Monolithic crowns fracture analysis: The effect of material properties, cusp angle and crown thickness

Shahmoradi, Mahdi; Wan, Boyang; Zhang, Zhongpu; Wilson, Tom J.; Swain, Michael V.; Li, Qing

doi:10.1016/j.dental.2020.04.022

Cited by 38 publications

(29 citation statements)

References 36 publications

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“…This might be related to the occlusal thickness as described in a previous study. 13 A second possible cause could be the thickness of the restoration as explained by an investigation of Shahmoradi et al (2020), 30 who claimed that the decreased load of crack initiation in thinner specimens of thickness 0.7 mm may be related to increased flexural and tensile stress on the intaglio surface of the crown which can potentiate the crack initiation. 30 A previous study showed that the calculated tensile stresses at the internal surface of the loaded and bonded ceramic crowns increased proportionally to cement thickness (8 times, from 50 to 500 µm).…”

Section: Rana Ashrafmentioning

confidence: 99%

“…13 A second possible cause could be the thickness of the restoration as explained by an investigation of Shahmoradi et al (2020), 30 who claimed that the decreased load of crack initiation in thinner specimens of thickness 0.7 mm may be related to increased flexural and tensile stress on the intaglio surface of the crown which can potentiate the crack initiation. 30 A previous study showed that the calculated tensile stresses at the internal surface of the loaded and bonded ceramic crowns increased proportionally to cement thickness (8 times, from 50 to 500 µm). 31 The cement effect could be attributed to the lower elasctic modulus compared to that of the ceramics (6.3 GPa and 64 GPa) and the resin cement shrinkage stresses could be more influential by increasing the cement thickness.…”

Section: Rana Ashrafmentioning

confidence: 99%

“…However, stimulatory role of mast cells in the growth of pathological lesions is more prevalent and obvious than their inhibitory effect (28) . With respect to several roles of mast cells such as participation in inflammation, degradation of extracellular matrix and bone resorption (29) , previous studies have identified mast cells in odontogenic cysts, but there were limited studies about the role of mast cells in the pathogenesis of odontogenic cysts (30) . There is a hypothesis that the more aggressive behavior of odontogenickeratocysts is related at least, partly, to distribution of mast cells.…”

Section: Introductionmentioning

confidence: 99%

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Infuence of Speed Sintering Protocol on Fracture Resistance of Translucent Fixed Restorations .

2020

Mansoura Journal of Dentistry

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Objectives: The aim of this in vitro study was to investigate the influence of speed sintering protocol on the fracture resistance of the translucent zirconia. Materials and Methods:Forty intact maxillary premolars were used in this study. All teeth were divided according to the type of zirconia into two main groups (n=20): Group K receiving KATANA HTML zirconia and Group Z receiving Zolid fx ML zirconia, Then, each group subdivided according to sintering protocol into two subgroups (n=10): KC and KS refer to KATANA HTML sintered by conventional and speed sintering protocols, respectively, while ZC and ZS refer to Zolid fx ML sintered by conventional and speed sintering protocols, respectively. The teeth were prepared by the aid of dental surveyor. After cementation with self-adhesive resin, the specimens were subjected to thermal cycling for 5000 cycles and mechanically loaded for 120,000 cycles.Then, the specimens were loaded to fracture. Mode of failure was assisted using stereoscopy and scanning electron microscope micrographs. Results: The highest mean value of fracture resistance was recorded in KC subgroup (3083.79 ±844.88) followed byKS subgroup (2864.41 ±692.15)vs ZC (2342.85 ±434.04) and ZS (1829.18 ±299.38) subgroups. Two-way ANOVA showed no interactions between variables (P=.448). Conclusions:Increasing the yttria content had negative impact on zirconia fracture resistance. Although, the sintering protocols did not influence the fracture resistance of the tested zirconia, Zolid fx ML was affected by the speed sintering protocol. Despite of the present results, the tested zirconia can be used safely at premolar area.

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Section: Rana Ashrafmentioning

confidence: 99%

Section: Rana Ashrafmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Infuence of Speed Sintering Protocol on Fracture Resistance of Translucent Fixed Restorations .

2020

Mansoura Journal of Dentistry

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“…Since, crowns with thicker margins, smaller cusp angle and totally bonded are recommended to reduce the prosthesis failure susceptibility (Zhang et al, 2016 ). This can be justified because a lower crown thickness and higher cusp angle promotes a lower crack initiation load (Shahmoradi et al, 2020 ). However, these information are not available for feldspathic ceramic CAD/CAM crowns.…”

Section: Introductionmentioning

confidence: 99%

Effect of occlusal anatomy of CAD/CAM feldspathic posterior crowns in the stress concentration and fracture load

Borges

Lima

Özcan

2021

Clinical & Exp Dental Res

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Objectives: This study evaluated the effect of restoration occlusal design on the maximum fracture load and stress distribution of a feldspathic ceramic crown.Materials and Methods: Twenty dentin analogues were used to simulate a full-crown preparation. Next, 20 feldspathic crowns were milled according to the occlusal design parameter available in the CAD database (Young or Adult). The crowns were cemented with dual cure resin-cement and loaded until fracture at 1 mm/min crosshead speed. Data were analyzed by using one-way ANOVA and Tukey tests (p < 0.05). The same geometry and experimental setup was modeled and exported to the computer aided engineering software and tensile stress concentration was calculated using the finite element method with 300 N occlusal load simulation. Results:The occlusal anatomy significantly influenced the load-to-fracture (p < 0.05).Adult design showed higher mean values (1149 ± 201 N) than Young design (454 ± 77 N). The maximum principal stress criteria showed similar stress pattern for both designs, however, the highest stress concentration was calculated for Young design (91 MPa) in the occlusal surface.Conclusions: An anatomy design with reduced cusp angulation and less evident occlusal sulcus can reduce the stress concentration and increase the fracture load for feldspathic CAD/CAM posterior crowns.

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“…10 However, its flexural strength of 470 MPa and fracture toughness of 2.54 MPa has led to questioning the use of lithium disilicate restorations in the posterior region, 11 where occlusal loads are higher 12 and materials with higher flexural strength and fracture toughness such as monolithic zirconia have been preferred. 13,14 Moreover, there is a widespread assumption that e.max lithium disilicate glass ceramic with a thickness less than 1 mm is more susceptible to catastrophic fracture, 15 which leads to more invasive tooth preparations or avoidance of the material.…”

mentioning

confidence: 99%

Comparison of 16.9-year survival of pressed acid etched e.max lithium disilicate glass-ceramic complete and partial coverage restorations in posterior teeth: Performance and outcomes as a function of tooth position, age, sex, and thickness of ceramic material

Malament

Margvelashvili‐Malament

Natto

et al. 2021

The Journal of Prosthetic Dentistry

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Statement of problem. Long-term clinical data are lacking on the comparison of the survival of adhesively luted pressed e.max lithium disilicate glass ceramic complete and partial coverage restorations in posterior dentitions and the effect that different technical and clinical variables have on their survival. Purpose. The purpose of this clinical study was to examine and compare the 16.9-year survival of posterior pressed e.max lithium disilicate glass ceramic complete and partial coverage restorations and associated clinical parameters on the outcome. Material and methods. Patients requiring either single-unit posterior defect-specific partial coverage or complete coverage restorations were recruited in a clinical private practice. The participants were offered the options of direct restorations, partial coverage cast gold, or glass ceramic (lithium disilicate) restorations. Those requiring complete coverage restorations were given the options of complete cast gold, metal-ceramic, or glass ceramic restorations. Only participants who chose glass ceramic partial and complete coverage restorations were included in the study. The overall survival of the glass ceramic restorations was assessed by the clinical factors determined at recall. The effect of various clinical parameters (type of restoration, dental arch, tooth position in the dental arch, age and sex of participant, and ceramic thickness) was evaluated by using Kaplan-Meier survival curves to account for attrition bias and other reasons for failure. The statistical significance of differences between parameters was determined using the log rank test (a=.05). Results. A total of 738 participants requiring 2392 lithium disilicate restorations in posterior teeth were evaluated. The mean age of the participants at the time of restoration placement was 62 (range: 20-99 years, 302 men and 436 women). Of 2392 units, 1782 were complete and 610 were partial coverage restorations. A total of 22 failures (bulk fracture or large chip) requiring replacement were recorded with the average time to failure 3.5 (0.02-7.9) years. The total time at risk computed for these units was 13227.9 years, providing an estimated failure risk of 0.17% per year. The 16.9-year estimated cumulative survival was 96.49%. The estimated cumulative survival of posterior complete (n=1782) and posterior partial coverage restorations (n=610) was 96.75% at 10.5 years and 95.27% at 16.9 years (P<.05). Of the 22, 16 failures were recorded for the complete coverage restorations. The total time at risk for these restorations was 10144.5 years, providing an estimated risk of 0.16 per year. The other 6 failures recorded occurred for the partial coverage restorations. The total time at risk for these restorations was 3083.5 years, providing an estimated risk of 0.19% per year. No statistically significant difference was found in the survival of posterior complete and partial coverage restorations among men and women, different age groups, or posterior tooth position in the dental arch (P>.05). The thick...

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Monolithic crowns fracture analysis: The effect of material properties, cusp angle and crown thickness

Cited by 38 publications

References 36 publications

Infuence of Speed Sintering Protocol on Fracture Resistance of Translucent Fixed Restorations .

Infuence of Speed Sintering Protocol on Fracture Resistance of Translucent Fixed Restorations .

Effect of occlusal anatomy of CAD/CAM feldspathic posterior crowns in the stress concentration and fracture load

Comparison of 16.9-year survival of pressed acid etched e.max lithium disilicate glass-ceramic complete and partial coverage restorations in posterior teeth: Performance and outcomes as a function of tooth position, age, sex, and thickness of ceramic material

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