Periodontics MCQs - Periodontal Microbiology


# Of the following four bacterial species, which is least likely to be found in plaque ?
A. Actinomyces viscosus
B. Streptococcus mutans
C. Streptococcus salivarius
D. Streptococcus sanguis

# The common etiology of periodontitis is:
A. Occlusal trauma
B. Systemic factors
C. Local irritating factors
D. Hormonal defects

# Predominant bacteria found in two days old plaque is:
A. Streptococci
B. Bacteroides
C. Spirochaetes
D. Actinomyces

# In deep older plaque :
A. Streptococci and Actinomyces are replaced by rod-like organism
B. Streptococci are completely replaced by Neisseria
C. Streptococci, Actinomyces and Veilonella remain prominent
D. Actinomyces are completely replaced by Streptococci

# Actinobacillus actinomycetemcomitans is commonly associated with:
A. Juvenile periodontitis
B. Adult periodontitis
C. Refractory periodontitis
D. All of the above

# Supragingival plaque causes:
A. Gingivitis
B. Periodontitis
C. Pericoronitis
D. Aphthous ulcers

# The organism least likely to be found in normal gingival crevices is:
A. Fusobacterium
B. Actinomyces
C. Diptheroids
D. Streptococci

# The sticky polysaccharide present in dental plaque is:
A. Dextran
B. Dextrin
C. Glycogen
D. Sucrose

# Which of the following organisms is not implicated in the etiology of periodontal disease:
A. Bacteroides
B. Wolinella
C. Neisseria
D. Eikenella

# Bacteria, which are not found in normal healthy periodontium, are:
A. Actinomyces
B. Capnocytophaga
C. Veillonella
D. Eubacterium

# Most important initiative factor for periodontitis is:
A. Dental plaque
B. Calculus
C. Trauma from occlusion
D. Food debris layer

# Dental plaque adheres to the tooth because:
A. Levans are gummy
B. Dextrans are insoluble and sticky
C. Plaque grows into the irregularities
D. Microorganisms produce sticky lipoproteins

# In which of the following conditions is the role of microbial plaque most obscure:
A. Periodontitis
B. Juvenile periodontitis
C. Desquamative gingivitis
D. Necrotizing ulcerative gingivitis

# "Corn-cub" appearance is seen in:
A. Supragingival calculus
B. Subgingival calculus
C. Supragingival plaque
D. Subgingival plaque

# Central gram negative core supporting outer coccal cells are called:
A. Bristle brush arrangement
B. Corncob arrangement
C. Bottlebrush arrangement
D. Hourglass arrangement

# Breakdown of periodontal fibers in periodontitis is due to bacterial enzyme:
A. Collagenase
B. Hyaluronidase
C. Coagulase
D. None of the above

# Pellicle formation involves:
A. Adsorption of acidic glycoproteins from saliva
B. Focal areas of mineralisation
C. Focal areas of necrosis
D. Bacterial colonisation

# Which of the follwing is the common factor for the initiation of both dental caries and periodontal disease?
A. bacterial plaque
B. lactic acid
C. calculus
D. no common factor

# Severe alveolar bone loss, as observed in juvenile periodontitis ia associated with:
A. Cyclic neutropenia
B. Lysis of neutrophils
C. Increased phagocytosis
D. Impaired neutrophil chemotaxis


# The inorganic component of plaque is primary:
A. Calcium and fluoride
B. Calcium and sodium
C. Calcium and phosphorus
D. Sodium and calcium

# Co-aggregation is mainly predominated by:
A. interaction between gram +ve bacteria
B. interaction between gram -ve bacteria
C. interaction between gram +ve and gram -ve bacteria
D. None of the above

# Which of the folowing is a periodontal pathogen?
A. S. sanguis
B. S. mutans
C. A. viscosus
D. P. gingivalis

# Increases in steroid hormones are associated with significant increases in:
A. Actinomyces viscosus
B. Prevotella intermedia
C. Streptococcus sanguis
D. Campylobacter rectus

# The carbohydrate not associated with dental plaque is:
A. Dextrose
B. Levans
C. Glucose
D. Rhamnose

# Specific plaque hypothesis was put forward by:
A. Jenco
B. Listgarten
C. Loesche
D. None of the above

# Which is the most numerous component of plaque?
A. Minerals
B. Food debris
C. Microorganisms
D. Leucocytes

# Which surface of tooth has most of plaque ?
A. Gingival third of tooth surface
B. Incisal one third of tooth surface
C. Middle third of tooth surface
D. Uniform on all surfaces

# A bacterial enzyme capable of altering the ground substance of the periodontal ligament is:
A. Amylase
B. Mucinase
C. Dextranase
D. Hyaluronidase

# In later phases of plaque development the organism which predominates is:
A. Staphylococci
B. Streptococci
C. Rods and filaments
D. Vibrio and Spirochetes

# Which of the following plaque is most harmful and causes spread of inflammation to the connective tissue leading to bone destruction?
A. Subgingival epithelial attached
B. Subgingival unattached
C. Subgingival plaque
D. Supragingival plaque

# Dental plaque is formed by reaction of enzymes on:
A. Sucrose and lipids
B. Glucose and proteins
C. Glucose and lipids
D. Sucrose and saliva

# The bacteria of oral flora which plays least role in periodontitis is:
A. Actinomyces
B. Actinomycetam comitans
C. Spirochetes
D. Bacteriodes

# Majority of oral microorganisms are:
A. Strict anaerobes
B. Gram positive bacilli
C. Spirochetes
D. Facultative anaerobes

# The bacterial flora associated with juvenile periodontitis is mainly:
A. Gram +ve aerobic cocci
B. Gram +ve anaerobic cocci
C. Gram -ve aerobic cocci
D. Gram -ve anaerobic cocci

# The inorganic component of subgingival plaque is derived from:
A. Saliva
B. Crevicular fluid
C. A and B
D. Fluids ingested

# Which of the following is the most likely source of collagenase ?
A. Staphylococcus aureus
B. Bacteroides gingivalis
C. Treponema microdentum
D. Veilonella alkalescens

# Plaque differs from materia alba in:
A. presence of bacteria
B. presence of glycoprotein
C. presence of saliva
D. Absence of glycoprotein

# Bacteria in plaque form:
A. Intracellular polysaccharides
B. Extracellular polysaccharides
C. Both A and B
D. Complex polysaccharides

# Which of the following is first formed after tooth brushing?
A. Materia alba
B. Plaque
C. Pellicle
D. Calculus

# Pellicle is a:
A. Salivary protein
B. Plaque
C. Microorganism
D. Calculus

# Pre-requisite for plaque formation:
A. Pellicle
B. Glycoprotein
C. Mucopolysaccharide
D. Dextran

# Tanerella forsythia is a ___________ periodontal pathogen.
A. Gram positive, non obligate
B. Non pleomorphhic rod
C. non obligate anaerobe
D. non motile, spindle shaped

# Electronic instrument used to measure gingival crevicular fluid is:
A. Pericheck
B. Periotemp
C. Perioscan
D. Periotron

# Ecologic determinants of plaque depend on all except:
A. Sugar content of diet
B. Host resistance
C. Age and sex of the patient
D. Status of dentition

# Salivary pellicle is composed of the following except:
A. Immunoglobulin G
B. Immunoglobulin A
C. Amylase
D. Albumin

# Biofilm in general have:
A. Crystalline structure
B. Stereoline structure
C. Organized structure
D. Disorganized structure

# A test that can be used for typing of class I histocompatibility antigens is:
A. Cell mediated Lympholysis (CML)
B. Donor-recepient mixed lymphocyte response
C. Primed lymphocyte typing
D. Antibody and complement mediated cytotoxicity

# Does sub-gingival scaling alters the microflora of periodontal pocket?
A. never gets altered
B. alters aerobes only
C. gets altered
D. alters anaerobes only

# The primary etiological factor in the development of furcation defect is:
A. Calculus
B. Plaque
C. Cemental caries
D. Root infection

# A glycoprotein that promotes new attachment and increased cell proliferation is:
A. Fibronectin
B. Fibropectin
C. Glycogen
D. Glycosaminoglycans

# In periodontal disease, ground substance is dissolved by:
A. Hyaluronidase
B. Coagulase
C. Phosphorylase
D. Acid phosphatase

# The biofilms found on tooth surface are termed as:
A. Enamel
B. Dental Caries
C. Dental Plaque
D. Saliva

# The lactoperoxidase thiocynate system present in saliva is against:
A. A. actinomycetemcomitans
B. Streptococcus
C. P. Gingivalis
D. Actinomyces

# Which is the enzyme that prevents the adhesion of Actinomyces to the tooth structure?
A. Enolase
B. Glucosyl transferase
C. Xanthine oxidase
D. Myeloperoxidase

# Commonly isolated organism from oral cavity is:
A. Streptococcus sanguis
B. Streptococcus pyogens
C. Neisseria gonorrhoea
D. Streptococcus pneumoniae

# Primary colonization of plaque is dominated by:
A. Facultative aerobic gram +ve rods
B. Facultative anaerobic gram -ve rods
C. Facultative aerobic gram negative cocci
D. Facultative anaerobic gram +ve cocci

# Periodontitis is caused by:
A. Malnutrition
B. Supragingival plaque
C. Biofilm
D. Faulty toothbrushing

# The gram negative bacteria most numerous in oral cavity is:
A. Streptococci
B. Veillonella
C. Selenomous
D. Eikenella

# Which one of the following species of Streptococci is usually not found in dental plaque?
A. S. mutans
B. S. sanguis
C. S. pyogens
D. S. salivarius

# Which component of diet affects plaque composition ?
A. Carbohydrate
B. Mineral
C. Protein
D. Fats/lipids

# Microorganism which uses steroids as growth factor is:
A. P. gingivalis
B. P. intermedia
C. S. sanguis
D. S. mutans

# Which of the following is the method of transferring information in a biofilm ?
A. Quorum sensing
B. Conjugation
C. Plasmid transfer
D. All of the above


# The growth of Porphyromonas gingivalis is enhanced by a metabolic byproduct succinate produced by:
A. Streptococcus
B. Capnocytophaga
C. Actinomyces
D. Veillonella

# All of the following organisms can be detected by BANA analysis except:
A. Tannerella forsythia
B. Porphyromonas gingivalis
C. Capnocytophaga
D. A. actinomycetemcomitans

# Bacteria in plaque are held together by:
A. Hydrophobic forces
B. Covalent forces
C. Vander waal's forces
D. All of the above

# Which one of the following complexes of periodontal microorganisms is associated with bleeding on probing?
A. Red complex
B. Orange complex
C. Green complex
D. Yellow complex

# Bacterial communication with each other in a biofilm is known as:
A. Corncob formations
B. Coaggregations
C. Quorum sensing
D. Translocation

# Which is characteristic of supragingival plaque and not of subgingival plaque in Humans?
A. motile bacteria are predominant
B. Spirochaetes are evident microscopically
C. gram negative bacteria are predominant
D. bacterial composition is altered by dietary sugar composition

# The number of bacteria in the oral cavity is greater:
A. in the morning
B. after meals
C. at night
D. after brushing

# Which of the following substances play a major role in regulating cell to cell and cell- matrix interaction in cementum?
A. Sharpey's fibers
B. Intrinsic fibers
C. Proteoglycans
D. Phosphoproteins

# Enterococcus fecalis in post treatment periodontitis:
A. cultured easily and disinfected
B. disinfected with saline and hydrogen peroxide
C. Tolerate pH upto 11.5
D. Treated with intracanal medicaments

# After enamel has been exposed to bacteria, irreversible bacterial colonization takes place in about:
A. 24 hours
B. Few minutes
C. 1-2 hours
D. 2-4 hours

# Supragingival plaque undergoes which of the following changes with time?
A. Plaque mass increases
B. Plaque microflora becomes more gram positive
C. Plaque microflora becomes more gram negative
D. Plaque microflora becomes predominantly spirochetal

# The red complex associated with bleeding in probing comprises of:
A. E. corrodens, A. actinomycetemcomitans, Capnocytophaga
B. A. naeslundii, A. viscosus, A. odontolyticus
C. P. gingivalis, T. forsythia, T. denticola
D. Streptococcus, Fusobacterium, Campylobacter

# Black pigmented bacteroides release ______ as agent responsible for unpleasant smell of breath.
A. methyl mercaptan
B. Hydrogen sulphide
C. dimethyl sulphide
D. Propionic acid

# Which of the following is true about tooth associated subgingival plaque?
A. has both gram +ve and -ve bacteria
B. extends till the junctional epithelium
C. may penetrate cementum
D. associated with gingivitis and periodontitis

# According to Glickman, maximum accumulation of plaque takes place in approximately:
A. 7 days
B. 15 days
C. 30 days
D. 60 days

# After cleaning and pumicing the tooth surface, plaque formation takes place within:
A. a few minutes
B. half to one hour
C. 2 to 4 hour
D. after 6 hours

# Which of the following species is found in abundance in adult plaque?
A. Fusobacterium
B. Leptotrichia
C. Bacteroides
D. All of the above

# Bacterial "finger printing" reveals that periodontal pathogens are:
A. Contagious
B. Non - contagious
C. Transmissible within member of same colonies
D. Non transmissible


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