The Influence of Loading Variables on Implant Strain When Supporting Distal-Extension Removable Prostheses: An In Vitro Study

Purpose: The purpose of this study was to determine the implant stress under distalextension removable prostheses (DERPs). Materials and Methods: A mandibular distal-extension cast and denture were fabricated. Strain gauges were attached to the implant, which was placed either parallel to the distal abutment or perpendicular to the ridge crest (inclined). Occlusal load was applied in five directions, and strains were compared using the Kruskal-Wallis test (P = .05). Results: When the implant was parallel, the strain was maximum at 20 degrees applied load direction. When the implant was inclined, the strain was minimum at 20 degrees mesial and maximum at 20 degrees applied distal load direction. Conclusions: Implant bending strain is reduced when the implant is loaded on its long axis and oriented parallel with the long axis of the most distal tooth.