Bonding strength of soft lining materials to thermoplastic resins

Method: Three thermoplastic resins [EstheShot Bright (Polyethylene Terephthalate; PET, i-CAST, Japan), Acrytone (Thermoplastic Acrylic Resin, High Dental Japan, Japan), and Reigning N (Polycarbonate, Toshinyoko, Japan)] and soft lining materials [Sofreliner Tough (Tokuyama Dental, Japan)] were used in this study. Thermoplastic resin plates (20.0×20.0×2.0 mm) were made, and their surfaces were abraded using emery paper (600 grit) and sandblasted with 50 mm alumina particles (0.48 MPa). As an adhesive agent, 4-META/MMA-TBB (Sun Medical, Japan) was primed on the surfaces. As a control, specimens without a bonding agent were also prepared. Soft lining materials were attached between the thermoplastic resin and acryl resin plate (2.0 mm thick). After polymerization, the specimens were stored in 37 ℃ distilled water for 48 hours. The tensile bonding strengths were measured using an autograph (EZ-S, Shimazu, Japan) at a crosshead speed of 2.0 mm/min. The data obtained (n=5) were analyzed using a one-way ANOVA and Tukey’s multiple comparisons test (a=0.05). 

Result: With and without a bonding agent, Acrytone had a significantly lower bonding strength than Reigning N and EstheShot Bright (p<0.05). The bonding strength increased according to the amount used; however, there were no significant differences in any of the thermoplastic resins regardless of the use of a bonding agent.

Conclusion: When using 4-META/MMA-TBB as a bonding agent in this study, there was no increase in bond strength over thermoplastic resins and soft lining materials.