Comparison of Mesiodistal Root Angulation Measured from Conventional and CBCT Derived Panoramic Radiographs in Orthodontic Patients.

Ibrahim Nasseh,Marcel Noujeim,Douglas Jensen

doi:10.2174/1874210601711010338

Abstract

Introduction:Use of cone beam computed tomography (CBCT) in orthodontics is increasing; however, some patients started treatment with conventional images. The objective of this study is to manipulate CBCT panoramic reconstruction to make it comparable to conventional panoramic image and to compare mesiodistal root angulations on both images.Materials and Methods:Concurrent conventional panoramics and CBCT volumes were obtained from 40 subjects. CBCT volumes were manipulated to generate pan-like images that mimic the occlusal plane angle of the corresponding panoramic, allowing comparison of mesiodistal root angulations and determination of the head-tilt required to produce the reconstruction.Results:Clinically meaningful differences (p < .05) in the mesiodistal root angulations between standard panoramics and CBCT reconstructions emerged for 13 out of 24 teeth (54%). Greatest variations were seen in the maxillary and mandibular sextants and in first molar regions. Ideal axial head-tilt for image acquisition was determined to be with Frankfort horizontal plane 3.3o nose down.Conclusion:CBCT pan images must be used with caution due to variation between methods in specific areas of arches. The images can be useful for the assessment of mesiodistal root angulations if the volume is properly manipulated to create a pan-like image.

Highlights

Use of cone beam computed tomography (CBCT) in orthodontics is increasing; some patients started treatment with conventional images
CBCT pan images must be used with caution due to variation between methods in specific areas of arches
It has been shown that several panoramic units are similar in the projection of mesiodistal root angulations [16].The consensus from several studies is that standard panoramics taken by various panoramic machines, including the Planmeca Proline used in the present study, have the tendency to project maxillary anterior roots slightly more mesially and posterior roots more distally than true angles found on typodonts

Summary

Introduction

Use of cone beam computed tomography (CBCT) in orthodontics is increasing; some patients started treatment with conventional images. The conventional panoramic radiograph (pan) serves as a diagnostic tool most often used to assess the teeth and their axial inclinations and to evaluate root parallelism prior to, during, and after orthodontic treatment [6, 7]. Despite their widespread use, conventional panoramics have been criticized for their dimensional inaccuracy [8 - 12]. Not withstanding its inherent inaccuracy with respect to assessment of mesiodistal root angulation, the relative mesiodistal inclination of the roots of the maxillary and mandibular teeth, as judged from a panoramic radiograph remains an important assessment factor in the American Board of Orthodontics examinationas well as to clinicians in practice as a convenient pre, mid, and post-treatment diagnostic tool [6,13]

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Conclusion