Background and Aim: The aim of this study was to evaluate the effect of glass-fiber on the flexural strength of composite resins.Methods & Materials: The study was done experimentally in which flexural strength of glass - fiber reinforced composite resins were assessed with a three-point load test on 22 samples. 11 samples of composite resin blocks and 11 samples of composite resins reinforced with glass- fiber were prepared in a mold of 25x6x2mm and stored in 100% of moisture for one month, until they were ready for testing in an Instron Universal Testing Machine using a crosshead speed of 1 mm/min. Student t test was used for statistical analysis.Result: Flexural strength in the first group was 22.39±3.38 MPa and in second group was 29.74±2.36 MPa. According to t test analysis, the difference between the two groups was statistically significant. (P<0.01).Conclusion: The results of this study suggest that the flexural strength of the fiber-reinforced composite made from glass - fibers was more than composite resin.

Background and Aim: Considering flexural strength of fiber-reinforced composites (FRC) and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar.Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195) with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and 1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on composite facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T test a significant statistical difference was observed between two groups (P<0.001). The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

In this study loss measurements in axial fiber displacements in a fiber-to-fiber design using two different light sources (white lamp & red LED) is reported. A fiber-to-fiber arrangement is used in which the source light is directly coupled to the first fiber and the second fiber delivers the light to a power meter. Using this arrangement the variation of the power and loss as a result of axial (Z-direction) displacements of the second fiber are monitored. Theoretical model is also to evaluate the power transmissions for comparison is made with the experimental results. Our results in general agree with the theoretical predictions and the small deviation is because of the fact that those theoretical formulas are more precise for the case of small core fibers for small axial displacements while we are using large core fibers and relatively long displacements. Important parameters of the reported optical system such as measurements reproducibility (about 0.001%), and hysteresis effect (about 0.034), are also investigated that verify the reasonable operation of such an optical system. The result of this experiment verify that fiber material and other fiber parameters affect the power transmission and such parameters can be investigated experimentally using the reported fiber-to-fiber arrangement.

The present study deals with effects of CMP fines on optical and physical properties of newsprint papers, for which, different batches for CMP fines (0%, 10%. 20%. 30%) of totally 80% pulp is taken, Where the remaining 20% of imported long fiber pulp was taken as fixed amount.The study focused on surving the effects of CMP fines on optical and physical properties of newsprint paper, after mixing the pulps and making the handsheets.Generally, the results show the increase in CMP fine amount lead to increase, Air Resistance and Opacity and decrease Caliper and Roughness, Also that changes in CMP fines has no effect on Brightness.