title: Comparison of changes in dental and bone radiographic densities in the presence of different soft-tissue simulators using pixel intensity and digital subtraction analyses.
abstract: OBJECTIVE
  To evaluate the influence of soft-tissue simulation materials on dental and bone tissue radiographic densities using pixel intensity (PI) and digital subtraction radiography (DSR) analyses.
  
  
  METHODS
  15 dry human mandibles were divided into halves. Each half was radiographed using a charge-coupled device sensor without a soft-tissue simulation material (Wm) and with 5 types of materials: acrylic (Ac), wax (Wx), water (Wt), wood (Wd) and frozen bovine tissue (Bt). Three thicknesses were tested for each material: 10 mm, 15 mm and 20 mm. The material was positioned in front of the mandible and the sensor parallel to the molar region. The radiation beam was perpendicular to the sensor at 30 cm focal spot-to-object distance. The digital images of the bone and dental tissue were captured for PI analyses. The subtracted images were marked with 14 landmark magnifications, and 2 areas of analyses were defined, forming the regions of interest. Shapiro-Wilk and Kruskal-Wallis tests followed by Dunn's post-test were used (p < 0.05).
  
  
  RESULTS
  DSR showed that both the material type and the thickness tested influenced the gain of density in bone tissue (p < 0.05). PI analyses of the bone region did not show these differences, except for the lower density observed in the image without soft-tissue simulation material. In the dental region, both DSR and PI showed that soft-tissue simulators did not influence the density in these regions.
  
  
  CONCLUSIONS
  This study showed that the materials evaluated and their thicknesses significantly influenced the density-level gain in alveolar bone. In dental tissues, there was no density-level gain with any soft-tissue material tested.
authors.affiliation: Department of Diagnosis and Surgery, School of Dentistry at Araraquara, Univ Estadual Paulista, Araraquara, São Paulo, Brazil.
authors.forename: R S
authors.initials: RS
authors.lastname: de Molon
authors.forename: R G
authors.initials: RG
authors.lastname: Batitucci
authors.forename: R
authors.initials: R
authors.lastname: Spin-Neto
authors.forename: G M
authors.initials: GM
authors.lastname: Paquier
authors.forename: C E
authors.initials: CE
authors.lastname: Sakakura
authors.forename: G M
authors.initials: GM
authors.lastname: Tosoni
authors.forename: G
authors.initials: G
authors.lastname: Scaf
mesh_terms: D015502:Absorptiometry, Photon; D000180:Acrylic Resins; D000539:Alveolar Process / Q000000981:diagnostic imaging*; D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging; D002417:Cattle; D006801:Humans; D007283:Inlay Casting Wax; D019252:Radiography, Dental, Digital / Q000379:methods; D012666:Semiconductors; D018709:Statistics, Nonparametric; D013382:Subtraction Technique; D014867:Water; D014934:Wood
chemical_list: D000180:Acrylic Resins; D014867:Water; D007283:Inlay Casting Wax
keywords: bone density; dental radiography; digital radiography; radiography; subtraction technique