Caries activity tests

  1. Lactobacillus Count Test
    1. It was introduced by Hadley in 1933.
    2. It estimates the number of bacteria in the patient’s saliva by counting the number of colonies appearing on tomato Peptone Agar at ph 5
    3. Interpretation of caries activity
      1. Immune: less than 1000 
      2. Slight: 1000 – 5000
      3. Medium: I5000 – 10,000
      4. High: more than 10000.
  2. Snyder Test 2m
    1. The rapidity of acid formation by cariogenic bacteria
    2. Stimulated saliva + Glucose in Agar Medium containing bacto peptone, sodium chloride, and bromocresol green 
    3. Dye changes from blue-green to yellow
    4. Interpretation of color change with caries activity 
  • High—24 hours
  • Medium— 48 hours
  • Slight—72 hours
  • Immune—no color change
  1. Streptococcus mutans Level in Saliva
    1. The number S.Mutans colonies per ml of saliva is indicative of caries activity.
    2. Saliva samples obtained by using tongue blades are incubated on MSB agar (Mitis Salivarius Bacitracin Agar).
  2. Buffer Capacity Test
    1. The test evaluated the quantity of acid required to lower the pH of saliva using an arbitrary pH interval
    2. Buffering Capacity is inversely proportional to the process of caries
  3. Swab Test
    1. Oral swab- the buccal surface of teeth and placing it in Snyder media. 
    2. This is incubated for 48 hours and the pH changes are read and correlated with caries activity.
  4. Fosdick Calcium Dissolution Test
    1. Patient saliva is mixed with glucose and powdered enamel
    2. Measuring of powdered enamel dissolved in 4 hours by acid formed
    3. This is not a single test and requires trained personnel
  5. Reductase Test
    1. Measures the activity of salivary enzyme reductase. 
    2. Stimulated Saliva + diazo resorcinol, which colors the saliva blue. 
    3. The change in color from blue to red is measured after 30 seconds – 15 minutes and this is taken as a measure of caries activity.
    4. Interpretation
      1. Non-Conducive: Remains blue after 15 minutes
      2. Slightly conducive: Orchid after 15 minutes
      3. Moderately conducive: Red after 15 minutes
      4. Highly conducive: immediately to red
      5. Extremely conducive: Changes to pink or white

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