For thermoplastic resin dentures, relining with a soft relining material may be necessary when the dentures show a poor fit, as well as the acrylic resin denture base. This in vitro study investigated the bonding strength of thermoplastic resins to soft lining materials. Three thermoplastic resins, polyamide (Valplast, Yunival), polyethylene terephthalate (Estheshot, i-CAST) and polycarbonate (Reining, Toshinyoko), and two soft lining materials, acryl (Soft-liner, GC) and silicone (Sofreliner Tough, Tokuyama Dental), were used in this study. The surfaces of thermoplastic resin plates (40.0 × 40.0 × 20.0 mm) were abraded using emery papers and sandblasted. As an adhesive agent, 4-META/MMA-TBB (Sun Medical, Japan) was primed on the surface. As a control, specimens without adhesive agent were also prepared. Soft lining materials were mixed and attached between the thermoplastic resin and acryl resin plate. After the specimens were subjected to thermocycling (5–55ºC) 5000 times, the tensile bonding strength was measured using a universal testing machine. The data obtained (n=5) were analyzed using a three-way ANOVA and Tukey’s multiple comparisons test (α=0.05) for each soft relining material. The bonding strength of acrylic-based soft lining materials to thermoplastic resins was considerably improved by the 4-META/MMA-TBB adhesive agent.

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The aim of the present study was to examine the effects of tannic acid on type I collagen derived from bovine Achilles tendon. Tannic acid was dissolved in distilled water and adjusted to a final concentrations of 0.1, 1, 10, and 20%. The collagen samples were immersed in these tannic acid solutions for varying durations, rinsed with distilled water, and then dried. The thermal denaturation temperature was determined using differential scanning calorimetry (DSC). Next, the collagen samples were etched with 40% phosphoric acid or 10% citric acid. Macroscopic changes in the samples were visually confirmed, and the thermal denaturation temperature was determined again by using DSC. The results showed that the thermal denaturation temperature of the collagen samples increased after treatment with tannic acid, although the temperature varied according to the tannic acid concentration and the immersion time. Collagen was not converted into gelatin after acid treatment; moreover, DSC showed that collagen was not denatured. These results suggest that tannic acid can strengthen type I insoluble collagen and improve the adhesion of adhesive resin cement to dentin.

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Because of the equivalent or higher bending strength, hardness, and toughness compared with yttria partiallystabilized zirconia, Ce-TZP/Al2O3 nano-composites (NANOZR) have been developed and are commercially available for frame and abutment materials. In this study, using four types of adhesive resin cement, we evaluated the bond strength and adhesive durability between titanium and two types of NANOZR. The two types of NANOZR (medium- and pre-sinter) were made by sintering the materials with low density after cutting to a higher density at different temperatures. Sand-blast treatment of the adhered surface of the medium- and pre-sinter specimens was performed using alumina particles of 50 μm in diameter at a pressure of 0.2 MPa, and ceramic or zirconia primer treatment was performed. Sand-blast treatment of the titanium surface was performed at a pressure of 0.4 MPa, and metal primer treatment was performed. Thereafter, they were adhered using each type of adhesive resin cement. For the shear bond strength test, some specimens were left in air at 37°C for 24 hours (NANOZRNANOZR, titanium-titanium, titanium-NANOZR specimens), and the others underwent 10,000 thermal cycles of repetitive immersion in distilled water at 4°C and 60°C for one minute (titanium-NANOZR specimens only). The values obtained were statistically tested (ANOVA, Fisher’s PLSD test, α=0.05). The bond strength between titanium and C-Pro NANOZR using resin cement, considering the bond strengths of NANOZR-NANOZR and titanium-titanium, was influenced by the bond strength between the resin cement and titanium. Pre-sinter specimens showed a significantly higher value than medium-sinter specimens, and excellent adhesive durability. Furthermore, resin cement containing phosphoric ester monomers showed a significantly higher value.

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We investigated the effect of adherend surface treatment on the shear bond strength (SBS) of repaired resin composite to a photo-cured resin composite surface prepared with Er,Cr:YSGG laser. Photo-cured resin composite blocks were ground using #600 silicon carbide paper, and then the resin composite surfaces were prepared using an Er,Cr:YSGG laser (Groups 1 to 6). The ground resin composite blocks without laser preparation were used as controls. Each resin composite surface was treated with only bonding agent (Clearfil SE Bond/Bond: SEB) in Group 1; silane coupling agent (a mixture of Porcelain Bond Activator: PBA and Clearfil SE Bond/Primer: SEP) and SEB in Group 2; phosphoric acid (K-etchant Gel: KET), a mixture of PBA and SEP, and SEB in Group 3 and control; KET, sodium hypochlorite (AD Gel: ADG), PBA with SEP and SEB in Group 4; only silane coupling agent (a mixture of Tri-S bond: TRI and SEP) in Group 5; and KET, ADG, and a mixture of TRI and PBA in Group 6. After each treatment, the resin composite (Clearfil Majesty) was placed and photo-cured. The specimens were subjected to SBS testing. The data were statistically analyzed with ANOVA and Tukey’s HSD test. The SBS values (MPa, mean ± SD) for each group were: Group 1: 13.8 ± 6.8, Group 2: 15.5 ± 2.7, Group 3: 16.0 ± 7.4, Group 4: 16.0 ± 4.0, Group 5: 15.9 ± 4.3, Group 6: 14.0 ± 7.9, and control: 15.8 ± 4.7. There was no significant difference among all experimental groups (p>0.05).

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