Bonding longevity of flowable GIC layer in artificially carious dentin

PurposeTo evaluate the bond longevity of glass ionomer cement (GIC) to sound and artificially carious dentin, using a high viscosity material with regular consistency and using a flowable GIC, after one year water storage.Material and methodsSixty bovine incisors were polished to obtain flat buccal dentin. Thirty teeth were submitted to pH-cycling model to simulate artificial caries. Teeth from both dentin conditions (sound and caries) were randomly reassigned according to the powder/liquid ratio of the GIC (n=15): (1) regular (1:1) and (2) flowable GIC (1:2). Polyethylene tubes with internal diameter of 0.76 mm were placed over the pre-treated dentin and filled up with GIC (KetacTM Molar Easy Mix, 3M ESPE), immediately protected with a layer of petroleum jelly. Half of the specimens were evaluated by microshear bond strength test after 24 h, the other half was evaluated one year later, after water storage at 37 °C. Data (MPa) were analyzed with 3-way repeated measures ANOVA and Tukey׳s post-hoc tests (α=0.05).ResultsStatistical analysis revealed reduction of GIC bonding effectiveness after one year of water storage (5.4±1.4 to 3.4±1.3 MPa) (p<0.001). No significant differences were observed (p=0.126) between regular (4.2±1.8 MPa) and flowable (4.6±1.5 MPa) GIC consistency. Moreover, GIC showed better bonding effectiveness on sound (5.1±1.7 MPa) than artificially carious dentin (3.7±1.3 MPa) (p<0.001).ConclusionsBoth powder/liquid ratio of GIC show similar reduction of bonding effectiveness after one year, especially in artificially carious dentin substrate.