Novel Primers for Dental amalgam Repair

Abstract

Objectives: Replacement procedure might be a feasible treatment option if dental amalgam restoration is defected. However, such a procedure is invasive and could generate Hg aerosols, which are harmful to dental team and patients. Thus, repair of dental amalgam by bonding with a resin composite and primers might be a better alternative. Nevertheless, the commercial primers do not produce promising results on resin composite-amalgam bonding. Therefore, the objective in this laboratory study is to develop workable novel primers to bond resin composite better with amalgam. Methods: 3 silanes, 3-acryloxypropyltrimethoxysilane (ACPS), bis-1,2-(triethoxysilyl)ethane (BTSE) and bis[3-(trimethoxysilyl)propyl]amine (BTMA), were used as novel primers with the following combinations: 1.0 vol% ACPS, 1.0 vol% ACPS + 0.5 vol% BTSE, 1.0 vol% ACPS + 0.5 vol% BTMA. These primers were applied on sand-blasted and silica-coated dental amalgam discs. A flowable resin composite was adhered onto the discs and shear bond strength (SBS) was measured at initial, after water storage (1 day, 1 week, 1 month and 3 months) and after thermocycling (1000, 3000 and 6000 cycles). Failure modes were classified. 2-way ANOVA was used to analyze the statistical difference.

Results: The initial SBS were 20.22 MPa for ACPS, 16.59 MPa for ACPS + BTSE, and 19.47 MPa for ACPS + BTMA. After 1 week water storage or 1000 cycles of thermocycling, the SBS remained stable, and decreased gradually with linearity in the rest of longer duration groups. After thermocycling, ACPS and ACPS + BTSE showed statistically higher SBS than ACPS + BTMA (p < 0.001); no statistically significance (p = 0.062) were found between these silanes after water storage. No cohesive failure were found within the resin composite; cohesive failure within amalgam and mixed failure were mostly observed.

Conclusions: Novel silane primers might be future repair materials which could enhance the resin composite-amalgam bonding.