The purpose of this study was to evaluate the enamel bond strength and durability of 4-META/MMA-TBB resin (Super-Bond, Sun Medical) used with a phosphoric acid etchant and a self-etching primer for surface treatment. Red Activator (RE, Sun Medical) and Teeth Primer (TP, Sun Medical) were applied to human and bovine enamel surfaces in accordance with the instructions of the manufacturer of the 4-META/MMA-TBB resin via the brush-dip technique. The enamel-resin interface was analyzed using a field emission scanning electron microscope (FE-SEM). The durability of adhesion to bovine enamel was assessed in terms of tensile bond strength after immersion in water at 37°C for 24 hours and after 200,000 times of 5/55°C thermal cycles. The micro-tensile bond strength to human enamel was measured following immersion in water at 37°C for 24 hours and after 20,000 times of 5/55°C thermal cycles. The results revealed that the teeth treated with phosphoric acid etching and selfetching primer exhibited improved bond strength and adhesion durability. In the FE-SEM images, the resin-tag formation could be clearly identified in the specimens treated with phosphoric acid only and the combination of the phosphoric acid and TP.

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In this study, we examined the chronological changes of hydrophobic recovery after helium plasma treatment of the surface of esthetic material. Zirconia (KATANA, ZR), CAD/CAM resin block (KATANA Avencia, RB1 and CeraSmart, RB2), hybrid composite resin (Estenia C&B, HC1 and Gradia Forte, HC2), and core build-up composite resin (Clearfil DC Core, BC1 and MI core LC, BC2) were used. Each prepared surface was treated with helium plasma after being polished with waterproof abrasive paper. The contact angle was measured before treatment, and at 0.5, 1, 6, 12, 18 and 24 hours after treatment. One-way ANOVA and Tukey correction were performed for statistical analysis (a = 0.01, n = 10). The contact angle showed no statistically significant difference between just after treatment and 30 minutes later in the ZR, RB1, RB2 and BC2 groups, between just after treatment and 6 hours later in the HC1 group, or between just after treatment and 1 hour later in the HC2 group. The contact angle showed a statistically significant difference between all conditions. In all samples, hydrophobic recovery occurred. Thus, the effect of the helium plasma treatment was maintained even after 24 hours.

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The purpose of this study was to investigate the influence of professional tooth cleaning (PTC) on the surface roughness of resin composites for indirect restoration, ESTENIA (Es) and EXPERIA (Ex). Blocks of the composites were fabricated in a mold of 10 × 10 × 2 mm3. Surfaces of the blocks were serially wet-polished using up to #2000, and then were ultrasonically cleaned. The blocks were divided into three groups receiving different PTC instrumentation as follows: Group S: air scaler, Group N: nylon brush attached to air scaler handpiece, and Group M: nylon brush attached to micromotor handpiece. In Experiment 1, PTC was performed with an approximate force of 0.5 N. In Experiment 2, PTC was performed free-handedly by seven dental hygienists. Surface roughness (Ra) of the composites was measured before and after PTC, and the difference in roughness (RA) was calculated. Two-way ANOVA and Bonferroni correction were performed for the statistical analysis (α = 0.01). In Experiment 1, RA of Es in Group N was significantly lower than those in Groups S and M. RA of Ex in Group N was significantly lower than that in Group S. In Experiment 2, both composites demonstrated that RA in Group N was significantly lower than that in Group S. These results suggested that the surface roughness of the resin composites was affected by the PTC method and the type of filler in the composite

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This study examined the effect of powder-liquid mixing ratios and thermal cycling on the bond strength of orthodontic resin-modified glass ionomer cements to bovine enamel. Using commercially-available chemical-cured type or light-cured type resin-modified glass ionomer cements, the standard metal brackets adhered on the fresh bovine enamel surfaces. The powder-liquid mixing ratios used were the manufacturer’s recommended ratio, as well as the ratios with 20% more or less powder than the manufacturer’s recommended ratio. After the brackets were bonded on the enamel, the following specimens were prepared: specimens kept moist (23°C, 95% RH) for 24 h; specimens subjected to thermal cycling (5–55°C, 2,000 cycles) after the 24-hour moist storage; and specimens stored in 37°C water for the duration equal to that of the thermal cycling used (111 h). The shear bond strengths of the brackets were determined immediately after each aging condition (n = 20). The light-cured type cement had significantly (p < 0.05) greater mean bond strength than the chemical-cured type cement in all experimental conditions. Thermal cycling showed no significant effect (p > 0.05) on the bond strengths of light-cured type cement within ±20% of deviation of mixing ratio from the standard ratio. The strength data and Weibull analysis suggested that the light-cured type cement has more stable bond strength than the chemical-cured type cement.

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The purpose of this study was to evaluate the effect of dental metal primers on the bond strength between oxidation heat-treated gold-silver-palladium alloy and MMA-TBBO resin. Adherends were fabricated with pure metal of Au, Ag, Cu, Pd or gold-silver-palladium alloy (MC12). Three different dental metal primers, namely Alloy Primer (AP), V-Primer (VP) and Epricode Opaque Primer (OP), were used. Also, two different resin cements, including Super-Bond C&B (Normal) or resin cement in which monomer liquid was replaced by pure MMA from 4-META-MMA of Normal, were used. On pure metal specimens, a total of sixteen groups including four pure metals, four surface treatments and Normal, were prepared (n = 5). On MC12 specimens, a total of 32 groups, including four heat treatment times, four surface treatments and two resin cements, were prepared (n = 7). After subjecting the specimens to 2,000 times of thermo-cycling, shear bond strengths were measured. As a result, specimens using VP demonstrated significantly higher bond strength than Ag and Cu in the presence of 4-META. Also, Cu specimens were easily oxidized by oxidation heat treatment, and increased in reactivity to non-noble metal primer. On the other hand, it was difficult for VBATDT to react unoxidized area through metal oxide film. Within the limitations of this study, it is concluded that oxidation heat treatment of MC12 restorations improves bond durability.

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