Purpose: To determine the bond stability and the change in interfacial ultrastructure of a conventional glassionomer cement bonded to dentin, with and without pretreatment using a polyalkenoic acid conditioner. Materials and Methods: The occlusal dentin surfaces of 10 teeth were ground flat. Glass-ionomer cement was bonded to the surfaces either with or without polyalkenoic acid conditioning. The teeth were sectioned into 1-mm2 stick-shaped specimens. The 200 specimens obtained were randomly assigned to four groups with different periods of storage in water: 1 week, 1 month, 3 months, and 6 months. The microtensile bond strength (μTBS) was determined for each storage time. Additional specimens were prepared for transmission electron microscopy (TEM); they were produced with or without prior polyalkenoic acid conditioning in the same manner as for the μTBS test. Results: There was no significant difference in μTBS to conditioned dentin (p > 0.05). After 6 months of aging, the μTBS to non-conditioned dentin was significantly reduced as compared to the 1-week, 1-month, and 3-month results (p 0.05). The failures appeared to be of a mixed nature, although aging caused more areas of cohesive than adhesive failure in all groups. TEM observation showed a demineralized layer and an amorphous gel phase in the polyalkenoic acid conditioned group. Conclusion: Aging did not reduce the bond strength of the conventional glass-ionomer cement to dentin when the surface was pretreated with a polyalkenoic acid conditioner. Keywords: adhesion, dentin, glass-ionomer cement, microtensile bond strength, transmission electron microscopy