MCQs

Question 1

Which rule is used to determine the position of the molar roots?

Answer 1

MBD rule

Question 2

What determines access cavity shape?

Answer 2

Pulp chamber shape

Question 3

Which is the first file that should be introduced to the canal?

Answer 3

K file

Question 4

What are the aims of the access cavity?

Answer 4

Ideal access forms funnel to allow instruments straight entry into canal orifices and into apical 1/3
Allow safe irrigation
Allow ease of shaping
To straighten out curves to allow more accurate working length determination

Question 5

Why may you dismantle coronal restorations during preparation?

Answer 5

The restoration may mask straight-line access
The restoration may be carious or broken down
Existing restoration may be suffering from marginal leakage
The restoration is going to be replaced after the RCT anyway

Question 6

Which of these answers is not a symptom of symptomatic irreversible pulpitis:

a. TTP
b. Woken at night
c. Spontaneous no provocation
d. Radiating pain
e. Residual throb
f. Provoked by hot and cold
g. Discomfort increasing on the pain scale 5+

Answer 6

F - provoked by hot and cold

Question 7

Which of these answers is not a symptom of symptomatic periapical periodontitis?

a. TTP
b. Responses to vitality testing
c. Pain constant and worsening
d. Pain severe especially in function or pressure
e. Swelling and reddening of the mucosa
f. Tender to palpation especially over the apices

Answer 7

B - responds to vitality testing

Question 8

If you don’t have enough time to complete an RCT, what should you do?

Answer 8

Cut down to vital tissue and place a sedative dressing e.g. ZOE
Bring the patient back as soon as practicable to complete RCT in one visit.

Question 9

What post-op instructions should be given after RCT?

Answer 9

The patient should be warned of post-operative discomfort or ache for 24 to 36 hours.

Question 10

Why can it be difficult to anaesthetise in pulpitic cases?

Answer 10

Afferent nerve fibres deriving from inflamed tissue sites have changed resting potentials and lowered excitability thresholds which extend through the affected nerve.
Very difficult for LA to prevent total nerve transmission
Patients under stress have a lowered pain threshold
Accessory innervation

Question 11

Briefly explain the principles underpinning the electronic apex locator

Answer 11

Two or more currents of varying frequencies emitted. The impedance of the tissues surrounding the endodontic file is compared to the impedance of the buccal mucosa. When the two impedance values match, the file is deemed to be at the apex of the tooth

Question 12

How can the electronic apex locator be used to accurately find the apical constriction?

Answer 12

It can’t really. However, it can assist in finding the apical foramen, which is when it will signal the “Zero reading”. As the apical foramen is approximately 0.5mm more apical than the constriction, 0.5mm should be taken from this measurement, giving an estimated working length to the constriction. This should be compared to the working length determined radiographically.

Question 13

Which of these irrigants can dissolve the inorganic matter of the smear layer?

a. Sodium hypochlorite 2%
b. Chlorhexidine 2%
c. EDTA 17.5%
d. NaOCl 1%

Answer 13

C - EDTA 17.5%

Question 14

In which of these cases should rotary NiTi instrumentation be avoided?

a. Upper incisor with a wide canal
b. Lower premolar with 2 root canals
c. Sclerosed canine where a glide path has been formed
d. S shaped root canals in an upper molar

Answer 14

D - S-shaped root canals in an upper molar

Question 15

What does Laser Doppler Flowmetry measure in pulpal blood?

a. Oxygen saturation
b. Glucose content
c. Number of red blood cells
d. Movement of red blood cells

Answer 15

D - movement of red blood cells

Question 16

What concentration does sodium hypochlorite need to be before it dissolves organic 
matter with a 10 minute contact time? 
a.	0.25% 
b.	0.5% 
c.	1.5% 
d.	2.5%

Answer 16

D - 2.5%

Question 17

Difference between lateral and periapical abscess

Answer 17

Lateral: of periodontal origin, collection of pus in connective tissue wall of periodontal pocket, red/ red-blue tissues, pain, TTP, mobile, high in occlusion, lymphadenopathy and fever may be present, presence of deep pocket, sinus tract be be present, caused by trauma blockage of reduction of host resistance, bone loss on RAD
Acute apical abscess: of endodontic origin, swelling, severe apin especially on pressure, maybe mobility, feeling that tooth is high in occlusion, fever malaise and lymphadenopathy, bone loss on radiograph, at apex of tooth
DIFFERENCES
-deep perio pocket
-location of bone loss
-restoration close to the pulp
-tooth vitality??
-pus in the pocket/ pus in the tissues

Question 18

Which two irrigants make a carcinogenic substance?

Answer 18

Chlorhexidine + NaOCl –> parachloroanaline