Oral and Maxillofacial Anatomy, Histology, and Physiology
What the exam tests
This domain checks whether you can locate structures precisely, connect microanatomy to clinical behaviour, and predict which nerve, vessel or gland is at risk in a given procedure.
Core rules
- FDI two-digit notation: the first digit is the quadrant (1 upper right, 2 upper left, 3 lower left, 4 lower right); the second is the tooth 1-8 from the midline. Tooth 38 is the lower-left third molar.
- Enamel is about 96% mineral by weight and built of rods; dentin is about 70% mineral with peritubular and intertubular components; cementum is thinnest at the cementoenamel junction and thickest apically.
- The pulp is a low-compliance space. Inflammation raises tissue pressure, collapses venous drainage and causes ischaemic pain that no antibiotic can relieve.
- Masseter, temporalis and medial pterygoid elevate the mandible; the lateral pterygoid depresses and protrudes it. Only the lateral pterygoid opens the jaw.
- The lingual nerve lies immediately beneath the mucosa, against the lingual plate in the third molar region; the inferior alveolar nerve enters the mandibular foramen on the medial ramus, above the lingual spine.
- Stensen's duct opens opposite the maxillary second molar; Wharton's duct opens at the sublingual caruncle.
Worked example
A 24-year-old reports numbness of the tongue one day after surgical removal of 38. Reasoning: the lingual nerve is unprotected by bone there, so a lingual flap retracted with a periosteal elevator, or a lingual split, can stretch or divide it. Document sensory mapping, review at 1, 4 and 12 weeks, and reassure: most stretch injuries recover, while a complete transection is a different, referral-level problem.
Traps that cost marks
- Naming the medial pterygoid as an opener, or forgetting that the temporalis also retrudes.
- Confusing the parotid and submandibular duct openings.
- Mixing FDI and Universal numbers; the exam usually offers both as distractors.