Porcelain Inlay and Onlay

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Porcelain Inlay and Onlay
Preparation and Restoration

• Dr. Ignatius Lee

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Restorative Options - Direct

• 1970s
• Posteriors amalgam
• Anteriors composite

• 2000s
• Posteriors amalgam (material specific),
  composite (lesion specific)
• Anteriors composite

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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.

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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 materials 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.

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Restorative Options - Indirect

• 1970s
• Cast gold inlay/onlay, 3/4 crown, full cast
  crown, PFM

• 2000s
• Cast gold inlay/onlay, 3/4 crown, full cast
  crown, PFM
• Porcelain/composite inlay/onlay

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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????

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Physical Properties

• What cavity preparation features do we need to
  modify?
• Bulk - more occlusal clearance
• Reinforcement - bonding
• Bevels contraindicated

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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.

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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.

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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

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Porcelain Fused to Metal Crown vs Empress
Similarities

• Highly esthetic
• Wear
• Brittle - reinforced through the bonding process

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Composite vs Empress Similarities

• Mode of retention - dentinal bonding agent
• Apply skills you learn for composite on the
  bonding process.

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Mechanism of Adhesion

• Porcelain etched with hydrofluoric acid
  (micromechanical)
• Bond between etched tooth and DBA - identical to
  composite/tooth
• Silane coupling agent - chemical bond

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Summary of Characteristics

• Highly esthetic
• Acceptable marginal fit
• Conservation of tooth structure
• Less occlusal wear
• Highly technique sensitive

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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

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Empress vs Gold Inlay/OnlayEmpress

• 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

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Empress vs PFMEmpress

• Advantages
• Conservative cavity preparation
• Foundation restoration may not be necessary
• Less abrasive to occluding dentition
• No metal collar
• Disadvantages
• Expensive
• Technique sensitive

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Cavity Preparation Design

• 1. Occlusal Depth/Cusp Reduction
• Occlusal Depth 1.5 to 2.0 mm
• Cusp ReductionFunctional cusp 1.5-2.0mm
• Nonfunction cusp 1.5 mm
• 2. Internal/External Line Angles
• Rounded

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Cavity Preparation Design

• 3. Draw
• Degree of draw approximately 12 to 15 degree
• 4. Bevel
• No bevel

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Mn first premolar- DO amalgam with fractured
lingual cusp, deep pulpal floor
Existing amalgam removed, making all walls
divergent, smoothed all cavosurface margins
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Mx first molar - MOD amalgam with deep pulpal
floor (4mm)
Existing amalgam removed
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Proximal walls and gingival seats extended,
occlusal wall divergent, clinical judgement was
made to cover DL cusp (with shoulder)
No cavosurface bevel on shoulder
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MOB amalgam on Mx first molar with deep pulpal
floor
Existing amalgam removed, make all walls
divergent and smoothed all cavosurface margins
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Occl amalgam on Mn first molar, normal pulpal
depth patient complaining about pain on
function- Dx DB cusp fractured
Patients occlusion
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Existing amalgam removed, DB cusp reduced by 2mm,
all walls divergent
No shoulder on DB cusp - WHY???
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MOD amalgam on Mn second molar with fractured Li
cusp. Normal pulpal depth all amaglam removed
Proximal box divergent, Li cusp - smoothed
cavosurface margin
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MOD amalgam on Mn first molar - occlusal fractured
Shade selection BEFORE rubber dam need dentin
shade (match shade at gingival third) and overall
shade
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Finished preparation rubber dam removed ready
for impressioning proximal box divergent, cusp
reduction, buccal cusp with heavy bevel (no
shoulder)
Buccal view
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Wax up on working cast
Special die for shade matching/staining - reason
for taking the dentin shade
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Restoration on die/working cast
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Trying in under rubber dam adjust proximal
contact do not adjust occlusal contact
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Cementation under rubber dam using resin cement
excess cement removed using cotton tip
Excess resin cement removed from
proximal/gingival margins using an explorer
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Rubber dam removed following cementation
Adjust occlusion using fine diamond in high speed
hand piece
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Laboratory Exercise - Mn first molar, MOD onlay
preparation for porcelain
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Finished Preparation - MOD porcelain onlay
preparation
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Restoration on die, back from laboratory
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Restoration seated under rubber dam
Bu view after cementation
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Restoration on die, back from laboratory
Restoration seated under rubber dam