Dentin and pulp

Why this matters

Every restoration you will ever place sits on dentine, and every one of them is a conversation with a living cell you cannot see. Dentine is not an inert substrate: it is 45 percent mineral by volume, nearly a quarter water, and drilled through by tubules that carry fluid and, near the pulp, nerve endings. Whether a tooth hurts, whether an adhesive holds, whether a deep cavity heals or dies, and whether a canal can be disinfected are all decided by the numbers in this lesson.

The big picture

One post-mitotic cell builds a tubular tissue, retreats into a rigid box behind it, and spends the rest of its life defending that box by filling the tubes back in. Dentinogenesis, sensitivity, tertiary dentine and every ageing change in this lesson are the same story told at different stages of that retreat.

The 15 cards in this lesson

1. 01One cell, induced once, that never divides again
2. 02Predentine appears the moment dentine starts; the cell-free zone appears only when secretion slows
3. 03Mantle and circumpulpal dentine mineralise by two different mechanisms
4. 04Von Korff fibres: a fifty-year argument about a term nobody defined
5. 05Dentine is not laid down at 20-30 micrometres a day
6. 06Tubule DENSITY is agreed across studies; tubule DIAMETER is not agreed at all
7. 07'1% of dentine at the junction, 22% at the pulp' is arithmetic, not a measurement
8. 08A tubule is not a hole in uniform dentine — it wears a hypermineralised collar
9. 09Tubules branch MOST where they are narrowest, and the S-curve is a permanent-tooth feature
10. 10Primary, secondary, tertiary — and the one question that separates reactionary from reparative
11. 11Clinical alert — in the lesson
12. 12In four whole human pulps imaged in 3D, vessels and nerves were each reported as four-tenths of the pulp volume
13. 13Dentine sensitivity: the hydrodynamic theory leads, but it has not won
14. 14Sclerotic dentine and dead tracts are opposites, and light tells them apart
15. 15The pulp chamber shrinks all your life, and the shrinkage is measurable enough to estimate age

You have got it when

You can: (1) say why reactionary versus reparative is a statement about cell survival, not texture; (2) give the measured predentine thicknesses with their sites; (3) state which tubule quantity the human studies agree on and which they do not; (4) show in one line that '20 to 30 micrometres per day' is five to seven and a half times too large; (5) name the four pulp zones and the three theories of dentine…