Purpose: The purpose of this study was to evaluate the serviceability of a resin-modified glass-ionomer cement for transitional restorations and subsequent core buildups in endodontically treated maxillary premolars. Materials and Methods: Fifty Vitremer restorations were made in 42 patients by one operator during a period of 5 months. After 1 year of follow up, the quality of the restorations was assessed for the variables occlusal contacts, proximal contacts, marginal adaptation, and surface roughness. Survival was estimated at 2 years of service either as a transitional restoration or as a core buildup. Results: The percentage survival of the transitional restorations was 85% ± 6%. When the crowned Vitremer restorations were added to the transitional restorations, the 2-year survival was 98% ± 2%. With respect to the quality assessment, the majority of the restorations showed either no or light occlusal contacts and no or light contacts on at least one of their proximal surfaces. Marginal integrity and surface roughness were considered to be suboptimal on average. Conclusion: The described restorations seem to perform adequately for a transitional period of 1 to 2 years. Their viability as substructures for permanent cast restorations remains to be tested in long-term clinical studies.