Kennedy Class II RPD Design Flashcards

Questions and Answers

What are the two main types of removable partial dentures?

Tooth support (Class III)

Tissue and tooth support (Class I, II, or IV)

Both A and B (correct)

None of the above

Which class has the majority of support from tissue?

Class I

Where do Class I and distal of Class II derive their support from?

Primary support is from tissues underlying the base and secondary support from the abutment teeth.

Where does Class IV derive their support from?

Primary tooth support and secondary tissue support. Signup and view all the answers

Where does Class III derive its support from?

All support from the abutment teeth. Signup and view all the answers

What should you expect when you see a distal extension partial denture?

Anticipate that there is a functional movement. Signup and view all the answers

What is the principal design for distal extension?

Mesial rest with combination clasp, bar type. Signup and view all the answers

How does changing the position of the mesial rest seat change the behavior of the retentive arm?

If the rest seat is distal to the retentive arm when you engage the tooth, it causes traumatic force on the tooth; if mesial, the retentive arm disengages the undercut. Signup and view all the answers

What is very important about I-bar RPI?

Use 0.01 midfacial undercut. Signup and view all the answers

Why is it important to use 0.01 midfacial undercut with I-bar RPI?

It prevents the I-bar from moving forward and disengaging the tooth under functional load. Signup and view all the answers

When is I-bar indicated?

Distal extension RPD. Signup and view all the answers

When is I-bar contraindicated?

Tissue undercut. Signup and view all the answers

Contraindications for the use of I-bar:

Deep tissue undercut = Contraindication Insufficient vestibular depth = Contraindication Lack of facial undercut = Contraindication Severe mesial inclined tooth = Contraindication Signup and view all the answers

When is I-bar commonly used?

Class I. Signup and view all the answers

What happens when the patient has a very shallow vestibule?

Buccal frenum pulls up, and you cannot design an RPI because the I-bar needs to go downward first. Signup and view all the answers

Why is it bad if a patient has a severely mesially inclined tooth?

The undercut will be positioned at the tip of the mesial, and the I-bar won't work effectively. Signup and view all the answers

What do we use when the bar is not working well?

Wrought wire (mesial rest + distal proximal plate + wrought wire). Signup and view all the answers

Where is wrought wire soldered?

10 mm away from the clasp tip, ensuring it is engaging a 0.02 mesial undercut. Signup and view all the answers

Once there is a distal extension, what else is there?

A fulcrum line. Signup and view all the answers

What are the three choices with Class II mod 1?

All of the above Signup and view all the answers

What do you need before you start your RPD design?

Periapical X-ray, articulated cast, and a surveyed cast. Signup and view all the answers

Study Notes

Removable Partial Dentures (RPD) Classifications

Two main types: Class III (tooth support) and Classes I, II, or IV (tissue and tooth support).
Class I has the majority of support from tissues.

Support Sources

Class I and distal portion of Class II: primary support from underlying tissues; secondary support from abutment teeth.
Class IV: primary support from teeth; secondary support from tissues.
Class III: all support derived from abutment teeth.

Distal Extension and Design Principles

Anticipate functional movement with distal extension partial dentures.
Principle design for distal extension involves mesial rest with a combination clasp or bar type.

Rest Seat Position Effects

If rest seat is distal to retentive arm, occlusal load can create traumatic forces; if mesial, load causes retentive arm to disengage from the undercut.
Important to use 0.01 midfacial undercut with I-bar RPI for proper engagement.

I-bar Indications and Contraindications

I-bar indicated for distal extension RPD.
Contraindicated with deep tissue undercuts, insufficient vestibular depth, lack of facial undercut, and severely mesially inclined teeth.

Special Cases

In shallow vestibules, buccal frenum elevation may hinder the design of an RPI.
Severely mesially inclined teeth can position the undercut too close to the interproximal area, making I-bar ineffective.

Wrought Wire Use

When conventional bar designs are ineffective, use wrought wire configured with mesial rest and distal proximal plate.
Wrought wire should be soldered 10 mm away from the clasp tip, engaging 0.02 mesial undercut.

Fulcrum Line Considerations

Distal extensions always create a fulcrum line influencing RPD stability.

Class II Modifications

Class II modification choices include:
- No clasp
- Wrought wire engaging 0.01 undercut
- Wrought wire not engaging undercut.

Stability Considerations

No additional stability needed in robust ridge conditions with multiple supporting teeth; no clasp required.
Need additional stability in cases of severely resorbed ridges; may use clasp that circumferentially wraps around the tooth without engaging undercuts.
Long edentulous spaces in the maxilla necessitate clasp placement to provide stability against gravitational forces.

Pre-Design Requirements

Before starting RPD design, obtain periapical X-rays and prepare articulated and surveyed casts.

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Description

This quiz focuses on the essential concepts of Kennedy Class II removable partial dentures (RPD) design and tooth modifications. It covers different classes of RPDs, their support mechanisms, and key terms related to the subject. Perfect for dental students and practitioners looking to reinforce their knowledge on RPD classifications.