BOND STRENGTH OF COMPOSITE TO SOUND AND ARTIFICIAL CARIOUS DENTIN

Purpose: To determine the in vitro bond strength of a composite (Hercu lite XRV) to sound dentin and artificial carious lesions in dentin. Ma terials and Methods: Buccal and lingual surfaces from extracted human molar teeth were ground to expose sound dentin surfaces. The buccal su rface was maintained as sound dentin, while an artificial carious lesi on was created in the lingual surface using an acidified gelatin gel. A bonding agent (Optibond) was applied to both buccal and lingual surf aces with and without prior etching with 37.5% phosphoric acid. The co mposite was applied and debonded under tension after 24 hours in water at 37 degrees C. Results: Both sound dentin (23.1 MPa) and etched sou nd dentin (22.2 MPa) had similar bond strengths, whereas artificial ca rious lesions in dentin that had been etched (11.8 MPa) and non-etched dentin lesions (8.8 MPa) had significantly lower bond strengths. Adhe sive failures were greatest for dentin lesions (60-95%) and least for sound dentin (40-50%). Etching with phosphoric acid did not improve th e bond strength of composite to sound dentin or artificial carious les ions in dentin.