If access is made in gold crown for endodontic procedure and after completion of procedure

 # If access is made in gold crown for endodontic procedure and after completion of procedure hole is filled with amalgam, which is correct about subsequent possible event?

A.  Amalgam will act as anode to gold  

B. Amalgam will act as cathode to gold

C. Circuit will not be formed

D. All of the above

The correct answer is A. Amalgam will act as anode to gold.

If an amalgam is in direct contact with an adjacent metallic restoration such as a gold crown, the amalgam is the anode in the circuit. This type of electrochemical corrosion is called galvanic corrosion and is associated with the presence of macroscopically different electrode sites.

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What happens if gypsum is heated above 700 degree celsius?

 # What happens if gypsum is heated above 700 degree celsius?

A. No by-product

B. Breakdown of CaSO4 which affect gold alloy

C. Breakdown of Na2SO4 which affect gold alloy

D. Gas inclusion porosities

The correct answer is B. Breakdown of CaSO4 which affect gold alloy.

Gypsum-bonded investments are used for casting gold alloys. These can withstand a temperature of 700°C. If gypsum investment is heated about 700°C, decomposition of CaSO4 occurs with emission of SO2 gas. This not only causes shrinkage of the investment but also contaminates the gold castings with the sulphides of the non-noble elements such as silver and copper. So gypsum investments should not be heated above 700°C. 

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Undercut desirable for wrought wire clasp:

 # Undercut desirable for wrought wire clasp:

A. 0.02 inches with clasp length 8 mm

B. 0.01 inches with clasp length 8 mm

C. 0.02 inches with clasp length 5 mm

D. 0.01 inches with clasp length 5 mm

The correct answer is A. 0.02 inches with clasp length 8 mm.

• Undercuts on the master cast may be measured with an undercut gauge, such as those provided with the Ney and Jelenko surveyors. 

• The amount of undercut is measured in hundredths of an inch, with the gauges allowing measurements up to 0.03inch. Theoretically the amount of undercut used may vary with the clasp to be used up to a full 0.03 inch. However, undercuts of 0.01 inch are often adequate for retention by cast retainers.

• Tapered wrought-wire retention may safely use up to 0.02 inch without inducing undesirable torque on the abutment tooth, provided the wire retentive arm is long enough (at least 8mm). 

• The use of 0.03inch is rarely, if ever, justified with any clasp. When greater retention is required, such as when abutment teeth remain on only one side of the arch, multiple abutments should be used rather than increasing the retention on any one tooth. 

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Vitamin related to coenzyme A:

 # Vitamin related to coenzyme A:

A. Thiamine

B. Riboflavin

C. Cobalamine

D. Pantothenic acid

The correct answer is D. Pantothenic acid.

• Co-enzyme A is an important component of fatty acid synthase complex. The Co-enzyme A is a complex molecule containing B complex vitamin pantothenic acid and a molecule of beta mercaptoethanol amine. 

• The ACP (acyl carrier protein) also contains pantothenic acid. 

• The important CoA derivatives are: - Acetyl CoA - Succinyl CoA - HMG CoA - Acyl CoA. 

• The functions of Pantothenic acid are exerted through CoA (A for acetylation). It is a component of Pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and Thiokinase. Besides the various functions through coenzyme A, pantothenic acid itself is a component of fatty acid synthase complex and is involved in the formation of fatty acids. 

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Angular cheilosis is frequently associated with the deficiency of:

 # Angular cheilosis is frequently associated with the deficiency of:

A. Thiamine

B. Riboflavin

C. Niacin

D. Folic acid

The correct answer is B. Riboflavin.

Magenta tongue (glossitis), fissures at corners of mouth (cheilosis), are common manifestations of  vitamin B2 deficiency. 

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Lazarine leprosy is a variant of:

 # Lazarine leprosy is a variant of:

A. Lepromatous leprosy

B. Tuberculoid leprosy

C. Intermediate leprosy

D. Dimorphic leprosy

The correct answer is A. Lepromatous leprosy.

Lazarine leprosy: This an unusual type of the disease characterized by ulceration and gangrene. The early lesions are bullae, which soon rupture and become gangrenous. It includes achromic and hypochromic spots of the lepra called lazarine (systematized nervous lepra with leprous erythema, pemphigoid and escharotic), and finally of mixed lepra. 

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Opsonins are:

 # Opsonins are:

A. C3a

B. IgM

C. Carbohydrate binding proteins

D. Selectins

The correct answer is C. Carbohydrate binding proteins.

Opsonins 

• Chemicals causing opsonisation 

• They are specific carbohydrate binding proteins 

Examples of opsonins 

• C3b 

• Fc fragment of antibody or IgG 

• Some serum proteins (like fibrinogen, mannose binding lectin and C reactive protein) 

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