] Previous studies have also reported that polished zirconia surfaces cause less enamel wear than does glazed zirconia. This may be due to wear and loss of the glazed surface, which leads to increased surface roughness. [16,17,22] Nevertheless, it has been reported that the combination of polishing and glazing reduces wear of the restoration and its antagonist. [15] Metal-ceramic (MC) restorations have been well examined for years, with survival rates of 94.4%-100% at 5 years and 87%-97.08% at 10 years of follow-up for crowns and fixed partial dentures (FPDs). They are considered the gold standard for fixed prostheses. [6,7,9,10,24,25] Therefore, new materials must provide outcomes comparable to those of MC restorations. [6,9,26,27] Clinical trials have suggested that zirconia can replace MC restorations in the near future. [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]