Comparative Study Of Fracture Resistance Between Monolithic Zirconia Crowns And Veneered Zirconia Crowns

Abstract Objectives The aim of this study was to compare the effects of two margin designs (shoulderless and slight chamfer) with two occlusal thicknesses on fracture resistance and failure mode of the monolithic zirconia crowns. Materials and Methods Forty nickel–chromium dies were duplicated from the previous two prepared teeth using a three-dimensional optical scanner. Nickel–chromium supporting dies were divided into two main groups (n = 20) according to the type of margin design: group A, slight chamfer margin design and group B, shoulderless margin design. These groups were further divided into two subgroups according to the occlusal thicknesses (0.5 and 1 mm). The digital imaging of each die was done using a three-dimensional optical scanner, then zirconia blocks were milled by 5-axis machine. The crowns were cleaned by alcohol, air dried, and cemented by resin cement. Next, the crowns were subjected to 500 hot and cold cycles (30 seconds for each cycle). The samples were subjected to a static load until failure using an electronic universal testing machine and fracture resistance was recorded in Newton (N). Statistical Analysis Data were analyzed using the test of normality (Shapiro–Wilk test) and two-way analysis of variance (ANOVA) test. Results The highest mean fracture load was recorded by the shoulderless (1 mm occlusal thickness) subgroup (3,992.5 N), followed by shoulderless (0.5 mm occlusal thickness) subgroup (3,244.4 N), and the slight chamfer (1 mm occlusal thickness) subgroup (2,811 N). The lowest mean of fracture load was recorded by slight chamfer (0.5 mm occlusal thickness) subgroup (1,632.9 N). The two-way ANOVA test revealed a significant difference between the four subgroups. Regarding the fracture mode, the slight chamfer subgroups showed a severe fracture of the restoration while the shoulderless subgroups showed a fracture through the midline of the restoration. Conclusion Within the limitation of the comparative study, shoulderless margin design has a more favorable outcome than a slight chamfer design in all thicknesses. Although the restoration with reduced occlusal thickness has lower fracture resistance than 1 mm occlusal thickness, the 0.5 mm restorations still can tolerate occlusal forces.

Download Full-text

Fracture Resistance of Monolithic Zirconia Crowns in Implant Prostheses in Patients with Bruxism

Materials ◽

10.3390/ma12101623 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1623 ◽

Cited By ~ 3

Author(s):

Ting-Hsun Lan ◽

Chin-Yun Pan ◽

Pao-Hsin Liu ◽

Mitch M. C. Chou

Keyword(s):

Cyclic Loading ◽

Computer Aided Design ◽

Fracture Resistance ◽

Testing Machine ◽

Von Mises Stress ◽

High Fracture ◽

Computer Aided ◽

Zirconia Crowns ◽

Monolithic Zirconia ◽

Von Mises

The aim of this study is to determine the minimum required thickness of a monolithic zirconia crown in the mandibular posterior area for patients with bruxism. Forty-nine full zirconia crowns, with seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm, were made by using a computer-aided design/computer-aided manufacturing system (CAD/CAM). Seven crowns in each group were subjected to cyclic loading at 800 N and 5 Hz in a servohydraulic testing machine until fracture or completion of 100,000 cycles. Seven finite element models comprising seven different occlusal thicknesses of 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0 mm were simulated using three different loads of vertical 800 N, oblique 10 degrees 800 N, and vertical 800 N + x N torque (x = 10, 50, and 100). The results of cyclic loading tests showed that the fracture resistance of the crown was positively associated with thickness. Specimen breakage differed significantly according to the different thicknesses of the prostheses (p < 0.01). Lowest von Mises stress values were determined for prostheses with a minimal thickness of 1.0 mm in different loading directions and with different forces. Zirconia specimens of 1.0 mm thickness had the lowest stress values and high fracture resistance and under 800 N of loading.

Download Full-text

Influence of Different Sintering Protocols on Translucency and Fracture Resistance of Monolithic Zirconia Crowns

Egyptian Dental Journal ◽

10.21608/edj.2020.42653.1257 ◽

2020 ◽

Vol 66 (4) ◽

pp. 2649-2660

Author(s):

Rasha Asaad ◽

Mostafa Aboushahba

Keyword(s):

Fracture Resistance ◽

Zirconia Crowns ◽

Monolithic Zirconia

Download Full-text

Occlusal Thickness and Cement-Type Effects on Fracture Resistance of Implant-Supported Posterior Monolithic Zirconia Crowns

The International Journal of Oral & Maxillofacial Implants ◽

10.11607/jomi.8503 ◽

2021 ◽

Vol 36 (3) ◽

pp. 485-491

Author(s):

Ali Bulut ◽

Saadet Atsü

Keyword(s):

Fracture Resistance ◽

Cement Type ◽

Zirconia Crowns ◽

Monolithic Zirconia

Download Full-text

Comparison of the Fracture Resistance and Fracture Mode of Contemporary Restorative Materials to Overcome the Offset of Mandibular Implant-Supported, Cement-Retained Crowns

Materials ◽

10.3390/ma14174838 ◽

2021 ◽

Vol 14 (17) ◽

pp. 4838

Author(s):

Salwa Omar Bajunaid ◽

Ibraheem Alshiddi ◽

Lamya Alhomaidhi ◽

Rania Almutairi ◽

Shoq Alolayan ◽

...

Keyword(s):

Fracture Mode ◽

Fracture Resistance ◽

Testing Machine ◽

Modes Of Failure ◽

Significant Difference ◽

Restorative Materials ◽

Zirconia Crowns ◽

Group A ◽

Monolithic Zirconia ◽

Group D

Background: The purpose was to compare the fracture resistance and the mode of failure of different contemporary restorative materials to restore implant supported, cement-retained mandibular molars. Methods: Two 5 × 10 mm titanium dental implants were mounted in resin blocks and prefabricated titanium and zirconia abutments were connected to each implant. Each implant received forty crowns resembling mandibular first molars. The specimens were divided into four groups (n = 10/group) for each abutment according to the type of material; Group A: porcelain fused to metal crowns; Group B: monolithic zirconia crowns; Group C: zirconia coping with ceramic veneer; Group D: all ceramic lithium disilicate crowns. Specimens were cemented to the abutments, mounted into a universal testing machine, and vertical static load was applied at a speed of 1 mm/min. The test stopped at signs of visual/audible fracture/chipping. Fracture resistance values were analyzed using ANOVA and Tukey’s tests (α ≤ 0.05). The modes of failure were visually observed. Results: A statistically significant difference (p < 0.001) of the fracture resistance values among tested groups was found. The group that showed the highest fracture resistance was Group A for both the titanium and the zirconia abutments (3.029 + 0.248 and 2.59 ± 0.39, respectively) while Group D for both abutments (1.134 + 0.289 and 1.68 ± 0.13) exhibited the least resistance. Conclusions: Fracture resistance and fracture mode varied depending on type of restorative material. For both titanium and zirconia abutments, porcelain fused to metal showed the highest fracture resistance values followed by monolithic zirconia.

Download Full-text