Shear Bond Strength of Denture Teeth to Heat- and Light-Polymerized Denture Base Resin

Abstract

To evaluate the shear bond strengths of highly cross-linked denture teeth bonded to heat-polymerized poly(methyl methacrylate) (PMMA) or a light-polymerized urethane dimethacrylate (UDMA) denture base resin with or without a diatoric and with or without an acrylate bonding agent. The denture base resins tested were Lucitone 199 (heat-polymerized PMMA) and Eclipse (light-polymerized UDMA). One hundred sixty mandibular central incisor denture teeth were divided into four groups (n = 40): group 1: ground surface as control; group 2: ground surface with diatoric; group 3: ground surface with bonding agent; group 4: ground surface with bonding agent and diatoric. Half of each group (n = 20) was processed with either heat- or light-polymerized resin. All specimens were treated with thermocycling for 1000 cycles, alternating between 5 and 55 °C with a dwell time of 30 seconds. Half the specimens in each group were treated with cyclic loading at 22 N for 14,400 cycles at 1.5 Hz. All specimens were tested with shear load to failure. Data were analyzed with student's t-test, 2- and 3-way ANOVA, and Dunnett's T3 method (p < 0.05). Statistical analysis demonstrated no significant effect on shear bond strength from cyclic loading. For the Lucitone 199 (L) specimens, mean shear bond strengths and standard deviations were (N) 66.5 ± 28.4, 72.7 ± 31.5, 80.6 ± 17.1, and 76.9 ± 21.9 for groups 1L, 2L, 3L, and 4L, respectively. For the Eclipse (E) specimens, mean shear bond strengths and standard deviations were (N) 3.7 ± 1.2, 7.3 ± 3.3, 90.0 ± 20.7, and 94.2 ± 17.8 for groups 1E, 2E, 3E, and 4E, respectively. No statistically significant differences in shear bond strengths were noted for the Lucitone 199 groups (p = 0.11). Eclipse shear bond strengths were significantly higher in groups 3E and 4E than in groups 1E and 2E (p ≤ 0.05). In a 3-way ANOVA for groups 3 and 4, the shear bond strengths for the Eclipse specimens were significantly higher than the Lucitone 199 specimens (p = 0.01). When evaluating the shear bond strength of IPN denture teeth to denture base resins, specimens using an acrylate bonding agent with the Eclipse (light-polymerized) resin yielded significantly higher shear bond strengths than all of the Lucitone 199 groups and the Eclipse resin groups without a bonding agent.