title: Radiographic technique and brackets affect measurements of proximal enamel thickness on mandibular incisors.
abstract: To investigate the influence of radiographic film and tube positioning, the presence and the size of brackets on in vitro measurements of proximal enamel thickness of mandibular incisors on periapical radiographs aimed to aid planning of interproximal enamel reduction procedures in orthodontics.
  
  
  
  Eighty human mandibular incisors were assigned to sets of four and located in a customized base. Periapical radiographs were taken with the film positioned at three different angles (0°, 2°, and 5°) in relation to the frontal plane and the tube head positioned at five angles (0°, -2°, -5°, +2°, and +5°) in relation to the sagittal plane. The proximal enamel width was calculated by means of computerized image analysis and compared with measurements obtained at 0°. Statistical analysis was carried out to compare the enamel measurements on radiographs made with all angular combinations with and without the presence of brackets of different dimensions.
  
  
  
  A significant difference (P < 0.05) was found between the measurements of proximal enamel width obtained at the different angles in relation to the frontal and sagittal planes for all sets with or without brackets. The presence of brackets significantly affected the measured width only for the enamel side further away from the radiation source at the sagittal plane (P < 0.05).
  
  
  
  Angular changes in taking periapical radiographs of mandibular incisors and the presence of brackets significantly affect interproximal enamel measurements made with image analysis software.
authors.affiliation: Department of Orthodontics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
authors.forename: Amy Giok Phing
authors.initials: AG
authors.lastname: Ang
authors.affiliation: Department of Dentistry, University of Groningen, University Medical Centre Groningen, Centre for Dentistry and Oral Hygiene, Groningen, The Netherlands and.
authors.forename: Pauline Antoinette Josephine
authors.initials: PA
authors.lastname: Steegmans
authors.affiliation: Department of Public and Individual Oral Health, University of Groningen, University Medical Centre Groningen, Centre for Dentistry and Oral Hygiene, Groningen, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: Kerdijk
authors.affiliation: Department of Orthodontics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands, c.livas@umcg.nl.
authors.forename: Christos
authors.initials: C
authors.lastname: Livas
authors.affiliation: Department of Orthodontics, University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands.
authors.forename: Yijin
authors.initials: Y
authors.lastname: Ren
mesh_terms: D003743:Dental Enamel / Q000737:chemistry*; D006801:Humans; D007180:Incisor / Q000737:chemistry*; D016910:Orthodontic Brackets; D011859:Radiography; D012984:Software / Q000592:standards*