Colour stabilities of three types of orthodontic clear aligners exposed to staining agents

Abstract

The aim of this study was to evaluate and compare the colour stabilities of three types of orthodontic clear aligners exposed to staining agents in vitro. Sixty clear orthodontic aligners produced by three manufacturers (Invisalign, Angelalign, and Smartee) were immersed in three staining solutions (coffee, black tea, and red wine) and one control solution (distilled water). After 12-h and 7-day immersions, the aligners were washed in an ultrasonic cleaner and measured with a colourimeter. The colour changes (ΔE*) were calculated on the basis of the Commission Internationale de I'Eclairage L*a*b* colour system (CIE L*a*b*), and the results were then converted into National Bureau of Standards (NBS) units. Fourier transformation infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) were conducted to observe the molecular and morphologic alterations to the aligner surfaces, respectively. The three types of aligners exhibited slight colour changes after 12 h of staining, with the exception of the Invisalign aligners stained with coffee. The Invisalign aligners exhibited significantly higher ΔE* values (ranging from 0.30 to 27.81) than those of the Angelalign and Smartee aligners (ΔE* values ranging from 0.33 to 1.89 and 0.32 to 1.61, respectively, P<0.05). FT-IR analysis confirmed that the polymer-based structure of aligners did not exhibit significant chemical differences before and after the immersions. The SEM results revealed different surface alterations to the three types of aligner materials after the 7-day staining. The three types of aesthetic orthodontic appliances exhibited colour stability after the 12-h immersion, with the exception of the Invisalign aligners stained by coffee. The Invisalign aligners were more prone than the Angelalign and Smartee aligners to pigmentation. Aligner materials may be improved by considering aesthetic colour stability properties.

Colorimetric and spectrophotometric measurements of orthodontic thermoplastic aligners exposed to various staining sources and cleaning methods

“…However, many patients do not have complete compliance [5] and consume coloring agents with their devices despite the orthodontists' or manufacturers' recommendations [6]. This leads to a change within the polymer forming the aligners, affecting their transparency, which is one of their main advantages [7][8][9].…”

Mechanical properties of “two generations” of teeth aligners: Change analysis during oral permanence

“…Actually, there are few articles in the scientific literature regarding the technical characteristics of the new polymer blend LD30 23,24,[32][33][34] . Only a pilot study has been published in the corporate archives of Align Tech.…”

“…The material's features that provide better performance include a gentle and more constant force, a more long-term action and improved adhesion thanks to the elasticity of the material, as well as convenience and ease of use for the patient. This new technology, LD30 has three main advantages compared with EX30: greater consistency of application of orthodontic forces, greater elasticity, chemical stability and an even more precise and comfortable aligner fit 23,24) .…”

Risk Factors of Composite Attachment Loss During Orthodontic Clear Aligner Therapy

“…The manufacturers of clear aligners also advise patients to remove aligners before eating, for both hygiene purposes and to protect the clear aligner material against food with high temperature which may reduce the lifetime of aligner. Other groups have shown that the softness of food did not directly affect the probability of attachment loss [18][19][20]. Future studies consist of larger population are needed to further investigate the in uence of food intake on aligner therapy.…”