Free Dental Caries MCQs with Answers

• A. Orland and Fizgerald
• B. Miller
• C. Synder
• D. Gottlieb

Explanation: Orland and Fitzgerald demonstrated that germ-free animals did not develop caries despite a high-carbohydrate diet, supporting the…

• A. Insoluble dextan and glucosyl transferase
• B. Dextranase and soluble dextran
• C. soluble dextan and glucosyl transferase
• D. None of the above

Explanation: Streptococcus mutans uses glucosyltransferase to convert sucrose into extracellular insoluble glucans, traditionally called insoluble…

• A. Enamel
• B. Dentin
• C. Pulp
• D. Cementum

Explanation: Once caries reaches dentin, bacteria commonly enter and advance through the dentinal tubules, making dentin the site associated with…

• A. Gottlieb
• B. G.V black
• C. Miller
• D. Schwartz

Explanation: Miller proposed the chemico-parasitic theory, stating that bacteria ferment dietary carbohydrates to acids and that these acids dissolve…

• A. low buffering capacity of acids
• B. Medium buffering capacity for acids
• C. Independent of buffering capacity for acids
• D. High buffering capacity for acids

Explanation: High salivary buffering capacity neutralises acids produced in plaque and helps maintain a safer pH around the tooth.

• A. Dentinoenamel junction
• B. Enamel spindles
• C. Enamel lamellae
• D. Striae of Retzius

Explanation: The dentinoenamel junction provides a relatively weak, continuous pathway along which caries can spread laterally after crossing enamel.

• A. Pit and Fissure caries can be prevented by using pit and tissue sealants
• B. Smooth surface caries occur due to streptococcus mutans
• C. Lactobacillus is main acusative organism in plaque
• D. Fluorides help in reducing caries incidence

Explanation: Lactobacilli are important in the progression of established caries but are not the main initiating organisms in plaque; mutans…

• A. Formation of large amount of acid
• B. Availability of carbohydrate food
• C. Viscosity of saliva
• D. Localization of acid over tooth surface

Explanation: Caries initiation requires acid to remain concentrated at a specific tooth surface long enough to lower the local pH and dissolve mineral.

• A. 1890
• B. 1920
• C. 1924
• D. 1980

Explanation: Miller proposed the chemico-parasitic, or acidogenic, theory of caries in 1890, explaining caries as acid production by microorganisms…

• A. Zone of bacterial invasion
• B. Zone which can not be remineralized
• C. Zone that need not be removed before restoration
• D. Zone in which collagen is irreversibly denatured

Explanation: Turbid dentin is infected dentin containing bacteria and collagen that has been irreversibly denatured, so it cannot be remineralized and…

• A. Fructose
• B. Cooked starch
• C. Sucrose
• D. Raw starch

Explanation: Raw starch is least cariogenic because its molecules are less accessible to salivary and bacterial enzymes than cooked starch, which has…

• A. Interprismatic substance
• B. Enamel cuticle
• C. Organic matrix
• D. Enamel lamellae

Explanation: The earliest enamel caries preferentially removes mineral from the interprismatic substance, producing microscopic porosity before more…

• A. 4.3-4.5
• B. 5.2-5.5
• C. 4.9-5.1
• D. 3.5-4.5

Explanation: Enamel begins to demineralize at the critical pH of approximately 5.5, represented by the range 5.2–5.5.

• A. Glucose
• B. Dextran
• C. Sucrose
• D. Polysaccharide

Explanation: Sucrose is especially cariogenic because it is readily fermented to acids and also supports the formation of sticky extracellular glucans…

• A. Zone of sclerosis, decalcification zone, bacterial invasion
• B. Decalcification zone, zone of scierosis, backterial invasion
• C. Zone of sclerosis, backterial invasion, decalcification zone
• D. Bacterial invasion, decalcification zone, zone of sclerosis

Explanation: Moving from the carious dentin at the dentinoenamel junction toward the pulp, the usual order is bacterial invasion, decalcification, and…

• A. Streptococcus agalactiae
• B. Streptococcus mutans
• C. Streptococcus bovis
• D. Streptococcus anginosus

Explanation: Streptococcus mutans is strongly associated with dental caries because it adheres to teeth, produces extracellular glucans, and converts…

• A. Strontium
• B. Vanadium
• C. Selenium
• D. Molybdenum

Explanation: Selenium is considered cariogenic among these trace elements, whereas strontium is generally associated with reduced caries activity.

• A. Enhances remineralisation
• B. Is rapidly hydrolysed in the mouth
• C. Does not diffuse through plaque
• D. Raises the PH in the oral cavity

Explanation: Starch is a large polysaccharide and penetrates dental plaque less readily than small sugars, so it is less available for rapid acid…

• A. Pseudopodia
• B. Cilia
• C. Flagella
• D. Fimbriae

Explanation: Actinomyces attaches to the tooth surface mainly through fimbriae, which mediate adhesion to acquired pellicle and other bacterial cells.

• A. Ph of Plaque
• B. Frequency of sugar intake
• C. Physical form of sugar
• D. Quantity of sugar intake

Explanation: The Stephan curve records the fall and recovery of plaque pH after sugar intake; the extent and duration of this pH fall determine caries…