The purpose of the study was to evaluate, in a clinical study over 2 years, the deterioration of two glass ionomer cements used with the atraumatic restorative treatment (ART) technique or approach. Fifty-five Fuji IX and 45 ChemFil Superior restorations were placed randomly in 23 adult patients, mainly in small occlusal preparations in molar teeth. The restorations were placed in a dental hospital by one dentist using the ART technique. Photographs, radiographs and replicas were obtained at baseline and subsequent recalls. Both cements were easy to mix and place, but the radiolucency of ChemFil Superior was a disadvantage. Both cements also showed early high losses of sealant and restorative material. After 2 years, 34.5% of the sealants appeared to be completely lost, with caries recorded in 5.3% of the exposed fissures. In some instances, these small lesions may have been present, but not detected clinically, at the time of sealing. Restoration failures of 7.0% were from wear and fracture of the cements and recurrent caries. Mean cumulative wear was 83.1 microm for Fuji IX and 104.0 microm for ChemFil Superior, which was not statistically significant. The cements became darker after their placement to more closely match the restored teeth, but there were few exact matches. There was no surface staining and only minor marginal discrepancies and staining associated with the restorations. Although the short-term clinical performance of the two glass ionomer cements was reasonable, the materials require further improvements in their mechanical properties, to reduce sealant losses and wear. The cements evaluated appear suitable for restricted use only, in posterior teeth.