ABSTRACT
The aim of this study was to evaluate the effect of glass-fiber on the flexural strength of composite resins. 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 25x6x2 mm 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. Flexural strength in the first group was 22.39 +/- 3.38 MPa and in second group was 29.74 +/- 2.36 MPa. According to test analysis, the difference between the two groups was statistically significant. [P<0.01]. The results of this study suggest that the flexural strength of the fiber-reinforced composite made from glass - fibers was more than composite resin
Subject(s)
Dental Materials , Composite ResinsABSTRACT
Bonding systems have been traditionally used on normal dentin, even though caries-affected and sclerotic dentin are often the clinically relevant bonding substrates. A self-etching primer adhesive system [Clearfil SE Bond] was evaluated for its ability to bond to caries-affected and normal dentin. In this experimental study, twelve extracted human primary molars with occlusal caries were selected. The enamel and superficial dentin were ground with a diamond disk and stained with a caries detector solution [propylen glycol and 1% acid red]. The red-stained soft dentin which was classified as infected dentin was excavated and the affected dentin and surrounding normal dentin were polished with a 600 grit silicon carbide paper under running water to achieve a flat surface. The entire flat surface was bonded with Clearfil SE Bond [Kuraray] according to the manufacturer's instructions and covered with composite resin Clearfil AP-X [Kuraray] to form a composite crown approximately 4.5 mm high. The teeth were stored in distilled water at room temperature for 24 hours and were then sectioned with a diamond saw under running water in both N and Y directions, perpendicular to the bonded surface with dimensions of approximately 0.8-1 mm, so that the bonded areas of the affected or normal dentin were isolated. The obtained rods were divided into two groups: Affected and sound dentin. After measuring the cross-sectional areas at the interface, the specimens were mounted in a microtensile tester machine and pulled under tension to failure. The mode of failure was evaluated using a streomicroscope and the data were analyzed by t-test. Statistical analysis indicated that the microtensile bond strength in affected dentin [21.53 +/- 6.52 MPa] was significantly lower [p<0.05] than normal dentin [26.98 +/- 7.31 MPa]. The studied self-etch system, attained lower microtensile bond strength in affected dentin as compared to normal dentin