Influence on residual ridge by different retention force of mandibular implant overdenture in locator attachment

Abstract

The McGill consensus statement determined in 2002 that a two-implant overdenture （2- IOD） should be the first choice of treatment for an edentulous mandible. In recent years, some researchers have reported on the success rate of 2-IOD supported by dental implant and stress analysis in a simulation model. However, there are indefinite factors such as denture base morphology, the number of artificial teeth, occlusal scheme and selection of attachment. We focused on locator attachments installed on 2-IOD and applied the edentulous jaw model. This study aimed to elucidate the influence on the residual ridge of different retention force of the mandibular implant overdenture in locator attachments.

Two implants （Φ3.75 mm × 11.5 mm, Bränemark System^® Mk Ⅲ Groovy RP, Nobel Biocare, Kloten, Switzerland） were placed at areas equivalent to the bilateral canines of an experimental jaw model and fabricated 2-IOD. Six miniature pressure sensors were embedded in the experimental denture to measure pressure in the bilateral buccal premolar regions, the bilateral buccal shelves, and the bilateral lingual molar regions. The load on the experimental dentures was set at 50 N with reference to the masticatory force of complete denture （CD） wearers. Measurements were performed using retention discs of different retention forces. The experimental CD was fabricated as a control.

Under the bilateral load conditions, the mucosal pressures exerted by 2-IOD were significantly lower in all sites with 2-IOD than with CD. Under the unilateral load conditions, the mucosal pressures exerted by 2-IOD were significantly lower in the buccal premolar regions and the buccal shelves （support regions of the denture）.

The results of this study revealed that when the same occlusal force is exerted in the case of CD or 2-IOD, locator attachments should reduce the impacts on residual ridge.