Etiology of dental caries
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Etiology of Dental Caries. Dr.Rai Tariq Masood. Early Theories. Worm Theory Humour Theory Parasitic Theory Vital Theory Chemical Theory Chemo-parasitic Theory Proteolytic Theory Proteolysis- Chelation Theory. Current Concepts of Caries Etiology. Keyes Circles

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Etiology of Dental Caries

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Etiology of dental caries

Etiology of Dental Caries

Dr.Rai Tariq Masood


Early theories

Early Theories

  • Worm Theory

  • Humour Theory

  • Parasitic Theory

  • Vital Theory

  • Chemical Theory

  • Chemo-parasitic Theory

  • Proteolytic Theory

  • Proteolysis-Chelation Theory


Current concepts of caries etiology

Current Concepts of Caries Etiology

Keyes Circles

  • Caries is multi-factorial disease comprising of four factors

  • Susceptible Tooth Surface

  • Micro-organism

  • Diet (Sucrose)

  • Appropriate time

    Each one of them is of equal importance in aetiology of caries


Classification based on morphology

Classification Based on Morphology

  • Occlusal Caries ( Pit & Fissure Caries)

  • Smooth Surface Caries

    Buccal & Lingual Caries

    Proximal Caries


Classification based on severity progression

Classification Based on Severity & Progression

  • Rampant Caries

  • Early Childhood Caries ( Baby Bottle Tooth Decay)

  • Radiation Caries


Classification based on part of tooth involved

Classification Based on Part of Tooth Involved

  • Enamel Caries

  • Dentinal Caries

  • Cemental Caries


Classification based on activity

Classification Based on Activity

  • Primary Caries

  • Secondary Caries

  • Residual Caries

  • Arrested Caries


Clinical manifestations of caries process

Clinical Manifestations of Caries Process

1-Early Changes

  • First time demineralization of enamel when PH falls below 5.2 – 5.5

  • Demineralization can not be detected clinically


2 white spot lesion

2- White Spot Lesion

  • First visible clinical presentation

  • Caused by sub-surface enamel demineralization

  • Surface is intact

  • It may or may not progress to frank cavitation


3 hidden or occult caries

3- Hidden or Occult Caries

  • Calcium and Phosphate moves from subsurface to the surface.

  • Calcium and Phosphate along with fluoride from saliva precipitate on effected surface enamel.

  • It will occlude the pores that limits demineralization of surface enamel.

  • Hence intact surface enamel and caries in subsurface level.

  • Not clinically visible.


4 frank cavitation

4- Frank Cavitation

  • Sub-surface carious lesion increases in dimensions.

  • Collapse of surface layer

  • Cavitation

  • More plaque accumulation so rapid tooth destruction.

  • It takes 18 (+- 6 months) to progress from white lesion to cavitation.


5 arrested caries

5- Arrested Caries

  • Carious lesion can become arrested at any stage.

  • If the causal factors are changed or protective factors are increased.

  • Example :Proximal Carious lesion and if adjacent tooth is lost then it becomes self cleansing.


Micro biology of dental caries

Micro-Biology of Dental Caries

Streptococcus Mutans

  • Ability to stick to tooth surfaces

  • Ability to produce lactic acid

  • Resist the acidogenic environment

  • Produce intracellular polysaccharide

    Streptococcus Sobrinus

    Lactobacillus


Formation o f plaque

Formation of Plaque

  • Adherence of bacteria to pellicle or enamel surface.

  • Adhesion between bacteria by polysaccharide chains

  • Subsequent growth of bacteria


Risk factors protective factors

Risk Factors/Protective Factors

  • Total oral Bacterial population

  • Tooth Morphology

  • Salivary secretion rate

  • Intake of carbohydrates

  • Oral Hygiene Habits

  • Use of Fluorides


Role of saliva in caries

Role of Saliva in Caries

  • Also called Liquid Enamel because of high mineral content

  • Cleansing Action

  • Buffering Capacity

  • Antibacterial Action by Lysozyme,Lactoperoxidase,hemoprotein enzyme (Prevents bacterial colonization)

  • Saturated with Calcium and Phosphate

  • Most prominent antibody in saliva IGA.

  • Proteins like statherin protects hydroxyapetitecrystals.


Etiology of dental caries

  • Flow rate: Role of saliva, with respect to caries, is in the removal of bacterial and debris. Average un-stimulated flow rate is 0.3 ml/minute and amount prior to swallowing 0.9-1.2 ml

  • Quantity: Normal is 700-800 ml/day. Less leads to rampant caries as seen in Xerostomia.

  • Viscosity: Thick saliva associated with high caries but not confirmed.

  • pH: Depends on bicarbonate content.Saliva may be slightly acidic as it is secreted at unstimulated flow rates but may reach PH of 7.8 at high flow rates.


Buffering action

Buffering Action

  • Bicarbonates are most important buffers

  • It reacts with acid and release weak carbonic acid.

  • Carbonic acid is rapidly decomposed into water and carbon dioxide.

  • So acid is completely removed.

  • When there is excess sucrose intake,intense acid production will breakdown the buffers.


Etiology of dental caries

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