Predictability of Maxillary Molar Distalization and Derotation with Clear Aligners: A Prospective Study

Clear aligners are employed daily for the treatment of Class II malocclusions, when a valid option involves distalization and derotation of the upper first and second molars. Evidence regarding the predictability of these movements is slight, and the treatment outcome that clinicians plan may not be achieved. Therefore, the purpose of this study is to assess the accuracy of distalization and derotation with clear aligners. Geomagic Control X, a 3D quality control software, was used to superimpose digital models of the pre-treatment, post-treatment, and virtual plan (ideal post-treatment) measurements of 16 patients (4 M, 12 F; mean age 25.7 ± 8.8 years). Linear and angular measurement tools were used to calculate the amount of tooth movement prescribed and achieved. Distal displacement of the buccal cusps had an overall accuracy of 69% for the first molar and 75% for the second molar. The accuracy of molar derotation was higher for the first molar (77.5%) than for the second molar (62.7%). The aligners were not able to achieve 100% of the ideal post-treatment result; thus, planning of refinements is often needed. However, clear aligners can be regarded as a valuable option for the distalization of first and second molars.

Visual Feedback of Target Position Affects Accuracy of Sequential Movements at Even Spaces

The role of visual feedback during movement is attributed to its accuracy, but findings regarding the utilization of this information are inconsistent. We developed a novel dot-placing task to investigate the role of vision in arm movements. Participants conducted pointing-like movements between two target stimuli at even spaces. In Experiment 1, visual feedback of targets and response positions was manipulated. Although visual loss of target stimuli hindered accuracy of movements, the absence of the position of previously placed dots had little effect. In Experiment 2, the effect of movement time on accuracy was assessed, as the relationship between these has been traditionally understood as a speed/accuracy trade-off. Results revealed that duration of movement did not impact movement accuracy.