[Retraction of the upper incisors with pseudoelastic treatment elements. Their computational and biomechanical testing and clinical use].

Based on the favorable results achieved by the application of pseudoelastic T loops in the course of canine retraction, this study investigates their application to the retraction of maxillary incisors. A modified Burstone T loop was made of a pseudoelastic orthodontic nickel titanium wire and then subjected to experimental testing. The results obtained were compared with extensive numerical studies. The results of the tests showed that forces and moments generated by the T loop are suitable for the retraction of upper incisors. The clinical application of the pseudoelastic spring was performed using an individualized retraction arch enclosing the whole front segment. Whereas during canine retraction the experimental and clinical results corresponded very well, such was not observed during the retraction of upper incisors. This result implies that the location of the center of resistance of the upper incisors has not been completely clarified. It is thus recommended that this matter should be given further study.