Bonding longevity of flowable GIC layer in artificially carious dentin

Abstract

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 0.76mm 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 24h, 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±1.3MPa) (p<0.001). No significant differences were observed (p=0.126) between regular (4.2±1.8MPa) and flowable (4.6±1.5MPa) GIC consistency. Moreover, GIC showed better bonding effectiveness on sound (5.1±1.7MPa) than artificially carious dentin (3.7±1.3MPa) (p<0.001). ConclusionsBoth powder/liquid ratio of GIC show similar reduction of bonding effectiveness after one year, especially in artificially carious dentin substrate.