|
| Groups of predictor variables | Variable/definition | Classification |
|
| Body weight | Body mass index (BMI) (weight [kg] divided by height squared [m2]) | 1: 25.0–29.9 (overweight) |
|
| Demographic | Gender | 1: Female |
| 2: Male |
| Age | 1: <25 years |
| 2: ≥25 years |
|
| Clinical | Associated pathologies (condition associated to the 3rd molar) | 1: None |
| 2: Pericoronitis |
| 3: Caries |
| 4: Bone resorption |
|
|
Radiographic | Level of occlusal plane—Pell and Gregory (occlusal plane of the 3rd molar in relation to the 2nd molar) | 1: High—larger part of crown of the 3rd molar above or on the same level as the 2nd molar |
| 2: Medium—larger part of crown of the 3rd molar between the occlusal plane and the cementoenamel junction of the 2nd molar |
| 3: Low—crown of the 3rd molar completely below the cementoenamel junction of the 2nd molar |
| Available retromolar space—Pell and Gregory (distance between distal-most point of the 2nd molar crown and the anterior-most point of the ascending ramus) | 1: (A) Sufficient—space greater than or equal to the mesiodistal distance of the 3rd molar |
| 2: (B) Reduced—space greater than half and less than the mesiodistal distance of the 3rd molar |
| 3: (C) Insufficient—space less than half of the mesiodistal distance of the 3rd molar |
| Impaction angle (Winter), measured in degrees (angle between the crossing of the long axis of the 3rd molar and the occlusal plane) | 1: Horizontal 0° to 30° |
| 2: Mesioangular 31° to 60° |
| 3: Vertical 61° to 90° |
| 4: Distoangular > 90° |
| Number of roots | 1: One fused root |
| 2: ≥2 roots |
| 3: Tooth germ |
| Root curvature (angle between the long axis of the crown and the root of the 3rd molar) | 1: Nondilacerated < 10° |
| 2: Dilacerated > 10° |
| Tooth relation with mandibular canal (distance [mm] from the root apex to the cortex of mandibular canal) | 1: Negative—apex with no contact with the cortex of the mandibular canal |
| 2: Positive—apex in contact with the cortex of the mandibular canal |
| Relation with the 2nd molar (relation of the 3rd molar crown with the 2nd molar) | 1: No contact |
| 2: Contact with the crown alone |
| 3: Contact with the crown and the root |
| 4: Contact with the root alone |
| Crown width (mesiodistal distance of the 3rd molar crown compared with the 2nd molar) | 1: Nonbulbous (equal to or less than that of the 2nd molar) |
| 2: Bulbous (greater than that of the 2nd molar) |
| Periodontal space (status of space between the root of the 3rd molar and the alveolar cortex) | 1: Radiolucent (fully radiolucent space) |
| 2: Mixed (radiolucent and radioopaque) |
| 3: Radioopaque (totally radiopaque space) |
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