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Comparative Study of three composite Materials in bonding Attachments for clear aligners.

OBJECTIVE
The aim of this study was to assess the operation time, shear bond strength, placement accuracy and wear resistance of three 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 three composite materials were evaluated.


RESULTS
The operation time of Z350XT Flowable and SonicFill was shorter than Z350XT (P<0.05). The shear bond strength of SonicFill was higher than Z350XT and Z350XT Flowable (P<0.05). 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<0.05). The wear volume loss of SonicFill and Z350XT was less than that of Z350XT Flowable (P<0.05).


CONCLUSION
SonicFill seems to represent a suitable material for producing attachments, which optimized the property combination.