Stability of Mandibular Overdentures Before and After Attachment Wear. An in vitro Study

Abstract

Purpose: The aim of this research was to evaluate and compare the maximum stabilizing force and stabilizing energy of mandibular overdentures with several attachments during anterior, lateral, and posterior dislodgement before and after wear simulation. Changes in the maximum retentive force and maximum stabilizing force of each attachment during various levels of wear simulation were also examined.Methods: Ten samples, each of 8 different overdenture attachments, were sequentially embedded in mandibular overdentures in pairs. Maximum stabilizing force and stabilizing energy were measured during anterior, lateral, and posterior dislodgement by a universal testing machine before and after wear simulation. A total of 5000 insertion-removal cycles were performed. The maximum retentive force of each sample was measured during various levels of wear simulation by a micro material testing machine.Results: The mean maximum stabilizing force ranged from 1.94N to 28.6N, and the mean stabilizing energy ranged from 1.9N•mm to 30.24N•mm before wear simulation. After wear simulation, the values ranged from 1.03N to 20.49N for maximum stabilizing force and from 1.9N•mm to 21.51N•mm for stabilizing energy. This study revealed a decrease (4.13-84.46 %) and an increase (1.23-41.8 %) in maximum stabilizing force. A decrease (6.5-85.42%) and increase (5.35-23.55%) were also seen for stabilizing energy.Conclusions: Maximum stabilizing force and stabilizing energy can each be used to evaluate the stability of overdentures. Both parameters were different during anterior, lateral, and posterior dislodgement after and before wear simulation. The changes in the maximum retentive force for each attachment during wear simulation were different. Among the attachments tested, Hyperslim 4013 was the least sensitive to wear simulation.