歯科矯正用ポリエステルアライナーの熱成形および歯科矯正時のひずみの変化

抄録

Removable orthodontic aligners made of polymeric materials have advantages over metal wires, which are currently the mainstream in clinical treatment of teeth array alignment, because of better aesthetics and cleanliness. However, unintentional movement of teeth occurs during the treatment using aligners. Hence, deeper understanding of the load applied to teeth from the aligner is required. In the authors’ previous study, the strain distribution in polyester aligner when mounted on misaligned teeth was measured with the help of DIC (digital image correlation) technique, and it was found out that the strain recovery plays an important role in the treatment, which leads to the driving force to move the teeth. In this study, the strain was measured including the thermoforming process, and the strain recovery was investigated by comparing the strains in two situations with teeth misalignment and without misalignment after treatment. Since DIC is not applicable to the strain measurement during compression molding, large deformation of a 2 mm square grid printed on the polyester sheet was tracked for the calculation of deformation gradient tensor and stretch tensor. The strain was increased when the aligner was mounted on a misaligned tooth, but was recovered when it moved to a correct position.