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Objective: this study aimed to evaluate discoloration of two inorganic nanohybrid composite and an organic modified ceramic resin composite (ormocer) into two solution at different periods of time.Methods: 60 discs of (admira fusion voco, tetric evoceram vivadet ivoclar , tetric N-ceram vivadent ivoclar) were prepared with dimentions of (2mm x 5mm) and devided into three group (A ,B, C) Each group of 20 specimens were randomized into two subgroups, one of them were immersed in coffee and the other in cola for 1, 7, and 28 days of immersion. Color measurements were recorded every time period using Vita Easy shade compact according to the CIE L*a*b* system and results were saved for comparing .The ΔE values between the study time points were calculated. Results: Admira Fusion x-tra showed the lowest ΔE variations (P < 0.01) at all periods of time comparing with Tetric evoceram and Tetric N-ceram at both solution. Coffee caused higher discoloration at all periods of time.Conclusion: Staining beverages caused significant discolorations for all the materials tested. Coffee caused higher discoloration comparing with cola. Nanohybrid ormocer composite reported the lowest color variations.

Background: Fiber reinforced composite resin (FRC) posts are used to restore endodontically treated teeth. Many factors affect the bond strength of posts; however, there is a concern regarding the mismatch between the posts and oval root canals and its effect on posts retention. Aim: To compare the bond strength of circular and oval-shaped fiber-reinforced composite posts in oval shaped canals. Materials and Methods: Forty Five extracted single rooted human premolars with single oval-shaped root canals were decorated, endodontically treated and prepared to receive quartz reinforced composite resin posts, then they were randomly assigned to three groups, the posts in the first group (control) (n=15) were parallel with circular cross section (Match post, RTD, France), the posts in the second group (n=15) were taper with circular cross section (DtLight Illusion post, RTD, France), The posts in the third group were oval shaped (Macro lock oval post, RTD, France). The posts in the three groups were cemented with dual cure resin cement (Permflo DC Composite Luting, Ultra dent, USA). All samples were then stored in 100% relative humidityat at room temperature for 24 hours then pull-out test was performed and data were analyzed using one-way analysis of variance (ANOVA) followed by Bonferonni's post hoc test (a = 0.05). Results: Oval shaped posts showed higher bond strength values than circular posts, whether the circular posts were conical(taper)or parallel (control) (p<0.05).Conclusions: The bond strength of fiber reinforced composite resin posts in oval root canals increased when the posts were oval-shaped.

Introduction:The increasing use of composite resin as a posterior restorative material puts it under constant masticatory stresses. Depth of cure, considered as the most important factor helps resist these stresses. Objectives:The aim of the study was to assess the curing depth and degree of conversion of four different nano-hybrid composites (two conventional methacrylate and two pure Ormocer composites), using ISO 4049 digital caliper and micro-hardness test. Material and methods: 20 cylindrical composite samples per group were created using Admira Fusion x-tra (Admira Fusion; VOCO GmbH, Cuxhaven, Germany) and Tetric N-Ceram Bulk Fill (Ivoclar Vivadent; Schaan, Liechtenstein) composites. Curing depth was calculated using ISO 4049 digital caliper, and micro-hardness test was applied to assess degree of conversion of all composites using digital micro-Vickers hardness tester (Galileo LTF; Italy). 20 seconds of curing was performed with curing LED unit (Guilin Woodpecker Medical Instrument Co., Ltd.; China), with a light intensity of 1,000 mw/cm 2 . A statistical analysis was done using SPSS, version 17, and the results were compared with one-way and multiple-way analysis of variance (ANOVA). P-value < 0.05 was considered statistically significant. Results: Average curing depth of Tetric N-Ceram was 1.60 mm (± 0.09), with mean micro-hardness of 78.17%. Tetric N-Ceram Bulk Fill mean curing depth was 2.76 mm (± 0.18), and micro-hardness of 73.97%. Admira Fusion x-tra showed 2.92 mm (± 0.15) as mean depth of cure and 80.20% of micro-hardness, while for Admira Fusion it was 1.71 mm (± 0.19), with micro-hardness of 80.605%. Conclusions: All the tested materials showed acceptable results according to ISO 4049 test. Only Admira Fusion and Admira Fusion x-tra accomplished micro-hardness tests.