Bonding of maxillofacial silicone elastomers to an acrylic substrate

Abstract Objective To investigate the effect of three different primers on shear and peel bond strengths between three maxillofacial silicone elastomers and an acrylic resin after 360 h of accelerated daylight-aging. Materials and methods Peel and shear-bond strengths of three maxillofacial silicone elastomers (TechSil S25, Cosmesil M511, Cosmesil Z004) to acrylic denture resin bases using three adhesive primers (611, A304, A330-G) were assessed at baseline and after 360 h of accelerated artificial light-aging. Data were collected and statistically analyzed by two-way ANOVA, one-way ANOVA, and Bonferroni post hoc tests ( α = 0.05). Independent t -test was used to investigate the effect of light-aging on bond strengths ( α = 0.05). Modes of failure were visually analyzed and categorized as adhesive, cohesive, or mixed. Results In the peel bond test, at both baseline and after aging, there was a significant influence of primers and silicones on bond strength ( p < 0.001) and a strong interaction was also found between primers and silicones ( p < 0.05). Peel bond strengths ranged from 0.85 to 5.31 and 0.76 to 8.22 N/mm at baseline and after aging, respectively. The Z004 and 611 and Z004 and A330-G combinations showed the highest peel bond strength (5.31 and 8.22 N/mm, respectively) ( p < 0.05), as baseline and after aging. In the shear-bond test, there was only a significant influence of silicones on shear-bond strength ( p < 0.001), whereas primers did not affect it ( p > 0.05), and no interaction between primers and silicones was found ( p > 0.05). Shear-bond strengths ranged from 0.42 to 0.66 and 0.48 to 1.00 MPa at baseline and after aging, respectively. The combinations of Z004 and 611, Z004 and A304, Z004 and A330-G, M511 and A304, M511 and A330-G exhibited the highest bond strength (0.59–0.65 MPa) at baseline, and the Z004 with any of the primers (611, A304, and A330-G) showed greater bond strengths (0.89–1.00 MPa) ( p < 0.05) after aging. All the silicone elastomers at baseline, regardless of the adhesive primers, failed predominantly by cohesive debonding under peel and shear forces (68.9% and 100% respectively). However, after light-aging, peel and shear forces predominantly exhibited adhesive (79.5%) and cohesive (84.4%) failures, respectively. Conclusions Shear and peel test-regimes were both relevant and suitable for studying bonding and debonding characteristics of maxillofacial silicone elastomers bonded to an autopolymerising acrylic resin. Th