Enamel

Question 1

Characteristics caused by enamel rods

Answer 1

Incremental lines

 - long parallel rods = cross strait ions 
 - consequence of daily growth
 - adj to surface directly 

Brown transverse striae (brown striae of retzius)

 - consequence of weekly formed enamel
 - darker lines from ash to surface but much less direct 
 - link to perikymata 

Neonatal line

 - major growth band
 - looks like grace travelling long ways through enamel

Question 2

Describe the orientation of enamel rods

Answer 2

• run in an S shape (adj to surface)

- adjacent groups run in opposite S shape (causes Hunter-schreger bands)

Question 3

What is gnarled enamel

Answer 3

At cusps rods so concentrated look intertwined

Question 4

Features of ADJ enamel

Answer 4

Enamel tufts
- hypomineralised regions as residual matrix protein

Enamel lamella

 - groups of prisms not matured (fault line through whole thickness) 
 - looks like neonatal lone but runs with flow of prisms 

Enamel spindles
- where can see odontoblast processes extending into enamel

Question 5

What is scalloping of the enamel

Answer 5

At ADJ enamel not flat against dentine, for increased SA is bumped

Question 6

When does primary dentine end and secondary dentine start

Answer 6

Ends when tubules start to change direction (close to the pulp) - while tooth forming, where secondary begins to form after tooth formed

Question 7

types of tooth surface loss (4)

Answer 7

1. acid reflux
2. attrition (bruxism)
3. abrasion (tooth weakened cervically, paired with abrasion of toothbrush)
4. abfractions (stress lesions) - wedge shaped notch away from occlusion, where enamel and cementum meet and are weak, so strong occlusion can cause this.