Comparison of linear dimensions and angular measurements on panoramic images taken with two machines

Background and aims. Panoramic radiography is a method widely used because of low absorbed dose in patients (approximately 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). Materials and methods. Twenty radiographs taken with each apparatus from a human dry skull were scanned. Horizontal, 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 dimensions (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. Conclusion. Panoramic radiography technique can be used for evaluation of angles but it is better to use other radiography techniques for vertical and horizontal measurements.