Impact of Digital Panoramic Radiograph Magnification on Vertical Measurement Accuracy

Abstract

Objectives. The purpose of this panoramic radiography study was to assess the impact of image magnification on the accuracy of vertical measurements in the posterior mandible. Methods. Six dental implants, inserted in the posterior segments of a resin model, were used as reference objects. Two observers performed implant length measurements using a proprietary viewer with two preset image magnifications: the low (1.9 : 1) and the medium (3.4 : 1) image magnifications. They also measured the implant lengths in two Digital Imaging Communications in Medicine viewers set at low (1.9 : 1), medium (3.4 : 1), and high (10 : 1) image magnifications. Results. The error between the measured length and the real implant length was close to zero for all three viewers and image magnifications. The percentage of measurements equal to the real implant length was the highest (83.3%) for the high image magnification and below 30% for all viewers with the low image magnification. Conclusions. The high and medium image magnifications used in this study allowed accurate vertical measurements, with all three imaging programs, in the posterior segments of a mandibular model. This study suggests that a low image magnification should not be used for vertical measurements on digital panoramic radiographs when planning an implant in the posterior mandible.

Accuracy of measurements performed on digital panoramic radiographs with and without an extra-oral calibration object

“…In this study we used the metal scale ruler placed extra-orally so that it appears in the middle of the panoramic radiograph as the most accurate calibration object [22]. In our study vertical distortion ratio varied from mean of 1.00 in incisor and canine region to 1.04 in molar region on JPEG image format with calibration achieved by the metal ruler being positioned in the middle of the panoramic radiograph, similarly as in DICOM image format.…”

“…They did not find any significant differences in the vertical measurements of implants (the mean vertical DR=0.99) and metal balls (the mean vertical DR=0.97), respectively, and the accuracy was unrelated to the mandibular sites [14]. Many previous studies reported the accuracy of vertical measurements on digital panoramic radiographs but there is limited evidence regarding the accuracy of horizontal measurements [14,[19][20][21][22][23][24][25].…”

“…Each observer examined the largest horizontal and vertical distance on each of 32 metal balls, randomly, on 5 different radiographs using a mouse-driven pointer (Figure 2). Because of different image distortion in different panoramic radiograph regions, we divided measurements in four groups according to the teeth position in dental arch (tooth numbering): incisors (11,12,21,22,31,32,41,42), canines (13,23,33,43), premolars (14,15,24,25,34,35,44,45) and molars (16,17,18,26,27,28,36,37,38,46,47,48).…”

Knowledge, attitude and practice on use of magnification in dentistry among dental students

“…Sharp injuries can occur due to the careless use of loupes during dental procedure. Passing skills must be well-coordinated between the clinician and the assistant to avoid injuries (41). Very little numbers of studies have been published on the topic of dental magnification among dental practitioners (42).…”