No abstract

The purpose of this study was to determine the elastic modulus of components at the resin-dentin interface with the use of an ultrasound device. Dentin slabs were obtained from freshly extracted bovine incisors shaped into a rectangular form. After demineralization, the dentin specimens were immersed in adhesives and polymerized. Adhesives were also polymerized and trimmed into the same shape as the dentin slabs. The specimens were then immersed in distilled water at 37°C for up to one year. The ultrasound equipment employed in this study was a Pulser-Receiver, transducers and an oscilloscope. By measuring the longitudinal and shear wave sound velocities, the elastic modulus was determined. When the elastic modulus of adhesive resin-infiltrated demineralized dentin was compared with that of adhesives, slightly but significantly lower values were found for adhesives used in a self-etching primer system. On the other hand, a higher elastic modulus was observed for resin-infiltrated dentin than for an adhesive used in an etch and rinse system. The elastic modulus of the resin-infiltrated dentin prepared with the etch and rinse system was affected by long-term storage in distilled water. (J. Oral Sci. 50, [481][482][483][484][485][486] 2008)

By measuring the ultrasonic propagation velocity, it can be concluded that CDR application has an ability to promote bovine enamel remineralization.

This study investigated the effect of a coating material containing S-PRG fillers on the demineralization of bovine enamel and dentin, by measuring changes in the transmitted ultrasonic velocity. Bovine enamel and dentin specimens with and without coating (n=6 for each condition) were cut into blocks, immersed in 0.1 M lactic-acid buffer solution (pH 4.75) for 10 min twice daily throughout the test period, and stored in a demineralising artificial saliva solution (pH 7.0) between treatments. The propagation time of longitudinal ultrasonic waves was measured by a pulser-receiver with a transducer. Data were evaluated using ANOVA followed by Tukey's HSD test (α=0.05). The sonic velocity decreased over time for specimens stored in demineralising solution; however, coated specimens had a significantly higher sonic velocity than those without coating. The coating material containing pre-reacted glass-ionomer fillers therefore appeared to reduce the demineralisation of enamel and dentin.

The purpose of this study was to examine the microtensile bond strength of a single-step selfetch adhesive system (Clearfil tri-S Bond and One-Up Bond F Plus) to bovine dentin. Adhesive was applied to a flat dentin surface, and resin composite was bonded according to the manufacturers' instructions. After 24 h storage in distilled water at 37°C, hourglassshaped specimens were produced. These were subjected to microtensile bond strength testing at a cross-head speed of 1.0 mm/min. The results were analyzed using Student's t-test at a significance level of 0.05. Fieldemission scanning electron microscopy (FE-SEM) observations of the fractured specimens and the adhesive-treated dentin surfaces were also conducted. The bond strength of Clearfil tri-S Bond was not significantly different from that of One-Up Bond F Plus, 41.1 ± 10.1 versus 42.3 ± 6.0 MPa. Mode of failure analysis for Clearfil tri-S Bond revealed an equal distribution between the three types of failure, and the predominant mode of failure was adhesive for One-Up Bond F Plus. FE-SEM observations of dentin to which adhesive had been applied revealed that the smear layer had been removed and the collagen fibers exposed. (J. Oral Sci. 49, [183][184][185][186][187][188][189] 2007)