Effect of three different attachment designs in the extrusive forces generated by thermoplastic aligners in the maxillary central incisor

Abstract

Introduction: Orthodontic aligners use have increased in dentistry. The resolution of complex movements such as extrusion demands the use of attachments to reach the aimed force, but just a few studies have been developed to evaluate the biomechanical performance of the aligners and their accessories. Objective: The objective of this study was to evaluate on the three axes (X, Y and Z) the forces generated by three different attachment designs for the extrusion of the maxillary central incisor using esthetic orthodontic aligners. Methods: Three prototypes of maxillary models were developed, each one with a specific attachment inserted in the central incisor. Three aligners were manufactured for each of the three attachment designs, with 0.33-mm activation in the direction of the extrusion. An analytical device was used to evaluate the forces applied to the three axes by each aligner/attachment. The data were assessed by one-way ANOVA and Tukey’s test (α = 0.05). Results: All of the studied attachment designs could satisfactorily perform the extrusion movement. However, force intensities were different in the three designs (design 1 = 2.5 N; design 2 = 2.2 N, and design 3 = 1.1 N). Furthermore, two of the three attachment designs (designs 1 and 2) eventually exerted significant forces on the X (mesiodistal) and Y (buccopalatal) axes. Conclusion: The attachment design 3 presents the best distribution of forces for extrusion movement, generating almost null forces on X and Y axes, and lower intensity of force on the Z axis.

Correction of anterior open bite of varying severity using clear aligner therapy- a case series

“…In cases wherein greater aligner fit is required, the attachments may be placed both on the labial and palatal surfaces. 18 Relative and absolute extrusion of the incisors are effectively controlled by using large rectangular-shaped attachments with beveled edges toward the gingiva -placed as incisally as possible. 19,20 Use of additional intermaxillary elastics may aid with their extrusive movements in AOB cases of moderate severity (as seen in case 2).…”

Correction of anterior open bite of varying severity using clear aligner therapy—A case series

“…In cases wherein greater aligner fit is required, the attachments may be placed both on the labial and palatal surfaces. 22 …”

“…15 Conventional attachments (with a beveled edge toward the gingiva) allow for appropriate pressure from the aligner in order In cases wherein greater aligner fit is required, the attachments may be placed both on the labial and palatal surfaces. 22 Relative and absolute extrusion of the incisors are effectively controlled by using large rectangularshaped attachments with beveled edges toward the gingiva-placed as incisally as possible. 23,24 Use of additional intermaxillary elastics may aid with their extrusive movements in AOB cases of moderate severity (as seen in case 2).…”

Clear Aligners: Between Evolution and Efficiency—A Scoping Review

“…Initially, they were only ellipsoidal in shape: horizontal for active intrusion movements and vertical for retentive purposes. We then moved on to rectangular ones distinguished by horizontal, vertical and beveled shapes [ 47 ]. The horizontal ones are for intrusions and extrusions on premolars and incisors, on premolars to increase aligner stability when using class II or III elastics, for retention in subjects with short dental crowns or hypodivergent patterns (to control the Spee curve and deep bite), and on restored teeth because the attachment’s bonding area is smaller.…”