title: Comparison of linear dimensions and angular measurements on panoramic images taken with two machines.
abstract: OBJECTIVE
  Panoramic radiography is a method widely used because of low absorbed dose in patients (ap-proximately 10 times less than that in the full mouth survey), reasonable cost and time. Disadvantages of this radiography technique are magnification and distortion as a result of unequal magnification, which can influence dimensional and angular measurements used in clinical dentistry to determine root length, dental arch space, relative angulations of teeth, and implant site assessment. The aim of this study was comparison of linear dimensions and angular measurements on panoramic images taken with two machines (Planmeca and Panoura).
  
  
  METHODS
  Twenty radiographs taken with each apparatus from a human dry skull were scanned. Hori-zontal, vertical and angular dimensions were measured on the skull, which were compared along with the images using Corel DRAW Software, V13.
  
  
  RESULTS
  Independent t-test analysis showed that horizontal magnification assessed on images from Panoura was more than that from Planmeca (P < 0.00025). There were no significant differences between the two groups in vertical di-mensions (P = 0.66). Mean magnification of angular measurements assessed on images from Panoura was less than that from Planmeca (P < 0.00025). Independent t-test analysis showed that distortion of Planmeca images were more than that of Panoura. One sample t-test showed that angular measurements were more reliable than linear dimensions.
  
  
  CONCLUSIONS
  Panoramic radiography technique can be used for evaluation of angles but it is better to use other ra-diography techniques for vertical and horizontal measurements.
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Tabriz University of Medical Sciences,Tabriz, Iran.
authors.forename: Tahmine
authors.initials: T
authors.lastname: Razi
authors.forename: Seyed Hosein
authors.initials: SH
authors.lastname: Moslemzade
authors.forename: Sedighe
authors.initials: S
authors.lastname: Razi