Abstract
BACKGROUND: Invisalign® attachments are divided into two main groups: the conventional group and the optimized group, which is also known as the SmartForce™. The aim of this study is to compare the movements produced by an optimized crescent-shaped attachment in superior incisor teeth with the movements produced by a conventional rectangular attachment (vertical and horizontal) in the same teeth. MATERIAL AND METHODS: This retrospective study examined the movement table of the initial ClinCheck® and the first refinement of 95 patients (mean age 44.18 ± 4.125, 40 males and 55 females). It represented 147 upper incisors divided into two groups: 87 with rectangular attachment and 60 with optimized attachment. Applying Kravitz's accuracy formula for each movement and each tooth of interest (with attachments of interest), we underlined the effectiveness of each attachment. Mann-Whitney U test, Kruskal-Wallis test, and Pearson and Spearman correlation coefficients were used for statistical analysis. RESULTS: The accuracies of rotation, mesio-distal angulation and vestibulo-lingual inclination are highly significantly related to the type of attachment used on the upper lateral incisor. The optimized attachment presented greater accuracy in the rotation of the lateral incisors than the conventional attachment. However, conventional vertical attachment showed a higher accuracy (p<.01) in the mesio-distal angulation and horizontal attachments showed a higher accuracy (p<.01) in the vestibulo-lingual inclination in the same group of teeth. CONCLUSIONS: Optimized attachments rotate better lateral incisors; conventional vertical attachments are more efficient to improve mesio-distal angulation; and horizontal attachments serve best for torque movements. Key words:Orthodontics, clear aligners, orthodontic tooth movements, attachments.