Free Dental Caries MCQs with Answers

• A. Destructive potential of streptococcus mutans
• B. Destructive potential of lactobacillus acidophilus
• C. Lateral spread of caries along DE junction and weakening of the outer covering enamel
• D. Mastectomy force and unrelated to the extent of carious process

Explanation: A visible cavity develops when caries spreads laterally along the dentinoenamel junction, undermining enamel until the weakened outer…

• A. Significant increase in number of oral bacteria
• B. Shift towards more aerobic microflora
• C. Significant decrease in number of oral bacteria
• D. Shift towards more acidogenic microflora

Explanation: Reduced salivary flow decreases sugar clearance and buffering, allowing acid-tolerant and acid-producing organisms to become more…

• A. Lactobacilli
• B. Streptococci
• C. Veillonella
• D. Bateroides

Explanation: Lactobacilli are commonly associated with the progression of established, deep carious lesions because they tolerate and produce acid.

• A. Microcosm
• B. Pioneer bacteria
• C. Advancing bacteria
• D. Anaerobic bacteria

Explanation: The first organisms to enter and colonise a developing carious lesion are termed pioneer bacteria.

• A. Rapid growth
• B. Negligence in visiting the dentist
• C. Frequency of sucrose intake
• D. Carelessness in oral hygiene habits

Explanation: Caries risk is influenced more by how often sucrose is consumed than by a single large intake, because repeated acid attacks keep plaque…

• A. Glucose
• B. Fructose
• C. Lactose
• D. Sucrose

Explanation: Glucosyltransferase uses sucrose as the substrate and splits it to form glucans from its glucose component.

• A. Exist regularly in the dental plaque
• B. Produce extracellular amylopectins
• C. Be lethal for gnotobiotic animals
• D. Produce intracellular dextrans

Explanation: Regular presence in dental plaque is a basic requirement for a bacterium to be considered a caries pathogen, because plaque is the…

• A. Forms a gelatinous matrix
• B. Metabolizes substrate from saliva
• C. Derives energy from enamel constituents
• D. Lives symbiolically with lactobacillus

Explanation: S. mutans produces extracellular glucans that form a sticky, gelatinous matrix, allowing the bacteria to attach firmly to enamel while…

• A. Maxillary 1st premolar
• B. Maxillary 2nd molar
• C. Mandibular 1st molar
• D. Mandibular 2nd molar

Explanation: The mandibular first molar is generally the most caries-susceptible permanent tooth because it erupts early and has deep, complex pits and…

• A. Apex to base
• B. Base to base
• C. Apex to apex
• D. None of the above

Explanation: In smooth-surface caries, the enamel cone has its apex toward the dentinoenamel junction, while the dentinal cone has its broad base at…

• A. Lichen planus
• B. Dental caries
• C. Herpes simplex
• D. Syphilis

Explanation: Miller’s oral focal infection concept relates oral infectious foci, particularly diseased teeth and their supporting tissues, to systemic…

• A. Actinomyces
• B. Lactobacillus
• C. Strep. mutans
• D. Strep. viridans

Explanation: Streptococcus mutans is the main organism associated with initiation of smooth-surface and fissure caries because it adheres to enamel…

• A. S. Sarcinus
• B. S. macae
• C. S. salivarius
• D. S. sanguis

Explanation: Streptococcus sanguinis is an oral streptococcus that participates in early plaque formation and can contribute to caries alongside S.

• A. Proteolytic theory
• B. Proteolytic chelation theory
• C. Autoimmune theory
• D. Acidogenic theory

Explanation: The acidogenic theory explains caries as demineralization caused by organic acids produced when plaque bacteria ferment dietary…

• A. One
• B. Five
• C. Four
• D. Two

Explanation: Classical dentinal caries is described in five zones, progressing from relatively intact or sclerotic dentin toward softened…

• A. unaffected
• B. less than the patient with normal salivary flow
• C. More than the patient with normal salivary flow
• D. None of the above

Explanation: Saliva washes away food, buffers bacterial acids, and supplies protective factors, so reduced salivary flow removes important protection…

• A. Mucopolysaccharide
• B. Amylopectin
• C. Glycogen - like glucan
• D. Dextran-like glucan

Explanation: Cariogenic streptococci use sucrose to form sticky extracellular glucans that help them adhere to enamel and build plaque; these are…

• A. Are secondary invaders
• B. Can produce insoluble extracellular polysaccharides
• C. Can attack to smooth enamel surfaces
• D. Are the main causative agent

Explanation: Lactobacilli usually do not initiate enamel caries because they adhere poorly to intact smooth enamel.

• A. Tooth wear due to bruxism
• B. Tooth wear due to gastric secretion
• C. Tooth wear due to dentifrices
• D. Peripheral blood cell destruction

Explanation: Perimolysis is chemical erosion of tooth surfaces caused by repeated exposure to gastric acid, as in vomiting or reflux.

• A. Cemental dysplasia
• B. Focal periapical osteopetrosis
• C. Condensing osteitis
• D. Cemental aplasia

Explanation: Hypercementosis can resemble cemental dysplasia, condensing osteitis and focal periapical osteopetrosis on radiographs.