Dental Caries: History, theories, and definitions Flashcards
What are the exogenous theories of dental caries?
Worm theory
Chemical (acid) theory
Parasitic (septic) theory
What are the endogenous theories of dental caries?
Humoral theory
Vital theory
What are the non-exogenous AND non-endogenous theories of dental caries?
The acidogenic theory
The proteolytic theory
Proteolysis Chelation theory
Sucrose Chelation theory
What are the current concepts of caries aetiology?
Demineralisation and remineralisation
What is the worm theory of dental caries?
Dental caries are the result of a “worm that drunk blood of the teeth and fed
on the roots of the jaws”
What is the chemical theory of tooth destruction?
During the 17th and 18th centuries the theory was that teeth were destroyed by acids formed in the oral cavity.
In this theory it was believed that putrefaction of protein led to formation of ammonia which was subsequently oxidised to nitric acid. In other words, fermentation was considered a non-vital process.
What is the humoral theory of tooth destruction?
A persons physical and mental constitution was determined by the relative
proportions of the four elemental fluids of the body which correspond to the four humors,
What is the proteolytic theory of tooth decay?
Caries-like lesions are initiated by proteolytic activity at a slightly alkaline pH and considered that the process involved depolymerisation and liquefaction of the organic matrix of enamel.
Microorganisms invade the organic pathways (lamellae) of enamel and
initiate caries by proteolytic action. Subsequently the organic salts are
dissolved by acidogenic bacteria
What is the acidogenic theory of tooth decay?
Dental decay is a chemo-parasitic process consisting of two stages:
- i) Decalcification (preliminary step)
- ii) Dissolution(subsequent step)
What did the acidogenic theory of tooth decay show?
Showed that the degradation of carbohydrate containing food resulted in acid formation and tooth tissue destruction
Demonstrated this process invitro, with isolated oral bacteria and extracted teeth
What were miller’s conclusions in the acidogenic theory of tooth decay?
Dental caries are caused by multiple species of oral bacteria
No specific bacteria was implicated
Traditional non-specific plaque hypothesis
Proper prevention is therefore needed to remove or minimise multiple bacterial species
What were the limitations of the acidogenic theory?
Unable to explain site-specificity (esp.smooth surface)
Does not determine specific bacterial aetiology
Does not explain why some populations are caries free
Cannot explain arrested caries
What is the specific plaque hypothesis?
In the 1970s, culture-based techniques and microscopy allowed discrimination of
specific bacterial species
It was noticed that the antibiotic kanamycin was particularly effective against cariogenic species such as oral streptococci and reduced caries formation
Removing cariogenic bacteria from the oral cavity using antibiotics could prevent caries
What are the limitations of the specific plaque hypothesis?
Use of kanamycin resulted in overall reduction of caries but at some surfaces the caries rate increased.
Cariogenic bacteria were not eliminated after treatment.
How was the specific plaque hypothesis updated?
To the non-specific plaque hypothesis. Specific pathogens from the SPH were indigenous bacteria and sometimes common bacteria in health.
During this time most researchers seemed to agree that gingivitis was a non-specific inflammatory reaction to a complex indigenous microbiota.
Some bacteria could be more virulent than others
What is the ecological plaque hypothesis?
Disease is the result of an imbalance in the total microflora due to ecological stress resulting in enrichment of some oral pathogens or disease related microorganisms.
This was extended by the NSPH to relate to the changes in microbial composition to changes in environment of the mouth such as presence of nutrients and essential cofactors, pH and redox potential.
What does keye’s triad tell us? How was this modified in the modified keyes triad?
Caries are the result of 3 things coming together; these things are dental plaque, diet, and the tooth surface.
The modified keye’s triad adds time as an influencing factor.
What is the caries balance a balance between?
Pathological factors such as acid producing bacteria, frequent eating/drinking of fermentable carbs, sub-normal saliva flow and function.
Protective factors: Saliva flow and components, fluoride (remineralisation), and antibacterials (Chlorhexidine, xylitol, etc)
What is the current definition of dental caries?
Dental caries is a continuum of disease states of increasing severity and tooth destruction that ranges from sub-clinical sub-surface changes at the molecular level to lesions with dentinal involvement, either with an intact surface or obvious cavitation.
What are the plaque hypotheses?
Traditional non-specific plaque hypothesis
Specific plaque hypothesis
Updated non-specific plaque hypothesis
Ecological plaque hypothesis
Keystone pathogen hypothesis
Where can dental caries appear?
Tooth
Surface
Sub and supragingivally
How can dental caries present in terms of status?
Demineralised
Arrested
Uncavitated
Cavitated
How far can caries extend?
Into enamel, dentine, pulp
What are the types of developmental defects that can affect teeth?
Fluorosis
Molar incisor hypomineralisation
Amelogenesis imperfecta
Dentinogenesis imperfecta
What is the difference between infected and affected dentine?
Affected dentine:
Does not contain micro-organisms
Can be remineralised
Accepted to preserve affected dentine during cavity preparation
Leathery and partially demineralised
Infected dentine:
Contains microorganisms
Cannot be remineralised (Irreversibly damaged)
Should be removed during cavity preparation
Soft, demineralised, easy to remove with an excavator
