title: Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging.
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.
authors.affiliation: Postgraduate School of Orthodontics, University of Ferrara, Via Montebello 31, 44100, Ferrara, Italy. dott.lulombardo@gmail.com.
authors.forename: Luca
authors.initials: L
authors.lastname: Lombardo
authors.affiliation: Postgraduate School of Orthodontics, University of Ferrara, Via Montebello 31, 44100, Ferrara, Italy. angela_arreghini@yahoo.com.
authors.forename: Angela
authors.initials: A
authors.lastname: Arreghini
authors.affiliation: Postgraduate School of Orthodontics, University of Ferrara, Via Montebello 31, 44100, Ferrara, Italy. robertamaccarone@hotmail.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Maccarrone
authors.affiliation: Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17/19, 44121, Ferrara, Italy. bna@unife.it.
authors.forename: Anna
authors.initials: A
authors.lastname: Bianchi
authors.affiliation: Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17/19, 44121, Ferrara, Italy. santo.scalia@unife.it.
authors.forename: Santo
authors.initials: S
authors.lastname: Scalia
authors.affiliation: Postgraduate School of Orthodontics, University of Ferrara, Via Montebello 31, 44100, Ferrara, Italy. sci@unife.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Siciliani
mesh_terms: D003116:Color; D004954:Esthetics; D006801:Humans; D008027:Light; D008422:Materials Testing; D016382:Orthodontic Appliance Design; D009967:Orthodontic Appliances; D012464:Saliva, Artificial / Q000737:chemistry; D013053:Spectrophotometry / Q000379:methods; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014087:Tooth Movement Techniques / Q000295:instrumentation*
chemical_list: D012464:Saliva, Artificial
keywords: F22 Aligner; Orthodontic aligners; Spectrophotometry; Transparency