A retrospective evaluation of treatments with implant-supported maxillary overdentures

Background: Considerably lower success rates have been presented for implant-supported overdentures in the maxilla compared with the mandible. Purpose: The aim of the study was to report the outcome of implant-supported maxillary overdentures from one clinic. Methods: All patients treated with implant-supported maxillary overdentures in the Department of Prosthetic Dentistry, Central Hospital, Skovde, Sweden, between 1993 and 2002 were identified from patient charts and included in the study. All patients had a rigid cast gold alloy bar designed with ball attachments retaining an overdenture. Results: Twenty-seven subjects were included, of whom 13 were originally planned for overdenture treatment (group 1) and the other 14 for a fixed prosthesis (group 2). The mean observation period was 5.7 years for subjects in group 1 and 5.5 years for those in group 2. One hundred forty-five implants were placed, and the majority of the failures were diagnosed as early ones and were found in group 2. The cumulative implant survival rate after 5 years was 77% in group 1 and 46% in group 2. The probability of having implant failure was almost three times higher among subjects in group 2 compared with subjects in group 1. Most technical and biologic complications were related to the retention system. Conclusion: Maxillary implant-supported overdentures show a high implant failure rate, but fewer implant failures occurred for patients originally planned for overdenture treatment.