Dentine Histology Flashcards
What is primary dentine?
Primary aka developmental dentin is that which formed during tooth development, before the teeth erupt.
It is the most prominent type in the tooth.
It is divided into mantle and circumpulpal dentin.
Mantle dentin is the first formed dentin and is situated immediately subjacent to the enamel and cementum.
Circumpulpal dentin is formed after the layer of mantle dentin, and constitutes the major part of developmental dentin.
What is pre-dentine?
Predentine is an unmineralised calcified matrix that is formed between odontoblastic layer and mineralised dentine
Pre-dentin becomes mineralised by deposition of calcium and phosphorous into the matrix
What is secondary dentine?
Formed w age - Develops after formation of the apical foramen aka root formation.
Almost absent in children - hence cavity preps shallow relativer to crown size.
In multi-rooted teeth, secondary dentine is thicker on the roof and floor of pulp chamber.
What is the difference between secondary and primary dentine?
Deposition is continuous with primary however secondary is slower, fewer tubules, tubules change direction to a more wavy course.
What is tertiary dentine?
Forms at a localised area in reaction to a stimulus
Dentinal tubules less in number and irregular arrangement
There are 2 types of tertiary dentine:
Reparative dentine
- Stimulus destroys original odontoblasts
- Newly differentiated odontoblasts replace them
- They lay down atubular dentine
Reactionary dentine
- If odontoblasts survive the provoking stimuli then it is known as reactive dentiner
- very irregular arrangement
What are lines of von ebner?
Fine lines (A) run almost perpendicular to the dentinal tubules from top to bottom on the screen. Note that these lines occur at regular increments. These are the incremental lines of von Ebner. They lie 4 microns apart.
The lines of von Ebner represent cyclic activity of the odontoblasts during dentin formation
What are adrensen lines?
Similar to lines of von ebner, however instead of showing diurnal growth it shows weekly growth.
What are contour lines of owen?
Caused by variation in organic content in tubules
Intercept the enamel striae of retzius at the ADJ
What is the primary and secondary curve in dentine histology?
Primary curve - big S ADJ to Pulp
Secondary curve - small wiggles in the big S (zoomed in)
