The professional term dentists use for their X-rays is radiographs, and the practice of taking them is called radiography. While “X-ray” refers to the electromagnetic energy used, “radiograph” specifically denotes the resulting image or film that the dentist interprets. Radiography is a non-invasive procedure that provides a view of internal oral structures hidden from a visual examination.
Images Taken Inside the Mouth
The most common types of dental images are categorized as intraoral, meaning the sensor or film is positioned inside the patient’s mouth during exposure. These localized views offer sharp, detailed images of individual teeth and the surrounding bone. Intraoral images are primarily used to diagnose specific issues like decay, periodontal disease, and infections.
A periapical (PA) radiograph captures the entire tooth, from the crown to the root tip and the surrounding bone structure. Dentists use this image to assess root health and look for periapical pathology, such as infection or inflammation at the root end. Bitewing images are designed to check for decay forming between adjacent teeth (interproximal caries), which are difficult to see visually. These images show the crowns of the upper and lower teeth in one area, along with the crest of the supporting bone.
Occlusal radiographs provide a broader view of an entire arch of the jaw, either the upper or the lower. The larger sensor is held between the biting surfaces of the teeth. This technique is useful for localizing impacted teeth, such as canines, and for identifying large cysts or fractures in the jawbone.
Images Taken Outside the Mouth
Extraoral radiographs are taken with the imaging sensor and X-ray source positioned entirely outside the patient’s mouth. These techniques capture a comprehensive, wide-area view of the jaw, skull, and surrounding structures. They are used for broad screening, orthodontic planning, or complex surgical cases.
The Panoramic X-ray (Panorex) captures a single, two-dimensional image of the entire mouth, including all teeth, the sinuses, and the temporomandibular joints (TMJs). This technique is valuable for assessing wisdom teeth position, checking for jaw fractures, or identifying developmental abnormalities. The Cone-Beam Computed Tomography (CBCT) scan is an advanced extraoral technique that uses a cone-shaped X-ray beam to generate three-dimensional (3D) images of hard tissues. Dentists utilize CBCT for specialized procedures like detailed implant planning and evaluation of bone density before surgery.
The Diagnostic Role of Dental Imaging
Radiographs are an indispensable tool, revealing conditions impossible to detect through a purely clinical examination. The images allow the dentist to evaluate the dense structures of the teeth and bone beneath soft tissue. For instance, a radiograph can detect early-stage decay forming between teeth before it is visible to the naked eye, allowing for less invasive treatment. They also provide crucial information about the supporting bone structure, assessing bone levels around the roots to diagnose and monitor periodontal (gum) disease.
Radiographs are also used to locate non-erupted or impacted teeth, such as wisdom teeth. They help identify hidden pathology like abscesses, cysts, or tumors forming within the jawbone.
Patient Safety and Technological Advances
Concerns about radiation exposure are addressed through continuous technological advancements and strict safety protocols. Modern digital radiography uses electronic sensors instead of traditional film, dramatically lowering the required radiation dose. Digital systems can reduce exposure by up to 80% to 90% compared to older film-based methods.
Dental professionals follow the principle of “As Low As Reasonably Achievable” (ALARA), ensuring the smallest possible dose is used to obtain a diagnostic-quality image. Protective measures, such as the use of a lead apron over the torso and sometimes a thyroid collar, are standard procedure to shield the patient.
Digital technology also provides near-instantaneous image display, eliminating chemical processing and allowing for immediate image manipulation to enhance quality.