Porcelain Inlay and Onlay| Properties, Preparation and Restoration | PPT

December 17, 2012 | By | Reply More

Porcelain Inlay and Onlay| Properties, Preparation and Restoration | PPT

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Porcelain Inlay and Onlay

www.neuronarc.com

Restorative Options – Direct

1970’s

Posteriors: amalgam

Anteriors: composite

2000’s

Posteriors: amalgam (material specific), composite (lesion specific)

Anteriors: composite

 

Evolution of Cavity Preparation Design for Posterior Composite

Taking into consideration the differences in the physical properties between the two materials (amalgam vs composite); and based on the rationale of the cavity preparation design for amalgam

Questions were asked: Do we need convergent walls? retention grooves? Worry about unsupported enamel? Extension for prevention? Do we need bulk?

New cavity preparation design for posterior composite was created; it was based on specific  characteristic of the material.

 

Why are we talking about amalgam/composite

Example of utilizing the skill/knowledge we acquired in using a specific material/procedure (amalgam restoration) and applying it on a new material/procedure (composite restoration)

Preparation skills should be easily transferable.

Knowledge on the rationale of cavity preparation will allow us to adapt to the new material based on the material’s specific characteristic.

Answer to your question on “why are we still teaching cast gold inlay/onlay”? – when only a few dentists are doing these kinds of procedures in their offices.

 

Restorative Options – Indirect

1970’s

Cast gold inlay/onlay, 3/4 crown, full cast crown, PFM

2000’s

Cast gold inlay/onlay, 3/4 crown, full cast crown, PFM

Porcelain/composite inlay/onlay

 

Differences between gold and porcelain restorations

Physical properties – porcelain more brittle

Mode of retention – bonding vs mechanical retention

Concept of margin

 

Based on these differences, can we design a cavity preparation for using porcelain intra coronally??

Starting with cavity preparation design for cast gold inlay/onlay, what features do we have to modify for porcelain????

Physical Properties

What cavity preparation features do we need to modify?

Bulk – more occlusal clearance

Reinforcement – bonding

Bevels contraindicated

 

Mode of Retention

Cast gold preparation rely on 6 to 7 degree of divergent walls and sharp internal line angles.

Porcelain rely on the bonding process, no need for 6 to 7 degree divergent wall and sharp internal line anlges.

 

Marginal Adaptation

Cast gold – rely on close adaptation (20u); lack of adhesion between tooth structure/cement/gold interface

Porcelain – rely on the adhesion between tooth structure/resin cement/procelain to  create a gap free continuous margin.

No gingival bevels needed to minimize the gap.

 

Empress Procelain System
All procelain restoration used for inlay, onlay, full crown

Castable

Adequate marginal fit

Better wear characteristic than conventional procelain

Similar to cast gold inlay/onlay in terms of cavity preparation design

 

Porcelain Fused to Metal Crown vs Empress: Similarities

 Highly esthetic

 Wear

 Brittle – reinforced through the bonding process

 

Composite vs Empress: Similarities

 Mode of retention – dentinal bonding agent

Apply skills you learn for composite on the bonding process.

 

Summary of Characteristics

Highly esthetic

Acceptable marginal fit

Conservation of tooth structure

Less occlusal wear

Highly technique sensitive

 

Indications

High esthetic demand

Replace moderate to large existing restoration

Fractured tooth/restoration

Moderate to large primary caries

 

Contraindiations

Unable to adequately isolate the field

Parafunctional habits – bruxing, clenching, excessive wear

 

Empress vs Gold Inlay/Onlay
Empress

Advantages

ESTHETIC

Conservation of tooth structure (gold onlay vs porcelain inlay)

Less complicated cavity design??

 Disadvantages

Expensive

Technique sensitive – bonding process

Abrasive to occluding dentition

 

Empress vs PFM
Empress

Advantages

Conservative cavity preparation

Foundation restoration may not be necessary

Less abrasive to occluding dentition

No metal collar

 Disadvantages

Expensive

Technique sensitive

 

Cavity Preparation Design

1. Occlusal Depth/Cusp Reduction

Occlusal Depth = 1.5 to 2.0 mm

Cusp Reduction:Functional cusp = 1.5-2.0mm

Nonfunction cusp = 1.5 mm

2. Internal/External Line Angles

Rounded

3. Draw

Degree of draw = approximately 12 to 15 degree

4. Bevel

No bevel

 

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