Immediate dentin bond strength of flowable glass ionomer-based liner materials without surface pretreatment

The aim of this in vitro study was to evaluate the dentin bond strength of different flowable glass ionomer-based liner materials without surface pretreatment.

Twenty-one extracted human molars were randomly assigned to three groups (n = 7), each receiving a different material (Groups A-C). Mid-coronal dentin surfaces were prepared and standardized using silicon carbide paper to create a uniform smear layer. Three flowable glass ionomer-based liner materials were applied without any surface pretreatment or adhesive system. Cylindrical specimens (2 mm diameter × 2 mm height) were light-cured according to the manufacturers' instructions. After 24 hours of storage at 37 °C and 100% humidity, shear bond strength was measured using a universal testing machine at a crosshead speed of 1 mm/min. Failure modes were evaluated under a stereomicroscope and scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test (α = .05).

The mean [±SD] bond strength values were 12.76 [±5.5] MPa for Group A, 12.74 [±6.6] MPa for Group B, and 19.25 [±7.9] MPa for Group C. Although Group C showed numerically higher values, no statistically significant difference was found among the groups (P = .13). Adhesive and mixed failure modes were predominantly observed, whereas cohesive failures were rare.

Within the limitations of this in vitro study, the evaluated flowable glass ionomer-based liner materials exhibited comparable immediate dentin bond strength under simplified application conditions without surface pretreatment.