The relationship between actual size of premolar teeth and the size of them on panoramic radiography

Abstract

Panoramic radiography is one of the commonly used techniques in diagnostic processes especially for orthodontic treatment plans. Besides the advantages of this modality, clinician should always notice its magnification of anatomical structures which influences the measurements and diagnostic interpretation. Therefore, the aim of this study was to compare the actual crown and root dimensions of the upper premolar teeth with their counterparts in panoramic radiograph measurements and to produce a mathematical formula to estimate the teeth dimensions from the panoramic imagines. Methods & Materials: Crown and root length,and mesiodistal dimensions of 33 upper premolars teeth of patients undertaken orthodontic treatments were measured before extraction, on panoramic images, and after extraction, on the teeth outside of the mouth. Statistical tests including pearsons and spearmans correlation test were employed for analysis. A linear regression model was used to estimate the difference between the actual and radiographic dimensions. Results: There was a significant co-relation between actual and radiographic measurements of crown and root lengths. The relevant mathematical formula was: Radiographic root length=-1.41+(1.2*actual root length), and Radiographic crown length=2.82+(0.71*actual crown length). But there was not such a co-relation regarding mesiodistal width of teeth. Conclusions: Panoramic radiography is a reliable modality for predicting the actual crown and root lengths of teeth but not for horizontal dimensions.