Magister Scientiae - MSc / Nowadays, the availability of radiographic modalities from conventional radiography to more advanced approaches such as medical computed tomography as well as cone beam computed tomography have been useful in providing insights of relevant anatomy prior to surgical procedures. The increased popularity of cone beam computed tomography has prompted interest in the utility of this approach for diagnostic application in dentistry, including the assessment of the proximity of impacted mandibular third molars to the inferior alveolar canal. It is important to understand the reliability of conventional panoramic radiograph in the assessment of this criterion since it is more commonly used as first line radiographic approach due to its availability and lower radiation dose. This study is aimed to investigate the reliability of conventional panoramic radiograph in the evaluation of the proximity of impacted mandibular third molar root tip to the inferior alveolar canal by correlating the results with cone beam computed tomography. A retrospective study of forty nine patients who underwent panoramic radiography as well as cone beam computed tomography for examination of impacted mandibular third molars was conducted. Two observers were participated in all image evaluation. In this study, both observers recorded statistically significant differences in the measurement of the apices of vertically impacted third molars and the inferior alveolar canal from panoramic radiographs and cone beam computed tomography images. The low reliability of panoramic radiograph to assess the vertical proximity between these two anatomical structures suggests the importance of additional assessment with cone beam computed tomography in cases where panoramic radiograph shows superimposition of the third molar root on the roof of the canal, presence of root below the roof of the canal and presence of bone height of less than one millimetre separating the third molar from the inferior alveolar canal.