MCQs on Oral Histology - Dentin Part 3

# Formula of hydroxyapatite crystal is :
A. Ca3(Po4)2.CaCO3
B. 3Ca3(Po4)2. Ca(OH)2
C. CaPo4. Ca(OH)2
D. None of the above

# The type of dentin that is formed prior to root completion is :
A. Inter tubular dentin
B. Peritubular dentin
C. Circumpulpal dentin
D. Secondary dentin

# Accentuated incremental lines in dentin due to disturbances in matrix and mineralisation process is:
A. Incremental lines of Retzius
B. Incremental lines of von Ebner
C. Contour lines of Owen
D. None of the above

# The pain transmission through dentin is :
A. Direct neural stimulation
B. Fluid or hydrodynamic theory
C. Transduction theory
D. All of the above

# Which of the following is correct ?
A. Reparative dentin is characterized by having fewer and more twisted tubules than normal dentin and may include odontoblasts
B. Dead tracts appear black in transmitted and white in reflected light
C. Sclerotic/transparent dentin appears transparent or light in transmitted light
D. All of the above


# First formed dental tissue :
A. Enamel
B. Dentin
C. Cementum
D. Bone

# Dentinal tubules are calcified in:
A. Sclerotic dentin
B. Secondary dentin
C. Primary dentin
D. Interglobular dentin

# Dentin formed throughout the life is:
A. Sclerotic dentin
B. Secondary dentin
C. Repartive dentin
D. All of the above

# Regarding teeth which statement is wrong ?
A. Enamel is harder than dentin
B. Enamel has no cells
C. Ameloblast secrete enamel and dentin
D. Odontoblast produce dentin

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MCQs on Oral Histology - Dentin Part 2

# The dentin receptors are unique because:
A. They elicit pain to hot and cold
B. They elicit pain to touch and pressure
C. They elicit pain to chemicals
D. Elicit only pain as a response

# The main bulk of dentin is formed by :
A. Peritubular dentin
B. Mantle dentin
C. Inter tubular dentin
D. Predentin

# The zone of dentin most recently formed and uncalcified is known as:
A. Mantle dentin
B. Circumpulpal dentin
C. Predentin
D. Secondary dentin

# Inter globular dentin results due to:
A. Failure of coalescence of calcospherites
B. Fracture of the dentin
C. Artifact in light microscopy
D. Disturbance in dentinal tubules

# Dentinogenesis by odontoblasts first behins at :
A. Pulpal end
B. Cusp tip
C. Tooth bud stage
D. Cervical area


# Sclerotic dentin has following features :
A. Caries susceptible
B. Insensitive
C. Hypersensitive
D. Resistant to caries

# The microhardness of dentin is about:
A. 1/2 that of enmel
B. 1/7 that of enamel
C. 1/4 that of enamel
D. 1/5 that of enamel

# Shape of the crown and the size of the roots is determined by:
A. Pulp
B. Dentin
C. Enamel
D. Cementum

# Physically and chemically, the dentin is closely related to:
A. Bone
B. Acellular cementum
C. Enamel
D. None of the above

# Organic portion can be separated from the mineral by :
A. Incineration / Organic chelation
B. Decalcification
C. Devitrification
D. Combustion

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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