Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging

Luca Lombardo, Angela Arreghini, Roberta Maccarrone, Anna Bianchi, Santo Scalia, Giuseppe Siciliani, Luca Lombardo, Angela Arreghini, Roberta Maccarrone, Anna Bianchi, Santo Scalia, Giuseppe Siciliani

Abstract

Background: The aim was to assess and compare absorbance and transmittance values of three types of clear orthodontic aligners before and after two cycles of in vitro aging.

Methods: Nine samples of orthodontic aligners from three different manufacturers (Invisalign, Align Technology, Santa Clara, CA, USA; All-In, Micerium, Avegno, GE, Italy; F22 Aligner, Sweden & Martina, Due Carrare, PD, Italy) were selected, and each sample was subjected to spectrophotometry analysis of both its transmittance and absorbance a total of 27 times. Samples were subsequently aged in vitro at a constant temperature in artificial saliva supplemented with food colouring for two cycles of 14 days each. The spectrophotometry protocol was then repeated, and the resulting data were analysed and compared by means of ANOVA (p < 0.05).

Results: All types of aligners tested yielded lower transmittance and higher absorbance values after aging, but the difference was not significant in any case. That being said, the F22 aligners were found to be most transparent, both before and after aging, followed by Invisalign and All-In, and these differences were statistically significant.

Conclusions: Commercial aligners possess significantly different optical, and therefore aesthetic, properties, both as delivered and following aging.

Keywords: F22 Aligner; Orthodontic aligners; Spectrophotometry; Transparency.

Figures

Fig. 1
Fig. 1
The nine aligner samples used in the experiment
Fig. 2
Fig. 2
The UV–vis Jasco mod.V630PC spectrophotometer
Fig. 3
Fig. 3
Positioning the samples in the spectrophotometer
Fig. 4
Fig. 4
a Saliva bath used to age the samples. b Aging protocol
Fig. 5
Fig. 5
Comparison of absorbance values of the All-In aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 6
Fig. 6
Comparison of absorbance values of the Invisalign aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 7
Fig. 7
Comparison of absorbance values of the F22 aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 8
Fig. 8
Absorbance curves ± SD of the three aligners before aging
Fig. 9
Fig. 9
Absorbance curves ± SD of the three aligners after aging
Fig. 10
Fig. 10
Comparison of transmittance values of the All-In aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 11
Fig. 11
Comparison of transmittance values of the Invisalign aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 12
Fig. 12
Comparison of absorbance values of the F22 aligner before and after aging. The curves are the average of nine spectrophotometry measurements ± SD
Fig. 13
Fig. 13
Transmittance curves ± SD of the three aligners before aging
Fig. 14
Fig. 14
Transmittance curves ± SD of the three aligners after aging
Fig. 15
Fig. 15
Comparison of absorbance values of the three aligners before and after aging
Fig. 16
Fig. 16
Comparison of transmittance values of the three aligners before and after aging

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Source: PubMed

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