Dental X-rays fall into two main categories: intraoral, where the film or sensor is placed inside the mouth, and extraoral, where imaging is captured outside the mouth. Each type serves a distinct diagnostic purpose.
Intraoral X-Rays
Bitewing X-rays
Bitewing X-rays capture the upper and lower back teeth in a single image, showing the crowns of the teeth and part of the supporting bone. You bite down on a small tab or wing-shaped holder to keep the film in place during the image. These are the most commonly taken X-rays during routine dental visits. They are used primarily to detect decay between teeth, identify decay beneath existing fillings, check the fit of crowns or bridges, and assess early bone changes associated with gum disease.
Periapical X-rays
A periapical X-ray shows the entire length of one or two teeth, from the crown to the tip of the root and the surrounding bone. The sensor or film is placed inside the mouth next to the tooth being examined. These images are used to examine root structure, detect infections or abscesses, identify cysts or other abnormalities at the root tip, and assess the bone supporting the tooth.
Occlusal X-rays
Occlusal X-rays capture the full arch of either the upper or lower teeth in a single image. The film or sensor is held between the biting surfaces of the teeth while the image is taken. They are used to identify extra or missing teeth, locate teeth that have not yet emerged, detect jaw fractures, and identify cysts, abscesses or other pathology. Occlusal X-rays are more commonly used in children to evaluate dental development.
Extraoral X-Rays
Panoramic X-ray (OPG)
A panoramic X-ray, also known as an orthopantomogram (OPG), captures a wide-angle view of the entire mouth in a single image. This includes all the teeth, the upper and lower jaws, the jaw joints and the maxillary sinuses. During the procedure, a rotating arm moves around your head to capture the image. A small bite-blocker is placed between the teeth to ensure proper alignment; no film or sensor is placed inside your mouth.
Panoramic X-rays are used to assess wisdom teeth, evaluate jaw conditions, plan dental implants, detect cysts and tumours, and provide an overview of overall oral health. Because no film is placed inside the mouth, panoramic X-rays may also be recommended for patients with a sensitive gag reflex who find intraoral sensors uncomfortable.
Note on limitations: While the panoramic X-ray provides a broad view, it offers lower resolution than intraoral X-rays such as bitewing or periapical images. For detailed assessment of individual teeth or specific areas of concern, your dentist may recommend supplementary intraoral X-rays alongside the panoramic image.
Lateral Cephalometric X-ray
A lateral cephalometric X-ray captures a side view of the entire head, showing the relationship between the teeth, jaw and facial structure. It is commonly used in orthodontic treatment planning to assess how the teeth and jaws align and to guide decisions about braces or other corrective appliances.
Cone Beam Computed Tomography (CBCT)
CBCT is a form of three-dimensional dental imaging that provides detailed cross-sectional views of the teeth, jaw, nerve pathways, sinuses and surrounding structures (White & Pharoah, 2014). A rotating arm captures data from multiple angles, which is then reconstructed into a 3D image. CBCT is used for complex treatment planning, including dental implants, surgical removal of impacted teeth, assessment of jaw pathology and certain root canal cases. Unlike some forms of CT scanning, CBCT can be performed at a dental clinic rather than a hospital or specialist imaging centre. It delivers more radiation than conventional dental X-rays and is used selectively based on clinical need.