Abstract
This study aimed to clarify the effects of chemical surface treatment of denture base resin on the shear bond strength between denture base resin fabricated by additive manufacturing and autopolymerizing resin in non-aged conditions. Five surface-treatment conditions were applied to specimens fabricated from two additively manufactured resins (AM 1 and AM 2): no treatment (NT); application of a dichloromethane-containing resin primer for 5 s (M5s), 60 s (M60s), or 120 s (M120s); and application of an ethyl acetate-containing resin primer for 120 s (E120s). Three surface-treatment conditions (NT, M5s, and E120s) were applied to control specimens fabricated from autopolymerizing denture base resin. The autopolymerizing resin was bonded to each specimen after chemical surface treatment. The shear bond strength was measured, and the failure modes on the specimen surfaces were observed. The highest median shear bond strength was 16.8 MPa for the AM 1 specimens in M60s, 16.7 MPa for the AM 2 specimens in M5s, and 17.2 MPa for the autopolymerizing resin specimens in M5s. Substrate failure was observed in AM 1 specimens following M60s treatment. Cohesive failure was observed in AM 2 specimens following M5s treatment. Under non-aged conditions, chemical surface treatment of additive manufacturing resins with a dichloromethane-containing resin primer improved the shear bond strength to the autopolymerizing resin. Furthermore, the most effective application time of the dichloromethane-containing primer varied depending on the type of additive manufacturing denture base resin.