Introduction: The use of CBCT to visualize the relationship between the inferior alveolar canal and the mandibular third molar roots continues to grow as it is becoming the standard of care. It becomes important to understand the impact that luminance, one of the factors that affects the viewing conditions of digital images, has on appropriately assessing the third molar-canal relationship. To date, no study has assessed the impact of luminance on visualizing anatomic structures on CBCT. The aim of this study is to determine if there is a difference in the ability to appropriately assess the root development and the third molar-canal relationship on a medical grade monitor with four different luminance settings on CBCT. Materials and methods: 285 scans were randomized and evaluated by three calibrated and masked evaluators. The evaluations were completed on a Barco MDNC-3321 Nio Color 3MP monitor (Kortrijk, Belgium) monitor at four different luminance settings; 200 cd/m2, 300 cd/m2, 400 cd/m2, and 500 cd/m2. The gold standard was established by two board-certified oral and maxillofacial radiologists. All evaluations were performed in a controlled subdued environment lighting of less than 15 lux. There was a washout period of at least one week between each of the four evaluations by an observer. Results: The accuracy of two of the three evaluators was substantial to almost perfect independent of luminance. None of these assessments showed any statistical significance (P = 0.05). The accuracy of one evaluator was moderate to almost perfect for all evaluations with one assessment of one canal showing statistical significance (P = 0.05). Conclusion: There is no difference in the ability to appropriately assess the third molar canal relationship or the root development of third molars on a medical grade monitor at luminance settings between the range of 200 cd/m2 and 500 cd/m2 when viewed in a dimly lit room.

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.