OBJECTIVETo evaluate the effects of surface treatments on the bonding of silicone elastomer to acrylic resin.

METHODSNinety acrylic resin specimens were randomly divided into 9 groups which were assigned to 9 different surface treatments: finished by 80-, 240-, 400-, 600-, 800-, 1000-, 1500-grit silicon carbide paper under running water, or polished or sandblasted. Roughness of the specimen surface was tested in each group, and the microstructure was observed with scanning electron microscopy (SEM). ZY-1 silicone elastomer, ZA-1 primer and acrylic resin specimens were prepared. Shear bond strength were tested and failure modes were assessed for all specimens.

RESULTSThe roughness of all 9 groups showed significant difference (P < 0.05). The sandblasted group showed the highest roughness [(2.97 + or - 0.48) microm], the 1500-grit silicon carbide paper finished group showed the lowest roughness [(0.21 + or - 0.14) microm]. The sandblasted groups showed the lowest bonding strength [(0.98 + or - 0.11) MPa] (P < 0.05) while the 600-grit silicon carbide paper finished group showed the highest strength [(2.13 + or - 0.14) MPa].

CONCLUSIONSOver high surface roughness does not improve the shear bond strength between silicone elastomer and acrylic resin. Treatment of acrylic resin surface with 600-grit silicon carbide paper can increase the shear bond strength between silicone elastomer and acrylic resin.