Round versus Locator Attachment Effect on The Retention Forces of Implant-Supported Maxillary Overdentures. A Comparative In Vitro Study

This study aimed to evaluate and compare the effect of round bar versus locator attachments on the retention of an implant-supported maxillary overdenture. An acrylic resin model of an edentulous maxilla without alveolar undercut was fabricated, and four laboratory implant analogs were inserted in the canine and second premolar areas. Mucosal simulation was prepared over the model. The implants were attached by bar attachment. According to the types of bar attachment were classified into two groups: Group I: Round bar attachment (Control group). Group II: Locator attachment. (Test group). Maxillary experimental overdentures were made. The UTM was used to measure dislodging forces at the beginning of the study (initial retention) and after 540 cycles of denture insertion and removal (final retention). Then the statistical analysis was performed. The initial and final retention forces after repeated insertions and removals for vertical dislodging force. Rounded bar recorded the higher retentive force than the Locator attachment. Conclusion: Rounded bar recorded significantly higher retentive forces compared to Locator attachment.