Lecture 1: Intro to RPD, Custom Tray Fabrication, Surveying

What are the 3 goals of prosthodontics treatment?

1. elimination of oral disease

2. preservation of health & relationships of teeth & oral/paraoral structures

3. restoration of oral function

When a patient removes their RPD, it allows their tissues to ____.

Rest

Why is an RPD an indication in a long span edentulous area?

Not desirable for long-span bridge

Is an RPD easier or harder for plaque removal compared to a FPD?

Easier

What are the 9 components of an RPD?

1. Direct retainer

2. Major connector

3. Minor connector

4. Rest

5. Proximal plate

6. Indirect retainer

7. Denture base connector/plastic retention area/retentive framework

8. Denture base

9. Denture teeth

What is a "tooth-support" prosthesis design?

teeth on both sides of edentulous space (tooth-bound RPD)

What is a "tooth-tissue" prosthesis design?

tooth on one side of edentulous space and tissue on the other

What is a "musosa/tissue" prosthesis design?

no teeth support, sits on top of mucosa only

What are the indications for a mucosa/tissue prosthesis design?

Flippers; otherwise not used

T/F: All caries must be removed PRIOR to RPD treatment planning.

True

What can existing restorations conditions tell you about a patient during RPD treatment planning?

The patient and their needs

What should be evaluated about periodontal conditions during RPD treatment planning?

If there is enough bone support & if there is any disease present

Why is the vitality of abutment teeth observed during RPD treatment planning?

Need stable teeth for tooth-supported denture

Why should the residual ridge conditions be checked during RPD treatment planning?

The quality of the mucosa determines if it will support the RPD; check if hyperplasia present

How are the occlusal plane, arch form, and occlusal relationship observed during RPD treatment planning?

Diagnostic mounting

The Kennedy Classification System was proposed by who and in what year?

Dr. Edward Kennedy in 1925

Which Kennedy classification type is the most common?

Class I

Which Kennedy classification type is the least common?

Class IV

What are additional areas of edentulism referred to as in the Kennedy classification system?

Modification spaces

Describe Kennedy Class I

Bilateral edentulous areas located posterior to the natural teeth; most common type

What type of prosthesis design is Kennedy Class I?

tooth-tissue support

Describe Kennedy Class II

A unilateral edentulous area located posterior to the remaining natural teeth

What type of prosthesis design is Kennedy Class II?

Tooth-tissue support

Describe Kennedy Class III

A unilateral edentulous area with natural teeth remaining both anterior and posterior to it

What type of prosthesis design is Kennedy Class III?

Tooth-tooth support

Describe Kennedy Class IV

A single, but bilateral (crossing the midline) edentulous area located anterior to the remaining natural teeth; least common type

T/F: No modification areas can be included in Class IV arches?

True

What are the rules called that dictate the Kennedy Classification System?

Applegate's Rules

In Applegate's Rules, should classification occur before or after any extractions?

After

In Applegate's Rules, if a 3rd molar is missing and it is NOT to be replaced, is it considered in the classification?

No

In Applegate's Rules, if a 3rd molar is present and is to be used as an abutment, is it considered in the classification?

Yes

In Applegate's Rules, if a 2nd molar is missing and is NOT to be replaced, is it considered in the classification?

No

In Applegate's Rules, what edentulous space always determines the classification?

Most posterior edentulous space

In Applegate's Rules, what are edentulous areas other than those that determine the classification referred to as?

Modifications

In Applegate's Rules, what are modifications designated by?

Numbers

In Applegate's Rules, is the extent of the modification or the number of additional edentulous areas considered?

Only the number of modifications

In Applegate's Rules, why are NO modification areas included in Class IV arches?

Other edentulous areas that lie posterior to the single bilateral areas crossing the midline would instead determine the classification

How far away should the pencil borders be from the gingival margins in custom tray fabrication?

3-5 mm

How far away should be pencil borders be from the depth of the vestibule in custom tray fabrication?

2-3 mm

What areas should be included in a custom tray?

All areas that will facilitate prosthesis fabrication

How many sheets of wax should be used in a custom tray?

1 sheet over edentulous areas & 2 sheets over teeth

What is the purpose of adding a tray stop?

Prevents the tray from being pushed down too far

Where should tray stops be placed?

Non-critical areas: incisal edge or edentulous ridge

What areas should be avoided when placing tray stops?

Abutment teeth or any tooth surfaces that will be covered by RPD framework

What is the purpose of the wax sheets in a custom tray?

Provide space for the impression material

What is the purpose of aluminum foil in a custom tray?

Ease of removal prior to final impression procedure

When is the wax and foil removed from the custom tray in a clinical scenario?

After border molding (provides tray stability during)

How is the handle placed on an RPD custom tray?

Horizontally

Does tooth-tissue support require border molding?

Yes

Does tooth-tooth support require border molding?

No

When can wax be removed from the custom tray in a tooth-tooth supported RPD?

Prior to the clinical session due to NO border molding

What does removing the wax from the custom tray do?

Removes the horizontal stop

What does failure to relieve the frenum area in a custom tray lead to?

Overextended border

What type of surveyor is used at IUSD?

Ney Tech Dental Surveyor

What is a surveyor?

A paralleling instrument (parallelometer)

What is the purpose of a surveyor?

used in making a dental prosthesis to locate and delineate the contours and relative positions of abutment teeth and associated structures

What does a surveyor determine?

Parallelism of 2 or more surfaces of teeth or other parts of the cast

What is an undercut gauge used for?

Determining the undercut amount that should be utilized in the design of length, shape, and thickness of the clasps

Does a longer and thinner undercut gauge show greater or less undercuts?

Greater

Does a shorter and thicker undercut gauge show greater or less undercut?

Less

What undercut gauge is not as retentive and easy to dislodge?

0.01"

What undercut gauge is the deepest, most secure, and most retentive?

0.03"

What are the types of undercut gauges?

0.01", 0.02", 0.03"

What type of undercut gauge is only used for wrought wire?

0.02"

What is the path of insertion?

Specific direction in which a prosthesis is placed

What is the purpose of the analyzing rod?

Analyzes undercuts of the teeth & tissue, determines the proper path of insertion

T/F: When all clasps are designed with the model set at the same fixed angle of survey table with the spindle, the common path of insertion is automatically established.

True

When you change the tilt of the cast, what do you also change?

Change guide planes, relocate the hight of contour, change the undercuts (to facilitate the use of specific clasps for better function/esthetics), may eliminate soft tissue interferences

What are guiding planes?

2 or more vertically parallel surfaces on abutment teeth and/ or fixed dental prostheses oriented so as to contribute to the direction of the path of placement and removal of a RPD, maxillofacial prosthesis, and overdenture; can be natural or created

What does the survey line correspond with?

Path of insertion

The survey lines mark the largest dimension of the tooth which is also known as ______.

Height of contour

Is the same survey table tilt/angulation used when marking teeth with survey lines?

Yes - all teeth marked at the same manner

What is the lower cone below the survey line?

Undercut area

If a clasp is placed ABOVE an undercut, is there retention?

No

If a clasp is placed BELOW an undercut, is there retention?

Yes

What is the first step of the survey process?

Identifying the most favorable tilt/path of insertion

How should the occlusal plane be positioned when surveying?

parallel to the platform of the surveyor

What should be checked when identifying the most favorable tilt/path of insertion?

Presence of suitable undercuts, elimination of hard & soft tissue interferences, creation of desirable esthetic, establishment of appropriate guiding planes

Where should the analyzing rod contact on a guide plane?

Occlusal 1/3 of proximal surface of abutment teeth

What does it mean if the tooth surface on a guide plane is concave?

Might have to prep tooth

What does it mean if the tooth surface on a guide plane is flat?

Guide plane is already there

T/F: Exaggeratedly tilted path of placement when surveying is acheivable.

False

What is the second step of the survey process?

Tripod the cast

What is the purpose of a tripod?

To record the cast position in relation to the selected path of insertion for future reference

How do you tripod a cast?

Locating 3 dots or parallel lines on the cast on anatomical areas that are not likely to change

Where should the tripod dots be placed on the cast?

Lingual surface

T/F: The vertical arm of the surveyor does not need to be locked in position when making a tripod

False

What is the third step of the survey process?

Analyzing the undercuts

What is the fourth step of the survey process?

Placing survey lines (heights of contour)

What is the fifth and last step of the survey process?

Locating and marking measured undercuts

While different type of retainers require different degrees of undercuts, they should always be where in relation to the survey line?

Under

Where are the undercut areas on a tooth?

3 aspects on buccal (MB, mid-buccal, DB), 3 aspects on lingual, 1 on each proximal

T/F: Infrabulge clasps should be avoided if soft tissue undercuts are present.

True