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Öğe Fracture load and microcrack comparison of crowns manufactured from tooth-shaped and traditional blocks(2021) Arslan, Merve; Tosun, İlgiThis study intended to analyze microcracks and fractographic markings on the surface of all ceramic crowns after milling and compare the fracture loads. 90 crowns were manufactured from two feldspathic (Priticrown-Pr and Vita Mark II-Vi) and a lithium disilicate (EmaxCAD-Em) blocks (n = 30). Two groups (n = 15) were prepared for each ceramic. In the first group, crowns were analyzed twice via the fluorescent penetrant method for microcrack detection, after the manufacturing process and thermal cycles. The load to fracture test was applied at a crosshead speed of 0.5 mm/min until catastrophic failure. Second group crowns were directly cemented onto the Co-Cr dies following the manufacturing process and loaded to fracture. Fractographic markings were analyzed through scanning electron microscope. Spearman correlation analysis, Kruskal–Wallis H test, Mann–Whitney U test, and Wilcoxon Signed Rank test were applied (α =.05). Fracture loads of Em crowns were higher than other groups (p <.05), with and without the aging procedure. Except for second group Pr (r = −.532), no significant relationship was found between microcrack numbers and fracture loads (p >.05). Thermal cycling did not affect microcrack numbers and fracture loads (p >.05). Tooth-shaped multilayered Pr blocks did not provide an advantage in terms of microcrack and fracture loads.Öğe A comparative study of translucency and color perception in monolithic zirconia and lithium disilicate veneers(Elsevier Ltd, 2024) Aydoğdu, Hasan Murat; Yıldız, Pınar; Ünlü, Damla GüneşCeramic laminate veneers which are a conservative approach to restoring anterior teeth, combining minimal preparation and esthetics. This study aims to evaluate the impact of the thickness of monolithic zirconia laminate veneers on their optical properties and color perception, comparing them to lithium disilicate. A total of 60 laminate veneers were prepared using two ceramic materials, divided into three groups for each material (n = 10) with thicknesses of 0.5, 0.7, and 1.0 mm. CIELab color parameters of the veneers were measured using a spectrophotometer and translucency parameters were calculated. The veneers were cemented onto uniform dies and final L, a, b values of the restorations were measured. The color difference between the different thicknesses was calculated using the CIEDE2000 formula. Two-way ANOVA and Bonferroni HSD post hoc tests were conducted to compare the color parameters (α = 0.05). The results showed that both material type (p < 0.001) and thickness (p < 0.001) influenced translucency values. The translucency values of zirconia veneers were significantly lower than those of lithium disilicate. The color differences (ΔE00) resulting from thickness changes (0.5–1.0 mm) were near or below the perception threshold for lithium disilicate, but distinct for zirconia restorations. In conclusion, monolithic zirconia veneers demonstrated lower translucency compared to lithium disilicate. Changing the material thickness affected the translucency of both materials, but not the color perception only for zirconia.Öğe Influence of Different Plaque Control Methods and Hydrothermal Aging on Structural Properties of Monolithic Zirconia(Adnan Menderes University, 2021) Öztürk Ulusoy, Habibe; Aktaş, ÇağatayObjective: This study aimed to investigate the effect of hydrothermal aging and various plaque removal methods, which are a part of professional dental cleaning, on zirconia’s structural properties. Materials and Methods: Seventy-two disk-shaped monolithic zirconia specimens (diameter 12 mm and thickness 1 mm) divided into six groups were subjected to no surface treatment, instrumentation with steel curette and ultrasonic steel scaler, and air abrasion with sodium bicarbonate, erythritol, and glycine before being aged in an autoclave at 0.2 MPa and 134 °C for 2 h. Specimens were analyzed using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometry, and atomic force microscopy to evaluate crystal structure, microstructure, and surface roughness. Further, the contact angle and Vickers hardness measurements were performed for wettability and hardness evaluations. A biaxial bending test was applied to measure the durability of the material. Results: According to the results, no significant change was found in the crystal structure, surface roughness, and bending strength of zirconia (p>0.05). In contrast, a substantial decrease in surface hardness values and a significant increase in wettability values were observed in the steel curette and ultrasonic steel scaler groups compared with other groups (p<0.05). Conclusion: The use of abrasive powders in dental plaque control after prosthetic treatment can help maintain periodontal health and long-term use of prosthesis after restoration of monolithic zirconia.Öğe Effects of high temperature on dental restorative materials for forensic purposes(Springer, 2021) Çarıkçıoglu, Burak; Misilli, Tuğba; Deniz, Yeşim; Aktaş, ÇağatayThis study aimed to observe the efects of high temperature on diferent restorative dental materials by detecting changes in their microstructural and elemental composition. Disk shaped samples (10 mm diameter, 2 mm depth) were prepared from 8 dental materials (compomer, glass carbomer, ormocer, giomer, zinc reinforced glass ionomer (GI), silver-alloy reinforced GI, zirconia reinforced GI, and conventional GI). Scanning electron microscopy/Energy dispersive X-ray spectroscopy (SEM/EDS) was used to characterize sample surface structures and elemental composition. The same samples were also analyzed using X-ray fuorescence (XRF) to determine the trace element content. Each sample was placed in a porcelain furnace and exposed to 900 °C for 30 min. Observations of macroscopic changes in samples after exposure high temperature were recorded. The microstructural changes in sample surfaces after incineration were detected by SEM. The elemental compositions obtained before and after the incineration were compared after repeating the XRF and EDS analyses. Dental materials demonstrated specifc macroscopic changes and microstructural deteriorations detected by SEM images after exposure to high temperature. While several changes occurred in the elemental content of materials in terms of amount, the original elemental composition was preserved. The ability to distinguish dental materials by elemental analyses has had an important impact on the identifcation process.
