Objectives: The aim of this in vitro study was to evaluate the microtensile bond strength (μTBS) of different glass ionomer cements (GICs) on sound/caries-affected dentin and to assess the fluoride release/recharging ability. Methods: After creating artificial caries lesions, teeth with sound and caries-affected dentin were assigned to be restored with one of the GICs: Ketac N100; GC Equia; GCP Glass Fill, and tested using a microtensile test. Ten of each material were prepared, and fluoride ion-release was measured at 10 different intervals. After 1.23% acidulated phosphate fluoride-gel immersion, fluoride re-release was then measured at the same intervals. Results: In sound dentin, GC Equia exhibited significantly higher μTBS value (P < 0.05). The mean μTBS of Ketac N100 to caries-affected dentin was significantly lower than the other materials (P < 0.05). All materials showed maximal fluoride release at 24 h, GC Equia released the most fluoride. Conclusion: The bond strength of GICs is affected by tooth substrate. High-viscosity GICs show higher initial fluoride release as well as greater fluoride recharge capacity.