What are Amelogenins?
Hydrophobic proteins rich in proline, histidine and glutamine. Represent the main protein present in forming enamel; expression stops when enamel reaches full thickness.
What are Ameloblastins?
Protein present in much smaller amounts compared with amelogenin; it is found mostly in newly formed (secretory stage) enamel and more so at the outer surface than in deeper areas closest to the DEJ.
What are Enamelins?
Protein is the largest of the enamel proteins and the least abundant of the enamel matrix proteins; is present only at the growing enamel surface
Name the 3 main enamel proteins and their respective percentages of enamel makeup
**(Ameloblastin and Enamelin = 10% of remaining protein)
T or F, Enamel is highly mineralized structure containing approximately 5% inorganic matter
False, Approximately 95% inorganic matter
T or F, Enamel is hihgly semipermeable. This property of enamel allows fluoride ions to be absorbed on the hydroxyapatite crystals
Which has a higher lower solubility product constant? Fluorapatite or Hydroxyapatite?
This makes the tooth more resistant to bacteria-producing acids
T or F, Enamel is softer than bone
What is enamel hypoplasia?
A general term referring to all quantitative defects of enamel thickness. They range from single or multiple pits to small furrows and wide troughs to entirely missing enamel.
*Occurs as a defect in the formation of the enamel matrix
What is the general term used to describe a defect in the mineralization of the formed enamel matrix?
Tooth erosion in bulimic patients is due to what?
Solubility of hydroxyapatite in acid
T or F, Enamel hypoplasia is strongly associated with amelogenesis imperfecta
What is the key enzyme produced by S. mutans to demineralize the tooth surface leading to dental caries?
Glucosyltranferase (dextran sucrase)
Describe the type of secretion that each of the following glands produce:
Parotid gland: Mainly Serous secretion
Sublingual gland: Mainly Mucous secretion
Submandibular gland: Mainly a Mixed secretion
Which of the two types of glandular secretions contain the enzyme salivary amylase? What does salivary amylase do?
- Splits starch into alpha-dextrin, maltotriose and maltose
The primary physiological control of the salivary glands is by what nervous system?
**However, both the sympathetic and parasympathetic subdivisons of the autonomic nervous system can stimulate salivary secretion
What are the 4 important properties of saliva?
1. Large flow rate relative to the mass of gland
2. Low osmolarity
3. High K+ concentration
4. Organic constitutents - including enzymes, mucins and growth factors
T or F, The inorganic composition is entirely dependent on the sitmulus and the rate of salivary flow
A maximum salivary flow rate of less than what is associated with high caries risk?