MCQs on Oral Histology - Dentin

# Dentinal tubules are :
A. Concave
B. Straight
C. S-Shaped
D. None of the above

# The cells that form secondary dentin are:
A. Cementoblasts
B. Fibroblasts
C. Odontoblasts
D. Osteoblasts

# Dead tracts in ground section appears as:
A. Dentinal tubules
B. Coarse fibril bundles arranged at right angle to the dentinal surface
C. Black in transmitted light and white in reflected light
D. White in transmitted light and dark in reflected light

MCQs on Dental Caries Part 4

# Chemico-parasitic theory of dental caries is proposed by :
A. G.V. Black
B. Miller
C. Gottlieb
D. Schwartz

# Which of the following organisms is found in deep carious lesions rather than in incipient lesions ?
A. Streptococci
B. Lactobacilli
C. Veillonella
D. Bacteroides

# Pioneer bacteria in dental caries are in:
A. Enamel
B. Dentin
C. Pulp
D. Cementum

# The most pronounced effect on the oral microflora of a reduction in rate of salivary flow is a :
A. Significant increase in number of oral bacteria
B. Shift towards more acidogenic microflora
C. Significant decrease in number of oral bacteria
D. shift towards more aerobic microflora

# Ammonia causes:
A. increase in plaque formation
B. increase in calculus formation
C. decrease in plaque formation
D. precipitation of salivary proteins

# Cavity formation in a tooth, due to dental caries is due to:
A. Destructive potential of Streptococcus mutans
B. Destructive potential of Lactobacillus acidophilus
C. Lateral spread of caries along DEJ and weakening of the outer covering enamel
D. Mastectomy force and unrelated to the extent of carious process


# Animals maintained in a germ free environment did not develop caries fed on a high carbohydrate diet is given by:
A. Gottlieb
B. Miller
C. Snyder
D. Orland and Fizgerald

# Which of the following factors in the Stephan's curve is related to the caries incidence and sugar intake ?
A. Physical form of sugar
B. Frequency of sugar intake
C. pH of plaque
D. Quantity of sugar intake

# Initiation of caries by Streptococcus mutans is by the production of the :
A. Dextranase and soluble dextran
B. Insoluble dextran and glycosyl transferase
C. Soluble dextran and glycosyl transferase
D. None of the above

# The attachment of Actinomyces species to the tooth surface is facilitated by:
A. Fimbriae
B. Cilia
C. Flagella
D. Pseudopodia

# Caries associated with pre-eruptive enamel hypoplasia:
A. Secondary caries
B. Chronic caries
C. Occult caries
D. Incipient caries

# Bacteria free zone of dentinal caries is :
A. Zone of decomposed dentin
B. Zone of bacterial invasion
C. Zone of decalcification
D. Zone of dentinal sclerosis

# The legend of worms, endogenous theories, chemical theories and parasitic theory are early theories explaining:
A. Dental caries
B. Gingivitis
C. Periodontitis
D. Osteomylitis

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MCQs on Dental caries Part 3

# Streptococcus mutans is considered to be a principal etiologic agent of caries because it produces acid and it:
A. forms a gelatinous matrix
B. metabolizes substrate from saliva
C. derives energy from enamel constituents
D. lives symbiotically with lactobacillus

# Miller put forth the acidogenic theory of dental caries in the year:
A. 1890
B. 1920
C. 1924
D. 1980

# For a bacterium to be seriously considered in the etiology of dental caries, it must :
A. exist regularly in the dental plaque
B. produce extracellular amylopectins
C. be lethal for gnotobiotic animals
D. produce intracellular dextrans

# Initiation of dental caries depends upon:
A. formation of large amount of acid
B. availability of carbohydrate food
C. viscosity of saliva
D. Localisation of acid over tooth surface

# Caries, all are true except:
A. Lactobacillus is the main causative organism in plaque
B. Smooth surface caries occur due to streptococcus mutans
C. Pit and fisssure caries can be prevented by using pit and fissure sealants
D. Fluorides help in reducing caries incidence


# The enzyme glucosyl transferase secreted by Streptococcus mutans synthesizes glucans from:
A. Glucose
B. Fructose
C. Sucrose
D. Lactose

# The lateral spread of dental caries is facilitated mostly by the :
A. Enamel spindles
B. Dentinoenamel junction
C. Enamel lamellae
D. Striae of Retzius

# The probable reasons for a high incidence of dental caries in the teenage population relates most directly to:
A. Rapid growth
B. Frequency of sucrose intake
C. Negligence in visiting the dentist
D. Carelessness in oral hygiene habits

# In a caries free individual, the saliva has:
A. low buffering capacity for acids
B. medium buiffering capacity for acids
C. High buffering capacity for acids
D. Buffering capacity of saliva is independent of caries incidence

# Early invading bacteria in carious lesions are called:
A. Microcosm
B. Pioneer bacteria
C. Advancing bacteria
D. Anaerobic bacteria

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MCQs on Dental caries Part 2

# Streptococcus mutans is involved in dental caries initiation. Other bacteria also involved is:
A. S. sarcinus
B. S. macae
C. S. sanguis
D.S. salivarius

# The dietary carbohydrate most likely involved in etiology of dental caries is :
A. Glucose
B. Sucrose
C. Dextran
D. Polysaccharide

# Bacteria responsible for initiation of caries is :
A. Actinomyces
B. Streptococcus mutans
C. Lactobacillus
D. Streptococcus viridans

# What is the pH at which initiation of caries begins?
A. 4.3-4.5
B. 5.2-5.5
C. 4.9-5.1
D. 3.5-4.5

# Oral foci of Miller's are seen in :
A. Dental caries
B. Lichen planus
C. Herpes simplex
D. Syphilis


# In the earliest stages of carious lesion, there is loss of :
A. Enamel cuticle
B. Interprismatic substance
C. Organic matrix
D. Enamel lamellae

# Smooth surface caries is characterized by spread of caries in enamel and dentin as cones. These alignment in enamel and dentin is:
A. Base to base
B. Apex to base
C. Apex to apex
D. None of the above

# Least cariogenic among these:
A. Raw starch
B. Cooked starch
C. Sucrose
D. Fructose

# Which tooth in the permanent dentition is the most susceptible to dental caries ?
A. Maxillary first premolar
B. Maxillary second molar
C. Mandibular first molar
D. Mandibular second molar

# Turbid dentin in carious tooth is all EXCEPT:
A. Zone of bacterial invasion
B. Zone which cannot be remineralised
C. Zone in which collagen is irreversibly denatured
D. Zone that need not be removed before restoration

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MCQs on Dental Caries

# Lactobacilli are numerous in carious lesions because they:
A. Are the main causative agent
B. Can produce insoluble extracellular polysaccharides
C. Can attach to smooth enamel surfaces
D. Are secondary invaders

# Starch is considered to be less cariogenic than monosaccharides and disaccharides because it
A. Does not diffuse through plaque
B. is rapidly hydrolysed in the mouth
C. enhances remineralisation
D. raises the pH in the oral cavity