Shear bond strength of quartz fiber reinforced composite posts by microwave surface treatment

d 7). The other 9posts were immersed in the same solution under microwave irradiation for 60sec, 90sec, 120sec respectively (group 2, 3, and 4). After the treatment, all posts were rinsed and coated with silane coupling agent. For group 8, the posts were only coated with silane coupling agent and no surface treatment was applied to the posts in group 9 (control group). Core buildup composite resin were fabricated on the posts in each group, then sectioning for 1mm-thick specimens. These specimens were tested for shear bond strength using push-out test with cross-head speed 0.5mm per minute. In surface roughness testing, two pieces of the posts in each group were randomly selected and evaluated for the surface roughness using atomic force microscope. Two-way ANOVA revealed that group 1 and 2 achieved highest shear bond strength (P

A Comparison of Retention Between Acetal Resin and Stainless Steel Wrought Wire Retentive Clasp Arms

The objective of this study was to compare the retention of three different groups of acetal resin retentive clasp arm and a group of stainless steel wrought wire retentive clasp arm. The differences in design of acetal resin retentive clasp arms were as follow: group A, 1/3 terminal clasp arm was below a survey line and engaged retentive undercut 0.02˝ ; group B, 1/3 terminal clasp arm was below a survey line and engaged retentive undercut 0.03˝ ; group C, 2/3 terminal clasp arm was below a survey line and engaged retentive undercut 0.03˝ where as group D, stainless steel wrought wire clasp arm engaged retentive undercut 0.02˝ Tensile load of each clasp arm was performed by a Universal testing machine and the retentive force for group A, B, C, and D were 1.21, 1.67, 1.51, and 6.32 N respectively. One way ANOVA and Dunnett T3 multiple comparison reveal no significant difference in retentive force between group B and C but there were significant differences between these two groups and group A and D at p \<0.05.\  Keywords:\ acetal resin retentive clasp arm, stainless steel wrought wire retentive clasp arm

Effect of Plasma Treatment Time on Tensile-shear Bond Strength between Fiber-reinforced Composite Post and Flowable Composite Core and Wettability on Polymer Surfaces

Plasma treatment is an alternative way in improving bonding properties of fiber-reinforced post. However, technical parameters of this treatment need to be clarified, especially treatment time. The purpose of this study was to evaluate the effect of plasma treatment time on adhesion between fiber-reinforced post and a flowable composite core. Two types of post, methacrylate-based matrix (FRC Postec) and epoxy resin-based matrix (DT Light post) were treated with the mixture of Helium and Nitrogen (He+N2) plasma using a radiofrequency generator with various times before bonding to flowable methacrylate-based composite. Pull-out tests were performed using a universal testing machine. One-way ANOVA revealed that the best plasma treatment time for FRC Postec and DT Post was 10 and 15 minutes respectively. The adhesive properties of both posts tend to degrade with longer plasma treatment time. Water advancing contact angles on methacrylate-based polymer and epoxy resin-base polymer were decreased as the plasma treatment time was increased.Keywords: Fiber-reinforce composite post, tensile-shear bond strength, plasma treatment, contact angle