Eleven patients who had only two remaining natural teeth, vital mandibular canines, were treated using experimental 12-unit fixed partial dentures and complete maxillary dentures. The marginal bone support was 60% in one patient and 80% to 100% in the others. The patients were studied for 20 years. After 15 years, seven patients had prostheses that were still functional, two had prostheses that failed, one lost the prosthesis following treatment for oral cancer, and one patient died. Nine of the 22 abutments required endodontic treatment. After 15 years, the fixed partial dentures began to tilt distally and considerable resorption was found under the pontics. The periodontal tissues withstood the increased stress, and the prostheses were stable.