title: Evaluation of low-contrast perceptibility in dental restorative materials under the influence of ambient light conditions.
abstract: OBJECTIVE
  This study aimed to assess how details on dental restorative composites with different radio-opacities are perceived under the influence of ambient light.
  
  
  METHODS
  Resin composite step wedges (six steps, each 1-mm thick) were custom manufactured from three materials, respectively: (M1) Filtek™ Z350 (3M/ESPE, Saint Paul, MN); (M2) Prisma AP.H™ (Dentsply International Inc., Brazil) and (M3) Glacier(®) (SDI Limited, Victoria, Australia). Each step of the manufactured wedge received three standardized drillings of different diameters and depths. An aluminium (Al) step wedge with 12 steps (1-mm thick) was used as an internal standard to calculate the radio-opacity as pixel intensity values. Standardized digital images of the set were obtained, and 11 observers independently recorded the images, noting the number of noticeable details (drillings) under 2 dissimilar conditions: in a light environment (light was turned on in the room) and in low-light conditions (light in the room was turned off). The differences between images in terms of the number of details that were observed were statistically compared using ANOVA, Cronbach's alpha coefficient and Wilcoxon and Kruskal-Wallis tests, with a significance level setting of 5% (α = 0.05).
  
  
  RESULTS
  The M2 showed higher radio-opacity, the M1 displayed intermediate radio-opacity and the M3 showed lower radio-opacity, respectively; however, all three were without significance (p > 0.05) compared with each other. The differences in radio-opacity resulted in a significant variation (p < 0.05) in the number of noticeable details in the image, which were influenced by characteristics of details, in addition to the ambient-light level.
  
  
  CONCLUSIONS
  The radio-opacity of materials and ambient light can affect the perception of details in digital radiographic images.
authors: 1 Department of Specific Formation, Area of Dental Radiology, Dental School of the Fluminense Federal University, Rio de Janeiro, Brazil.
authors: A D
authors: AD
authors: Cruz
authors: I C
authors: IC
authors: Lobo
authors: A L B
authors: AL
authors: Lemos
authors: M F
authors: MF
authors: Aguiar
mesh_terms: D000535:Aluminum; D003188:Composite Resins; D004867:Equipment Design; D008027:Light; D019047:Phantoms, Imaging; D019252:Radiography, Dental, Digital; D019279:Resin Cements
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C533204:filtek Z350; C471182:glacier hybrid composite; C073466:Prisma APH; D000535:Aluminum
keywords: composite resins; contrast sensitivity; optical illusions; radiography; visual perception
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