Does the retention system influence the stability of implant-supported maxillary overdentures? A comparison with fixed and conventional dentures.

PURPOSE: The purpose of this in vitro study was to compare the stability of removable implant-supported maxillary overdentures with fixed complete dentures and conventional dentures. METHODS: Four types of complete dentures were tested: conventional complete dentures; overdentures retained by a male resilient attachment system; overdentures retained by a combination of clip bar and attachment system; and fixed complete dentures. Each group was placed in the posterior and anterior region and the stability was recorded by measuring the vertical displacement of the prosthesis. RESULTS: There was a difference in the vertical movement of the prosthesis according to the type of system. The results showed that the behavior of the overdenture retained by a combination of a clip bar and attachment system is comparable with the stabilization of an implant-retained fixed complete denture. CONCLUSIONS: Overdentures retained by a combination of a clip bar and attachment presented better stability and retention capacity under our experimental conditions, close to that of the positive control (fixed complete denture), with the advantages of removable overdentures.