Effect of Poly(Alkenoic Acids) Molecular Weight on Microshear Bond Strength of Glass Ionomer Cement to Dentin

Objective To assess the influence of poly(alkenoic acids) (PAA) molecular weight (MW) on the microshear bond strength (µSBS) of conventional glass ionomer cements (GICs) to dentin. Materials and Methods Twenty‐four third molars were sectioned mesiodistally to expose flat buccal halves and randomly divided into four main groups. Three PAA solutions were synthesized with different MWs: (i) high molecular weight (HMW: Mw = 46,300 Da), (ii) low molecular weight (LMW: Mw = 15,700 Da), and (iii) mixed molecular weight (MixMW: 1:1 mixture of HMW and LMW polymers). The PAA solutions were hand‐mixed with a commercial GIC restorative powder (Fuji II, GC Corp., Tokyo, Japan) at a powder‐to‐liquid ratio of 1.5:1 (wt/wt). Each tooth specimen received microcylinders at the mesiobuccal and distobuccal line angles from the four tested materials, including the control group and the experimental groups. µSBS was tested after subjecting the specimens to thermocycling (5000 cycles; 5–55°C) using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed using a one‐way ANOVA test ( p < 0.05). Failure modes were assessed using a stereomicroscope at 40× magnification. Result There was a significant difference between the groups. There was a significant difference between the groups. The mixture of PAA containing both HMW and LMW exhibited higher µSBS values compared with both the HMW group and the control group. Mixed failures were the most common, while adhesive failures occurred least frequently among the experimental groups. Conclusion The selected mixed ionomers of different MWs had a statistically significant effect on the µSBS of GIC to dentin.