Radiopacity
Pronunciation: ray-dee-oh-PAH-sih-tee
The property of a dental material that causes it to appear lighter (more opaque) than surrounding tooth structure or soft tissue on a radiograph, allowing clinical identification of restorations and detection of voids or secondary caries.
Full Definition
Radiopacity in dental materials refers to the degree to which a material attenuates X-ray photons, resulting in a lighter appearance on radiographic images compared to tooth structure. ISO 4049 requires resin-based restorative materials to exhibit radiopacity equivalent to at least 1 mm of aluminium to ensure radiographic detectability. Radiopacity is achieved by incorporating heavy metal oxides such as barium sulphate or barium glass fillers into composite and glass ionomer formulations. Editors should note that 'radiopacity' and 'radiolucency' are antonyms; the latter describes materials or lesions that appear dark on radiographs. Both terms are unhyphenated in standard usage.
Usage
Usage note: The preferred unhyphenated spelling is 'radiopacity'. Correct 'radio-opacity' to 'radiopacity' unless house style dictates otherwise. Always distinguish from 'radiolucency'.
In Context
- "The composite's radiopacity was measured against an aluminium step wedge and reported as equivalent to 2.5 mm Al." — ISO standardisation test report
- "On the periapical radiograph, the glass ionomer restoration was identified by its characteristic radiopacity." — Clinical case notes