Most common reason for failure of rest seat in RPD is :

 # Most common reason for failure of rest seat in RPD is : 

A. Improper rest seat preparation 

B. Contaminated metal 

C. Distorted occlusal rest 

D. Excessive occlusal forces 

The correct answer is A. Improper rest seat preparation.

The most common reason for failure of rest seat in RPD is improper rest seat preparation. Inadequate preparation will result in either occlusal interference or perforation of the metal due to lack of clearance. Failure of rest seat due to contaminated metal or distortion is very rare. 

Reference: McCracken's

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The function of reciprocal clasp arm is:

 # The function of reciprocal clasp arm is:

A. To balance the denture 

B. To act as a direct retainer 

C. To counteract the movement of denture which is caused during engagement of retentive arm  

D. None of the above 

The correct answer is C.  To counteract the movement of denture which is caused during engagement of retentive arm 

The rigid reciprocal arm helps in reciprocating stress generated against the tooth by the retentive arm. It also stabilizes the denture against horizontal movement and is always situated above the height of contour. 

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Intracoronal retainer placed in the abutment tooth has the following disadvantage:

 # Intracoronal retainer placed in the abutment tooth has the following disadvantage:

A. It is unaesthetic

B. They cannot provide support and stability

C. Difficult laboratory procedures

D. Difficult to repair and replace

The correct answer is D. Difficult to repair and replace.

The advantages of internal or precision attachments are improved esthetics by elimination of a visible retentive component and vertical support. Its disadvantages are difficulty in repair and replacing, greater cost to the patient and inability to use in teeth having short clinical crowns and tissue supported distal extension denture bases. 

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A minor connector contacting the axial surface of an abutment should not be located on a:

 # A minor connector contacting the axial surface of an abutment should not be located on a:

A. Flat surface

B. Concavo-convex surface

C. Convex surface

D. Concave surface

The correct answer is C. Convex surface.

Minor connector contacting the axial surface of an abutment should not be located on a convex surface. Instead, it should be located in an embrasure. 

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The first step in surveying the cast for RPD is:

 # The first step in surveying the cast for RPD is: 

A. Establishment of guiding plane

B. Establishments of undercuts for retention

C. Establishment of tooth contour for esthetics

D. Establishment of interferences for major connector

The correct answer is A. Establishment of guiding plane.

The step by step procedures in surveying are:

- Guiding planes

- Retentive areas

- Interferences

- Esthetics

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A wrought wire clasp is considered most effective in Kennedy Class:

 # A wrought wire clasp is considered most effective in Kennedy Class: 

A. III cases for periodontally weakened abutment teeth

B. I cases for periodontally weakened abutment teeth

C. II cases for the non edentulous side

D. IV cases with periodontally weakened teeth

The correct answer is B. I cases for periodontally weakened abutment teeth.

The wrought wire clasp is generally considered to flex and be kinder to the abutment tooth periodontally although it engages the undercuts about two to three times greater than a cast clasp. 

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# Cotton wool appearance is seen in:

 # Cotton wool appearance is seen in:

A. Paget’s disease

B. Osteomyelitis

C. Fibrous dysplasia

D. Achondroplasia

The correct answer is A. Paget's disease.

The radiographic appearance of chronic diffuse sclerosing osteomyelitis is, as the name suggests,

that of a diffuse patchy, sclerosis of bone often described as ‘cotton-wool’ appearance. This radiopaque lesion may be extensive and is sometimes bilateral. In occasional cases, there is bilateral involvement of both the maxilla and the mandible in the same patient. Because of the diffuse nature of the disease, the border between the sclerosis and the normal bone is often indistinct. The pattern may actually mimic Paget’s disease of bone or cemento-osseous dysplasia.

Reference: Shafer's 

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