Oral and Maxillofacial Radiology

Dental and Maxillofacial Radiology is that specialty of Dentistry concerned with performance and interpretation of diagnostic imaging used for examining the craniofacial, dental and adjacent structures . OMFR or DMFR is one of nine dental specialties recognized by the American Dental Association, Royal College of Dentists of Canada, and Royal Australasian College of Dental Surgeons.

Oral and maxillofacial imaging includes, but is not limited to, cone beam CT, multislice CT, MRI, PET, ultrasound scan, dental panoramic radiology, cephalometric imaging, intra-oral imaging (e.g. Bitewing, peri-apical and occlusal radiographs) in addition to special tests like sialographs. Visible light, optical coherence tomography and tera ray imaging are examples of additional methods in use or under development. Image guidance includes Haptic and Robotic devices.

Dental radiography

Dental Radiographs are commonly called x-rays. Dentists use radiographs for many reasons: to find hidden dental structures, malignant or benign masses, bone loss, and cavities.

A radiographic image is formed by a controlled burst of X-ray radiation which penetrates oral structures at different levels, depending on varying anatomical densities, before striking the film or sensor. Teeth appear lighter because less radiation penetrates them to reach the film. Dental caries, infections and other changes in the bone density, and the periodontal ligament, appear darker because X-rays readily penetrate these less dense structures. Dental restorations (fillings, crowns) may appear lighter or darker, depending on the density of the material.

The dosage of X-ray radiation received by a dental patient is typically small (around 0.150 mSv for a full mouth series, according to the American Dental Association website), equivalent to a few days’ worth of background environmental radiation exposure, or similar to the dose received during a cross-country airplane flight (concentrated into one short burst aimed at a small area). Incidental exposure is further reduced by the use of a lead shield, lead apron, sometimes with a lead thyroid collar. Technician exposure is reduced by stepping out of the room, or behind adequate shielding material, when the X-ray source is activated.

Once photographic film has been exposed to X-ray radiation, it needs to be developed, traditionally using a process where the film is exposed to a series of chemicals in a dark room, as the films are sensitive to normal light. This can be a time-consuming process, and incorrect exposures or mistakes in the development process can necessitate retakes, exposing the patient to additional radiation. Digital x-rays, which replace the film with an electronic sensor, address some of these issues, and are becoming widely used in dentistry as the technology evolves. They may require less radiation and are processed much more quickly than conventional radiographic films, often instantly viewable on a computer. However digital sensors are extremely costly and have historically had poor resolution, though this is much improved in modern sensors.