Mandibular overdentures supported by 6-mm dental implants: a 1-year prospective cohort study.

BACKGROUND The extremely resorbed edentulous mandible, with a bone height of 8 mm or less, is still a challenge in implant dentistry. Recently, dental implants of 6 mm in length have been developed. PURPOSE The purpose of this 1-year prospective cohort study was to evaluate treatment outcome of mandibular overdentures supported by four 6-mm dental implants. MATERIALS AND METHODS Twelve edentulous patients with a mandibular height between 6 and 8 mm participated. The patients were treated with an overdenture supported by four 6-mm OsseoSpeed dental implants (Astra Tech AB, Mölndal, Sweden). Clinical and radiographic parameters were evaluated 1 year after completion of the prosthetic treatment. Patients' satisfaction was scored before implant surgery and 1 year after prosthetic treatment. RESULTS One-year implant survival rate was 96% (two implants were lost). One patient had a fracture of the mandible in the region of one of the implants 3 weeks after implant surgery. Mean scores for plaque, calculus, gingiva, bleeding, and pocket probing depth were low. Patients' satisfaction was high. CONCLUSION One-year follow-up data revealed that four 6-mm dental implants inserted in an extremely resorbed edentulous mandible provided a solid basis for a bar-retained overdenture.