Objectives: Evaluating the fracture resistance and failure mode of human maxillary premolars restored with two ceramic onlay materials prepared with two preparation designs. Materials and methods:A total of 40 extracted, human maxillary premolars were selected and divided into two groups according to preparation design; Group A: MOD cavity with anatomical reduction of functional cusp and Group F: MOD cavity with flat reduction of the functional cusp. Each group was divided into two subgroups according to the material of construction; Subgroup S: restored using zirconia-reinforced glass-ceramic and Subgroup E: restored using hybrid ceramic. The finished onlay restorations were luted to prepared teeth using self-adhesive resin cement. Specimens were exposed to thermocycling for 5000 cycles. Fracture resistance was assessed using a Universal testing machine. Failure mode was evaluated using a stereomicroscope. Two-way ANOVA was used to assess the effect of different tested variables and their interaction. Intergroup comparison was done using one-way ANOVA followed by Tukey's post hoc test. The significance level was set at p≤0.05 within all tests.Results: Two-Way ANOVA showed that ceramic material had no significant effect on the fracture resistance of restored teeth. While the preparation design had a statistically significant effect. The interactions between the independent variables, ceramic materials, and preparation designs had a significant effect on the fracture resistance of teeth. Conclusion:Both preparation designs and materials showed clinically acceptable fracture resistance of onlay restorations. All subgroups showed high fracture resistance and favorable failure modes except VITA SUPRINITY with anatomical reduction of the functional cusp.
Statement of problem:Ceramic is subjected to multiple firing which exposed it to more heat treatments. The effect of these heat treatments on optical and mechanical properties of lithium disilicate glass-ceramics is not fully studied.Objective: To evaluate the Impact of multiple firings cycles on color change, translucency, and flexural strength of lithium disilicate ceramic fabricated by press and milled technology.Material and Methods: Lithium disilicate ceramics fabricated by two methods were used. Sixty disk-shaped samples (10x 1mm) were prepared from ceramics thirty for each group (Amber press (P) and Amber mill (M)) (n=30). Then each group (P and M) was divided into three subgroups according to the number of firing cycles one, three, and five times (n=10). After finishing firing cycles for each group, color change (ΔE) and translucency measurement (TP) were done using Vis-NIR spectrophotometer. The biaxial flexure strength was measured for all samples. Two-way Analysis of Variance (ANOVA) was made to analyze the effect of ceramic type, firing cycles and their interaction on mean TP, ΔE and biaxial flexural strength. When ANOVA test is significant so Bonferroni's posthoc test was used for pair-wise comparisons. The significance level was set at P ≤ 0.05.Results: Statistical analysis showed that ceramic type and firing cycles had a statistically significant effect on mean colour change (ΔE), translucency (TP) and biaxial flexural strength. The interaction between the two independent variables had a statistically significant effect on mean ΔE. Conclusions:Multiple firings affect the color change and translucency of lithium disilicate ceramics. More firing cycles led to more reduction in flexural strength of Amber milled compared to that of Amber press. Amber mill has better translucency and biaxial flexural strength than the Amber Press.
Objectives: To investigate and compare the color stability and surface roughness of provisional restorative materials fabricated by 3D printing, milling and conventional techniques after immersion in different storage media. Materials and methods:The 84-disc specimens were fabricated and divided into 3 groups according to the technique of fabrication (n=28), group C: Conventional techniques, group M: milled technique, group P: 3d printed technique. Each group was divided into 4 subgroups according to storage media (n=7), Subgroup D: distilled water, subgroup C: coffee solution, subgroup Co: cola, and subgroup O: orange juice. Baseline color was measured using spectrophotometer then measured after 2 and 4 weeks of immersion in different storage media. Color change (ΔE) was assessed using of the CIE L*a*b* system. Surface roughness was also measured using profilometer for all specimens before and after immersion in staining solutions. The data was then collected and statistically analyzed using two-way ANOVA. The significance level was set at p<0.05 within all tests.Results: Two-way ANOVA showed that the fabrication technique and interaction between variables had a significant effect on surface roughness. There was a significant interaction between fabrication method, solution type and storage time on color stability. Conclusions:The surface roughness of 3D printed materials was higher than milled and conventional groups. 3D printed and CAD-CAM milled materials had better color stability compared to conventional group.
Objectives: Comparing debonding time of three different ceramic materials lithium disilicate, ultra-translucent zirconia and hybrid-ceramic with dentin using Er, Cr:YSGG laser application. Materials and methods:Thirty recently extracted human mandibular molars were selected for study. They were fixed in acrylic resin blocks and their buccal surfaces were ground to expose dentin to provide flat surface for bonding then stored in distilled water at room temperature. Three different ceramic materials used in this study, lithium disilicate glass ceramics, hybrid-ceramic, ultra-Translucent Zirconia. A total of thirty square shaped Samples 4x4mm and 1mm thickness resembling crowns prepared from CAD/CAM (computer aided design/computer aided manufacture) ceramic blocks of these ceramic materials, 10 samples for each material. Samples bonded to dentin using dual cure self-adhesive resin cement (TOTALCEM ITENA, France). Laser debonding of ceramic samples of all three materials using Er,Cr:YSGG laser (Waterlase by Biolase). Data were parametric and showed variance homogeneity, so they were analyzed using independent t-test. The significance level was set at p<0.05 within all tests.Results: Results showed that there was a significant difference between different groups (p<0.001). The highest value was found in Vita Enamic samples (160.00±22.91) followed by BruxZir (21.57±5.26), while the lowest value was found in Emax samples (7.00±1.29). Conclusions:The Ultra translucent zirconia and Lithium disilicate were deboned from dentin using Er,Cr:YSGG laser. Using laser for debonding Ultra translucent Zirconia consumses higher time than for Lithium disilicate. Destruction of hybrid ceramics when it was exposed to Er,Cr:YSGG laser to debond it from dentin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.