Caries Causation Flashcards
Primary causal factor of dental caries?
Plaque
Plaque biofilm is the necessary and sufficient cause of dental caries.
False, it is not sufficient to cause dental caries but it is necessary.
Dental caries is a non-communicable __________ disease.
Bacteria-related
The responsible bacteria, and other micro-organisms, are located in a biofilm - ___________ - which adheres to tooth surfaces.
Dental plaque
When plaque bacteria are exposed to refined carbohydrates, especially ______, in the human diet, sucrose is ____________ by particular bacterial species.
Sucrose; fermented to acid
The acid is ______ against the tooth surface by the plaque biofilm and _____ through the enamel layer into dentine resulting in dissolution of the tooth mineral.
Trapped; diffuses
The Stephan curve describes ________ in plaque following exposure to sucrose or glucose.
pH changes
Describe the pH levels after exposure to glucose.
Plaque pH falls quickly following exposure to glucose and will rise back to its original value after 20 minutes or so, unless exposure continues.
What happens to enamel in sustained pH fall?
Enamel decalcification occurs.
What happens when pH returns to around 6?
Enamel calcification occurs; the decalcified enamel remineralises
What is this?
Stephan curve
Describe this graph/result
Duplicate curves of pH changes in plaque as measured by a microelectrode built into an extracted tooth on 2 days showing that the curves are reasonably reproducible.
Describe this curve
Effect of plaque pH of the local application of drops of 0.5% sugar solutions at 2-min intervals - note the marked response to low concentrations of sugar and the prolonged fall.
The sugar did not reach the tongue so that saliva flow was not stimulated - this result may, therefore, differ from the changes during normal eating when saliva flow is stimulated and the saliva probably reaches the plaque, but may resemble the changes in plaque when saliva cannot easily reach it as in fissures and inaccessible contact points.
Describe this figure
Effect of sugar rinse on the pH of plaque of different ages measured by microelectrodes built into an extracted tooth.
With the older plaques, the pH fall begins during the sugar rinse, reaches lower pH values and returns more slowly than with the 1-day-old plaque.
Mature 5-day plaque has the greater cariogenic potential. The pH dropped immediately rinsing commenced and remain depressed.
Which sites do carious lesions occur at?
Occurs at sites where mature plaque remains undisturbed - in fissure pits, between teeth on approximal surfaces, and along gingival margins.
Organic acids (the sucrose fermentation products) dissolve dental mineral in enamel (and at a later stage in dentine) known as _____, which is crystalline __________.
Apatite; calcium phosphate
When fermentation is complete following a _____ sucrose exposure ____________________________, saliva neutralises the acid and remineralisation occurs - salivary calcium and phosphate precipitate back into the enamel. There is no _____ of mineral.
Brief; and in the absence of another exposure; no net loss of mineral
Multiple cycles of _______ and ________ occur throughout the day associated with exposures to sucrose.
Demineralisation; remineralisation;
The process of demineralisation and remineralisation is considered physiological and normal if?
If there is no net loss of tooth mineral
When sucrose exposure is sustained ___________, the balance between demineralisation and remineralisation is tipped in favour of demineralisation with consequent net loss of mineral.
During which acid conditions persist
When sustained acid conditions persists, macroscopic signs of enamel demineralisation (_______) emerge and indicate the disease of dental caries has initiated.
White spot lesions
White spot lesion is not the disease - it is merely a?
Merely a manifestation of the disease
How to identify white spot or a cavity?
Caries lesion
When can we claim that caries is in remission?
Only when all white spot lesions have arrested and when the incidence of new lesions is zero.
Explain this model
Mouth is represented by the pink circle. The black circle represents the environment.
Risk of caries depends on what is shoveled into the mouth and how individuals manage their plaque control. Importantly, what individuals do depends mainly on their social circumstances and peer group pressure.
This helps to explain the wide variation in caries experience (DMFS) across individuals and social groups.
Epidemiological studies show that tooth loss due to dental caries far outweighs tooth loss due to periodontal disease.
True
Withdrawal of all measures of oral hygiene in 12 healthy persons with clinically normal gingivae resulted in?
Gross accumulations of soft debris and the development of marginal gingivitis in all subjects.
The time necessary to develop gingivitis varied from?
10 to 21 days
This is an example of?
Clean teeth
Describe this electron micrograph
Shows a scratch on a recently cleaned enamel surface - note bacterial colonies at the base of the scratch withstood the cleaning process
What’s happening in this EM?
Bacterial colonies at the base of the scratch quickly multiplied and spilled out over the previously clean surface.
Describe this electron micrograph
Other species adhere in succession - cocci are not the original colonisers
Describe this electron micrograph
Cocci became sandwitched between the next layer
Describe this image
Thick plaque covering the maxillary central incisors has been present for weeks.
List the plaque index
Score 0 Clean surface - no visible plaque
Score 1 - no visible plaque but it can be wiped off the tooth surface with a periodontal probe
Score 2 Visible plaque - will appear after 24 hours following careful toothbrushing
Score 3 Thick visible plaque has been present for days or weeks
Describe the calculation of the Plaque Index (PII)
Each tooth is scored on the 0-3 scale. The PII is the mean of the tooth scores.
This index score, by itself, is not very useful - it is difficult to interpret, for example, a score of 0.5??
It is more meaningful to report the percentage of teeth or tooth surfaces scored 0, 1, 2, or 3.
Similarly for the Gingival Index (GI)
Describe this image
There is no sign of inflammation along the gingival margins of 11 and 21. Gingival Index Code 0
Describe this image
Marginal inflammation on 11 and 21. Gingival Index Code 1 or 2??
Describe this image
The gingiva bleeds on gentle probing, therefore Code 2
Describe this image
The teeth in the previous slide have been brushed, but the gingivitis remains. Dentists/hygienists know if teeth have been just cleaned prior to a dental visit
Describe this image
gingival Index Code 3 - the gingiva bleed spontaneously when inspected with sharp eyes.
Concurrent bacteriological examinations showed what in the Lo
