Computed Tomography Improves the Reliability of Diagnosis of Periapical Inflammatory Lesions of Upper Molars

Objective: Computed tomography (CT) provides three-dimensional visualization of teeth and adjacent tissues. Consequently, CT may contribute to the diagnosis and treatment planning of teeth with periapical lesions. In this pilot study we investigated information available from axial CT scans compared to periapical radiographs in diagnosis of upper molars having periapical lesions. Methods: Sixteen patients having periapical lesions of the first (14) or second (2) upper molar were studied. Two periapical radiographs of 10º horizontal angle differences were taken using parallel technique at 65 kV and Kodak Insight films. Further, axial CT scans were taken using standard technique at 120 kV, 50 mA. Slice thickness was 1.25 mm. Axial scans were taken from marginal bone crest up to hard palate. Radiation dose for each patient was registered. The visualization and localization of lesion in relation to apex, cortical bone, marginal bone and maxillary sinus were studied. Location of sinus floor in relation to roots was also evaluated. Two specialists in oral and maxillofacial radiology analyzed radiographs. Results: Effective dose (mean) of periapicals was 0.006 and 0.052 mSv in CT, respectively. Both techniques showed periapical lesions in one or several roots in all 16 teeth. Apical-marginal communication was found in 35%. A lifted sinus floor was seen in 25%. In addition, CT showed the location of lesion close to or in cortical bone in 60% of cases. In 30% the bone plate was perforated. The sinus floor was located at the level of apex or between the roots in 70% of teeth. Conclusions: The effective dose from CT was ten times higher than intraoral radiographs. However, compared to intraoral radiographs the use of CT also provided bucco-palatinal visualization of investigated area and added beneficial information of maxillary molars with periapical inflammatory lesions prior to surgical retreatment.