Tooth preparation for Metal ceramic crowns.
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Transcript of Tooth preparation for Metal ceramic crowns.
Metal Ceramic Crown Preparation
• Most widely used.• Improvement in:
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Technology.Skills.Growing cosmetic demands.
• Complete coverage by metal.• Veneer porcelain
mimics
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Extention varies natural teethnatural teeth
Major requirement:
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More amount of tooth reduction
areas Metal veneered with ceramic.
Place for - Metal- Porcelain
Sufficient bulk.
- Mask metal.- Esthetics.
Least conservative preparation.
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Other problems
• Alloy’s compatibility with ceramics.
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- Physical properties.- Adequate bond strength.
High fusing range.Low thermal expansion.
Indications
• Esthetic demands.
• Durability More ( than all ceramic ).
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Marginal fit
better in all ceramics.
• Crown and bridges metal substrate.
• Allows placement of rests, if RPD is a part of treatment.
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connectors
• Extensive tooth destruction:
• Correction of malocclusion.• Correction of occlusal plane.
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- Caries.- Trauma- Existing restoration- Endodontically treated
Contra indications
• Patient with active caries.• Untreated periodontal diseases.• Young patients with large pulp chambers.
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Risk of pulp exposure
- Porcelain laminates.- Composite laminates.
• If more conservative restoration is possible.• Long Spans.• If facial walls are intact.
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Partial veneer is possible and favorable.
Advantages
• Strength Good, compared to all ceramics
• Mimic natural appearance Characterization
• Good retention All axial walls are included.
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Reinforcement and support to brittle ceramic.
stains IntrinsicExternal.
Disadvantages• More amount of tooth removal.• Facial margins often Subgingivally
• Inferior esthetics compared to all ceramics.
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PDL diseaseMargins supra gingivally esthetics not a problem
Indicated:
• Brittle fracture Poor design.• Difficulty design / shaping and shade
matching.• Many procedural steps.
• Expensive.
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- Casting.- Porcelain adaptation.
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Preparation
• Guiding groves.• Incisal / Occlusal reduction.• Labial / buccal reduction.• Axial reduction
• Final finishing.
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Proximal .Lingual surfaces.
Anterior tooth preparation
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PUTTY INDEX
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Incisal bevel
• Palatally directed Maxillary anteriors.• Buccaly directed Mandibular
anteriors.
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Incisal Preparation
• Incisal edge 2mm reduction.
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Adequate thickness
Translucency
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• Cervical plane of reduction determines
• Incisal plane Provides space for porcelain veneer.
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Path of withdrawal.
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Lingually• Concavity
• Use foot ball shaped bur / doughnut or any other suitable bur.
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Adequate clearance
Centric contacts
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Wing preparation
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Variants
• Wing less preparation.
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No definite Trancession from chamfer to shoulder
Shoulder gradually narrows lingually.
Prevention of trauma to pulp
• Adequate coolant while preparing ( copious irrigation ).
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• Intermittent strokes Preparation.
• Care while preparation of Subgingival margins
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• Permanent gingival recession.
Finishing
• Smooth glass like / satin like finish.• Rounden all line angles.• No scratches marks.• Use gingival retraction.
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POSTERIOR TOOTH PREPARATION
POSTERIOR METAL-CERAMIC CROWN
POSTERIOR METAL-CERAMIC CROWNS
STEP NO : 1OCCLUSAL REDUCTION FOLLOWED BY FUNCTIONAL CUSP BEVEL.barell
POSTERIOR METAL-CERAMIC CROWNS
STEP NO : 2DEPTH ORIENTATIONGROOVES
POSTERIOR METAL-CERAMIC CROWNS
STEP NO :3FACIAL REDUCTION-OCCLUSAL HALF
POSTERIOR METAL-CERAMIC CROWN
STEP NO :4
FACIAL REDUCTIONGINGIVAL HALF
POSTERIOR METAL-CERAMIC CROWN
STEP NO: 5
PROXIMAL AXIAL REDUCTION
POSTERIOR METAL-CERAMIC CROWN
STEP NO :6
LINGUAL AXIAL REDUCTION
POSTERIOR METAL-CERAMIC CROWN
STEP NO : 7
AXIAL FINISHING
POSTERIOR METAL-CERAMIC CROWN
STEP NO :8
GINGIVAL BEVEL
POSTERIOR METAL-CERAMIC CROWN