Influence of material thickness on fractural strength of CAD/CAM fabricated ceramic crowns

Zimmermann, Moritz; Egli, G.; Zaruba, Markus; Mehl, Albert

doi:10.4012/dmj.2016-296

Cited by 46 publications

(40 citation statements)

References 16 publications

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“…The finding that the chamfer design crowns fractured at a higher load than did the slice design crowns in both production‐method groups indicates that the commonly recommended chamfer margin design gives the strongest crowns. This is in accordance with previous studies . The increased thickness in the crown margin probably explains this result.…”

Section: Discussionsupporting

confidence: 93%

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Effect of margin design on fracture load of zirconia crowns

Skjold

Schriwer

Øilo

2018

European J Oral Sciences

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Zirconia‐based restorations are showing an increase as the clinicians’ preferred choice at posterior sites because of the strength and esthetic properties of such restorations. However, all‐ceramic restorations fracture at higher rates than do metal‐based restorations. Margin design is one of several factors that can affect the fracture strength of all‐ceramic restorations. The aim of this study was to assess the effect of preparation and crown margin design on fracture resistance. Four groups of bilayer zirconia crowns (with 10 crowns in each group) were produced by hard‐ or soft‐machining technique, with the following four different margin designs: chamfer preparation (control); slice preparation; slice preparation with an additional cervical collar of 0.7 mm thickness; and reduced occlusal thickness (to 0.4 mm) on slice preparation with an additional cervical collar of 0.7 mm thickness. Additionally, 10 hard‐machined crowns with slice preparation were veneered and glazed with feldspathic porcelain. In total, 90 crowns were loaded centrally in the occlusal fossa until fracture. The load at fracture was higher than clinically relevant mastication loads for all preparation and margin designs. The crowns on a chamfer preparation fractured at higher loads compared with crowns on a slice preparation. An additional cervical collar increased load at fracture for hard‐machined crowns.

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Section: Discussionsupporting

confidence: 93%

“…Reducing the occlusal thickness resulted in weaker crowns as expected based on previous studies (). This was, however, only statistically significant for the HM group.…”

Section: Discussionsupporting

confidence: 85%

Effect of margin design on fracture load of zirconia crowns

Skjold

Schriwer

Øilo

2018

European J Oral Sciences

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“…Also, some of these studies were investigating fracture strength on titanium abutments, which have an elastic modulus much higher than MZ100 composite. Few studies have looked at ultra‐thin monolithic e.max crowns at such an extreme and uniform occlusal thickness as this study, but the fracture loads reported were similar to what was found in this study. The ability to carefully create standardized dimensions and geometries for a variety of substrate materials provides reproducibility in studying the fracture resistance for complex geometries.…”

Section: Discussionsupporting

confidence: 76%

Fracture Resistance of Various Thickness e.max CAD Lithium Disilicate Crowns Cemented on Different Supporting Substrates: An In Vitro Study

Chen

Park

Wang

et al. 2019

Journal of Prosthodontics

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Purpose:To investigate the influence of abutment material properties on the fracture resistance and failure mode of lithium disilicate (IPS e.max) CAD/CAM (computeraided design/manufacturing) crowns on traditionally and minimally prepared simulated tooth substrates. Materials and Methods: Thirty lithium disilicate (IPS e.max) CAD/CAM crowns were divided into three groups (n = 10): TD: traditional thickness crowns cemented on Paradigm MZ100 abutments; MD: minimal thickness crowns cemented on Paradigm MZ100 abutments; ME: minimal thickness crowns cemented on e.max abutments. The 3Shape system was used to scan, design and mill all abutments and crowns with a die space set to 40 µm. Traditional thickness crowns were designed based on manufacturer guidelines with 1.5 mm occlusal thickness and 1.0 mm margins. Minimal thickness crowns were designed with 0.7 mm occlusal thickness and 0.5 mm margins. MZ100 composite and e.max abutments were selected to simulate dentin and enamel substrates, respectively, based on their elastic-modulus. Variolink Esthetic was used to cement all samples following manufacturer's instructions. A universal testing machine was used to load all specimens to fracture with a 3 mm radius stainless steel hemispherical tip at a crosshead speed 0.5 mm/minute along the longitudinal axis of the abutment with a 1 mm thermoplastic film placed between the loading tip and crown surface. Data was analyzed using ANOVA and Bonferroni post hoc assessment. Fractographic analysis was performed with scanning electron microscopy (SEM). Results: The mean fracture load (standard deviation) was 1499 (241) N for TD; 1228 (287) N for MD; and 1377 (96) N for ME. Statistically significant difference between groups did not exist (p = 0.157, F = 1.995). In groups TD and MD with low e-modulus abutments, the dispersion of a probability distribution (coefficient of variation: CV) was statistically higher than that of group ME with high e-modulus abutments. SEM illustrated larger micro-fracture dimensions in Group MD than Group ME. Conclusion: Minimal thickness e.max crowns did not demonstrate statistical difference in fracture resistance from traditional thickness crowns. Fracture mechanisms of minimal thickness e.max crowns may be affected by the e-modulus of the substrate. Minimal thickness e.max crowns may be a viable restorative option when supported by high e-modulus materials.

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“…High-strength CAD-CAM ceramics include IPS e.max CAD ® (Ivoclar Vivadent, Schaan, Liechtenstein), composed of lithium disilicate (LDS), and VITA SUPRINITY ® (VITA Zahnfabrik, Bad Zäckingen, Germany) catalogued as zirconium-reinforced lithium silicate (ZRLS), composed of two crystalline phases (lithium metasilicate and zirconium dioxide) [12][13][14]. Hybrid materials can be classified as polymer-infiltrated ceramic networks (PICN), such as VITA ENAMIC ® (VITA Zahnfabrik, BadZäckingen, Germany), and resin nanoceramics (RNC), such as LAVA™ ULTIMATE (3M, St. Paul, Minn, USA) [15][16][17] ( Table 1) [18,19]. According to the literature, there is little consensus with regard to the biomechanical behavior of these new restoration materials.…”

Section: Introductionmentioning

confidence: 99%

Fracture Resistance of New Metal-Free Materials Used for CAD-CAM Fabrication of Partial Posterior Restorations

et al. 2020

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Background and Objectives: To evaluate in vitro the fracture resistance and fracture type of computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Discs were fabricated (10 × 1.5 mm) from four test groups (N = 80; N = 20 per group): lithium disilicate (LDS) group (control group): IPS e.max CAD ® ; zirconium-reinforced lithium silicate (ZRLS) group: VITA SUPRINITY ® ; polymer-infiltrated ceramic networks (PICN) group: VITA ENAMIC ® ; resin nanoceramics (RNC) group: LAVA™ ULTIMATE. Each disc was cemented (following the manufacturers' instructions) onto previously prepared molar dentin. Samples underwent until fracture using a Shimadzu ® test machine. The stress suffered by each material was calculated with the Hertzian model, and its behavior was analyzed using the Weibull modulus. Data were analyzed with ANOVA parametric statistical tests. Results: The LDS group obtained higher fracture resistance (4588.6 MPa), followed by the ZRLS group (4476.3 MPa) and PICN group (4014.2 MPa) without statistically significant differences (p < 0.05). Hybrid materials presented lower strength than ceramic materials, the RNC group obtaining the lowest values (3110 MPa) with significant difference (p < 0.001). Groups PICN and RNC showed greater occlusal wear on the restoration surface prior to star-shaped fracture on the surface, while other materials presented radial fracture patterns. Conclusion: The strength of CAD-CAM materials depended on their composition, lithium disilicate being stronger than hybrid materials.

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Influence of material thickness on fractural strength of CAD/CAM fabricated ceramic crowns

Cited by 46 publications

References 16 publications

Effect of margin design on fracture load of zirconia crowns

Effect of margin design on fracture load of zirconia crowns

Fracture Resistance of Various Thickness e.max CAD Lithium Disilicate Crowns Cemented on Different Supporting Substrates: An In Vitro Study

Fracture Resistance of New Metal-Free Materials Used for CAD-CAM Fabrication of Partial Posterior Restorations

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