Questions and Answers
What is the approximate flexural strength of IPS e.max Press?
What is the composition of IPS e.max ZirPress?
What is the strength of IPS e.max CAD in its 'soft' state?
What is the volume percentage of lithium disilicate crystals in the microstructure of IPS e.max Press?
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What is the crystal size of lithium disilicate crystals in the final stage of IPS e.max CAD?
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What is the process used to precipitate lithium meta-silicate crystals in IPS e.max CAD?
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What is the volume percentage of lithium meta-silicate crystals in the 'blue' stage of IPS e.max CAD?
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What is the crystal size of lithium meta-silicate crystals in the 'blue' stage of IPS e.max CAD?
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What is the primary reason pure ZrO2 is not a useful dental ceramic?
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Which of the following oxide ceramics contains 99.9% alumina?
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What is the primary purpose of ZirLiner in IPS e.max ZirCAD frameworks?
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What is the purpose of magnifying the die in the Y-CSZ method of fabrication?
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What is the characteristic of IPS e.max Ceram that makes it suitable for layering?
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Which of the following is NOT an indication for IPS e.max Press?
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What is the primary use of oxide ceramics in dentistry?
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What is the characteristic that makes Procera AllCeram unique among dental ceramics?
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What is the advantage of IPS e.max over other types of ceramics?
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What is the composition of IPS e.max ZirCAD?
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What is the purpose of firing at 1120°C for 4 hours in the laboratory procedure for Slip-casting of core reinforced ceramics?
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Which of the following laboratory procedures involves scanning the preparation and transmitting the data to a milling unit?
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Which of the following is an indication for both IPS e.max Press and IPS e.max CAD?
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What is the primary limitation of other types of ceramics compared to IPS e.max?
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What is the characteristic of oxide ceramics in dentistry?
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What is the benefit of using IPS e.max ZirCAD for posterior bridges?
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What is the primary purpose of tooth preparation for all-ceramic crowns?
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What is the ideal depth of reduction on the midfacial aspect of a typical maxillary central incisor?
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What is the convergence angle recommended for all-ceramic preparation?
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Why is resin cement preferred for most all-ceramic crowns?
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Which surface treatment is recommended for Dicor, IPS Empress I and II ceramics?
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What is one of the esthetic advantages of all-ceramic restorations?
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Why are ceramics considered biocompatible?
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What is one of the challenges in using all-ceramic crowns?
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What is one of the classifications of all-ceramic crowns?
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Which of the following is an example of a castable ceramic?
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Why are surface flows in ceramics a concern?
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Study Notes
Rationale behind using all-ceramic restorations
- Esthetic: transmit light similarly to adjacent teeth, recreate value, control brightness and opacity
- Biocompatibility: ceramics are one of the most biocompatible materials with no allergic effect
Shortcomings of dental ceramics
- Brittleness: weak under tensile forces
- Cracks: surface flaws act as a start point for cracks, which can grow under alternating mastication forces and water presence
Challenges in using all-ceramic crowns
- Parafunctional activity
- Insufficient support from tooth preparation
- Insufficient porcelain thickness in the lingual aspect
- Opposing teeth that occlude with the cervical fifth of the crown
- Short clinical crowns
Classification of all-ceramic crowns
- Condensation ceramics (e.g., Porcelain for PFM)
- Castable ceramics (e.g., Dicor)
- Hot pressed or pressable ceramics (e.g., IPS Empress I and II)
- Slip-casting ceramics (e.g., In-ceram Alumina, Spinell, Zirconia)
IPS e.max Press
- Biocompatible lithium disilicate glass-ceramic ingots
- Flexural strength of 400 MPa
- Microstructure consists of approximately 70% volume of needle-like lithium disilicate crystals in a glassy matrix
Composition of materials for Press technique
- IPS e.max ZirPress: fluorapatite glass-ceramic ingots for pressing onto IPS e.max ZirCAD frameworks
Composition of materials for CAD/CAM technique
- IPS e.max CAD: lithium disilicate glass-ceramic
- IPS e.max CAD acquires final strength of 360 MPa and esthetic characteristics during a simple crystallization process
- Two-stage crystallization process: lithium meta-silicate crystals precipitate during the first step, and lithium disilicate crystallizes in a second heat treating step
- Final glass ceramic contains approximately 70% volume lithium disilicate crystals in a glass matrix
Indications for several types of e.max porcelain
- IPS e.max Press and CAD: anterior and posterior crowns, veneers, inlays, onlays, implant restorations
- IPS e.max Ceram: layering ceramic for achieving highly esthetic results on glass-ceramics and zirconium oxide
Advantages of e.max over other types of ceramics
- No high-value and opaque substructure material
- No strong bond interface required between dissimilar ceramic materials
- Flexural strength and fracture toughness of the layering ceramic are not a concern
Laboratory procedure for Slip-casting of core reinforced ceramics
- In-Ceram Alumina, Spinell, and Zirconia
- Special die for In-ceram
- Core build-up
Oxide ceramics: Y-CSZ composition and fabrication
- Combination of ZrO2 and Yttria oxides (Y2O3) to suppress phase transformation and cracking
- CAD/CAM system for scanning and milling
- Presintered or unsintered form
- Veneering with compatible porcelain
Oxide ceramics: Procera AllCeram
- Composition: densely sintered high-purity aluminum oxide core combined with compatible AllCeram veneering porcelain
- Fabrication: CAD/CAM system, dry pressing onto die, sintering, and veneering
- Clinical uses: posterior crowns and bridges, implant abutments, and implants
- Characteristics: high strength, low translucency, high opacity
Clinical procedure: preparation, impression, cementation
- Preparation: provide support for restoration, uniform porcelain thickness, ideal incisal reduction, shoulder or deep chamfer finish line
- Impression: surface treatment, acid etching, sandblasting
- Cementation: resin cement preferred to block crack propagation and affect shade due to high translucency
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Description
This quiz covers the rationale and benefits of using all-ceramic restorations in dentistry, including their esthetic and biocompatible properties. It also touches on the shortcomings of dental ceramics.
