DENTAL CARIES

THEORIES & eTIOLOGY
1. Theories of Dental Caries
  1. Early Theories
    1. The legend of the worm
  2. Endogenous Theories
    1. Humoral theory
    2. Vital theory
  3. Exogenous Theories
    1. Chemical (acid) theory
    2. Parasitic (septic) theory
    3. Miller's chemicoparasitic/ acidogenic theory
      1. By Miller (most accepted theory)
      2. States that dental decay is a chemico-parasitic process consisting of decalcification of hard tissues followed by dissolution of the softened residue
    4. Proteolytic theory
      1. By Gottileb
      2. States that organic portion of the tooth such as enamel lamellae and enamel rod sheaths play an important role in the carious process since they serve as a pathway for microorganism through the enamel
    5. Proteolysis chelation theory
      1. By Schartz & Martin
      2. Keratinolytic microorganisms cause breakdown of protein and keratin. This results in the formation of substances which form soluble chelates with the mineralized component of the tooth and thereby decalcify the enamel
  4. Others
    1. Auto immune theory
2. Etiology
  1. Keys triad
    1. A susceptible host tissue
    2. Microflora with a cariogenic potential
    3. A suitable local substrate
  2. Newbrun tetrad
DIETARY STUDIES
1. Vipeholm study
  1. Described by Gustaffson et al in 1954 and summarised by Davies in 1955
  2. It was a 5 yr investigation of 436 adult inmates of Vipeholm hospital of Sweden, an institution for the mentally challenged
  3. The inmates are divided into 7 groups based on the diet given
    1. -Control group -Sucrose group -Bread group -Caramel group -Chocolate group -8 Toffee group -24 Toffee group
  4. The institution diet was nutritious but contained little sugar, with no provisions for between meal snacks
  5. Main conclusions
    1. An increase in carbohydrate mainly sugar definitely increases the caries activity
    2. The risk of caries is greater if the sugar is consumed in a form that will be retained on the surfaces of teeth
    3. The risk of sugar increases, if the sugar is consumed between meals
    4. Upon withdrawal of sugar rich foods, the increased caries activity rapidly increases
    5. Caries lesions may continue to appear despite the avoidance of refined sugar and maximum restrictions of natural sugar
2. Hopewood house study
  1. By Harris & Sullivan (1942-1967)
  2. Hopewood house is an institution for children of age 7 -14 yrs
  3. Two principal features
    1. The absence of meat
    2. Rigid restriction of refined carbohydrate
  4. Water fluoride concentration was non-significant and oral hygiene was poor throughout the study
  5. Mean DMFT per 13 yr old child at the end of study : 1.6
    1. Corresponding figure for the general child population : 10.7
  6. Caries free children of 13yrs old at the Hopewood House : 53%
    1. Corresponding figure for the general child population : 0.4%
  7. Conclusion of the study
    1. In institutionalized children, dental caries can be reduced by carbohydrate restricted diet even in the presence of unfavorable oral hygiene
3. turku sugar study
  1. By Sheinin & Makinen et al in 1975 for a period of 25 months
  2. Investigated the effects of sucrose, fructose , xylitol on caries development
  3. Conclusion
    1. Sucrose - Highly cariogenic
    2. Fructose - Cariogenic as sucrose for the first 12 months but become less at the end of 24 months
    3. Xylitol - Anti-cariogenic with 85% reduction in dental caries
4. Tristan da cunha
  1. Is an island in South Atlantic area. Because of volcano entire community moved to England
  2. Investigator is Fisher
  3. Fisher carried dental examination in 1932, 1937, 1953 in island and again in England in 1962 and again 1966 in the island when the people returned to the island
  4. Caries prevalence in first molars of 6-19 yrs old
    1. Before migration : 0%
    2. After migration: 50%
5. hereditary fructose intolerance
  1. Due to reduced levels of enzyme Fructose-1- phosphate aldolase required for the metabolism of sucrose or fructose
  2. Affected persons experience symptoms of nausea, vomiting, excessive sweating and even coma on ingestion of foods containing fructose/ sucrose
  3. Newbrun in 1969 tabulated the caries prevalence of 31 persons with HFI and found that dental caries prevalence was extremely low
caries indices
1. DMFT Index
  1. Decayed - Missing -Filled Teeth Index
  2. By Henry Klein, Carole Palmer and Knutson in 1938
  3. Principles and Rules
    1. 1. No tooth must be counted more than once
    2. 2. Decayed, missing, filled teeth must be recorded separately
    3. 3. 'D' also includes restorations with recurrent decay
    4. 4. M-component should include teeth missing due to caries only. Badly decayed teeth indicated for extraction are also included
      1. Not counted as Missing - Unerupted teeth - Missing due to accident - Congenitally missing teeth - Teeth extracted for orthodontic purposes
    5. 5. A tooth may have several restorations but it is counted as one tooth
    6. 6. Deciduous teeth not included
    7. 7. Tooth is considered erupted when its occlusal surface is totally exposed
    8. 8. Tooth is considered as present even if the crown has been destroyed and only the roots are left
  4. WHO modification 1987
    1. All 3rd molars are included
    2. Temporary restoration are considered as 'D'
    3. Initial lesions like chalky spots are not considered as 'D'
    4. M-component should include teeth missing due to caries only
  5. WHO modification 1997
    1. Instruments
      1. Mouth mirror WHO probe
    2. For people >30yrs , M-component should include teeth missing due to caries or other reason
    3. For people <30yrs , M-component should include teeth missing due to caries only
2. DMFS Index
  1. Decayed - Missing -Filled Surfaces Index
  2. By Henry Klein, Carole Palmer and Knutson in 1938
  3. To assess prevalence of coronal caries
  4. More sensitive index
  5. Index of choice in a clinical trial of a caries preventive agent
3. def Index
  1. decayed - extracted - filled Index
  2. By Gruebbel in 1944
  3. Equivalent to DMF index for measuring dental caries in primary dentition
  4. Modifications
    1. dmf index Used in children before the age of exfoliation
    2. df index Missing tooth is ignored Used by WHO in their basic survey techniques
4. Significant Caries Index
  1. By Bratthall in 2000
  2. To bring attention to individuals with the highest caries scores in each population
5. Root Caries Index
  1. By Ralph Katz in 1979
  2. Only teeth with gingival recession is examined
CARIES ACTIVITY TESTS
1. Lactobacillus Colony Count Test
  1. By Hadley in 1933
  2. Oldest & most widely used
  3. Reference test for new caries activity test
  4. Estimates the no. of acidogenic and aciduric bacteria in the patient's saliva by counting the no. of colonies on tomato peptone agar plates (pH 5) after inoculation
  5. Very sensitive to diet changes & highly influenced by intake of dietary carbohydrates thus reflecting the amount of bacterial substrate and indicating an acid environment
2. Colorimetric Snyder Test
  1. Devised by Snyder in 1951
  2. Measures the ability of salivary microorganisms to form organic acids from a carbohydrate medium
  3. The glucose agar medium contains the indicator dye "Bromocresol green" which changes color from green to yellow in the range of pH 5.4-3.8
3. Swab Test
  1. Developed by Grainger in 1965
  2. No collection of saliva needed. Used in very young children
  3. Same principle as Snyder test
4. Albans Test
  1. Simplified substitute for Snyder test
  2. Less agar is used
5. Salivary Reductase Test
  1. Measure the activity of the reductase enzyme present in salivary bacteria
  2. Dye used "Diazo resorcinol"
6. Streptococcus mutans Screening Test
  1. Saliva/ Tongue blade method
  2. The test estimates the no. S mutans in mixed paraffin stimulated saliva when cultured in MSB agar
  3. Developed for use in large no. of school children
  4. Simplified and practical method for filed studies
OTHER KEY POINTS
1. Stephan's curve
  1. pH curves of plaque in different individuals studied after rinsing the mouth with 10% glucose or sucrose solution
  2. Critical pH: 5.2 -5.5
2. Caries Vaccine
  1. Caries vaccine is based on Ig A antibody. Monoclonal antibodies are formed which attach to the tooth surface by adhering to the salivary pellicle
  2. Strep. mutans bind to the antibodies
  3. Strep. fecalis takes the place occupied by strep. mutans
3. Cariogram
  1. Model by Douglas Bratthall in 1996 to illustrate interactions between caries related factors
  2. Main purpose
    1. Demonstrate the caries risk graphically
    2. Expressed as the "chance to avoid new caries" in the near future
  3. Green - Actual chance to avoid new cavities
  4. Dark blue - Diet (content & frequency)
  5. Red - Bacteria
  6. Light blue - Susceptibility
  7. Yellow - Cicumstances
  8. The bigger the green sector the better it is from a dentist's point of view
  9. For other sectors the smaller the sector the better from a dental health point of view
Lactobacillus Colony Count Test
1. No. of Lactobacillus/ml
  1. Symbolic designation
    1. Degree of caries activity
2. 0-1000
  1. +-
    1. Little or no activity
3. 1000-5000
  1. +
    1. Slight activity
4. 5000-10,000
  1. ++
    1. Moderate activity
5. More than 10,000
  1. +++
    1. Marked activity
Swab Test Interpretation
1. pH
  1. Caries activity
2. < or = 4.1
  1. Marked caries activity
3. 4.2-4.4
  1. Active
4. 4.5-4.6
  1. Slightly active
5. >4.6
  1. Caries inactive
Color observations in Snyder test
1. 24 hrs
  1. 48 hrs
    1. 72 hrs
2. If YELLOW marked caries susceptibility
  1. If YELLOW marked caries susceptibility
    1. If YELLOW limited caries susceptibility
3. If GREEN Continue to incubate & observe at 48 hrs
  1. If GREEN Continue to incubate & observe at 72 hrs
    1. If GREEN caries inactive
Important Dyes used
1. Modified Quigley Hein index
  1. Basic fuschin
2. Salivary reductase test
  1. Diazoreorinol
3. Snyder test
  1. Bromocresol green
4. The disclosing agent that differentiates b/w mature & newly formed plaque
  1. Two tone solution
5. Caries detection dye used to stain infected dentin contains
  1. 1% acid red solution in 0.2% propylene glycol
6. Dye used in staining of fracture line in a suspected tooth
  1. 2% iodine
7. Dye used in carisolv
  1. Erythrosine dye
Interpretation of Salivary Reductase Test
1. Colour
  1. Time
    1. Score
      1. Caries Activity
2. Blue
  1. 15 min
    1. 1
      1. Non conducive
3. Orchid
  1. 15 min
    1. 2
      1. Slightly conducive
4. Red
  1. 15 min
    1. 3
      1. Moderately conducive
5. Red
  1. Immediately
    1. 4
      1. Highly conducive
6. Pink/White
  1. Immediately
    1. 5
      1. Extremely conducive