Pg 109 - 116 Flashcards
- Write the chemical formula of hydroxyapatite
Ca10 (PO4)6 (OH)2
or
Ca5 (PO4)3 OH
- Explain how ion substitutions affect hydroxyapatite tooth structure
In the crystal lattice, other ions can substitute for the various inorganic ions. The presence of sub ions can either increase or decrease susceptibility to chemical attack depending upon the particular substitution.
More substition = more flex, which makes them more sensitive to acid.
- Define the critical pH of enamel
The pH below which dissolution predominates in the oral cavity, which is about 5.5
- Explain the two reasons as to why caries usually appear in certain sites on the teeth.
These sites are generally:
- Favorable for plaque retention (hard to “mow the lawn”)
- Limited access for saliva
- What are examples of caries-susceptible sites?
- Pits and fissures (“O” of molars and premolars, “B” of molars, and “P” of max incisors)
- Approximal surfaces of adjacent teeth just cervical to the contact point
- Cervical margin just coronal to the gingival margin
- Exposed root surfaces (if gingival recession)
- Margins of deficient restorations
- Tooth surfaces adjacent to dentures and bridge
- Discuss the role that plaque biofilm plays in caries development
Creates a suitable environment for acid-producing, bacterial metabolism, and diminishes the saliva protection mechanisms.
- Give the sequence of events in plaque development beginning from a perfectly clean tooth surface
Salivary proteins -> Pelicle -> Plaque biofilm -> Calculus/Caries
- Pelicle (acquired)
- Spontaneous formation?
- Bacteria necessary for formation?
- Easy to remove?
- If removed, how quickly does it reform?
- It forms a suitable environment for what bacteria?
- Forms spontaneously on teeth
- Bacteria not necessary for formation
- Hard to remove - requires meticulous cleaning
- If removed, forms within minutes to a few hours
- Forms suitable environment for bacterial pioneer species adherence and multiplication
- What is a pelicle?
An acellular, homogenous, organic film that forms on enamel and other hard surfaces by selective adsorption of salivary proteins and glycoproteins
- What are examples of ion substitutions for hydroxyapatite?
Ca10 (PO4)6 (OH)2
For calcium: Lead, Strontium, Radium, etc
For phosphate: Carbonate, etc
For hydroxyl: Fluoride, etc
- Write the chemical equation for hydroxyapatite being dissolved by acid
Ca10 (PO4)3 (OH)2 + 14 H –> 10 Ca + 6(H2PO4) + 2 H2O
Shift right: Dissolution
Shift left: Remineralization
- The formation of carious lesions depends on a combo of what four factors?
- Microorganisms (bacteria to form sugars)
- Metabolic substrates (quantity/quality of sugars)
- Teeth and their environment (quality of teeth, saliva, and immunity)
- Time (duration and frequency of sugar consumption)
- Reproduce the simple figure that explains the relationship between dietary carbs, saliva, and plaque biofilm
(Diet -> Saliva -> Plaque -> Enamel)
DIET of starches (glucose, frutcose), lactose, and sucrose leads to…
SALIVA with starches, glucose, fructose, lactose, and sucrose, which leads to…
PLAQUE accumulation, which leads to acid and extracellular polymers (Glucans and Fructans) and decreases saliva effectiveness (buffering and washing), which leads to…
ENAMEL developing a caries lesion due to too much acid accumulation.
