Dental imaging refers to the use of x-ray images (radiographs) to visualize the dentition and its surrounding structures. Radiographic technology has evolve significantly over the years and most modern dental practices would now be equipped with digital units which require lower effective doses. Higher end equipment are often capable of producing both 2D as well as 3D images.
Benefits of taking dental X-rays.
With the use of x-rays, your dentists will be able to locate hidden dental structures (e.g. roots of teeth, buried teeth), establish bone levels and detect disease (e.g. cavities, benign or malignant masses, bone loss) that are otherwise not visible to dentist.
Is it safe?
An X-ray image is formed when a controlled release of X-ray radiation penetrates the oral structures before striking a film or sensor. Dense objects (e.g. teeth and bone) impedes x-ray radiation penetration appear lighter as less radiation will strike the film or sensor. Dental caries and soft tissues appear darker as they are less dense and are easily penetrated by the X-rays. Dental restorations (fillings, crowns) may appear lighter or darker, depending on the density of the material used in their fabrication.
The X-ray radiation dosage received by a dental patient is typically very small, equivalent to a few days’ worth of background environmental radiation, or an airplane flight between Singapore and Shanghai. The beam is concentrated into one short burst aimed at a small area and incidental exposure of other parts of the body is further reduced by the use of a lead apron.
Traditionally, exposed x-ray films is developed using a series of chemicals in a dark room. The adoption of electronic x-ray radiation sensors have made this process faster, more environmental friendly and reduce the effective radiation dosage, making it safer for patients and staff.
Common views taken at a dental practice.
The x-ray view is dependent on the location, size and structure of the ‘area of interest’ to the dentist. Smaller images often require for the film/sensor to be placed in the mouth (collectively known as intra-oral views) while larger images require the film/sensor to be located outside the mouth (collectively known as extra-oral views).
The periapical view aims to capture the tip of the tooth root/s and its surrounding bone. This is especially useful in the investigation of pathology affecting a specific tooth and recording the progress of root canal treatment.
The bitewing view is taken to visualize the crowns of the back teeth and height of the alveolar bone. This allows your dentist to investigate for the presence of decay occurring between the back teeth, under existing restorations (e.g. fillings, crowns) and recording treatment progress during gum treatment.
The occlusal view is useful to visualize midline pathology (e.g. buried teeth, cysts etc.) that are located at the front part of the palate or floor of mouth.
Full mouth series
A full mouth series comprises of up to 4 bitewings and 14 periapical views. It is used selectively in patients with multiple or generalized dental problems due to the high cumulative dosage.
A cephalogram is a standardized extra-oral view that is used to evaluate facial proportions and identify the skeletal contribution of a poor bite (malocclusion). It is called a Lateral Cephalogram when it is taken from the side and Antero-Posterior Cephalogram when it is taken with the patient facing forward.
A panoramic film is a very versatile, extra-oral view that provides a great overall view of the dentition, the upper and lower jaw bones, the heads and necks of the mandibular condyles, the coronoid processes of the mandible, the nasal cavity and the maxillary sinuses. It is very useful in the detection and localization of buried teeth, fractures and other pathologic entities involving the jaw bones.
Cone Beam Computed Tomography (CBCT Scan)
CBCT scans have the ability to produce good quality 3D images of the jaw bones and teeth. This is especially useful in the placement of dental implants, planning jaw surgery, locating buried teeth and identifying tooth root canal morphology. CBCT scanners are specifically designed for use in the oro-facial region and exposes the patient to a much lower radiation dosage when compared to traditional CT scanners, albeit more than routine dental x-ray views.
How often should dental x-rays be taken?
It is possible for both tooth decay and periodontal disease to be missed during clinical examination. X-ray imaging of the dental and periodontal tissues is an essential element of comprehensive oral examination.
The principle of ALARA (As Low As Reasonably Achievable) is used by healthcare practitioners when recommending the use of dental x-rays. The frequency and type of x-ray investigations is dependent on the suspected presence of active disease and nature of treatment.