Effect of Unsplinted Attachments on Strain of Palateless Implant Overdentures

Objectives: In palateless maxillary implant overdentures, various types of attachments has been used depending on patient situation. However, the effect of attachment on palateless overdenture have not been focused yet. Therefore, this study was conducted to examine the strain of palateless maxillary implant overdenture using unsplinted attachments under various implant configurations.
Methods: A maxillary edentulous model with simulated mucosa was fabricated and six implants were placed in the anterior, premolar and molar area. Three types of unsplinted attachments: ball, locator and magnet, and healing abutments were set on the implants distributed in various configurations. Palateless maxillary experimental dentures were fabricated and two strain gauges were attached on the surface of anterior midline of the labial and palatal side. A vertical occlusal load of 98N was applied, the shear strains of dentures were calculated. The measurements of strains were compared with the Kruscal-Wallis test (P=0.05).
Results: The strains of palatal side were larger than those of labial side regardless of attachments. When comparing the strains among three attachments, those using only anterior implants with magnet attachment were the largest and those with ball attachments were the smallest. When using healing abutments, the strains were much larger than those when using other three attachments in labial side, but there were no significant differences in palatal side. The strains using molar implants were not significantly different with those using other implants regardless of implant configurations and attachments.
Conclusions: The strains of palateless overdenture were different according to the attachments and implant distribution. The strains using three types of attachments were much smaller than those using healing abutments and when using ball attachment on anterior implants, the strains were significant smaller than others.