Bond Strength of Adhesive Resin Cements to Tooth Structure as Affected by Moisture and Storage Time

^{Purpose: To compare bond strengths to extracted teeth of M-Bond (M) and C&B Metabond (C) with moist (m), wet (w) and dry (d) conditions after 10 minutes and 24 hours. Methods: Extracted human teeth were sectioned bucco-lingually and embedded. Specimens of enamel, superficial and deep dentin were ground using 600-grit SiC paper. Specimens (3-mm diameter at bonded surface) made of composite were bonded tooth substrates using the cements according to the manufacturers’ instructions with 3 surface conditions (n=8). After bonding, the specimens were stored in water at 37oC for 10 minutes or 24 hours. All specimens were debonded in tension at a crosshead speed of 0.5 mm/minute. Bond strengths (MPa) and failure modes were determined. Results: Means (sd) are listed for superficial dentin.}

^{Fisher’s PLSD intervals (p=0.05) for comparisons of means between cements, among conditions of moisture, among substrates, and between times of testing were 1.1, 1.3, 1.3, and 1.1 MPa. For superficial dentin, M after 10 min was mw and after 24 hr was d>m>w. For M/m, bond strength was 10 min=24 hr, M/w was 10 min>24 hr, M/d was 10 min<24 hr. For C/m, bond strength was 10 min<24 hr, C/w was 10 min<24 hr, C/d was 10 min<24 hr. For C, superficial dentin failure modes were primarily adhesive in nature. With M, failures were mostly cohesive in cement. Conclusions: M had higher bond strength than C in all times and conditions except on moist superficial dentin after 24 hours. Funded by Tokuyama Dental Corporation.}