This study evaluated ascending order of light attenuation distance (0,2,4,8 mm) and specimen dimensions (2x2x10, 2x2x12, 2x2x15 mm3) differing from requirements of ISO 4049 (2x2x25 mm3) on the flexural strength of nano-hybrid resin composite. Specimens (N=160) were prepared accordingly and randomly assigned into groups for the factors studied. Specimens were photo-polymerized from increased distances through 1, 2, 3 and 5 overlapping cycles depending on the specimen length after which they were subjected to three-point bending test (0.5 mm/min). Data were statistically analyzed using one-way, twoway ANOVA and Tukey's HSD post-hoc tests (=0.05). Two-parameter Weibull modulus, scale (m) and shape (0) were calculated. Both light attenuation distance (p0.001) and specimen dimensions (p0.001) significantly affected the results. Regardless of the specimen dimensions, 0, 2 mm polymerization distance resulted in significantly higher mean flexural strength compared to 4 and 8 mm. Polymerization distance did not significantly affect the mean flexural strength of specimens prepared according to ISO norms (p>0.05). Weibull distribution presented the highest shape (m) for 10-8 mm (24.65), 12-4 mm (14.54), 15-2 mm (12.32), 25-2 mm (17.56), length-light distance combinations. Specimen dimensions prepared in accordance with ISO 4049 do not allow for comparison of the effect of light attenuation distance on the flexural strength of resin composite tested.

(2016). Effect of polymerization protocol on the degree of conversion of photo-and dual-polymerized self-etch adhesives. Journal of Adhesion Science and Technology, 30(3) Bond Universal DC, 3M ESPE) were tested. All adhesives were applied on potassium bromide pellets (KBr) following the manufacturer's instructions. The KBr pellets were divided into 10 experimental groups for the photo-polymerized adhesives and 12 experimental groups for the dual-polymerized adhesives according to the two levels of the study, Level 1: Polymerization protocol and Level 2: Adhesive system. For the photo-polymerized adhesives, the adhesives were polymerized either at 1 mm or 10 mm from the KBr pellets. For the photo-polymerized adhesives, the adhesives were photo-polymerized either at 1 mm or 10 mm distance or polymerized chemically. The DC% of the unpolymerized and polymerized adhesives was assessed using Fourier transform infrared spectroscopy (FTIR). Data were analyzed using two-Way ANOVA to evaluate the effect of polymerization protocol, adhesive system and their interaction on the DC% of the self-etch adhesives. For the photo-polymerized and dual-polymerized adhesives, one-Way ANOVA and Tukey HSD post hoc test was used to evaluate the effect of adhesive system within each polymerization protocol and the effect of polymerization protocol within each adhesive for the dual-polymerized adhesives (p=0.05). Student t-test was used to compare the effect of polymerization distances within each photo-polymerized adhesive. For both photo-and dual-polymerized adhesives, the polymerization protocol and adhesive system had a significant effect on the DC (p=0.000). The interaction between the two factors (polymerization protocol and adhesive system) revealed also a significant effect on the DC% of the different 3 adhesives (p=0.000). Polymerization distance of 1 mm showed significantly higher DC% compared to 10 mm distance. When the dual-polymerized adhesives were left to set chemically, they showed the lowest DC% among all polymerization protocols. DC varied depending on the chemical composition of the self-etch adhesives. The tip of the polymerization device should be positioned as close as possible to the surface to achieve higher DC% of the tested adhesives. Photo-polymerization of the dualpolymerized self-etch adhesives is a mandatory step to improve their DC.

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The aim of this study was to evaluate the effect of surface treatment and storage time on immediate repair bond durability of methacrylate- and ormocer-based bulk fill composites. In total, 265 discs were divided into 32 groups (n = 8/group) according to: (1) Material: X-tra fil and Admira Fusion X-tra; (2) Surface treatment: oxygen inhibition; matrix; Futurabond M+; Silane/Futurabond M+; Admira Bond; Silane/Admira Bond; ceramic repair system; and Silane/Cimara bond; and (3) Storage time: 24 h and 6 months. Each disc received three micro-cylinders from the same material. Specimens were subjected to micro-shear bond strength testing either at 24 h or 6 months. Data were analyzed using ANOVA/Tukey’s test/Student t-test (p = 0.05). All experimental factors had significant effect on bond strength (p < 0.0001). Drop in bond strength was noticed in both materials after six months (p < 0.05), except for Admira Fusion X-tra treated with silane/cimara adhesive (p = 0.860). Both materials showed insignificant values with Admira bond either at 24 h or 6 months (p = 0.275 and p = 0.060, respectively). For other treatments, X-tra fil showed significantly higher values at 24 h and 6 months (p < 0.05). Ceramic repair system can be used to immediately repair both methacrylate- and ormocer-based composites.

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