Measurement of applied force to dislodge orthodontic temporary anchorage devices

摘要

Aims: To measure the force required to dislodge three different orthodontic temporary anchorage devices (TADs) from artificial test blocks and to investigate whether varying the cortical thickness of the test block will affect these forces.ududMaterials and Method: The TADs were embedded into test blocks consisting of polyurethane foam, laminated with either 2mm or 3mm short-fibre-filled epoxy sheets and a horizontal dislodging force applied, using an Instron universal testing machine. The maximum force applied before the TAD was fully dislodged was recorded. Three TADs were tested: InfinitasTM, Ancor ProTM and Ortho ImplantTM. 150 of each design were tested in the 2mm thickness test block and a further 150 of each were tested in the 3mm thickness test block.ududResults: The mean force required was 468N in the 2mm test blocks and 567N in the 3mm test blocks. No significant difference was observed between the InfinitasTM and Ancor ProTM TADs, however there was a significant difference (P>0.05) between both of these TADs and the Ortho ImplantTM. The force required in the 3mm test blocks was significantly higher than the force required in the 2mm test blocks.ududConclusion: All of the TADs were functionally acceptable, in terms of resistance to dislodgement forces. The Ortho ImplantTM required a significantly higher force to be dislodged from both the 2mm and 3mm test blocks. The thickness of the test block had a significant effect on the force required to dislodge each of the TADs.ud