Physical n Chemical injuries of teeth

Question 1

1. The smear layer consisting of components of enamel, dentin,
   water and saliva can be beneficial to the cut surface of dentin by
   one of the following actions

(a) Reducing permeability of enamel
(b) Increasing the caries resistance of enamel
(c) Increasing surface of contact between tooth structure and
restorative material
(d) Reducing permeability of dentin

Answer 1

(d) Presence of smear layer over the cut surface helps to reduce
the permeability of dentin by closing off the opening of the
dentinal tubules and prevents the exit of dentinal fluid.

Question 2

2. Lesion manifested as alteration in ground substance, fibrosis,
   edema, odontoblastic disruption and reduced predentin
   formation in pulp directly opposite the cavity site produced by

high speed instrumentation is called
(a) Smear layer
(b) Tertiary dentin
(c) Dead tracts
(d) Rebound response

Answer 2

(d) This response is supposed to be caused by waves of energy
transmitted to the pulp tissue by the pulpal walls.

Question 3

3. Which amongst the following reactions is not directly attributable

to restorative materials on tooth?
(a) Hypercementosis
(b) Pulpal necrosis
(c) Tertiary dentin formation
(d) Dead tracts formation

Answer 3

(a) Majority of the restorative materials exert their pulp irritant
action only after coming in close contact with pulpal
tissues. Materials with high irritant action are avoided
these days. Also with the use of cavity liners and varnishes,
the incidence of pulp irritation has drastically come down.
Hypercementosis is not a response associated with most
restorative materials

Question 4

4. Identify the incorrect statement regarding traumatic bone cyst.

(a) Most commonly occurs in mandible
(b) Appears as a well-defined, unilocular radiolucency
(c) It is lined by stratified squamous epithelium
(d) Thought to arise due to trauma, followed by degeneration
of clot.

Answer 4

(c) Traumatic cyst is classified as a pseudocyst, i.e. a cyst that
lacks an epithelial lining.

Question 5

5. Which one of the following lesions cannot be considered in the
   differential diagnosis of focal osteoporotic bone marrow defect?

(a) Dentigerous cyst
(b) Odontogenic keratocyst
(c) Traumatic bone cyst
(d) Residual cyst

Answer 5

(a) A dentigerous cyst by definition, is attached to the neck of
the tooth, while other lesions including focal osteoporotic
bone marrow defect are not intimately associated with a
tooth.

Question 6

6. Apart from the base of socket, where else is new bone deposited
   during extrusive movement of tooth?
   (a) Outer surface of labial cortical plate
   (b) Crest of alveolar socket
   (c) Outer surface of lingual cortical plate
   (d) Inner surface of lingual cortical plate

Answer 6

(b) The tissue changes produced by extrusive movements consist
of deposition of new bone spicules at the alveolar crest and
base of the alveolar socket with the spicules arranged in a
direction parallel to the direction of orthodontic force

Question 7

7. Which amongst the following is not directly attributable to
   bruxism?

(a) Gingival recession
(b) Root resorption
(c) Severe tooth attrition
(d) Loosening of teeth

Answer 7

(b) Bruxism or night grinding is the habitual biting or grinding
of teeth during sleep or as an unconscious act even during
waking hours. Local, systemic, psychogenic as well as
occupational factors are recognized in the etiology. In
well-established cases, severe attrition, gingival recession,
drifting of teeth, facial pain, TMJ disturbances and
hypertrophy of masticatory muscles especially master have
been reported.

Question 8

10. Which one of the following is not a cause of tooth ankylosis?

(a) Periapical inflammation as a result of pulp infection
(b) Damage to PDL resulting from endodontic treatment
(c) Fracture of crown without pulp involvement
(d) Occlusal traumatism

Answer 8

(c) Ankylosis occurs when partial root resorption is followed by
repair with either cementum or bone that unites the root and
the surrounding alveolar bone. It is rarely seen in deciduous
teeth and is even rarer in permanent teeth. While occlusal
trauma, periapical inflammation and endodontic treatment
resulting in PDL damage can predispose to ankylosis, crown
fracture is not associated with tooth ankylosis.

Question 8

8. Fractures of teeth most commonly occur in
   (a) Maxillary posterior teeth
   (b) Maxillary anterior teeth
   (c) Mandibular anterior teeth
   (d) Mandibular posterior teeth

Answer 8

(b) Fracture of teeth is very common and can occur in a great
variety of setting, but the commonest is a sudden, severe
trauma like a blow, fall or other common incidents with
which children are usually involved. Expectedly, it is the
maxillary anterior teeth that are most prone to accidental
injuries

Question 9

9. Vitality of a tooth is most likely to be maintained if

(a) Crown is fractured without pulp involvement
(b) Crown is fractured with only a very thin layer of dentin
remaining
(c) Crown is fractured with pulp exposure
(d) Root is fractured with pulp involvement

Answer 9

(a) Except (a), in all other instances, the pulp is either vulnerable
or is exposed and irreversibly inflamed leading to its death

Question 10

11. Riga-Fede disease represents

(a) Recurrent aphthous ulcerations
(b) Traumatic ulcerations caused by erupting teeth during
nursing, in infants
(c) Herpetic ulcerations
(d) Linea alba

Answer 10

(b) Riga-Fede disease occurs in infants between one week
and one year of life. Lesions are observed usually on
anteroventral surface of tongue caused by contact of tongue
with erupting mandibular incisors.

Question 11

12. All of the following terms except ____ represent Epulis fissuratum.

(a) Denture injury tumor
(b) Denture epulis
(c) Inflammatory papillary hyperplasia
(d) Inflammatory fibrous hyperplasia

Answer 11

(c) Epulis fissuratum is one of the most common tissue
reactions to chronically ill-fitting denture. It is manifested as hyperplasia of tissue along the denture borders, characterized by development of elongated rolls of tissue
in the mucobuccal or mucolabial fold, area in which the
flange of a denture sits.

Question 11

14. Which amongst the following is not associated with occlusal
    trauma?

(a) Attrition
(b) Faulty occlusion
(c) Bruxism
(d) Epulis fissuratum

Answer 11

(d) Physiologic tooth wear, drifting of teeth, high filling, faulty
occlusion, bruxism, improper orthodontic tooth movement
are all commonly associated with chronic occlusal
trauma.

Question 12

13. Blowing of compressed air into a root canal can result in

(a) Cervicofacial emphysema
(b) Anesthetic necrosis
(c) Pneumoparotid
(d) Motsus humanus

Answer 12

(a) Emphysema refers to swelling due to presence of air in
the interstices of connective tissue. This can occur due
blowing of air into root canal(s) or periodontal pocket,
spontaneously due to patient’s breathing action following
some surgical procedures, etc

Question 13

15. White or reddish, ulcerative or superficial erosions on marginal
    and attached gingivae involving maxillary canine and premolars
    is most likely to be
    (a) Recurrent aphthous ulcers
    (b) Herpetic gingivostomatitis
    (c) Toothbrush trauma
    (d) Epidermolysis bullosa

Answer 13

(c) Toothbrush trauma lesions can be very commonly mistaken
for vesiculobullous lesions or infective lesions if the history
is not elicited properly.

Question 14

16. Which amongst the following cells is the most sensitive to ionizing
    radiation?

(a) Germ cells
(b) Developing bone cells
(c) Salivary glands
(d) Pancreas

Answer 14

(a) Although there is a great variation in radiosensitivity of
different types of living cells, it is generally agreed that
embryonic, immature or poorly differentiated cells are
more easily injured than the differentiated cells of same
type. Once these cells are injured, they usually show greater
recovery properties.

Question 15

17. All of the following except ________________ occur in osteoradionecrosis.

(a) Intense bone pain
(b) Pathological fractures
(c) Xerostomia
(d) Sequestrum formation

Answer 15

(c) Osteoradionecrosis refers to an acute form of osteomyelitis
due to damage to the intraosseous blood vessels and is
characterized by painful infection and necrosis followed
by sequestration of necrosed bone. Factors like radiation,
trauma and infection are believed to be involved in its
etiology.

Question 16

18. Within one hour of an operative procedure, clinical features of
    a rapidly enlarging unilateral soft tissue swelling of face with crepitus and minimal pain initially followed by variable pain,
    mild fever and facial erythema are suggestive of

(a) Acute osteomyelitis
(b) Buccal space infection
(c) Cervicofacial emphysema
(d) Canine space infection

Answer 16

(c) The facial enlargement can be confused with angioedema,
but can be differentiated by identifying crepitus within the
swelling. If emphysema spreads into mediastinum, it can
cause dysphagia or dyspnea.

Question 17

19. Features of a thin blue-black line on the marginal gingiva, burning
    sensation of oral mucosa and a metallic taste are suggestive of

(a) Bismuth poisoning
(b) Dilantin sodium overdose
(c) Mercury poisoning
(d) Arsenic poisoning

Answer 17

(a) Earlier used in the treatment of syphilis, Bismuth is still used
for treatment of certain skin diseases. The classical bismuth
line is manifested as a thin blue-black line in marginal
gingiva. It represents bismuth sulfide granules produced by
the action of hydrogen sulfide on bismuth compound in the
tissues. The H2
S inside oral cavity is produced by microbial
degradation of food debris.

Question 18

20. _____ is not usually associated with gingival hyperplasia.

(a) Dilantin sodium
(b) Nifedipine
(c) Cyclosporine
(d) Aspirin

Answer 18

(d) Aspirin use is associated with aspirin burn which occurs
when the tablet is placed against the painful tooth, allowing the cheek or lip to hold it in position. The caustic action of
aspirin causes sloughing of epithelium

Question 19

21. Plumbism is a term used to describe poisoning by which element?

(a) Lead
(b) Arsenic
(c) Mercury
(d) Bismuth

Answer 19

(a) Lead intoxication or plumbism is manifested by severe GIT
disturbances which include nausea, vomiting, colic and
constipation. A peripheral neuritis can also develop leading
to the characteristic wrist or foot-drop.

Question 20

22. Oral mucosal ulcerations caused by cancer therapeutic drugs is
    usually due to

(a) Leukocytosis
(b) Neutropenia
(c) Agranulocytosis
(d) Thrombocytopenia

Answer 20

(b) Oral mucosal erosion and ulceration is the common oral
reaction to cancer chemotherapy drugs. These ulcers are
diffuse and multiple and are mostly due to neutropenia
caused directly by the cytotoxic effects of the drug used.

Question 21

24. Which one of the following factors is responsible for causing
    xerostomia?

(a) Sialadenitis
(b) Salivary duct cyst
(c) Sialorrhea
(d) Mouth breathing

Answer 21

(d) Amongst the given causes, mouth breathing is a cause of
temporary xerostomia. However, xerostomia has a variety
of causes amongst which are developmental aplasia, water/
metabolite loss, medication, radiation to head and neck
region, diabetes, psychogenic, HIV infection, decreased
mastication, smoking and mouth breathing to name just a
few.

Question 22

23. Which element is responsible for acrodynia?

(a) Mercury
(b) Lead
(c) Arsenic
(d) Bismuth

Answer 22

(a) Acrodynia, also referred to as Pink disease or Swift’s disease is
a mercurial toxic reaction. The source of this mercury may be
a teething powder, ammoniated mercury ointment, calomel
lotion or dichloride of mercury disinfectant.

Question 23

25. Cutright lesion represents

(a) Ossifying fibroma
(b) Osteoma
(c) Reactive osseous and chondroid metaplasia
(d) Fibroma

Answer 23

(c) Osseous and chondromatous metaplasia can occur due to
mechanical denture irritation. Such metaplasia is usually
seen along the crest of the posterior mandibular alveolar
ridge in long-term denture wearers with atrophic ridges. It
is manifested as an extremely tender and localized area of
the alveolar ridge is typically noted that may be associated
with local enlargement.

Question 24

26. Which one of the following factors is not responsible for
    producing Linea alba?

(a) Denture injury
(b) Frictional irritation
(c) Sucking trauma
(d) Pressure

Answer 24

(a) Linea alba (white line) is a common alteration of the buccal
mucosa that is mostly associated with pressure, frictional
irritation, or sucking trauma from the facial surfaces of the
teeth. It is not associated with problems like insufficient
horizontal overlap or rough restorations of the teeth

Question 25

27. Which one of the following lesions is not produced as a result of
    injury/trauma?

(a) Solitary bone cyst (b) Aneurysmal bone cyst
(c) Mucocele (d) Ranula

Answer 25

(b) Lesions like solitary/traumatic bone cyst, mucocele
and ranula are induced by trauma, while hemodynamic
disturbance is considered responsible for development of
aneurysmal bone cyst.

Question 26

28. The most common location for occurrence of anesthetic necrosis
    is

(a) Gingiva
(b) Lips
(c) Hard palate
(d) Tongue

Answer 26

(c) Administration of a local anesthetic agent can, on rare
occasions be followed by ulceration and necrosis at the site
of injection. This necrosis is thought to result from localized ischemia. Faulty technique such as subperiosteal injection
or administration of excess solution in tissue firmly bound
to bone has been blamed.

Question 27

30. Localized argyrosis is another name for

(a) Amalgam tattoo
(b) Silver nitrate poisoning
(c) Plumbism
(d) Aspirin burn

Answer 27

(a) Implantation of dental amalgam into oral tissues is called
amalgam tattoo. Localized argyrosis has been used as
another name for amalgam tattoo, but this nomenclature
is inappropriate because amalgam contains not only silver
but also mercury, tin and other metals.

Question 28

29. A persistent scaling and flaking of the vermilion border secondary
    to habits such as lip licking, lip biting, lip picking, or lip sucking
    is called

(a) Angular cheilitis
(b) Actinic keratosis
(c) Exfoliative cheilitis
(d) Riga-Fede disease

Answer 28

(c) This chronic condition usually involves both the lips and
only those cases that are proven to be caused by chronic
injury are termed exfoliative cheilitis.