Comparative study of three composite materials in bonding attachments for clear aligners

Abstract

Objective The aim of this study was to assess the operation time, shear bond strength, placement accuracy and wear resistance of 3 composite materials (Filtek Z350XT, Filtek Z350XT Flowable and SonicFill) that were used to make attachments for clear aligners. Settings and sample population Laboratory of Stomatology of Shanghai Ninth People’s Hospital affiliated to Shanghai Jiao Tong University School of Medicine. A total of 129 human mandibular premolars were collected, 69 of which were assigned to 3 groups (A1, B1 and C1). The remaining 60 teeth were divided into 3 groups (A2, B2 and C2). Methods Z350XT composite resin was used in groups A1 and A2 to bond the attachments. Z350XT Flowable composite resin was used in groups B1 and B2. SonicFill composite resin was used in groups C1 and C2. The operation time, shear bond strength, the placement accuracy and wear volume loss of 3 composite materials were evaluated. Results The operation time of Z350XT Flowable and SonicFill was shorter than Z350XT (P < .05). The shear bond strength of SonicFill was higher than Z350XT and Z350XT Flowable (P < .05). The SEM showed that the bonding interface of Z350XT and SonicFill was compact. The 3D deviation and volumetric change in the 3D designed attachments and the attachments after actual bonding of Z350XT Flowable were greater than that of Z350XT and SonicFill (P < .05). The wear volume loss of SonicFill and Z350XT was less than that of Z350XT Flowable (P < .05). Conclusion SonicFill seems to represent a suitable material for producing attachments, which optimized the property combination.

Bonding of Clear Aligner Composite Attachments to Ceramic Materials: An In Vitro Study

“…Results showed that Filtek Z350 had higher SBS value than Filtek Z350 supreme Ultra flowable. This result is similar to the findings reported by Chen et al who evaluated the effect of the same composite types on the SBS of extracted premolars and found that the flowable composite showed lower bond strength (15.3 +/− 2.33 MPa) compared to the conventional Filtek Z350 (20.53 +/− 2.59 MpPa) [2]. It is likely that the amount of inorganic fillers played a major role in these results.…”

“…For bonding attachments to natural teeth, Chen et al in 2020 found that the highest SBS was gained by bonding attachments with SonicFill composite (23.49 MPa). Filtek Z350XT had an SBS of 20.53 MPa while bonding with Filtek Z350XT Flowable resulted in 20.53 MPa [2]. The AFM images support these results since air abrasion and HFA had a rougher surface than PhA specimens.…”

“…By increasing inorganic filler content, polymerization shrinkage and stresses can be decreased resulting in a high bond strength. Consequently, a high SBS ensures a more stable treatment because attachments are less likely to fall off [2]. However, the SBS of both composites when bonded to natural teeth was higher than the SBS of both composites when bonded to lithium disilicate.…”

“…There are several characteristics of the ideal attachment material, including its ease of use, resistance to wear and difficulty of fall off. Currently, there is constant progress in clinical research on clear aligner technology, whereas research into attachment material selection is still limited [2]. Based on viscosity, two commonly used composite resins for attachment bonding were used in this study.…”

“…Removable clear aligners have become increasingly popular, especially with increasingly aesthetic demands [1][2][3][4][5]. Clear aligners were introduced by Align Technology in 1998 as a series of clear, removable, thermoplastic appliances to be worn by the patient in a sequence to obtain the proper targeted results [6,7].…”