The Effect of Thickness on the Fracture Strength and Failure Modes of Zirconia Crowns

2016 ◽  
Vol 697 ◽  
pp. 629-632
Author(s):  
Li Xian Zhang ◽  
Rui Li ◽  
Yu Niu ◽  
Yu Xiao Liu
Keyword(s):  
Fracture Strength ◽  
Failure Modes ◽  
Statistical Significance ◽  
Dental Practice ◽  
Significant Difference ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Different Thickness

To explore the effect of thickness on the fracture strength and failure modes of zirconia crowns, four crown models with different thickness (1.2 mm, 1.0 mm, 0.8 mm, 0.6 mm) with the same shape were designed by Dental Designer software in CAD/CAM system. They were manufactured to 40 zirconia crowns by CAM carving machine. The fracture strength and the failure modes of each crown was measured, while porcelain fused to metal (PFM) crowns as control. The average fracture strength of different zirconia crowns were recorded as below: 1308.38 ± 111.38 N (Group 0.6 mm), 1841.60 ± 68.21 N (Group 0.8 mm), 2429.88 ± 315.03 N (Group 1.0 mm), 3068.31 ± 233.88 N (Group 1.2 mm). There was no significant difference between Group 1.0 mm and Group 1.2 mm (P > 0.05), and statistical significance was obtained among every other two groups (P < 0.05). The failure modes of different thickness zirconium crowns are similar. There are more broken pieces from thicker crowns compared to thinner ones. It is concluded that the thickness can influence the fracture strength of zirconia crown. With the increase of the thickness, the fracture strength of the zirconium crowns also increases. We recommend zirconia crowns thicker than or at least 1.0 mm in dental practice.

Fracture Strength and Precision of Fit of Implant-Retained Monolithic Zirconia Crowns

2018 ◽  
Vol 44 (5) ◽  
pp. 330-334 ◽  
Author(s):  
Pauliina Moilanen ◽  
Jenni Hjerppe ◽  
Lippo V. J. Lassila ◽  
Timo O. Närhi
Keyword(s):  
Fracture Strength ◽  
Computer Aided Design ◽  
Testing Machine ◽  
Implant Surface ◽  
Computer Aided ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Failure Loads ◽  
Monolithic Zirconia ◽  
Aided Design

New monolithic zirconia materials can be used to fabricate full-contour fixed dental prostheses with the computer-aided design/computer-aided manufacturing (CAD/CAM) method. The aim of this study was to examine the fracture strength and precision of fit of screw-retained monolithic zirconia crowns made directly on implants or by cementing on prefabricated titanium (Ti) bases. Monolithic screw-retained implant crowns (n = 6) were produced by CAD/CAM method using partially (PSZ) and fully stabilized (FSZ) zirconia. Industrially produced zirconia crowns were used as a reference. A lateral incisor study model was made onto an implant replica. Crowns were produced either directly on the implant or through cementing on a prefabricated titanium base (PSZ+Ti, FSZ+Ti). The crowns were tightened to implant replicas with a torque of 35 Ncm. The gap between the replica and the abutment or crown was measured from ×400 scanning electron microscope images for precision of fit. Mechanical testing until failure was completed with a universal testing machine with loading angle of 45°. Statistical analysis was performed (analysis of variance). Mean (±SD) failure loads were 259 ± 23 (PSZ), 140 ± 13 (FSZ), 453 ± 25 (PSZ+Ti), 439 ± 41 (FSZ+Ti), and 290 ± 39 (Procera). Mean (±SD) gap values were 2.2 ± 0.2 (PSZ), 2.5 ± 1.0 (FSZ), 7.0 ± 1.0 (PSZ+Ti), 7.7 ± 1.6 (FSZ+Ti), and 6.7 ± 1.7 (Procera). Monolithic zirconia crowns with a Ti base clearly show higher fracture strengths than the crowns fixed directly on the implant surface. Better marginal fit can be achieved with direct zirconia crowns than with crowns on a titanium base or industrially produced zirconia crowns.

scholarly journals In Vitro Comparison of Marginal and Internal Fit of Zirconia Copings Fabricated by One CAD/CAM System with Two Different Scanners

2021 ◽  
Author(s):  
Zahra Khamverdi1 ◽  
Elmira Najafrad ◽  
Maryam Farhadian
Keyword(s):  
T Test ◽  
Marginal Fit ◽  
Significant Difference ◽  
Computer Aided ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Monolithic Zirconia ◽  
The Mean ◽  
Internal Fit ◽  
Paired T Test

Objectives: Marginal and internal fit of restorations are two important clinical factors for assessing the quality and durability of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated monolithic zirconia restorations. The purpose of this study was to evaluate the marginal and internal fit of CAD/CAM zirconia crowns with two different scanners (i3D scanner and 3Shape D700). Materials and Methods: Twelve extracted sound human posterior teeth were prepared for full zirconia crowns. Two different extraoral scanners namely i3D scanner and 3Shape D700 were used to digitize type IV gypsum casts poured from impressions. The crowns were milled from presintered monolithic zirconia blocks by a 5-axis milling machine. The replica technique and MIP4 microscopic image analysis software were utilized to measure the marginal and internal fit by a stereomicroscope at ×40 magnification. The collected data were analyzed by paired t-test. Results: The mean marginal gap was 203.62 μm with 3Shape D700 scanner and 241.07 μm with i3D scanner. The mean internal gap was 192.30 μm with 3Shape D700 scanner and 196.06 μm with i3D scanner. The results of paired t-test indicated that there was a statistically significant difference between the two scanners in marginal fit (P=0.04); while, there was no statistically significant difference in internal fit (P=0.761). Conclusion: Within the limitations of this study, the results showed that type of extraoral scanner affected the marginal fit of CAD/CAM fabricated crowns; however, it did not have a significant effect on their internal fit.

scholarly journals Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants

2015 ◽  
Vol 41 (S1) ◽  
pp. 352-359 ◽  
Author(s):  
Tonino Traini ◽  
Roberto Sorrentino ◽  
Enrico Gherlone ◽  
Federico Perfetti ◽  
Patrizio Bollero ◽  
...  
Keyword(s):  
Fracture Strength ◽  
Glass Ceramic ◽  
Ceramic Materials ◽  
Fracture Load ◽  
Fractographic Analysis ◽  
Core Material ◽  
Loading Test ◽  
Significant Difference ◽  
Cad Cam ◽  
Ceramic Crowns

Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

scholarly journals Evaluating the effect of different combination of impression and pouring materials on marginal and internal adaptation of zirconia crowns.

2020 ◽  
Vol 9 (5) ◽  
pp. 414-422
Author(s):  
Safoura Ghodsi ◽  
◽  
Sara Mogharrabi ◽  
Samane Jalali ◽  
Asadallah Ahmadzadeh ◽  
...  
Keyword(s):  
Finish Line ◽  
Significant Difference ◽  
Different Types ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Maxillary Premolars ◽  
Internal Adaptation ◽  
The Mean ◽  
Internal Gap ◽  
Exact Relationship

Purpose: Two important factors in dental prosthesis are making an accurate impression and producing a suitable cast which represents the exact relationship between prepared tooth and oral structures. This study, aimed to investigate the effects of different combinations of impression and pouring materials on marginal and internal adaptation of premolar zirconia crowns. Material and Methods: Forty maxillary premolars were prepared considering round shoulder finish line. The impressions were made either by additional (Panasil) or condensation (Speedex) silicon, and poured by two different types of gypsum materials (Siladent or GC gypsum) (N=10). Zirconia crowns were fabricated using a CAD-CAM system. The crowns were cemented, and the samples were cut in bucco-lingual direction. Marginal and internal gaps were measured by stereomicroscope (×25). Results: The mean marginal gaps for Pansil-Siladent, Panasil-GC, Speedex-Siladent, and Speedex-GC were 141 μm, 143 μm, 131 μm, and 137 μm respectively. The internal gaps were 334 μm, 292 μm, 278 μm, and 257 μm respectively. The independent T-Student test showed no significant differences in average marginal or internal gap among various impression and gypsum materials or their interactions (p>0.05). Two-way ANOVA test showed no significant differences in maximum marginal or internal gap among various impression and gypsum materials and their interactions (p>0.05). Conclusion: The present study revealed no statistically significant difference in marginal/internal gap among crowns prepared using different combinations of impression-pouring materials evaluated.

Efficacy of Direct Restorative Materials in Proximal Box Elevation on the Margin Quality and Fracture Resistance of Molars Restored With CAD/CAM Onlays

2020 ◽  
Vol 45 (1) ◽  
pp. 52-61 ◽  
Author(s):  
TD Grubbs ◽  
M Vargas ◽  
J Kolker ◽  
EC Teixeira
Keyword(s):  
Fracture Resistance ◽  
Statistical Significance ◽  
Cyclic Fatigue ◽  
Control Group ◽  
Type Ii ◽  
Glass Ionomer ◽  
Significant Difference ◽  
Computer Aided ◽  
Cad Cam ◽  
Proximal Box Elevation

SUMMARY Purpose: The purpose of this study was to investigate the effect of four direct restorative materials that can be used in the proximal box elevation (PBE) technique. Methods and Materials: Seventy-five molar teeth were randomly assigned to one of five groups (n=15): type II glass ionomer (GI), type II resin-modified glass ionomer (RMGI), resin-based composite (RBC), bulk-fill (BF) resin-based composite, and a control with no box elevation procedure. Specimens were prepared for a standard mesio-occlusal-distal, computer-aided design/computer-aided manufactured (CAD-CAM) resin, nanoceramic onlay with mesial cervical margins located 1 mm above the cementoenamel junction (CEJ) and distal cervical margins located 2 mm below the CEJ. PBE was used to elevate the distal margins to 1 mm above the CEJ in all groups except the control group. For the control group the onlay margin was placed directly on the prepared distal tooth structure without PBE. A Lava Ultimate CAD/CAM resin, nanoceramic onlay restorative was manufactured and bonded on all specimens with RelyX Ultimate adhesive resin cement. The quality of the tooth-PBE material and PBE material-onlay interface was evaluated with scanning electron microscopy using epoxy resin replicas before and after cyclic loading (100,000 cycles, 1.2 Hz at 65N and 37°C). In addition to margin quality, the fracture resistance of each group was measured using a universal testing machine. Fracture pattern was recorded by visual examination. The Levene test for homogeneity and the Welch analysis of variance were completed for fracture resistance and margin quality. A χ2 test was completed for break mode. Results: For dentin margins, a statistically significant difference was detected between the RMGI and control groups at baseline (p=0.0442). All other groups—GI, RBC, and BF—showed no difference from the control at baseline (p&gt;0.05). No statistical significance was observed among groups for post-cyclic fatigue (p=0.8735). For onlay margins, no statistical significance was observed among groups for pre-cyclic fatigue, post-cyclic fatigue, or change (p=0.9713, p=0.528, p=0.4385, respectively). No significant difference was observed for the fracture resistance among groups or for the type of break by material used (p=0.1593, p=0.77, respectively). Conclusion: Within the parameters of this study, after mechanical fatigue, the materials used for PBE: RMGI, RBC, and BF, did not influence results in terms of margin quality and fracture resistance. Therefore, collective findings suggest that these materials might be suitable for PBE procedures. Nevertheless, clinical caution is recommended with any PBE procedure and further testing of GI materials is needed.

scholarly journals Effect of Veneering and Hydrothermal Aging on the Translucency of Newly Introduced Extra Translucent and High Translucent Zirconia with Different Thicknesses

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Sevki Cinar ◽  
Bike Altan
Keyword(s):  
Statistical Analysis ◽  
Contrast Ratio ◽  
Zirconia Ceramics ◽  
Hydrothermal Aging ◽  
Material Type ◽  
Significant Difference ◽  
Before And After ◽  
Cad Cam ◽  
Different Thickness

Purpose. The purpose of this study was to evaluate the effect of veneering and aging on the translucency of newly introduced extra and high translucent zirconia with different thickness. Materials and Methods. One hundred forty disk-shaped specimens were fabricated from two translucent zirconia blocks (VITA YZ XT and VITA YZ HT), and they are milled with CAD/CAM system. Then, specimens were divided into nonveneered (XT, HT) and veneered groups (XTV, HTV). Nonveneered groups were prepared with four different thicknesses (0.5-1-1.5-2 mm). Veneered groups were divided into three subgroups ( n = 10 ) for veneering with base dentin ceramic with thicknesses of 0.5 + 0.5 , 0.5 + 1 , and 0.5 + 1.5   mm . A spectrophotometer was used to calculate the translucency parameter (TP) and contrast ratio (CR) of all specimens before and after aging. Statistical analysis was performed using 3-way ANOVA and Tukey HSD tests ( p < 0.05 ). Results. TP values were significantly affected by thickness of specimens ( p < 0.001 ). VITA YZ XT was significantly found more translucent than VITA YZ HT. The highest translucency was observed in the XT-0.5 mm group. There is no significant difference between translucency of the veneered and nonveneered groups in the same thickness for XT. On the contrary, veneering significantly affected translucency of HT. TP values significantly decreased after aging for all groups. After aging, translucency value difference before and after aging was the highest in the XT-0.5 mm group whereas the HTV-2 mm group showed the lowest difference after aging. TP decreased significantly as thickness of specimen increases regardless of the material type. Extra translucent and nonveneered zirconia groups are more prone to hydrothermal aging. Conclusions. The translucency parameter of zirconia ceramics was significantly influenced by both material type and veneering. Also, extra translucent and nonveneered zirconia groups are more susceptible to hydrothermal aging.

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 Evaluation of Marginal Gap / Fit of Zirconia Copings & Full Contoured Monolith Zirconia Crowns (CAD / CAM) - A Comparative In-Vitro Study

2021 ◽  
Vol 10 (20) ◽  
pp. 1483-1488
Author(s):  
Liya Zacharias
Keyword(s):  
Experimental Study ◽  
P Value ◽  
Marginal Gap ◽  
Marginal Fit ◽  
Type Iv ◽  
Significant Difference ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Group 2

BACKGROUND Inadequate marginal fit of fixed restorations leads to plaque accumulation, recurrent caries and periodontal problems. The purpose of this experimental study is to evaluate and compare the marginal fit/gap of computer-aided design and computeraided manufacturing (CAD/CAM) fabricated zirconia copings and zirconia full contoured monolith crowns fabricated on type IV gypsum die having a definite cement spacer thickness of 0.05mm. METHODS This is an in-vitro experimental study carried out from November 2018 to November 2019. A master stainless steel die was used to make 52 type IV die stone models which were randomly divided into 2 groups of 26 samples each. Group 1: zirconia copings and group 2: zirconia monolith full contoured crowns. These restotations were fabricated using CAD/CAM. The marginal gap of each zirconia copings and zirconia full contoured crowns was assessed using scanning electron microscopic analysis on four different pre-marked points (GEMINI SEM 500; ZEISS). Observations were tabulated and analyzed statistically. Independent t-test was used to compare the measurements between zirconia copings & zirconia monolith crowns. RESULTS The least marginal gap observed was for group 2 (zirconia full contoured crown) with a mean value of 29.88 ± 9.16 μm while that of group1 (zirconia coping) was 73.64 ± 28.13 μm. There was a statistically significant difference in the measurements between zirconia copings and zirconia full contoured monolith crowns (P - value < 0.001). There was statistically significant difference in each side of zirconia monolith crowns when compared to the corresponding side of zirconia copings (P - Value < 0.001). CONCLUSIONS CAD/CAM milled full contoured zirconia crowns showed least marginal discrepancy when compared to zirconia copings. All samples had marginal gap within the clinically acceptable range of 120 μm. KEY WORDS Monolith, Zirconia Crowns, Zirconia Copings, Full Contoured Crowns, CAD-CAM

scholarly journals Fracture Strength and Translucency of CAD/CAM Zirconia Crown for Primary Anterior Tooth

2020 ◽  
Vol 47 (2) ◽  
pp. 205-212
Author(s):  
Seung-Hwan Ong ◽  
Jongsoo Kim ◽  
Jongbin Kim ◽  
Jisun Shin ◽  
Seunghoon Yoo
Keyword(s):  
Fracture Strength ◽  
Computer Aided Design ◽  
Testing Machine ◽  
Compressive Force ◽  
Computer Aided ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Pulp Exposure ◽  
Aided Design ◽  
Strip Crown

The purpose of this study is to evaluate the validity of primary anterior zirconia crown made with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) technology by analyzing fracture strength and translucency parameter.<br/>Zirconia crown was designed with CAD software, using 3D scanned data of #61 tooth model. Crown fabrication was performed with CAM machine using zirconia block. Zirconia crowns were divided into 3 groups according to thickness(0.3, 0.5, and 0.7 mm), and fracture strength was compared with 1.0 mm thickness of resin strip crown. The compressive force was applied with universal testing machine at 30° along the incisal edge at increments of 1 mm/min. For translucency evaluation, 0.3, 0.5, and 0.7 mm thickness of zirconia specimens were fabricated and translucency was measured with spectrophotometer.<br/>Among zirconia groups, there was a significant increase in fracture strength as thickness increased (<i>p</i> < 0.05). The fracture strength of zirconia crown was significantly higher than resin strip crown in all groups (<i>p</i> < 0.05). Translucency parameter was highest in 0.3 mm group, and significantly decreased as thickness increased to 0.5 and 0.7 mm (<i>p</i> < 0.05).<br/>Thin primary anterior zirconia crown can be designed and fabricated according to individual needs by using CAD/CAM. Restoration with thin crown would reduce the amount of tooth reduction, risk of pulp exposure, and make more esthetic restoration possible.

scholarly journals Soft Denture Liner Adhesion to Conventional and CAD/CAM Processed Poly(Methyl Methacrylate) Acrylic Denture Resins-An In-Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6614
Author(s):  
Sara Mohammad Al Taweel ◽  
Hanan Nejer Al-Otaibi ◽  
Nawaf Labban ◽  
Afnan AlFouzan ◽  
Huda Al Shehri
Keyword(s):  
Bond Strength ◽  
Methyl Methacrylate ◽  
Surface Treatment ◽  
Failure Modes ◽  
Airborne Particle ◽  
Poly Methyl Methacrylate ◽  
Acrylic Resins ◽  
Significant Difference ◽  
Cad Cam ◽  
Denture Liners

This study aimed to evaluate the airborne-particle abrasion surface treatment effects on the tensile bond strength (TBS) between resilient denture liner and CAD/CAM or conventional heat polymerized poly (methyl methacrylate) (PMMA) acrylic denture resins. A total of 48 dumbbell-shaped specimens (70 mm in total length, and 12 mm and 7 mm in diameter at the thickest and thinnest section, respectively) were prepared from CAD/CAM and conventional acrylic resins. Before relining with denture liner, 12 specimens from each material were surface-treated by 110 µm Al2O3 airborne-particle abrasion, and the remaining specimens served as control (no treatment). Following relining, all the specimens were aged by thermal cycling (1000 cycles, 5–55 °C). The TBS of denture liner to acrylic denture resins was tested in a universal testing apparatus at a 5 mm/min crosshead speed. The debonded surfaces were visually examined for the failure modes. ANOVA and multiple comparisons posthoc analysis tests were applied to determine the significant difference in TBS between the study groups (α = 0.05). A significant difference in TBS was observed between the control and surface treated groups (p < 0.001) for both acrylic resins materials. However, there was no statistically significant difference in bond strength between the acrylic resins materials (p = 0.739). Surface treatment with airborne-particle abrasion demonstrated increased TBS of the soft denture liners to acrylic resins. The TBS of conventional and CAD/CAM acrylic resins to soft denture liners were not considerably different.

Sign in / Sign up

Export Citation Format

Share Document