Mandibular overdentures supported by two Brånemark, IMZ or ITI implants: a 5-year prospective study.

OBJECTIVES The aim of this prospective comparative study was to evaluate the survival rate and the condition of the peri-implant tissues of the IMZ implant system (two-stage cylindertype), the Brånemark implant system (two-stage screwtype) and the ITI implant system (one-stage screwtype) supporting a mandibular overdenture during a 5-year follow-up period. MATERIAL AND METHODS Three groups of 30 edentulous patients were treated with two endosseous implants in the interforaminal region of the mandible. Clinical and radiographic parameters were evaluated immediately after completion of the prosthetic treatment and after 1, 2, 3, 4 and 5 years of functional loading. RESULTS The five-year survival rate is 98.3% for the IMZ group, 98.3% for the Brå group and 100% for the ITI group. Mean scores on indices for plaque, calculus, gingiva and bleeding were very low at all evaluation periods. Mean marginal bone loss over a period of 5 years, was 1.4 mm for the IMZ group, 0.7 mm for the Brå group and 0.9 mm for the ITI group. CONCLUSION It is concluded that two implants placed in the interforaminal region, connected with a bar, supply a proper base for the support of a mandibular overdenture in the edentulous patient. After 5 years no clinically relevant and statistically significant radiographic changes had developed between the three implant systems.