Transcript Conservative Porcelain Restorations

Porcelain Inlay and Onlay
Preparation and Restoration
Dr. Ignatius Lee
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
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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
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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
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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.
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Marginal Adaptation

Cast gold - rely on
close adaptation (20u);
lack of adhesion
between tooth
structure/cement/gold
interface
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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
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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
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Composite vs Empress:
Similarities
Mode of retention - dentinal bonding agent
 Apply skills you learn for composite on the
bonding process.

Mechanism of Adhesion

Etched
Porcelain
Silane
Coupling
agent
Dentinal
Bonding
Agent
Etched
Tooth
Resin
Adhesive
Dentinal
Bonding
Agent
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Porcelain etched with
hydrofluoric acid
(micromechanical)
Bond between etched
tooth and DBA identical to
composite/tooth
Silane coupling agent chemical bond
Summary of Characteristics
Highly esthetic
 Acceptable marginal fit
 Conservation of tooth structure
 Less occlusal wear
 Highly technique sensitive

Indications
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High esthetic demand
Replace moderate to large existing restoration
Fractured tooth/restoration
Moderate to large primary caries
Contraindiations
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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
Cavity Preparation Design
3. Draw
Degree of draw = approximately 12 to 15
degree
4. Bevel
No bevel
Mn first premolar- DO
amalgam with fractured
lingual cusp, deep pulpal
floor
Existing amalgam
removed, making all
walls divergent,
smoothed all
cavosurface margins
Mx first molar - MOD
amalgam with deep pulpal
floor (4mm)
Existing amalgam
removed
Proximal walls and gingival
seats extended, occlusal
wall divergent, clinical
judgement was made to
cover DL cusp (with
shoulder)
No cavosurface bevel
on shoulder
MOB amalgam on Mx
first molar with deep
pulpal floor
Existing amalgam
removed, make all walls
divergent and smoothed
all cavosurface margins
Occl amalgam on Mn first
molar, normal pulpal
depth; patient complaining
about pain on functionDx: DB cusp fractured
Patient’s occlusion
Existing amalgam
removed, DB cusp
reduced by 2mm, all walls
divergent
No shoulder on DB cusp WHY???
MOD amalgam on Mn
second molar with
fractured Li cusp. Normal
pulpal depth; all amaglam
removed
Proximal box divergent,
Li cusp - smoothed
cavosurface margin
MOD amalgam on Mn
first molar - occlusal
fractured
Shade selection BEFORE
rubber dam; need dentin
shade (match shade at
gingival third) and
overall shade
Finished preparation;
rubber dam removed;
ready for impressioning;
proximal box divergent,
cusp reduction, buccal
cusp with heavy bevel (no
shoulder)
Buccal view
Wax up on working cast
Special die for shade
matching/staining - reason
for taking the dentin
shade
Restoration on die/working cast
Trying in under rubber dam;
adjust proximal contact; do not
adjust occlusal contact
Cementation under
rubber dam using resin
cement; excess cement
removed using cotton
tip
Excess resin cement
removed from
proximal/gingival margins
using an explorer
Rubber dam removed
following cementation
Adjust occlusion using fine
diamond in high speed hand
piece
Laboratory Exercise - Mn first molar,
MOD onlay preparation for porcelain
Finished Preparation - MOD porcelain onlay preparation
Restoration on die, back
from laboratory
Restoration seated
under rubber dam
Bu view after
cementation
Restoration on die, back
from laboratory
Restoration seated under
rubber dam