Diagnostic value of computed tomography in re-treatment of root fillings in maxillary molars S. Huumonen 1 , T. Kvist 2 , K. Gro¨ ndahl 1 & A. Molander 2 1 Department of Oral and Maxillofacial Radiology at the Sahlgrenska Academy; and 2 Department of Endodontology at the Sahlgrenska Academy, Go¨teborg University/Public Dental Health Service, Go¨ teborg, Sweden Abstract Huumonen S, Kvist T, Gro¨ ndahl K, Molander A. Diag- nostic value of computed tomography in re-treatment of root fillings in maxillary molars. International Endodontic Journal, 39, 827–833, 2006. Aim To compare the diagnostic information and radiation dose between intraoral radiography and computed tomography (CT) in re-treatment decis- ion making concerning root fillings in maxillary molars. Methodology Thirty-nine root-filled maxillary mo- lars with suspected apical periodontitis were examined with two intraoral periapical radiographs and CT. Presence of periapical lesion/s per tooth and root were analysed for both techniques. In addition, in the CT images, the number of root canals, erosion, or perfor- ation of cortical bone plates, and the distance between palatal root and cortical bone plates were evaluated. Radiation dose for CT was registered and calculated; and that of periapical radiographs used as reported previously (Ekestubbe et al. 2004). Results Periapical radiographs revealed periapical lesions in 33 teeth compared with 38 on CT images. A lesion of any root was detected more often with CT. The mesiobuccal root had two root canals in 30 teeth of which 27 of the MB2 canals were not filled, and 22 roots with an unfilled canal were associated a periap- ical lesion. Distances to palatal root, from the buccal and palatal cortex were measured in CT and varied between 5.0–12.0 mm and 0–4.0 mm, respectively. Based on the radiographic information, a variety of treatment alternatives were suggested. Mean effective dose of periapical radiographs was 0.02 mSv and that of CT 0.055 mSv. Conclusions Computed tomography may give important information in re-treatment decision when considering root fillings in maxillary molars. The radiation dose should be considered individually. Keywords: computed tomography, endodontically treated, maxillary molars, periapical radiography. Received 16 December 2005; accepted 24 April 2006 Introduction Root-filled teeth are frequently associated with periap- ical inflammatory lesions (Eriksen et al. 2002). When root-filled teeth are associated with post-treatment disease, several factors may influence the decision whether to retreat or not (Kvist 2001, Friedman 2002). If re-treatment is considered, the clinician can choose between a surgical or nonsurgical approach. The introduction of the surgical microscope and micro- instruments has made surgical re-treatment a standard option to nonsurgical re-treatment of maxillary molars. However, periapical surgery of the palatal root of maxillary molars is usually considered difficult (Rigo- lone et al. 2003). Consequently, a key factor in the decision process is whether the palatal root has a periapical lesion or not. If there is a lesion, detailed data are required of its extent, and of the anatomy of the root system and the alveolar process. Such information is not only crucial for the decision whether to treat or not. Should apical surgery be considered the treatment of choice, the information has an influence on whether to choose a buccal or a palatal access, or a combination Correspondence: Sisko Huumonen, Specialist Clinic for Oral and Maxillofacial Radiology, Medicinaregatan 12, SE-413 90 Go¨teborg, Sweden (Tel.: + 46 31 74 13 640; fax: + 46 31 82 73 51; e-mail: sisko.huumonen@odontologi.gu.se). ª 2006 International Endodontic Journal International Endodontic Journal, 39, 827–833, 2006 doi:10.1111/j.1365-2591.2006.01157.x 827