Table 1.
Summary of the defining criteria for each dental anomaly recorded.
| Anomaly | Description |
|---|---|
| Missing tooth | The tooth is not visible on clinical examination, photographs, or study models. Confirmed absent on the OPG |
| Congenital | There is no record of previous extractions for orthodontic or other dental purposes (e.g., caries) |
| Extraction | If one premolar is missing in a quadrant and it is not stated as being extracted for orthodontic purposes, it is recorded as a congenitally absent second premolar |
| Other | If the subjects report previous dental extractions for trauma or caries, then a tooth is marked as missing for dental purposes. If premolars were extracted for orthodontic purposes, the missing teeth are recorded as the first premolars |
| If photographs, study models, and OPG reveal a missing tooth with obvious spacing, with tilting or rotation of other teeth into the space but no record of a previous extraction or trauma, then the missing tooth is marked as other as it was presumed (but not confirmed) to have been extracted | |
| Supernumerary tooth | An extra tooth is visible on clinical or radiographic examination. Confirmed by study models and photographs |
| Microdontia | The tooth appears smaller than normal for tooth type. Visible clinically and confirmed by examination of study models, photographs, and the OPG |
| Impacted | Tooth is not expected to erupt completely into its normal functional position. Sometimes visible clinically, confirmed by the OPG as being present and not fully erupted |
| Transposed | Positional interchange of two adjacent teeth, or the development or eruption of a tooth in a position normally occupied by a non-adjacent tooth. Visible clinically confirmed by photographs, study models, and OPG |
| Enamel Defects | Defects of the enamel visible clinically confirmed by photographs and in the case of hypoplasia also confirmed by study models and OPG. Enamel defects are not defined by the aetiology |
| Hypomineralisation | Appearance of brown, white, mottled enamel affecting any surface of the tooth, with no loss of tooth structure. Visible clinically and confirmed by examination of photographs |
| Hypoplasia | Loss of tooth structure, with the appearance of grooved/pitted uneven enamel surface. Visible clinically also confirmed by photographs, study models, and radiographs |
| Discolouration | Intrinsic staining of the tooth either generalised or chronological. Visible clinically and confirmed by dental photographs |