Effect of ascorbic acid, ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

PURPOSE: The aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores. MATERIALS AND METHODS: Twenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at x20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM. RESULTS: Means of microtensile bond strength values (MPa) and standard deviations in the groups were as follows: G1: 9.70+/-0.81; G2: 12.62+/-1.80; G3: 16.60+/-1.93; and G4: 21.24+/-1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode. CONCLUSION: Application of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol.

Microtensile bond strength of quartz fiber posts to different composite cores

The aim of this in vitro study was to assess the microtensile bond strength of quartz fiber posts to different composites, and to composite combinations used as core materials. Thirty fiber posts were treated with a 24 percent hydrogen peroxide solution and silanized. The posts were divided into 5 groups according to the resin composite used as follows (n = 6): G1 - Ælite Flow (Bisco, Inc), G2 - Filtek Z250 (3M ESPE), G3 - Biscore (Bisco, Inc), G4 - Ælite Flow + Filtek Z250, G5 - Ælite Flow + Biscore. The resin composites were placed around the posts to produce cylindrical specimens. Two 1-mm² thick sticks containing the post in the center and composite cores on both ends were provided from each cylinder and tested for microtensile strength with a crosshead speed of 0.5 mm/min. One-way ANOVA and Tukey HSD tests were used for statistical analysis. Fractured surfaces were observed using a stereomicroscope with 20× magnification. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks. The results showed that G2 had the highest bond strength values, and the lowest values were seen with G3. There were significant differences between groups 1, 2, 4 and groups 3, 5 (p < 0.05). Under the stereomicroscope, most of the failures were adhesive between the post and core material. Under SEM, Ælite and Z250 had smoother surfaces than Biscore, containing less porosities and voids.