1995 Volume 8 Issue 2 Pages 136-142
We made an acrylic resin mandibular edentulous model by placing two Apaceram® implants (RS 0490, Pentax, Tokyo) in bilateral canine regions. Four strain gauges were placed on the resin surface around the right implant. A load cell was embedded in the right molar alveolar ridge. The rubber base material was covered with the model surface representing the oral mucous. An acrylic mandibular complete denture was constructed on the model. As the attachment for the connection between the implant and the denture, a magnetic attachment (M), our original ball attachment (B), a magnetic attachment with a magnet surrounded by a stress-breaking material (D), and no attachment as a control (C) were used. Static load of 500 N was applied to three loading sites (“Center”,“ Right”and“Left”) of the experimental denture.Dynamic load was applied by dropping a 20 g metal rod on“Center”site from 30 mm in height. The stress transferred to the molar region and the strains around the implant were examined when either static or dynamic load was applied.
The results were as follows:
1.When static load was applied,
1)The stress transferred to the molar region decreased in the order of C, D, B and M, and the strains around the implant increased in that order.
2)Loading site affected the stress and strains.The influence on the stress decreased in the order of C,D, B and M, and the influence on the strains increased in that order.
2.The result of applying a dynamic load was almost corresponded to that of a static load. Influence of structure of stud attachments in dynamic load was lower than that of a static load.
In case of implant-supported overdenture, the structure of stud attachments affected the stress and strains. The overall findings suggested that the occlusal stress had a tendency to concentrate in the implant.
