Impaction (Dental)
Pronunciation: im-PAK-shun
The state of a tooth that is prevented from fully erupting into its normal functional position by another tooth, bone, or soft tissue, as characterised radiographically by its angulation and depth.
Full Definition
Dental impaction is a frequent subject of dental radiology reports, particularly for third molars, maxillary canines, and supernumerary teeth. Radiographic classification of impaction is standardized and includes descriptors of angulation (mesioangular, distoangular, vertical, horizontal), depth relative to the adjacent tooth and the mandibular ramus (Pell and Gregory classification), and relation to the ramus (Class I, II, III). Editors must ensure that the classification system used is identified and applied consistently, and that 'impacted' is distinguished from 'unerupted' (a broader term that may include teeth that could still erupt) and 'embedded' (a tooth completely covered by bone and no longer capable of eruption). The noun form is 'impaction' and the participial adjective is 'impacted'.
Usage
Usage note: 'Impacted' implies a physical obstruction to eruption; 'unerupted' is broader. Specify the classification system when a formal angulation or depth class is cited.
In Context
- "The lower-right third molar showed mesioangular impaction at Pell and Gregory Class II, Position B." — Panoramic radiology report
- "Editors should verify that 'impacted', 'unerupted', and 'embedded' are not used interchangeably in surgical assessment reports." — Editorial style note