Lab 3- denture design part 1 Flashcards by Rabia Dosani

Name the stages of designing a denture

Saddle
Support
Retention
Reciprocation
(5. Guide planes)
Connectors

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What is the first thing you do when you are designing a denture

Outline the saddles

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After outlining the saddles what do we need to identify

Is the denture:
tooth borne
tissue borne
or both

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If the tooth is tooth borne what do we need to highlight on our design sheet

Occlusal rest

Cingulum rests

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Where do we position on the rests on a bounded saddle

Use the nearest abutment tooth to the saddle

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For a LOWER free end saddle where do we position the rest?

We use the furthest side of the abutment tooth

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When placing our rests what do we need to consider

The occlusion - make sure occlusal rests don’t interfere with the occlusion

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What can happen if a cingulum rest is sloping

It can have a tendency to push the tooth forwards

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How do we want to place a cingulum rest

We want the rest seat to be perpendicular to the long axis of the tooth

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How do we prep the tooth so that the cingulum rest is perpendicular to the long axis of the tooth

We can add composite onto the cingulum to ensure that the rest will be perpendicular to the long axis of the tooth

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What does perpendicular mean

90 degree angle to

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Why do we want the cingulum rest to be perpendicular to the long axis of the tooth

So that lateral force is directed downwards and doesn’t move the tooth from its original position

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How can we add retention to a partial denture

Clasps
Adhesion/ cohesion of saliva
Friction
Accessory retention such as magnets

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What do clasps require

Undercuts

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how do we identify where undercuts are on a tooth

By surveying

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What do we mark the survey line with

The SIDE of the surveyer lead

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How do we orientate the lead when using the surveyor

We make sure the lead is perpendicular to the direction sticky food will pull the denture

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What is a surveryer

A mechanical device that is used to identify where tissue and tooth undercuts are in the oral mucosa

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What are surveyors used for

Identifying undercuts for clasps

2. Identifying a path of insertion

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What is the path of withdrawal?

The direction that sticky food pulls

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How do we measure the horizontal depth of an undercut

Using pre measured gauges

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List some materials we can use to make clasps

Cobalt chrome
Stainless steel
Gold

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How much horizontal depth is needed for a cobalt chrome clasp

0.25mm

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How much the horizontal depths needed for a Stainless steel clasp

0.5mm

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How much the horizontal depth is needed for a Gold clasp

0.75mm

Why does cobalt chrome need less undercut

As it has a lower modulus of elasticity (it is stiffer) so needs less undercut

How can clasps approach the tooth

1. Occlusally | 2. Gingivally

Give examples of occlusally approaching clasps

1. 3 arm clasps | 2. Ring clasps

Give examples of gingivally approaching clasps

I bar

Name the 3 parts of a 3 arm clasp

1. Retentive arm 2. Reciprocal arm 3. Occlusal rest

Where does the retentive arm go

Into the undercut so below the survey line | first 2/3 will be above the undercut and terminal 1/3 in undercut

Where does the reciprocal arm go

Above the survey line

Do we put 3 arm clasps on a molar

no as the clasp is too short

How long does the retentive arm need to be

15mm

What can happen If the retentive arm is too short

The material will stretch beyond its elastic limit and break

What are the advantages of gingivally approaching clasps

1. More aesthetic 2. Can be made longer than occlusal approaching clasps 3. Can be used for pre molars and canines

What are the disadvantages of gingivally approaching clasps

1. More damaging to periodontal health | 2. Non undercut buccal surface may need to be built up first with composite

How can we manipulate undercuts

By adding composite (this can add or remove undercuts)

What happens to a patients smile/lip line as you get older

Lip line get lower so you can see more of the lower teeth

Ideally which teeth do we want to clasp

The closet teeth to the saddle

How many claps will give us maximum retention

One clasp on either end of the saddle (2 in total)

Other than saddles what else do we need to support

Extra components such as rests placed on teeth away from the saddle

What factors do we consider when choosing a clasp

Depends on: 1. Undercuts 2. Aesthetic demand

For molars what type of clasp do we sully choose?

Occlusally approaching clasps

Why do we choose occlusal approaching clasps for molars?

As they can be long enough and dont cover and gingival margins

For premolars what type of clasp do we choose?

Gingival approaching eg I bat

Why do we choose occlusal approaching clasps for molars?

They are long enough and more aesthetic

For premolars what type of clasp do we sully choose?

Gingival approaching eg I bat

Why do we choose Gingival approaching clasps for canines?

They are long enough and more aesthetic

What is the path of withdrawal

The direction sticky toffee wants to pull the denture

What is bracing

Resistance to lateral movement

List some potential functions of a connector

1. To join one or more saddles together 2. To provide rigidity to the design 3. To provide support 4. To provide bracing

List the major connectors we can use in the lower arch

1. Lingual bar 2. Sub lingual bar 3. Lingual plate 4. Dental bar 5. Buccal bar

List the major connectors we can use in the UPPER arch

1. Plate 2. Post, middle and anterior bar 3. Horeshoe 4. Ring

Name the most common major connector we use in the lower arch

Lingual bar

What is a lingual bar made from

A prefabricated blank pattern

What are the disadvantages of a lingual bar

Offers no support or direct retention

What do we need to ensure we have before placing a lingual bar

Need minimum of 4mmx2mm to have sufficient rigidity | 3mm gingival Clarence needed + 4mm height of bar

How much space do we need vertically to place a lingual bar

At least 7mm

What do we need to ensure we have before placing a sublingual bar

4mmx2mm | 3mm gingival Clarence and 2mm height

How much space do we need vertically to place a sublingual bar

5mm

What are the disadvantages of a sub lingual bar

Offers no support or retention | Needs careful impression technique!!!

What is better sublingual or lingual bar

Sub lingual as they sit more comfortably in the patients mouth

What is an advantage of a lingual plate

Give support and indirect retention

What is an disadvantage of a lingual plate

Gingival coverage is detrimental to oral health | Needs to be supported by teeth at both ends