scholarly journals An In Vitro Comparative Study to Assess Minimal Thickness Required for Monolithic Zirconia Crowns to Resist Fracture under Load on Rapid Prototyped Models

2020 ◽  
Vol 21 (2) ◽  
pp. 183-189
Author(s):  
Vinod Narayanan ◽  
Vandana Narayanan ◽  
Shivkumar A Devanarayanan
Keyword(s):  
Comparative Study ◽  
Minimal Thickness ◽  
Zirconia Crowns ◽  
Monolithic Zirconia

scholarly journals Load-Bearing Capacity of Zirconia Crowns Screwed to Multi-Unit Abutments with and without a Titanium Base: An In Vitro Pilot Study

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3056
Author(s):  
Hadas Heller ◽  
Adi Arieli ◽  
Ilan Beitlitum ◽  
Raphael Pilo ◽  
Shifra Levartovsky
Keyword(s):  
Failure Modes ◽  
Load Bearing ◽  
Zirconia Crowns ◽  
Group A ◽  
Monolithic Zirconia ◽  
Loading Tests ◽  
Group B ◽  
Iso 14801 ◽  
Static And Dynamic Loading

The static and dynamic load-bearing capacities and failure modes of zirconia crowns screwed to multi-unit abutments (MUAs) with and without a titanium base (T-base) were determined. Thirty-six monolithic zirconia crowns screwed to straight MUAs torqued to laboratory analogs (30 Ncm) were assigned to two groups (n = 18). In group A, the zirconia crowns were screwed directly to the MUAs; in group B, the zirconia crowns were cemented to the T-base and screwed to the MUAs. All specimens were aged in 100% humidity (37 °C) for one month and subjected to thermocycling (20,000 cycles). Afterwards, the specimens underwent static and dynamic loading tests following ISO 14801. The failure modes were evaluated by stereomicroscopy (20×). There was an unequivocally similar trend in the S-N plots of both specimen groups. The load at which the specimens survived 5,000,000 cycles was 250 N for both groups. Group A failed mainly within the metal, and zirconia failure occurred only at a high loading force. Group B exhibited failure within the metal mostly in conjunction with adhesive failure between the zirconia and T-base. Zirconia restoration screwed directly to an MUA is a viable option, but further studies with larger sample sizes are warranted.

scholarly journals Trueness and precision of 3D-printed versus milled monolithic zirconia crowns: an in vitro study

2021 ◽  
pp. 103792
Author(s):  
Henriette Lerner ◽  
Katalin Nagy ◽  
Nicola Pranno ◽  
Fernando Zarone ◽  
Oleg Admakin ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
3D Printed

scholarly journals Fracture Strength of Monolithic Zirconia Crowns with Modified Vertical Preparation: A Comparative In Vitro Study

2021 ◽  
Author(s):  
Marwah Ismael Abdulazeez ◽  
Manhal A. Majeed
Keyword(s):  
Fracture Strength ◽  
In Vitro Study ◽  
Fracture Load ◽  
Significant Difference ◽  
Zirconia Crowns ◽  
Group A ◽  
Monolithic Zirconia ◽  
Bonferroni Test ◽  
Group B

Abstract Objective The aim of this study was to evaluate the influence of different marginal designs (deep chamfer, vertical, and modified vertical with reverse shoulder) on the fracture strength and failure modes of monolithic zirconia crowns. Materials and Methods Thirty sound human maxillary first premolar teeth with comparable size were used in this study. The teeth were divided randomly into three groups according to the preparation design (n = 10): (1) group A: teeth prepared with a deep chamfer finish line; (2) group B: teeth prepared with vertical preparation; and (3) group C: teeth prepared with modified vertical preparation, where a reverse shoulder of 1 mm was placed on the buccal surface at the junction of middle and occlusal thirds. All samples were scanned by using an intraoral scanner (CEREC Omnicam, Sirona, Germany), and then the crowns were designed by using Sirona InLab 20.0 software and milled with a 5-axis machine. Each crown was then cemented on its respective tooth with self-adhesive resin cement by using a custom-made cementation device. A single load to failure test was used to assess the fracture load of each crown by using a computerized universal testing machine that automatically recorded the fracture load of each sample in Newton (N). Statistical Analysis The data were analyzed statistically by using one-way analysis of variance test and Bonferroni test at a level of significance of 0.05. Results The highest mean of fracture load was recorded by chamfer (2,969.8 N), which followed by modified vertical (2,899.3 N) and the lowest mean of fracture load was recorded by vertical (2,717.9 N). One-way ANOVA test revealed a significant difference among the three groups. Bonferroni test showed a significant difference between group A and group B, while a nonsignificant difference was revealed between group C with group A and group B. Conclusion Within the limitations of this in vitro study, the mean values of fracture strength of monolithic zirconia crowns of all groups were higher than the maximum occlusal forces in the premolar region. The modification of the vertical preparation with a reverse shoulder placed at the buccal surface improved the fracture strength up to the point that it was statistically nonsignificant with the chamfer group.

scholarly journals A Comparative Evaluation of the Marginal and Internal Fit of Laboratory-fabricated Monolithic Zirconia Crowns using Direct and Indirect Methods of Scanning: An in vitro Study

2017 ◽  
Vol 7 (1) ◽  
pp. 22-27
Author(s):  
Kushal N Gandhi
Keyword(s):  
Stainless Steel ◽  
Indirect Method ◽  
Direct Method ◽  
Indirect Methods ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
The Mean ◽  
Internal Fit ◽  
Direct And Indirect Methods

ABSTRACT Aim To evaluate the marginal and internal fit of laboratoryfabricated monolithic zirconia crowns using direct and indirect methods of scanning. Materials and methods A stainless steel master model was selected, which included stainless steel die, outer cap, and inner cap. The study was divided into two groups. In group I, direct method of scanning was carried out in which the stainless steel die was scanned directly with chairside scanner, and in group II, impression of the stainless steel die was made and gypsum die was fabricated, which was then subjected to scanning. Zirconia blanks or blocks were milled, sintered, and polished to obtain 10 zirconia crowns of each group. Replica technique was used to evaluate fit of crowns by using light body as cement analog. The crowns were then sectioned, viewed under a stereomicroscope, and each predetermined region was measured and evaluated for marginal and internal fit. Results The descriptive statistics showed that the mean marginal fit for indirect method was higher compared with that for direct method. The results of paired-sample t-test revealed that mean marginal and internal fit for indirect method was on the upper side of the scale, whereas the mean for the direct method is on the lower side of the scale. Thus, the difference in the means of two methods was quite large and likely to be significant. Conclusion The results did show better marginal and internal fit in crowns fabricated by the direct method; however, the crowns fabricated by the indirect method had more discrepancy, but were in the clinically acceptable limit. Clinical significance The present study would serve as a useful guide in deciding which method of scanning would give a better marginal and internal fit of monolithic zirconia crowns for longevity of restorations. How to cite this article Gandhi KN, Ram SM. A Comparative Evaluation of the Marginal and Internal Fit of Laboratory-fabricated Monolithic Zirconia Crowns using Direct and Indirect Methods of Scanning: An in vitro Study. J Contemp Dent 2017;7(1):22-27.

Influence of CAD/CAM Fabrication and Sintering Procedures on the Fracture Load of Full-Contour Monolithic Zirconia Crowns as a Function of Material Thickness

2020 ◽  
Vol 45 (2) ◽  
pp. 219-226 ◽  
Author(s):  
M Zimmermann ◽  
A Ender ◽  
A Mehl
Keyword(s):  
Computer Aided Design ◽  
Mean Value ◽  
Fracture Load ◽  
Significance Level ◽  
Material Thickness ◽  
Computer Aided ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Monolithic Zirconia

Summary Objective: The purpose of this in vitro study was to analyze the effect of computer-aided design/computer-aided manufacturing (CAD/CAM) fabrication and sintering procedures on the fracture load of monolithic zirconia crowns with different material thicknesses adhesively seated to methacrylate dies fabricated with stereolithography technology. Method: Monolithic zirconia crowns were fabricated from inCoris TZI C material with a chairside CAD/CAM system (CEREC MCXL) comprising three material thicknesses (0.5/1.0/1.5 mm, n=8 each). Two CAD/CAM fabrication procedures (milling, MI; grinding, GR), two chairside sintering procedures (superspeed, SS; speedfire sintering, SF), and one labside sintering procedure (classic, CL) were evaluated. In total, 144 crowns were fabricated. Restorations were adhesively seated to methacrylate dies fabricated with SLA technology. Thermomechanical cycling (TCML) was performed before fracture testing. Loading forces until fracture were registered and statistically analyzed with one-way analysis of variance (ANOVA), post hoc Scheffé test, and three-way ANOVA (α=0.05). Results: Test groups showed statistically significant differences (p<0.05). The highest mean value was found for 1.5-mm crowns of group GR_SF with 3678.6 ± 363.9 N. The lowest mean value was found for group 0.5-mm crowns of group MI_SF with 382.4 ± 30.7 N. There was a significant three-way interaction effect between thickness, sintering, and processing [F(4,126)=9.542; p<0.001; three-way ANOVA, significance level α=0.05]. Conclusions: CAD/CAM fabrication and sintering procedures influence the maximum loading force of monolithic zirconia crowns with different material thicknesses. A material thickness of 0.5 mm should be considered as a critical thickness for monolithic zirconia crown restorations.

In vitro performance of implant-supported monolithic zirconia crowns: Influence of patient-specific tooth-coloured abutments with titanium adhesive bases

2015 ◽  
Vol 43 (7) ◽  
pp. 839-845 ◽  
Author(s):  
Martin Rosentritt ◽  
Andreas Rembs ◽  
Michael Behr ◽  
Sebastian Hahnel ◽  
Verena Preis
Keyword(s):  
Patient Specific ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
In Vitro Performance

scholarly journals High-Strength Porcelain Veneering of Zirconia Prosthetic Mimetic Restorations (PRIMERO) by Cognitive Design and Manufacturing

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
High Strength ◽  
Long Term Effects ◽  
Design And Manufacturing ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
Color Gradients ◽  
Cognitive Design

Esthetic prosthetic restorations, with natural reflection, color from within and color gradients influenced by the internal dentinal core anatomy can best be accomplished by veneered zirconia, rather than with crowns of color and structure graded monolithic zirconia. Concern about the high incidence of chipping with some of the porcelains for zirconia substructures has led to a massive shift from veneered zirconia to the use of monolithic zirconia for crowns and bridges. Because zirconia has four times the hardness of metal, initial concern about antagonist abrasion could with numerous studies be negated. Clinical long-term effects of lack of abrasion of full zirconia crowns, in comparison with 30-75 μm/year for surrounding and opposing dentition is still poorly documented. Massive crack formation in enamel probes has been reported in specimens after in-vitro fatigue testing with opposing monolithic zirconia. In-vitro and clinical studies have shown that only reinforcement of the structure of veneering material can prevent chipping. This article compares the fatigue behavior of three-unit bridges with a substructure of Primero zirconia veneered with Primero Enamel (PR) with bridges with Cercon Base zirconia inner-structure veneered with Ceramco PFZ and Cercon Ceram S (CR1 and CR2) and assess the possibilities and increase their scope to cognitive design and manufacturing of porcelain veneered zirconia crowns and bridges. Fatigue testing of four times eight 3-unit bridges were produced for each of the three porcelains and a reference. The results show that efficient crack-stopping prevented chipping with the PR bridges, while the bridges with conventional porcelains CR1 and CR2, showed failures. We conclude that chipping is mainly porcelain related. Cognitive design and fabrication of the dentin zirconia core will lead to prosthetic mimetic restorations (PRIMERO) with natural esthetics.

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