Comparison of Three Types of Stud Attachments on Retention and Strain Energy in the Mandibular Implant Supported Overdentures

Background: The present in vitro study assessed the effects of three different Stud attachments on the retention and strain energy in the mandibular implant-supported overdentures.

Methods: Two parallel implants (Implantium System) were placed on the mandibular canines regions and a chrome-cobalt casting framework was prepared as the denture base. The implant fixtures were installed on the canine location and the pulling was performed by three orthodontic wires in the Instron machine with a speed of 0.5 min/mm. Dislodging forces were applied to the housings in two vertical and oblique directions on three different Stud attachments (Ball, Kerator, Positioner). All three wires were connected to the device in the vertical position while one wire was separated from the molars region in the oblique loadings. The retention of these three attachments was statistically analyzed by means of one-way analysis of variance.

Results: Significant differences were found between the attachments (F (2, 15) =33.01, p<0.0001). Furthermore, Retention forces in the oblique loadings were significant differences between the attachments (F(2,15)=175.10, p<0.0001). The effect size, calculated using eta squared, was 0.95, which is considered large. The strain energy was 4.08, 3.05 and 1.04 J for the Ball, Positioner and Kerator attachments in the vertical loadings and 4.05, 1.44 and 3.07 J in the oblique loading respectively.

Conclusion: The retentive forces and strain energy of ball attachments were greatest than other studied attachments in the vertical and oblique loadings.

Keywords: Stud attachments, Retention force, Strain energy, Overdenture.