The aim of this study was to compare implant-retained mandibular overdentures and two conventional treatments for their effects on functional ability (chewing, speaking, etc) patient satisfaction, and quality of life (psychosocial functioning). Assignment of 90 patients was executed by means of a balancing allocation computer program to ensure the pretreatment comparability of the three groups. Twelve months after treatment, the average scores for almost all specific quality-of-life measures had improved significantly in all three groups. On average, all patients experienced fewer restrictions in their social activities and had fewer psychological problems because of their full dentures. No impact on the general quality of life was established. One year after treatment, all three dental treatment modalities had a comparably positive effect on dental health0related quality of life.