# Acid etching is done to:

# Acid etching is done to:
A. Decrease microleakage
B. Decrease polymerization shrinkage
C. Decrease Coefficient of thermal expansion
D. Decrease porosity in restorative material

The correct answer is A. Decrease microleakage.

Acid-etching transforms the smooth enamel into an irregular surface  and increases its surface free energy. When a fluid resin-based material is applied to the irregular etched surface, the resin penetrates into the surface, aided by capillary action. Monomers in the material polymerize, and the material becomes interlocked with the enamel surface.The formation of resin microtags within the enamel surface is the fundamental mechanism of resin-enamel adhesion.

As measured in the laboratory, shear bond strengths of composite to phosphoric acid-etched enamel usually exceed 20 megapascals (MPa) and can range up to over 50 MPa, depending on the test method used. Such bond strengths provide adequate retention for a broad variety of procedures and prevent leakage around enamel margins of restorations.

# Iron content in 3M Nickel based steel crowns is:

# Iron content in 3M Nickel based steel crowns is: (MAN -01)
a) 20%
b) 40%
c) 60%
d) 10%

The correct answer is D. 10 %.

Composition of stainless steel crowns:
Stainless steel (18-8) austentic type of alloy is used. Eg.: Rocky mountain and unitek.
Iron -                 87%
Chromium - 17%
Nickel -         12%
Carbon -          0.08 - 1.15%

Nickel base crowns. Eg.: Iconel 600 and 3M crowns
Iron                     -  10%
Chromium -    16%
Nickel - 72%
others - 2%

# A gingival wall is difficult to obtain in primary molar when it extends too far gingivally in class II cavities because: (MAN-97)

# A gingival wall is difficult to obtain in primary molar when it extends too far gingivally in class II cavities because: (MAN-97)
a) Facial pulp horn may be exposed
b) Inclination of cervical enamel rods occlusally
c) Of marked cervical constriction
d) Prime contact is broad and flat

The correct answer is C. of marked cervical constriction.

Gingivally the enamel rods have an occlusal direction in primary teeth so bevel is not required as there will be no unsupported enamel rods. It is difficult to obtain gingival wall when lesion extends too far gingivally in primary molar due to the presence of marked cervical constriction.

# Dose adjustment of all of the following drugs will be required in patient with severe liver cirrhosis EXCEPT:

# Dose adjustment of all of the  following drugs will be required in a patient with severe liver cirrhosis EXCEPT:
a) Lorazepam
b) Theophylline
c) Paracetamol
d) Metronidazole

The correct answer is A. Lorazepam.

PHARMACOKINETICS

Most of the BZDS are metabolized in the liver to produce active products (thus long duration of action). Active metabolites may result in cumulative effects. After metabolism, these are conjugated

and are excreted via kidney. Estazolam, lorazepam, oxazepam, temazepam and triazolam are directly conjugated without metabolism to active products. These drugs are thus short-acting and do not

accumulate on repeated administration. Further these drugs can be safely administered in liver failure and in elderly because these are conjugated directly without undergoing metabolism in the liver.

(Mnemonics: @ TO-LET; Short-acting drugs are Triazolam, Oxazepam, Lorazepam, Estazolam and Temazepam,). Compounds with shorter half life are favored in patients with sleep-onset insomnia whereas longer acting BZDS are favored in patients with day time anxiety.

Adverse effects

Benzodiazepines are much safer than barbiturates (less chances of respiratory depression and coma) and also have less abuse potential. However, these drugs can also impair learning and memory

Flunitrazepam is a tasteless BZD and is implicated as a date rape drug due to its propensity to cause dose dependent amnesic effects.

Benzodiazepine Antagonist

Flumazenil is the substance that acts as competitive antagonist at BZD receptor. It blocks the depressant action of benzodiazepine, zolpidem and zaleplon as well as the convulsant action of inverse agonist (like B-carotene).  It is administered i.v. for the treatment of BZD poisoning (specitie antidote) and can also be used to reverse BZD anaesthesia.

# Of the following local anesthetics, which has intrinsic vasoconstrictive action? (MAN -97)

# Of the following local anesthetics, which has intrinsic vasoconstrictive action? (MAN -97)
a) Cocaine
b) Procaine
c) Xylocaine
d) Bupivacaine

The correct answer is : A. Cocaine

All local anaesthetics except cocaine are synthetic compounds and they are vasodilating in nature. Cocaine is a natural local anaesthetic agent and causes local vasoconstriction.

 (Cocaine increases the vasoconstrictive action of adrenaline. If LA with adrenaline is given risk of death is more in cocaine abusers. So they are known as  'walking time bombs.'

Which of the following is the preferred local anesthetic technique for hemophilics? (MAN -01)

# Which of the following is the preferred local anesthetic technique for hemophilics? (MAN -01)
a) Nerve block
b) Supraperiosteal
c) Intraligamentary
d) Field block

The correct answer is C. Intraligamentary.

 In hemophilics to avoid complications,  Intraligamentary  (an intraosseous technique) method of local infiltration technique is preferred. In this technique, the solution is deposited in depth of gingival sulcus. The needle should be inserted apically into the bone until resistance is met.

# Which of the following may least be used as an abutment: (PGI -2K)

# Which of the following may least be used as an abutment: (PGI -2K)
a) Tooth with minimum crown
b) Tooth with short tapered crown and conical roots
c) Rotated and tipped tooth
d) Pulp treated tooth

The correct answer is: B. b) Tooth with short tapered crown and conical roots

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