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Questions and Answers
Which technique is primarily used in the case of intra-coronal restorations?
Which technique is primarily used in the case of intra-coronal restorations?
The dipping method results in a thick layer of wax that captures all details of the preparation.
The dipping method results in a thick layer of wax that captures all details of the preparation.
False
What tool is used for measuring the thickness of wax?
What tool is used for measuring the thickness of wax?
Wax caliper
The wax pattern is primarily constructed using __________ techniques.
The wax pattern is primarily constructed using __________ techniques.
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Match the method of wax pattern construction with its description:
Match the method of wax pattern construction with its description:
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Which type of wax is used in the indirect technique?
Which type of wax is used in the indirect technique?
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Incremental method does not induce any stresses during construction.
Incremental method does not induce any stresses during construction.
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What is the main advantage of the indirect technique?
What is the main advantage of the indirect technique?
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In coping construction, the thickness of the layer should be approximately __________ mm.
In coping construction, the thickness of the layer should be approximately __________ mm.
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What should be done before removing the wax pattern from the die?
What should be done before removing the wax pattern from the die?
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What is the appropriate contour for axial surfaces of a pattern that allows oral hygiene and accommodates inter-dental papilla?
What is the appropriate contour for axial surfaces of a pattern that allows oral hygiene and accommodates inter-dental papilla?
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Contact areas of maxillary teeth should be located centrally.
Contact areas of maxillary teeth should be located centrally.
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What happens if a margin is over-contoured?
What happens if a margin is over-contoured?
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The palatal cusps of upper teeth and buccal cusps of lower teeth are referred to as __________ cusps.
The palatal cusps of upper teeth and buccal cusps of lower teeth are referred to as __________ cusps.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What should be done with the occlusal contacts to avoid wearing?
What should be done with the occlusal contacts to avoid wearing?
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Under-contouring is more significant than over-contouring for causing gingival issues.
Under-contouring is more significant than over-contouring for causing gingival issues.
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What is the recommended thickness of the veneering porcelain in a wax pattern for a PFM crown?
What is the recommended thickness of the veneering porcelain in a wax pattern for a PFM crown?
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The process of milling wax blocks using CAD/CAM machines is referred to as __________.
The process of milling wax blocks using CAD/CAM machines is referred to as __________.
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What is a consequence of an open contact between teeth?
What is a consequence of an open contact between teeth?
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What is the first step in the lost wax technique for cast restoration?
What is the first step in the lost wax technique for cast restoration?
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Type II wax is used for direct techniques inside the patient's mouth.
Type II wax is used for direct techniques inside the patient's mouth.
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What is the purpose of adding beeswax in the composition of the wax pattern?
What is the purpose of adding beeswax in the composition of the wax pattern?
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The process of burning out the wax pattern creates a ______ for the molten metal to flow into.
The process of burning out the wax pattern creates a ______ for the molten metal to flow into.
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Match the type of wax with its characteristic:
Match the type of wax with its characteristic:
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Which of the following is NOT a requirement of casting wax?
Which of the following is NOT a requirement of casting wax?
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The components of a wax pattern include paraffin wax, beeswax, and dammer resin.
The components of a wax pattern include paraffin wax, beeswax, and dammer resin.
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List two characteristics that casting wax should possess after carving.
List two characteristics that casting wax should possess after carving.
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The heating instrument used for wax pattern fabrication allows for accurate control of ______.
The heating instrument used for wax pattern fabrication allows for accurate control of ______.
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What is the main purpose of using a sprue former in the lost wax technique?
What is the main purpose of using a sprue former in the lost wax technique?
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Study Notes
Wax Pattern Overview
- The lost wax technique is used to create metal cast restorations from wax patterns.
- Process involves: wax pattern > sprue former > investment > burn out of wax > mold > molten metal casting.
Requirements of Casting Wax
- Must flow easily and preserve fine details until investment.
- Should accept additions and be carved without chipping.
- Must be polishable, have minimal stress relaxation, and evaporate without residues.
- Different color from die material essential for contrast.
- Should retain strength and rigidity after cooling.
Components of Wax Pattern
- Paraffin wax or synthetic wax (40-60%).
- Beeswax to boost melting temperature and rigidity.
- Damar resin included to reduce flaking.
- Dies used for color contrast.
Types of Wax
- Type I: Medium wax for direct techniques, softens at 37°C.
- Type II: Soft wax for indirect techniques, melts at 25°C.
Instruments for Fabrication
- Heating instrument (normal or electric) for precise temperature control.
- Waxing tools: includes droppers, burnishers, and various carvers.
- Wax caliper for measuring thickness.
- Zinc stearate powder to assess occlusal contact.
Techniques of Wax Pattern Fabrication
- Direct technique allows creation inside the patient's mouth, suitable for intra-coronal restorations using medium wax.
- Indirect technique involves preparing a die on a stone cast with soft wax, popular for efficiency.
- Indirect-direct technique combines both methods for final adjustments intra-orally.
Methods of Wax Pattern Construction
- Dipping method: involves dipping the die into molten wax to create a thin, uniform layer (coping).
- Incremental method: wax is melted and added in layers, but frequent additions can induce stress and distortion.
Steps of Wax Pattern Construction
- Coping Construction: Thin thimble non-anatomical crown adheres to preparation using dipping or droppers.
- Pattern Removal & Evaluation: Cool the wax pattern before removal; ensure accurate adaptation to die.
- Proximal Surface: Shape for oral hygiene; specific contact areas differ for maxillary and mandibular teeth.
- Buccal & Lingual Surfaces: Height of contour protects gingiva; avoid overcontouring to reduce plaque and gingival issues.
- Occlusal Surface: Functional and non-functional cusps defined for grinding and food prevention with tripoding concept.
- Margination: Margins refined before investing to improve adaptation, stress relief must be avoided.
Wax Pattern for Veneered Crowns
- Full anatomical wax pattern created, with controlled cut-back for uniform veneering porcelain thickness (0.8-1mm) to enhance properties.
Recent Advances
- CAD/CAM technology enables milling wax blocks for improved accuracy, documentation, and efficiency in fabrication.
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Description
This quiz covers the process of creating a wax pattern for cast restoration in dentistry using the lost wax technique. It includes steps from the initial wax pattern to the final casting of metal or ceramics. Test your understanding of this essential procedure in dental applications.
