I was recently asked “How should I read a cat scan as I was not taught how to do this in dental school?”
A structured approach is required as there is a huge amount of anatomy contained within the scanned volume and unless a careful systematic approach is used then it is likely that you will miss something.
My advice is:
Review the clinical history, medical history, chief complaints. Know which teeth have been removed in the last few months to explain areas of bone loss with healing/ disrupted bone. Know if bone grafts are present and date of surgery.
Review the axial slices starting with the anterior superior region (Frontal sinus), move down through the jaws and anterior face until you reach the cervical region. Then concentrate on the airway and spine and move up to the cranium. In this way you will cover the whole region. DO NOT THINK ABOUT THE CHIEF COMPLAINT as this will bias you away from looking at all the other areas.
Now read the coronal slices from front to back and come back to the mental region.
Lastly sagittal slices from right to left.
Create a panoramic tomograph view and count how many teeth are missing.
Adjust the field of view so you are only looking at the maxilla and in panoramic cross section work from right to left. Carefully examine all apices for widening of PLS, enlargement of the nasopalatine canal and presence of maxillary sinus bony septa as these should be avoided when performing sinus lifts.
Adjust the field of view so you are only looking at the mandible and in panoramic cross section work from left to right. If implants or removal of third molars are planned, trace the inferior alveolar canals. Again check apical areas. In the midline search for the lingual canal if anterior implants are planned to avoid cutting these vessels. A simple arrow can be used to note the position of the canals.
Lastly examine the region/s of the chief complaint/s and note abnormalities.
Allow plenty of time. An average adult 40 years of age with most of their teeth and 2-3 root canals will take at least 20 minutes including make copies of selected slices of interest. A patient with large restorations and multiple root treatments (5+) is likely to take at least 40 minutes as the probability of apical pathology is high.
The time spent will reward you handsomely as your treatment planning will be more thorough and you will avoid pitfalls of providing implants next to diseased teeth.
Dr. Douglas K Benn DDS PhD, Diploma in Dental Radiology (Royal College of Radiologists, England)
Oral and Maxillofacial Radiologist
3610 Leavenworth Court