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Past Oral Pathology MCQ(chapter Dental Caries)
1. All of the below given factors are responsible for causing dental caries except
- Dental plaque
- Diet
- Microorganisms
- Temperature
ANSWER d
The etiology of dental caries is a dynamic process that involves a susceptible tooth, cariogenic bacteria in dental biofilm (Streptococcus mutans and lactobacillus), and the detrimental effects of cariogenic carbohydrates.
Modifying factors also include the absence of fluoride, xerostomia, and inadequate oral hygiene.
2. Which of these factors has not been assigned an essential role in Miller’s chemicoparasitic theory of dental caries?
- Carbohydrates
- Microorganisms
- Heredity
- Acids
ANSWER c
- Proposed in 1890 by W. D. Miller in his book "The microorganisms of the human mouth" based upon the work done in Robert Koch’s laboratory
- “Dental decay is a chemico - parasitic process consisting of two stages,
| Decalcification of enamel | Total destruction |
| Decalcification of dentin | Preliminary stage followed by dissolution of the softened residue”. |
- The acid which caused the decay was derived from fermentation of starches and sugars lodged in the retaining centers on teeth.
- In his experiment he incubated a mixture of bread, meat and sugar with saliva at body temperature
- It produced enough lactic acid within 48 hours to decalcify sound dentin.
- In his hypothesis, Miller assigned essential roles to 3 factors –
| 1. Carbohydrate substrate |
| 2. Acid which caused dissolution of tooth minerals |
| 3. Oral micro organisms which produce acid and also cause proteolysis. |
- Showed that the degradation of carbohydrate-containing foods resulted in acid formation and was able to demonstrate this process in vitro with isolated oral bacteria and extracted teeth.
- Concluded that dental caries was caused by multiple species of oral bacteria.
- No specific bacteria was implicated – “non-specific”
3. From the properties given below identify which one does render carbohydrates cariogenic?
- Rapid clearance from oral cavity
- Stickiness of carbohydrates
- Frequent ingestion of carbohydrates
- Simple carbohydrates
ANSWER a
- Numerous studies confirm the fact that presence of readily fermentable carbohydrates are responsible for increased caries incidence.
- Cariogenic carbohydrates are dietary in origin since human saliva contains negligible amounts of carbohydrates.
- Also, whatever is present, is bound to salivary proteins and thus not available for microbial degradation.
Cariogenicity of carbohydrates depend upon –
- Frequency of its ingestion,
- Physical form,
- Chemical composition,
- Route of administration and presence of other food components.
Carbohydrates in detergent foods are less cariogenic than those in sticky,
retentive foods.
Polysaccharides are less easily fermented than monosaccharides by the plaque
organisms.
Meals high in fats, proteins or salt reduce the retentiveness of carbohydrates.
4. The mechanism of cariostatic action of chlorhexidine is
- Absorption into enamel crystals
- Absorption into enamel crystals and salivary mucins
- Inhibition of microorganisms
- Inhibition of carbohydrate degradation
ANSWER b
5. Nursing bottle caries is a type of _______ caries
- Acute
- Recurrent
- Rampant
- Arrested
ANSWER c
- The term early childhood caries includes the sometimes called nursing caries and rampant caries.
- “Baby bottle syndrome,” “nursing caries,” or “bottle mouth caries” are names to describe a pattern of caries where the deciduous upper incisors and molars are more severely disrupted.
- A key feature of this type of caries is the sparing of the lower incisors, which can be completely healthy or mildly affected.
- The term rampant caries is usually given to extensive caries affecting children of three to four years of age that do not follow the nursing caries pattern.
