Reference library.

ALARA and ALADA are the two radiation-protection principles named in dental radiography guidance. ALARA — as low as reasonably achievable — constrains the…

The alveolar crest is the alveolar bone crest — the interproximal bone landmark whose distance from the cemento-enamel junction is measured on bitewings.…

A bitewing radiograph is the intraoral posterior view that shows the anatomical crowns and the interproximal alveolar bone level in a single image.…

Cervical burnout is a radiolucency at the neck of a tooth caused by overpenetration of the thinner cervical tooth structure. It is an imaging artifact,…

A cone cut is the part of a radiograph the X-ray beam never reached, because the beam and the receptor were not lined up. The region is blank and sharply…

A corticated border is a thin radiopaque line running around the edge of a radiolucent lesion on a radiograph. Cysts that arise within bone typically have…

A double exposure is two radiographic images recorded on one receptor, one over the other. UK dental guidance lists it as an operator error under both…

Elongation and foreshortening are the two halves of one vertical angulation error. An elongated radiograph shows teeth longer than they are; a…

Furcation involvement is loss of the bone between the roots of a molar, starting where the roots divide. On a radiograph it shows as a radiolucency in the…

A ghost image is a radiopacity on a panoramic radiograph cast by an object that sat between the X-ray source and the machine's centre of rotation. It…

The herringbone artifact is the pattern a dental radiograph carries when the film packet was exposed from the wrong side: a repeating herringbone or…

The lamina dura is the thin layer of dense cortical bone lining a tooth socket. On a radiograph it reads as a fine radiopaque line running around the…

A lead apron artifact is the shadow a protective apron or thyroid collar casts when it ends up in the primary beam. On a panoramic radiograph an apron…

The Mach band effect is an optical illusion in which the eye exaggerates contrast where two densities meet, creating an apparent dark band that is not…

The mental foramen is the opening in the body of the mandible that carries the mental nerves and vessels [16]. On a radiograph it reads as a small round…

Movement artifact is the image degradation produced when a patient moves during a radiographic exposure. On an intraoral radiograph it appears as…

The nasopalatine canal, also called the incisive canal, is a bony canal through the anterior maxilla that connects the oral and nasal cavities [1].

Nutrient canals are passages through the alveolar bone that carry vessels and nerves to the teeth and their supporting structures.

Occlusal caries is a carious lesion on the pit-and-fissure surface of a posterior tooth. On a bitewing radiograph it stays largely invisible until it…

Overlapped contacts are the superimposition of two adjacent proximal surfaces on a bitewing radiograph, caused by horizontal angulation error. Where the…

The palatoglossal air space is the air left between the tongue and the palate when the tongue is not held against the roof of the mouth during a panoramic…

A panoramic positioning error is a fault in how the patient was placed in the machine, and it distorts the image rather than the anatomy. The focal trough…

A panoramic radiograph is a single image of both jaws, made by a source and receptor that rotate around the patient. Only a curved zone called the focal…

A periapical radiograph is an intraoral view showing a whole tooth — crown, root and apex — together with the bone immediately around the root tip. That…

The periodontal ligament space is the thin radiolucent line between a tooth's root and the lamina dura, the space the periodontal ligament occupies. It…

A photostimulable phosphor (PSP) plate is a reusable, cordless intraoral receptor. It stores the X-ray exposure as electrons trapped in a phosphor layer,…

A radiographic artifact is a feature on a radiograph that comes from how the image was made rather than from the patient — from the operator, the…

Radiographic caries depth classification grades how far a proximal radiolucency has penetrated the tooth on a bitewing radiograph. The common ladder runs…

Radiographic fog is unwanted density spread across a radiograph that raises the overall darkness and lowers contrast, leaving the image flat and grey.…

A radiographic search pattern is a fixed route you follow across every radiograph, in the same order, every time. It exists because finding one…

Radiolucent means dark on a radiograph; radiopaque means light. Which one a structure comes out as depends on how much of the beam it absorbed on the way…

Radiolucent restorative materials are fillings, bases, liners and cements that are less radiopaque than the tooth structure around them, so they read as a…

Reject analysis is a periodic audit that counts how many radiographs were taken but never used for diagnosis, and records why. In general-radiography…

Residual caries is demineralised carious tissue that was left in place when a restoration was placed. Secondary caries is a lesion that developed next to…

A restoration overhang is an extension of restorative material beyond the confines of the cavity preparation. On a bitewing radiograph it reads as a…

A restoration on a radiograph is any filling, inlay, crown or bridge unit that appears inside the tooth outline as material the beam passes through…

Secondary caries is a carious lesion at the margin of an existing restoration. On a bitewing it shows as a radiolucency at the restoration's edge, most…

Sensor dropout is a mark on a radiograph produced by damage to the receptor rather than by anything in the patient. On a phosphor plate it is usually a…

A Stafne bone cavity is a depression in the lingual surface of the mandible, usually holding part of the submandibular gland or fat. On a panoramic…

The tube shift technique locates an object buccal or lingual to its neighbouring teeth by comparing two radiographs taken with the X-ray tube in two…