Objective:The aim of this in vitro study was to evaluate the accuracy of shade matching using two spectrophotometric devices.Materials and Methods:Thirteen patients who require a full coverage restoration for one of their maxillary central incisors were selected while the adjacent central incisor was intact. 3 same frameworks were constructed for each tooth using computer-aided design and computer-aided manufacturing technology. Shade matching was performed using Vita Easyshade spectrophotometer, Shadepilot spectrophotometer, and Vitapan classical shade guide for the first, second, and third crown subsequently. After application, firing, and glazing of the porcelain, the color was evaluated and scored by five inspectors.Results:Both spectrophotometric systems showed significantly better results than visual method (P < 0.05) while there were no significant differences between Vita Easyshade and Shadepilot spectrophotometers (P < 0.05).Conclusion:Spectrophotometers are a good substitute for visual color selection methods.

No abstract

No abstract

ObjectivesThis study aimed to evaluate the influence of different shades and brands of resin-based luting agents on the final color of a leucite-reinforced veneering ceramic.MethodsThis in-vitro study was done on 36 ceramic discs (IPS Empress I, 11 × 0.5 mm, A2 shade) and 36 cement disks (11 × 0.2 mm) made of Panavia SA Cement Plus (Kuraray Medical Inc.) and Choice2 (Bisco Inc., Schumburg) brands in translucent, universal A2, and opaque shades (n = 6 per each color in each resin cement brand). Color parameters (CIEL*a*b*) of ceramic specimens were calculated without and with each brand/shade of resin-based luting agents by using a spectrophotometer, and put into CIELab formula. The color differences (ΔE) between the two sets of measurements were calculated and analyzed with two-way ANOVA and Tukey’s post hoc test (α = 0.05).ResultsBoth the resin-based luting agent shade (P < 0.001) and brand (P = 0.023) significantly affected the color differences. ΔE values were significantly different between Panavia-opaque and Choice2-opaque (P < 0.001). No significant difference existed between ΔE of the two brands in A2 (P = 0.178) and translucent shades (P = 0.079). The ΔE values of Panavia-A2 was significantly different from the translucent and opaque shades of the same brand. Moreover, the ΔE of Choice2-translucent shade was significantly lower than that of A2 and opaque shades. The ΔE values were higher than the clinically-acceptable threshold in all groups (ΔE > 3.7) except for Choice2-translucent (ΔE = 3.37).ConclusionsThe final color of leucite-reinforced veneering ceramic can be affected by the same shades of resin-based luting agents from different brands and different shades of resin-based luting agents from the same brand.

ObjectiveThis study aimed to evaluate the relationship between degenerative bony changes and condylar bone density in the temporomandibular joint structures using Cone Beam Computed Tomography (CBCT).Materials and methodsIn this retrospective cross‐sectional study, two groups were evaluated. The case group included 35 patients (34.91 ± 12.40 mean age) with clinical signs and symptoms of TMD according to the Helkimo Index. The control group included 35 samples (37.89 ± 10.89 mean age) without signs and symptoms of TMD. Degenerative bone changes including flattening, erosion, osteophyte, sclerosis, and pseudocyst were evaluated in CBCT images. The severity of degenerative bone changes was categorized into four groups; G0 (no degenerative changes), G1 (one degenerative change—mild), G2 (two degenerative changes—moderate), and G3 (three or more degenerative changes—severe). Grey Value (GV) was measured in CBCT images to determine condylar bone density. The relationship between the severity of degenerative bone changes and bone density was assessed using the One‐Way ANOVA test.ResultsThe frequency of osteophyte and sclerosis was significantly higher in the TMD patient group than in the control group. Grade 1 and Grade 2 changes in the TMD patient group were significantly more than the control group (p < 0.001). The mean Grey Value in patients was significantly higher than the control group (p < 0.001). The GV was significantly correlated with the severity of degenerative changes in both groups (p < 0.05).ConclusionThe degenerative changes were significantly associated with bone density (GV). Therefore, TMJ arthritis can cause changes in bone density.

A BSTRACT Aim: Use of monolithic zirconia for fabrication of all-ceramic crowns eliminates several shortcomings of layered zirconia crowns. Long-term success of restorations highly depends on the marginal fit. The crown thickness is among the factors that affect the marginal integrity. Meanwhile, reduced thickness of crowns has several advantages such as preservation of tooth structure. The aim of this study was to evaluate the marginal fit of monolithic zirconia crowns in reduced thickness and to compare the marginal fit of full-contour monolithic zirconia in different thicknesses with layered zirconia crowns. Materials and Methods: In this in vitro study, two standard brass dies (7 mm × 5 mm length diameter) were prepared with a heavy chamfer finish line with 0.5 and 1 mm depth. By using a CAD-CAM system, 30 crowns were made in three groups ( n = 10) of 1-mm thick layered zirconia, 1-mm thick monolithic zirconia, and 0.5-mm thick monolithic zirconia. Crowns were placed on master dies and randomly numbered. The marginal gap was measured on 18 points by using a digital microscope (×230). The mean ± standard deviation (SD) values were calculated and analyzed by Statistical Package for the Social Sciences (SPSS) software program through Kruskal–Wallis and Mann–Whitney tests (α = 0.05). Results: The marginal gap of 1-mm layered zirconia was significantly different from that of 1-mm monolithic zirconia ( P = 0.001) and 0.5-mm monolithic zirconia ( P = 0.004). Analysis of variance (ANOVA) revealed no significant difference between 0.5 and 1 mm thicknesses of monolithic zirconia ( P = 0.141). Conclusion: Marginal gap in all the three groups was clinically acceptable. The two different thicknesses of monolithic zirconia crowns had no significant effect on the restoration marginal fit; however, layered zirconia crowns showed a significantly higher marginal gap than monolithic zirconia crowns.

No abstract