Stress breaker in Partial Dentures

# Disadvantage of using a stress breaker in partial dentures is:
a) The partial denture becomes cumbersome
b) Ridge resorption occurs
c) Its is not economical
d) No disadvantages present

The correct answer is B. Ridge resorption occurs.

Stress breaker or equalizer is a device that allows some movement between the denture base and the direct retainer. This type of design protects the vulnerable abutment teeth and concentrates more stresses on the residual ridge.

Its disadvantages are:

• Increased residual ridge resorption

• Difficulty to fabricate and repair

• Less tolerated by the patient

• The need for frequent relining

• High cost

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Guiding planes in RPD

# Guiding plane in RPD should be located at:
a) In between edentulous space
b) Abutment surface adjacent to an edentulous area
c) Edentulous areas
d) Abutment area

The correct answer is: B. Abutment surface adjacent to an edentulous area. 

Guiding planes are surfaces on proximal or lingual surfaces of teeth that are parallel to each other and, more importantly, to the parts of insertions and removal of a removable partial denture. These planes may be created on enamel surfaces or on the surfaces of dental restorations.

The function of guiding planes are as follows:

• To provide one path of placement and removal of restoration.

• To ensure the intended actions of reciprocal, stabilizing and retentive components.

• To eliminate gross food traps between abutment teeth and components of the denture.

As a rule, proximal guiding plane surfaces should be about one half the width of the distance between the tips of adjacent buccal and lingual cusps or about one third of the buccal lingual width of the tooth. They should extend vertically about 2/3rds of the length of enamel crown portion of the tooth from the marginal ridge cervically.

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Dental Surveyor

# Dental surveyor is used to:
a) Measure resiliency of tissues
b) Indicate relative parallelism between two teeth
c) To determine primary stress bearing area
d) To determine the depth of undercut

The correct answer is D. To determine the depth of undercut.

 - Surveyor is used to determine the relative parallelism of two or more surfaces of teeth or other parts of dental cast. It is used to:
• Survey the diagnostic and master cast
• Contour wax patterns and crowns
• Measure specific depth of undercut
• Blocking out the master cast
• Place internal rests etc.

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Advantage of resin teeth over porcelain teeth

# The advantage of resin teeth over porcelain teeth is:
a) Greater wear resistance
b) Increased hardness
c) Better dimensional stability
d) Greater impact resistance

The correct answer is D. Greater Impact resistance.

Resin teeth display greater impact resistance and ductility and are less likely to chip or fracture when compared to porcelain.

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Occlusal Plane for Complete Denture

# The occlusal plane for the complete denture patient is determined by:
a) The face bow device which determines the occlusal plane
b) The position of the upper first molar
c) The height of the retromolar pad and anterior esthetic height
d) The curve of Spee and the anterior esthetics

The correct answer is: c) The height of the retromolar pad and anterior esthetic height.

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Palatal Hyperplasia due to Denture Irritation

# Treatment of choice for palatal hyperplasia occurring due to denture irritation is:
a) Discontinuation of dentures
b) Radicular excision
c) Supraperiosteal excision
d) No treatment necessary

The correct answer is C. Supraperiosteal excision.

Early treatment for papillary hyperplasia includes prosthesis adjustment, tissue conditioning and proper oral hygiene. Advanced treatment consists of supraperiosteal excision. There is no need to excise full thickness of palatal tissue. The techniques include removal of inflamed mucosa with electrosurgery loops, laser ablation, sharp dissection, dermabrasion brushes, and cryotherapy.

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Denture Cleaning Powder

# Which of the following is the main ingredient of denture cleaning powder or tablets?
a) Hydrogen peroxides
b) Detergents
c) Sodium perborates
d) Alkaline compounds

The correct answer is C. Sodium Perborates.

All the denture cleansing powder and tablets contain detergent, flavouring agent, alkaline compounds and sodium perborate. The main component is sodium perborate. It decomposes in water to form a peroxide solution which inturn breaks down to liberate oxygen. It is this oxygen bubbles that remove the debris on the denture surfaces.

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