Evaluation of the Clinical Variables Affecting Attachment Reproduction Accuracy during Clear Aligner Therapy

Abstract

Background: The purpose of this study was to evaluate some of the clinical variables that influence the accuracy of reproducing the planned attachment shape. The following clinical variables were considered: the template material, type of composite, and pressure application on the template during attachment curing. Methods: In this study, the evaluated materials for the thermoplastic transfer template construction are Erkolen 0.8 (polyethylene: PE) and Erkodur 0.8 (polyethylene terephthalate glycol—PET-G), and two types of composite resins: Enaflow (light-curing low-viscosity composite resin) and Enamel plus dentina HRI (light-curing high-viscosity composite resin). Two different light-curing lamps were used: Valo cordless color with no pressure and push light pressure (SCS). The 26 models included in the study were imported into the 3 Shape Ortho System 2022 (ver. 85.0.20 3 Shape, Denmark), and attachments were virtually placed on the dental elements of the first premolar and on both sides of the first upper molars. The accuracy of the attachment reproduction was evaluated through linear and angular evaluations against the reference model (MCAD). Three physical models were obtained: model A (MA), which was printed with attachments; model B (MB) with attachments made with a PE template; and model C (MC) with attachments made with a PET-G template. Results: The results showed statistically significant differences (p < 0.05) between the PE and PET-G templates with greater precision using the PET-G template. Statistically significant differences (p < 0.05) were found among the high-viscosity composite and low-viscosity composite with pressure curing. Conclusions: In light of the obtained data, using a PET-G template is recommended. The pressure application during composite curing reduces the reproduction accuracy with a low-viscosity composite.

Three-Dimensional Printed Attachments: Analysis of Reproduction Accuracy Compared to Traditional Attachments

“…The inadequate design or placement of these attachments could hinder their ability to exert the necessary force to achieve the desired dental positioning [11]. Another factor influencing the effectiveness of clear aligner treatment and its clinical results is the accuracy of replicating the shape of the attachments [17,19].…”

“…However, only a limited number of studies have evaluated the accuracy of reproducing the programmed shape required for the desired tooth displacement [17,19].…”

“…A recent study [19] assessed the accuracy and reproducibility of the attachment shape by comparing the attachment transfer with two different types of templates: Pet-G (glycolmodified polyethylene terephthalate template) and PE (polyethylene template); the study concluded that Pet-G allows more accurate reproduction of the attachment shape than PE. In addition, these authors also evaluated the influence of composite resin materials with different viscosities in reproducing the shape of the attachments, revealing that the accuracy of high-viscosity and low-viscosity composites is equivalent.…”

“…More authors have shown that 3D-printed materials offer good accuracy and reproducibility of details, including composite attachments; however, they may show lower strength than traditional materials, especially in terms of the resistance to forces applied during orthodontic treatment [23]. Based on data from the previous literature [19,22], a PET-G template was used in the present study to transfer both the traditional and 3D-printed attachments; in addition, the use of a flow composite was chosen to create the traditional attachments.…”