Computation of the Retentive Forces of Ball and Magnet Attachments in a Two-Implant-Retained Mandibular Overdenture

Advancements in tooth replacement have led to increased use of implant overdentures, prompting the proposal of various attachment systems. Unsplinted options like ball, magnetic, and telescopic attachments offer different retention methods. Ball attachments are straightforward but require periodic O-ring replacement and are limited by implant angulation. In contrast, magnet attachments are versatile and compact, thanks to rare-earth element alloys. Their strength and corrosion resistance make them advantageous.

This study compares magnetic and ball attachments' retention in mandibular implant overdentures, focusing on B and D implant positions. It aims to determine the most effective attachment for stability and ease of use.

In this in vivo comparative study, eight completely edentulous patients were selected randomly according to inclusion and exclusion criteria. Two-piece implants were placed in the mandibular arch at the B and D positions. After osseointegration, second-stage surgery was done, and a gingival former was placed. Two mandibular record bases were fabricated for each patient using heat-cure acrylic resin. One for ball attachment (Group A) and the other for magnet attachment (Group B), and retention was measured using a custom-made device. This device allows us to apply an increasing, vertical force on the record base. The force was increased gradually until dislodgement of the denture base occurred. The procedure was repeated three times for all eight patients with ball and magnet attachments. The applied vertical force was registered in kilograms (kg) by the weighing scale, and afterwards, it was expressed in newton (N).

The retention of ball attachment (Group A) was comparatively greater than that of the magnet attachment (Group B).

The retention of mandibular implant-retained overdenture by ball attachments (Group A) was found to be significantly more than that of magnet attachment (Group B).