General and Oral Anatomy, Histology, and Physiology
Scope
This domain tests the microstructure and composition of dental hard and soft tissues, the eruption timetable and tooth-numbering systems, and the physiology of saliva, mineralisation and pulpal sensation - the foundation for every clinical domain that follows.
Dental hard tissues
- Enamel: about 96% mineral by weight, organised into rods (prisms) of hydroxyapatite; aprismatic at the DEJ and outer surface; ameloblasts are lost at eruption, so enamel cannot regenerate - only remineralise.
- Dentin: about 70% mineral, 20% organic (type I collagen), 10% water; tubules converge pulpally, so tubule density is highest near the pulp.
- Cementum: acellular extrinsic-fibre cementum provides attachment; cellular cementum adapts to function.
Physiology
- Resting salivary flow is roughly 0.3–0.4 mL/min and rises several-fold on stimulation; parotid is serous (amylase), submandibular mixed, sublingual mucous.
- A-delta fibres carry fast, sharp dentinal pain; C fibres carry slow, dull pulpal pain.
Numbering
- FDI uses two digits: quadrant (1–4, maxillary right to mandibular right) then tooth position (1–8 from the midline).
- Universal uses 1–32, beginning at the maxillary right third molar.
Worked example
A chart records the mandibular right first molar. FDI = 46: quadrant 4 is the mandibular right, position 6 is the first molar. Universal = 30: teeth 17–32 run mandibular right to left, so 32 is the third molar, 31 the second and 30 the first.
Traps
- Confusing peritubular dentin (highly mineralised, lining the tubule) with intertubular dentin.
- Assuming enamel repairs itself - it only remineralises.
- Mixing FDI quadrant order with the Universal counting direction.