Forty-one patients received 49 single-tooth implants placed in different jaw locations. One implant was not osseointegrated at stage 2 surgery. Three successfully osseointegrated implants were not available for follow-up. Forty-five implants were monitored for 1 to 8 years after loading. Each one of the implants met all of the traditionally accepted success criteria, except for nine individual implants that did not meet the proposed bone level criterion. No success criteria exist for natural teeth adjacent to implants. Although preliminary results are favorable, extensive long-term studies are needed to determine which specific criteria comprise optimal functional and esthetic results with minimal risk of morbidity. Palabras clave: clinical study, dental implants, effectiveness, single-tooth implant