Preferred gingival finish line for veneer metal restoration

 # The preferred gingival finish line for veneer metal restoration is:

a) Shoulder 

b) Chamfer

c) Shoulder with bevel 

d) Radial shoulder

The correct answer is B. Chamfer.

#Shoulder Finish Line

Indications: • All ceramic crowns • PFM crowns • Injectable porcelains 

Advantages:  • Good crown contours • Esthetics  • Less distortion • Provides adequate bulk

Disadvantages: • Least conservative • Inferior marginal adaptation

# Shoulder with bevel Finish Line

Indications: • Proximal boxes of onlays and inlays • Labial finish line of metal ceramics • Occlusal shoulder of onlays 

Advantages:  • Superior marginal adaptation • Resists distortion • Facilitates removal of unsupported enamel rods

Disadvantages: • Requires subgingival extension • Detection of post cementation caries is difficult

# Chamfer Finish Line

Indications: • Cast metal restorations • Lingual aspect of metal ceramics

Advantages:  • Conservative • Good marginal adaptation • Provides bulk

Disadvantages: • Improper fabrication may result in an unsupported tip

# Knife edge Finish Line

Indications: • Young patients • MOD onlay • Inaccessible areas • Finish lines in cementum

Advantages:  • Conservative • Ideal for marginal adaptation 

Disadvantages: • Does not provide a distinct finish line • Waxing, polishing and casting becomes critical • Overcontoured restoration in an attempt to obtain bulk

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Partial veneer crown is contraindicated in:

 # Partial veneer crown is contraindicated in:

a) Long teeth 

b) Short teeth

c) Tipped teeth 

d) Tapered teeth

The correct answer is B. Short Teeth.

Indications for partial veneer crown:

• Intact or minimally restored teeth .

• Teeth with normal anatomic crown form i.e., without excessive cervical constriction.

• Teeth with adequate crown Length.

Contraindications for partial veneer crown:

• High caries rate.

• Short teeth.

• Bell shaped teeth.

• Teeth with insufficient buccolingual width.

• Excessively restored teeth.

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Retention of Partial Veneer Crown

 # In partial veneer crown, retention can be increased by:

a) Increased length of path of insertion

b) Increase in taper

c) Making path of removal parallel to long axis of adjacent teeth

d) None of the above

The correct answer is A. Increased length of path of insertion.

Crown preparation with long, parallel axial walls and grooves produces maximum retention. Increasing the taper decreases retention. A short, over tapered preparation, decreases the retention because the restoration can be removed along an infinite number of paths.

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Tooth Preparation for metal crown

 # The amount of reduction required for a tooth for all metal crown restoration is:

a) So that there is proper clearance between the teeth

b) So that the tooth architecture interferes with the arch of rotation

c) So that the tooth architecture doesn't interfere with the arch of rotation

d) At least 2mm on all the surfaces

The correct answer is: B. So that the tooth architecture interferes with the arch of rotation

The longer the occlusogingival length of the preparation, the greater is the retention. This is because longer preparations interfere with the arc of the casting pivoting about a point than shorter preparations.

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Finish lines of a complete coverage crown should lie:

 # Finish lines of a complete coverage crown should lie?

a) Supragingivally 

b) Subgingivally

c) Subgingival if required

d) Gingival margin

The correct answer is C. Subgingival if required. 

Whenever possible the finish lines of crowns should terminate supragingivally. Subgingival margins are required in the following situations.

• Esthetics.

• Cervical erosion and caries.

• Insufficient crown length for retention.

• Elimination of persistent root hyper sensitivity.

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Paired cartilages of larynx

 # Which of the following is a paired cartilage of larynx?

A. Thyroid

B. Cricoid

C. Epiglottis

D. Arytenoid

The correct answer is D. Arytenoid.

The laryngeal skeleton is made of nine cartilages: the thyroid cartilage, cricoid cartilage, epiglottis, arytenoid cartilages, corniculate cartilages, and cuneiform cartilages. The first three are unpaired cartilages, and the latter three are paired cartilages.

Paired = Arytenoid, Corniculate, Cuneiform

Unpaired= Thyroid, Cricoid, Epiglottis

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Extension of Larynx

 # Larynx extends from:

A. C2-C7

B. C1-C4

C. C5-C6

D. C3-C6

The correct answer is D. C3-C6

Larynx is the organ of voice (Phonation), an air passage sphincter at the inlet of the lower respiratory passage.

In adult male, it lies opposite to third, fourth, fifth, sixth cervical vertebrae, but in children, and in adult female, it lies at a higher level.

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