Assessment of the Interradicular Space in Panoramic Radiograph in Comparison to Computed Tomography
Euk Joo1 , Sun Mi Kwon2 , Hyung-Seog Yu2 , Kee-Joon Lee2
1 Department of Orthodontics, College of Dentistry, Yonsei University, Seoul
2 Department of Orthodontics, Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea
Purpose: It is important to minimize the dental root injury when applying orthodontic mini-implant in interradicular space. Distance between roots shown in panoramic radiographs is used as a reference in usual clinical practice, but panoramic radiograph has limitation of magnification and distortion. Thus, this research attempted to provide information of the magnification and distortion in panoramic radiograph for safe mini-implant placement by measuring and comparing the interradicular space in panoramic radiographs and CT scans, as well as by analyzing the pattern of magnification and distortion in panoramic radiographs.
Materials & Methods: CT scans and panoramic radiographs were taken on 30 maxillas and mandibles. Interradicular distances at 4 mm and 8 mm away from the cemento-enamel junction (CEJ) toward the apex and crown widths were measured. The interradicular distance was defined by measuring from the center of lamina dura.
Results: Based on panoramic radiograph, the magnification of crown width was generally consistent with a measure of 1.1 in anterior and 1.3 in posterior in both the maxilla and mandible. Magnification of interradicular distance in the anterior region was larger than the posterior region in both the maxilla and mandible, and the distortion was the largest in between the maxillary canine and first premolar region.
Conclusion: The panoramic radiograph can be used effectively in interradicular mini-implant placement recognizing the magnification rate. However, care must be taken when placing mini-implants in between the maxillary canine and first premolar region where the distortion is especially large.
Key words: Orthodontic mini-implant, Panoramic radiograph, CT, Interradicular space
Korean J Lingual Orthod 2018;7(1):1-8