Dental Anatomy and Morphology
What this domain tests
The Dental Anatomy and Morphology domain checks whether you can name, orient and reproduce tooth form - numbering systems, crown and root contours, contact areas, embrasures and pulp anatomy - and apply it when carving or waxing a restoration for a bench practical.
Core rules
- Three systems appear: Universal (1–32), FDI two-digit (quadrant + tooth, quadrants 1–4 running clockwise from the upper right) and Palmer. Practise converting in both directions; Universal begins at the maxillary right third molar.
- Permanent dentition: 32 teeth. Primary: 20, lettered A–J in Universal. Primary crowns are more bulbous with marked cervical constriction, and primary molars are wider buccolingually.
- On anterior teeth the mesial contact sits closer to the incisal edge than the distal contact; posterior contacts sit near the marginal ridge, with buccal embrasures wider than lingual ones in the mandible.
- Maxillary first molar: rhomboid occlusal outline, four cusps plus the cusp of Carabelli, an oblique ridge from the distolingual to the mesiolingual cusp, and three roots. The second molar is smaller, usually lacks Carabelli, and has more convergent roots.
- Mandibular first molar has five cusps, the second has four; the mandibular first molar is the widest posterior tooth.
Worked example
You are given a cast and asked to wax tooth 16. Check the quadrant: FDI 1 = maxillary right. If the occlusal outline is rhomboid and a fifth cusp sits on the lingual of the mesiolingual cusp, it is a first molar, not a second. Build the mesiolingual cusp tallest, then the distobuccal, and complete the oblique ridge before any fossa detail.
Traps that cost marks
- Mixing Universal and FDI numbers in one answer.
- Reversing mesial and distal because the cast was not oriented to the midline first.
- Confusing the oblique ridge with a marginal ridge.
- Waxing four cusps onto a mandibular first molar.