BACKGROUND: Implant-supported single-tooth replacements are an increasingly used method to replace teeth, especially in young patients. Therefore, long-term validation of different treatment modalities with different implant systems is of great importance. PURPOSE: The aim of the present study was to make a biologic, technical, and aesthetic evaluation of single-tooth replacement supported by the Astra Tech implant (Astra Tech AB, Mölndal, Sweden) during a 5-year period. MATERIALS AND METHODS: Twenty patients were divided into two consecutively treated groups. In group A the implants were placed "early" in the extraction sockets, and standard single-tooth abutments were used. In group B the implants were placed "delayed," and preparable abutments were used. Clinical examinations including registration of plaque, bleeding, crown lengths, soft tissue marginal level, papilla height, complications, and radiography were performed yearly. At the 3-year control examination the patient and a dentist evaluated aesthetic appearance with a visual analog scale. RESULTS: An implant survival rate of 100% and a crown survival rate of 95% over a period of 5 years were found. The mean loss of marginal bone adjacent to implants and neighboring teeth was less than 0.5 mm during the 5-year period, and there was no significant difference after crown placement between the treatment modality for group A and that for B. There were fewer clinical complications and repairs in group B than in group A. Soft tissue dimensions were more natural around implant crowns in group B as compared to group A, but this was not reflected in the patients' satisfaction with aesthetic appearance. On the other hand the dentist judged the restorations in group B higher concerning aesthetics than in group A. CONCLUSION: Implant-supported single-tooth replacement with the Astra Tech system is a reliable treatment resulting in a good 5-year prognosis and only few complications.