DENTINE
 The dental structure that is similar to bone
 65% inorganic 35% organic by volume
 45% inorganic 55% organic by weight

PRIMARY
 Mantle dentine- 1st formed dentine*
 Physiologic dentine occurring before root completion

CIRCUMPULPAL DENTINE
Represents most of the dentine formed.

SECONDARY
1. Physiologic dentine formed after root completion-naturally formed.
2. Gradually formed throughout life time.
3. Formation starts after root formation
4. Increases with age.

TERTIARY
1. Other names: REACTIONARY / REPARATIVE / SCLEROTIC DENTINE
2. Formed as pathologic response to irritation / trauma
3. Eg: DPC, IPC,TFO, Bruxism, Attrition, Erosion, Caries