Mineralization of Tooth Structure

Question 1

Describe function of amelogenins

Answer 1

Regulates HA crystal growth

• Mostly removed during maturation
• Acts as springs and allow rods to move up and down
• Reduces enamel brittleness (Bleaching destroys these proteins)

Question 2

Describe function of Fluoride replacing OH- with F-

Answer 2

• Fluoride is smaller and more symmetrical (better packing and bonding)
• Crystal structure is stabilized
• Fluorinated HA crystals have fewer defects and are more resistant
• Too much fluorine causes teeth become brittle

Question 3

In mature enamel, most of the matrix proteins are removed during maturation (amelogenins and fluoride replacing OH-)

Answer 3

True

Question 4

Describe mineralization of dentine

Answer 4

Odontoblasts secrete pre-dentine, which is later mineralized
- Pre-dentine = Unmineralized protein template for dentine

Dentine is 70% mineralized structure and 30% organic structures:
- in mature dentine, most matrix proteins remain

Question 5

Describe sclerotic dentine:

Answer 5

• When infection is sensed by odontoblast, the process retracts
• Sclerotic dentine is formed UNDER the carious lesion
• Contains more abnormal ions (e.g. Mg)

Question 6

Describe reactionary dentine:

Answer 6

• Odontoblasts increase the production of dentine
• Reactionary dentine is found in the pulpal space of dentine
• Has less rods than normal dentine
• Predentine usually looks irregular in these areas

Question 7

Describe the functions of salivary glands

Answer 7

1. maintain the calcium/phosphate concentration of slaiva
   - ensures that saliva is supersaturated for hydroxyapatite formation
2. Buffer the pH of oral cavity
   - Oral cavity pH needs to promote hydroxyapatite formation
   - Bicarbonate based
3. Anti-microbial activity
   - Ensure healthy flora populate the oral cavity

Question 8

Describe Major salivary glands

Answer 8

• Parotid, submandibular and sublingual

- Active only during mastication

Question 9

Describe minor salivary glands

Answer 9

• Located inside oral cavity
• Active at all-times but produce a relatively low amount of saliva
• Important for saliva production during speaking

Question 10

Describe saliva production and its functions and physiology in body

Answer 10

Saliva generated by salivary acini are different from the end-secreted saliva. Initial saliva has no buffering capacity.

Along the collecting ducts, the Cl- moleucles are substituted for bicarbonate ions (thus gains buffering ability). The buffering capacity is directly related to the velocity of the saliva in the salivary ducts. In the major salivary glands (stimulated salivary glands), the fluid flow is very fast so low buffering capacity per volume. The minor salivary glands have greater buffer capacity per volume (not overall) and are important to buffering the oral cavity during time between eating.