Effect of buccal part designs of polyamide resin partial removable dental prosthesis on retentive force

Abstract

Purpose: To identify buccal design criteria for retainer on polyamide resin removable partial dentures.

Methods: A left upper distal extension model was used for this study. Undercut was given on the buccal side of first and second premolars. Four different retainer designs were created. Undercuts of 0.5 and 0.75 mm were used. All 4 retainer designs started from distal surface of second premolar. The retainer extended to Design 1: covering to the mesial surface of second premolar; Design 2: covering to the distal surface of first premolar; Design 3: covering to the mesial surface of first premolar; and Design 4: covering to the distal surface of canine. For the 0.75 mm undercut experiment, only Design 1 and Design 3 were used. Each experimental denture was pulled and the force maximum required to remove the denture measured.

Results: On 0.5 mm undercut, no significant difference was found between Designs 1 and 2 or between Designs 3 and 4. Significant differences were found between all other combinations, however. On 0.75 mm undercut, a significant difference was found between the two.

Conclusion: The retentive force of a design for the buccal part of retainers in polyamide resin using large undercut was more effective than that of a design covering to the anterior abutment tooth.