Is “danger zone” really dangerous? - An endodontic perspective

Abstract

Aim: To evaluate the accuracy of panoramic radiography in determining dentin thickness of danger zone (DZ) using cone-beam computed tomography (CBCT) imaging to examine the dentin thicknesses of the mandibular molars at different levels. Materials and Methods: For the study, 250 mandibular molars were selected. Dentine thicknesses were measured on panoramic radiography. On the CBCT view, dentine thicknesses of mesiobuccal (MB), mesiolingual (ML), and distal roots were measured. The reference point was determined as 3 mm, 4 mm, and 5 mm below the furcation of mandibular molars. Statistical analysis was performed. Results: The discrepancy between CBCT and panoramic was 0.5 mm for MB, 0.48 mm for ML, and 0.43 mm for distal. The difference in the dentin thickness between 3 mm and 5 mm is not statistically significant(P>.05), whereas the 4 mm furcation level was significantly lower in either 3 mm and 5 mm for each root canal. This study showed that 0.5 mm distortion occurred in the danger zone on panoramic radiography. Conclusion: Our study showed that the dentin thickness of less than 1 mm in panoramic radiography is more prone to perforation because of distortion. The dentin thickness was lowest at 4 mm below the furcation. Our results can be a guide the clinicians in clinics or institutions where periapical radiography is not available.