Bond Strength of Direct Hard Relining Materials to Thermo-Acrylic Resin

Method: To evaluate the cohesive strength of the materials, were made double-cone shaped samples using: Heat-cured acrylic resin (Classico)- A(n=20); Ufi Gel Hard C (Voco)-U(n=10); Kooliner (GC America)- K(n=10); Rebase II Fast (Tokuyama)- R(n=10) and Rebase II Fast + Resin Hardner (Tokuyama)- RH(n=10). The samples were stored immersed in deionized water (37°C) for 7 days and then 10 samples of HA group were submitted to tensile test in universal testing machine (crosshead speed 1 mm/min, 500N load cell) and the others samples submitted to thermal aging (1000 cycles, 5°C-55°C) and after to tensile test. Fifty cone shaped samples were made using heat-cured acrylic resin, stored and aged in the same conditions, and after that the top surface of each cone was gently abraded with a diamond bur, chemically treated according to the recommendations of each manufacturer and second cones with the relining resins were build up using silicon molds. After 7 days of storage (deionized water; 37°C), the samples were submitted to tensile test. The obtained values (MPa) were submitted to one way ANOVA and Tukey’s test for statistical analysis (α= 5%).

Result: K/A-5,98(±1,90)a; RH/A-9,38(±1,78)a; R/A-9,69(±2,37)a; U/A-11,56(±1,98)a; A/A-21,17(±4,89)b; KCoe-22,29(±4,06)b; RCoe-23,99(±3,29)b; RHCoe-24,84(±3,88)b; UCoe-25,62(±3,03)b; AAged-36,06(±8,65)c and A-42,29(±7,68)c. Groups followed by the same letters do not show significant statistical differences.

Conclusion: The cohesive strength of acrylic resin is higher than the relining material; the bond strength of relining materials is smaller than the cohesive strength; the bond strength of acrylic resin to acrylic denture base material is higher than the other relining material and Ufigel Hard C showed the higher results of bond strength.