Overview
This lecture introduces foundational dental anatomy vocabulary, focusing on tooth numbering, surfaces, tooth division into thirds, contact points, embrasures, and heights of contour for effective tooth description.
Tooth Numbering & Quadrants
- Adult permanent dentition includes 32 teeth (16 maxillary, 16 mandibular).
- Teeth are grouped into four quadrants, each with 8 teeth.
- Universal numbering system: teeth numbered 1–16 (upper right to upper left), 17–32 (lower left to lower right).
- Memorize quadrant boundary teeth: 1, 8, 9, 16 (maxilla); 17, 24, 25, 32 (mandible).
- Canine teeth are numbers 6, 11, 22, 27.
Tooth Surfaces
- Mesial: surface closest to the midline.
- Distal: surface farthest from the midline.
- Buccal: cheek-facing surface of posterior teeth.
- Facial: lip-facing surface of anterior teeth.
- Lingual: tongue-facing surface (mandibular teeth).
- Palatal: palate-facing surface (maxillary teeth).
- Occlusal: biting surface of posterior teeth.
- Incisal: biting edge of anterior teeth.
Division of Teeth Into Thirds
- Crown and roots are divided into thirds for descriptive accuracy.
- Root thirds: apical (apex), middle, cervical (closest to crown-root junction).
- Crown thirds: cervical (closest to junction), middle, occlusal/incisal (biting edge/surface).
- Teeth can be divided mesiodistally and buccolingually for precise location referencing.
Contact Points
- Contact points are areas where adjacent teeth touch.
- Can be described using incisal/gingival (vertical) and buccolingual/faciolingual (horizontal) axes.
- Distal contact is always at the same or more gingival level than the mesial contact for anterior teeth.
- All teeth have buccolingual/faciolingual contact points in the middle third.
- Exception: mesial contact of all molars is at the junction of the occlusal and middle thirds.
Embrasures
- Embrasure: V-shaped space around contact points between adjacent teeth.
- Types: incisal/occlusal, cervical/gingival, facial/buccal, lingual.
- Embrasures allow food escape during chewing and help self-cleanse teeth.
- Facial embrasures are thinner than lingual, except mandibular centrals (equal) and maxillary first molar (facial > lingual).
Heights of Contour
- Height of contour: greatest bulge on a tooth surface.
- Facial/buccal height of contour is in cervical third for all teeth except mandibular molars (junction of cervical and middle thirds).
- Lingual height of contour: cervical third for anterior teeth, middle third for posterior teeth except mandibular second premolar (occlusal third).
Key Terms & Definitions
- Quadrant — one-fourth of the mouth containing 8 teeth.
- Universal Numbering System — method to number all teeth uniquely from 1–32.
- Mesial — surface of a tooth nearest the midline.
- Distal — surface farthest from the midline.
- Buccal — cheek-facing side of posterior teeth.
- Lingual — tongue-facing side (mandible).
- Palatal — palate-facing side (maxilla).
- Occlusal — chewing surface of posterior teeth.
- Incisal — cutting edge of anterior teeth.
- Cervical Third — area nearest the crown-root junction.
- Contact Point — area where adjacent teeth touch.
- Embrasure — V-shaped space around contact area.
- Height of Contour — greatest bulge on a tooth surface.
Action Items / Next Steps
- Review key tooth numbering landmarks and practice identifying them.
- Study diagrams/models for tooth surfaces and divisions into thirds.
- Prepare for individual tooth descriptions in the next lecture.