Surfaces of Teeth and Directions in Relation to Oral Cavity
- Axial: A plane parallel to the surface of a tooth.
- Buccal: The side of a tooth adjacent to the inside of the cheek.
- Cervical: The narrowing of the contours of the tooth surface at or near the CEJ.
- Coronal: The direction toward the crown of a tooth.
- Distal: The direction toward the gingiva beyond the most posterior tooth in each quadrant.
- Lingual: The side of a tooth adjacent to the tongue.
- Labial: The side of a tooth adjacent to the inside of the lip.
- Palatal: The side of a tooth adjacent to the palate.
- Vestibular: The side of a tooth adjacent to the inside of the cheek or lips.

Directions in Relation to Midline and Specific Terms for Teeth
- Mesial: The direction toward the anterior midline in a dental arch.
- Distal: The direction toward the gingiva beyond the most posterior tooth in each quadrant.
- Midline: An imaginary vertical line dividing the left and right sides of the mouth at the teeth.
- Superior: The direction toward the head.
- Inferior: The direction toward the feet.
- Incisal: The direction toward the biting surface of anterior teeth.
- Occlusal: The direction toward the biting surface of posterior teeth.
- Proximal: The surfaces of teeth that normally lie adjacent to another tooth.
- Marginal: The edge of tooth structure that is prepared to meet the edge of a prosthetic crown.
- Lateral: A tooth which is away from the midline.

Dental Quadrants and Sextants
- Upper right quadrant: Upper right first incisor to upper right wisdom tooth.
- Upper left quadrant: Upper left first incisor to upper left wisdom tooth.
- Lower right quadrant: Lower right first incisor to lower right wisdom tooth.
- Lower left quadrant: Lower left first incisor to lower left wisdom tooth.
- Sextant: One of six groups of adjacent teeth.

Combining of Terms
- Combining forms can be used to create terms for directions and axes in dentistry.
- Examples of combining forms include 'mesio-' for 'mesial' and 'disto-' for 'distal'.
- The coronoapical axis is the long axis of a tooth.
- Combining forms can be combined to create terms such as 'apicocoronal' (AC) and 'buccoapical' (BA).
- Abbreviations for combined terms should only be used in specific contexts and when explicitly defined.

Abbreviations and Ambiguity
- The abbreviations for combined terms in dentistry are often ambiguous and not specific to these terms.
- Some abbreviations are not even one-to-one specific within the list of combined terms.
- Spelling out the combined terms is generally recommended.
- Abbreviations should be used sparingly and only in restricted contexts.
- The abbreviations can help avoid extensive repetition, especially in academic articles.

Note: The references have been excluded from the groups as they are not directly related to the content organization.