Bond Strength Durability of Different Adhesives to Dentin After Aging in Two Different Solutions.

PURPOSE: To determine the influence of aging in artificial saliva compared to distilled water on the dentin microtensile bond strength (µTBS) of different adhesive systems. MATERIALS AND METHODS: Occlusal enamel and superficial dentin of 42 teeth were removed and roots were sectioned to expose the pulp chamber for connecting the tooth segments to an intrapulpal pressure assembly. According to the tested adhesives, tooth segments were allocated to three groups (n = 14): an etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, SBMP), a two-step self-etching adhesive (Clearfil SE Bond, CSE), and a singlestep self-etching adhesive (Clearfil S3 Bond, S3). Each adhesive system was applied to the dentin surface according to its manufacturer's instructions, while intrapulpal pressure was simulated. Resin composite (3M ESPE) was built up in two increments of 2 mm each. Each bonded specimen was sectioned to obtain eight sticks (0.8 ± 0.01 mm2). Sticks of each group were divided equally (n = 56) according to the storage solution, either distilled water or artificial saliva. For each storage solution, half of the sticks of each subgroup (n = 28) was stored for 24 h at 37°C and the other half was thermocycled for 10,000 cycles between 5°C and 55°C. Sticks were then subjected to µTBS testing. Data were statistically analyzed using multifactor ANOVA with repeated measures and Bonferroni's post-hoc test (p < 0.05). Student's t-test was used for pairwise comparison. Failure modes were determined for all tested sticks using scanning electron microscopy. RESULTS: The decrease in bond strength of the three adhesives was significantly higher in distilled water than in artificial saliva. The predominant failure modes were adhesive and mixed. CONCLUSION: The decrease in bond strength was more pronounced for specimens stored in distilled water than in artificial saliva.

Effect of ultrasound application during setting on the mechanical properties of high viscous glass-ionomers used for ART restorations.

This study was conducted to evaluate the effect of ultrasound application on the surface microhardness (VHN) and diametral tensile strength (DTS) of three high viscous glass-ionomer restorative materials (HVGIRMs). For each test (VHN and DTS), a total of 180 specimens were prepared from three HVGIRMs (Ketac-Molar Aplicap, Fuji IX GP Fast, and ChemFil Rock). Specimens of each material (n = 60) were further subdivided into three subgroups (n = 20) according to the setting modality whether ultrasound (20 or 40 s) was applied during setting or not (control). Specimens within each subgroup were then equally divided (n = 10) and tested at 24 h or 28 days. For the VHN measurement, five indentations, with a 200 g load and a dwell time for 20 s, were made on the top surface of each specimen. The DTS test was done using Lloyd Testing machine at a cross-head speed of 0.5 mm/min. Ultrasound application had no significant effect on the VHN. Fuji IX GP Fast revealed the highest VHN value, followed by Ketac-Molar Aplicap, and the least was recorded for ChemFil Rock. Fuji IX GP Fast and Ketac-Molar Aplicap VHN values were significantly increased by time. ChemFil Rock recorded the highest DTS value at 24 h and was the only material that showed significant improvement with both US application times. However, this improvement did not sustain till 28 days. The ultrasound did not enhance the surface microhardness, but its positive effect on the diametral tensile strength values was material and time dependent.

Repair Bond Strength of Aged Silorane-based Composite Using Intermediate Adhesive Systems Based on Different Monomers.

PURPOSE: To investigate the effect of pre-repair aging periods and intermediate adhesive systems based on different monomers on the repair bond strength of silorane-based resin composite. MATERIALS AND METHODS: A total of 32 Filtek P90 (3M ESPE) substrate specimens (4 mm diameter and 4 mm height) were made. Substrate specimens were grouped according to the pre-repair time periods into four groups (n = 8/group): 15 to 30 min, 24 h, 1 month, and 3 months. All substrate specimens were ground flat using a diamond stone and were etched using Scotchbond phosphoric acid etchant (3M ESPE). The specimens of each pre-repair time period were equally distributed among the two repair groups, using either silorane-based (P90 System Adhesive) or acrylamide-based (AdheSE One F, Ivoclar Vivadent) intermediate adhesive systems. Specimens of P90 System adhesive received Filtek P90 as the repair resin composite, and Tetric N-Ceram (Ivoclar Vivadent) was used with AdheSE One F specimens. Additional specimens were made from the repair resin composite materials to study the cohesive strength. Specimens were sliced into sticks (0.6 ± 0.01 mm2) for microtensile bond strength testing (µTBS). Modes of failure were determined. RESULTS: Two-way ANOVA with repeated measures revealed no significant effect for the pre-repair aging periods, intermediate adhesive systems based on different monomers, or their interaction on repair bond strength of silorane-based resin composite. CONCLUSION: Up to 3 months of pre-aging the repaired silorane-based resin composite had no negative effect on its repair bond strength, even when an intermediate adhesive system based on a different monomer (acrylamide) was used.