Objective: The aim of this study was to evaluate the degree of conversion and surface hardness of two bulk-fill composites and one incremental-fill composite. Methods: Bulk-fill composites (x-tra fil, Voco; QuiXfil, Dentsply) and incremental-fill composite (Grandio, Voco) were used. Twenty five cylindrical specimens (5 Â 4 mm) were made from each material in Teflon molds. Mold was filled in one increment for the bulk-fill composites and in two increments for the incremental-fill composite. Specimens were stored dry in dark at room temperature for 24 h before testing. Degree of conversion (DC) was determined using Fourier transform infrared spectroscopy (FTIR). A microhardness tester was used to measure the Vickers hardness number (VHN) on top and bottom surfaces of each specimen. Data for DC and VHN were analyzed by ANOVA and pair-wise Newmanekeuls test. Results: X-tra fill recorded significantly the highest DC, while no significant difference was noted between the other two composites. The VHN mean values of all composites tested were significantly different from each other (P < 0.0001), either in top or bottom surface, with Grandio showed the highest mean value and QuiXfil showed the lowest mean value. Only QuiXfil recorded no significant VHN difference between its top and bottom surfaces. There was no significant difference in bottom/top hardness ratio% among materials. Non significant Correlation between VHN and DC was noted. Conclusions: X-tra fil showed the most DC performance. Incremental-fill composite showed higher VHN than bulk-fill composites. Differences in DC and VHN values among materials proved to be a material dependent.

Objectives: The aim of this study was to investigate the mechanical properties as well as the structural analysis of autologous platelet-rich fibrin matrix (PRFM) as compared to autologous leukocyte-platelet-rich fibrin (L-PRF).Materials& Methods: Sixty three cubic centimeters (cc) venous blood was obtained from 10 male volunteers. Twenty seven cc were used to prepare 3 specimens of L-PRF (group 1), twenty seven cc were used to get 3 specimens of PRFM (group 2) and nine cc for whole blood analysis. After centrifugation, blood analyses were performed on the residual plasma after collecting L-PRF and PRFM. The L-PRF and PRFM membranes were processed for examination by light microscopy and transmission electron microscopy (TEM) and their mechanical properties were measured by a universal testing machine.Results:Tensile strength and maximum tensile strain of L-PRF group was significantly higher than PRFM group (p < 0.01). PRFM group was significantly stiffer than L-PRF group (p < 0.01). Light microscopy revealed that the platelets were less but more equally distributed in the PRFM than L-PRF. The border between the cellular components and the fibrin network appeared thicker in the PRFM samples than in the L-PRF samples and shows a highly organized network with continuous integrity. TEM showed that both membranes contained two components: a fibrillar material similar to fibrin filaments, and a cellular component that contains human platelet cells. TEM analysis demonstrated that PRFM membrane had more nonactivated platelets.Conclusion: The present study shows that the structural and mechanical properties of PRFM may fit characteristics desirable for GTR procedures more than that of L-PRF. KEYWORDS:Mechanical properties, platelet-rich fibrin matrix, leukocyte-platelet-rich fibrin (1532) Reham Lotfy Aggour, et al.

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Aim: To compare the micro shear bond strength and the solubility of resin sealer with and without the addition of Nano silver. Materials and Methods: This study was carried out on 30 human freshly extracted upper first premolars. After preparation of tooth surfaces for microshear bond strength test, The prepared teeth were assigned to three groups 10 of each: Group A: AH Plus sealer was used, Group B: AH Plus sealer with 0.2% Nano silver incorporated to the already mixed sealer was used, group C: AH Plus sealer in addition to 0.5% Nano silver incorporated to the already mixed sealer was used. A shear load with tensile mode of force was applied via materials testing machine, Micro-shear bond strength was measured. For solubility test 30 PVC rings with 20 mm in internal diameter and 5 mm in thickness were placed onto a thin cellophane sheet supported by a glass plate and filled with sealers as follows: Group A, 10 rings filled with AH Plus sealer mixed according to the manufacturer's instructions. Group B, 10 rings filled with AH Plus sealer mixed according to the manufacturer's instructions, in addition to 0.2% Nano silver incorporated to the already mixed sealer. Group C, 10 rings filled with AH Plus sealer mixed according to the manufacturer's instructions, in addition to 0.5% Nano silver has incorporated to the already mixed sealer. The samples were kept in an environment with temperature of 37˚C for up to three times the setting time of each sealer group. After that, the samples were removed from the rings. Each sample was weighed on precision scale and suspended through the nylon thread inside a large opening flask containing 50 ml of ultrapure water and all samples were maintained into the incubator at 37˚C for 7 days. Then the samples were placed into desiccators for 24 hours for new weighing. The difference between the first and the second weight represents the mass loss for each of the specimens. Results: Group A showed the highest mean value of microshear bond strength among all groups. Group B showed a mean value of microshear bond strength, lower than Group A and there was a statistically significant difference between them, but was higher than that of Group C and there was no statistically significant difference between these two groups B and C. Group C showed