Background: The aim of this study was to determine the accuracy of linear measurements of the lower third and second molar crowns in the digital panoramic radiographs and to compare them with plaster models as the calibration standard.
Materials and methods: The digital panoramic radiographs and plaster models of the orthodontic patients were used in the study. Standardized metal calibration gauges (MCGs) were bonded to the buccal surface of the lower molars bilaterally. Measurements in the panoramic radiographs were done using Dolphin Imaging 11.8 Premium program.
Results: Forty-one panoramic radiographs and diagnostic plaster models of the orthodontic patients (mean age 18.45 ± 2.35) were analyzed. Eighty-two lower third molars, 82 second molars, and 82 first molars were evaluated. The magnification coefficients (MCC) calculated according to the plaster models ranged from 1.07 to 1.08. The magnification coefficients calculated according to the bonded MCG were about 1.04. The differences between the teeth groups and right-left sides were not statistically significant (P > 0.05). Spearman correlation showed a positive medium correlation between the magnification using the calibration with plaster models and metal gauges (P < 0.05).
Conclusions: The magnification in the lower first, second, and third molars regions showed almost the same values. The calculation of magnification coefficient using bonded metal calipers was more accurate than calculation according to the plaster models, but the differences were not statistically significant. The use of the plaster models for calibration of the magnification coefficient in the good-positioned lower molars' region might be used as an alternative to the bonded MCGs.
Keywords: Lower second molar; lower third molar; magnification.