Evaluation of shear bond strength between maxillofacial silicone and fiber-reinforced composite resin after various surface treatments

The most common reason for remaking a facial prosthesis is the debonding of maxillofacial silicone from the substructure. Improved bonding would help overcome this problem. The purpose of this in vitro study was to evaluate the shear bond strength between maxillofacial silicone and fiber-reinforced composite resin after various surface treatments. Acrylic resin specimens were prepared with a dimension of 14.4 mm in diameter and 25 mm in height with a depression of 5 mm in depth and 8 mm in diameter, according to International Organization for Standardization technical specification (ISO/TE) 11405:1994. Fiber-reinforced composite resin was dispensed and packed into the depressed part of acrylic resin and allowed to polymerize. A total of 120 specimens were fabricated, and primer was then applied over the specimens. They were washed with acetone and subjected to various surface treatments, including airborne-particle abrasion, silicon carbide paper abrasion, and laser etching. The maxillofacial silicone was mixed according to the manufacturer’s instructions and packed into the cylindrical die with dimensions of 3 mm in thickness and 8 mm in diameter. The shear bond strength test on the specimens was carried out in a universal testing machine at a 5-mm/min crosshead speed, at 24 hours after fabrication and 200 hours after accelerated aging. The values were statistically analyzed using 1-way ANOVA and the Tukey honest significant difference (HSD) post hoc test. The mean shear bond strength values of the control group was 24.7 ±2.1 MPa, 26.9 ±1.8 MPa for the airborne-particle abraded group, 28.4 ±1.9 MPa for the silicon carbide abraded group SiCp, and 33.4 ±1.8 MPa for the laser-treated specimens at 24 hours after fabrication and 34.2 MPa at 200 hours after accelerated aging. The shear bond strength between the maxillofacial silicone and the fiber-reinforced composite resin was increased after laser surface treatment compared with airborne-particle abrasion and silicon carbide paper abrasion 200 hours after accelerated aging.