Dental Ceramics Quiz

Inorganic, non-metallic materials produced by heating raw minerals at high temperatures.

Ceramics containing a glassy matrix strengthened by crystalline structures like alumina and mica.

A classification of ceramics where crystalline phases are formed from a glassy phase.

A material's ability to resist breaking when stretched or pulled.

A material's ability to withstand crushing forces.

A classification of ceramics based on the temperature required for firing.

Ceramics used in PFM restorations, typically fired between 950°C and 1020°C.

A multiphase solid with a glass phase and finely dispersed crystals. Controlled crystallization of the glass results in evenly distributed crystals.

A process that converts glass into a partially crystalline glass, involving two phases: nucleation and crystallization.

The stage where tiny crystalline nuclei form within the heated glass, creating the foundation for larger crystals.

The stage where the temperature is increased, causing the nuclei to grow into larger crystals, resulting in the desired degree of crystallinity.

A key component in dental ceramics, it acts as the basic glass former and provides translucency after firing.

These are added to the ceramic mix to reduce the melting point and increase the coefficient of thermal expansion.

A crucial component of ceramic mixtures, silica acts as a filler that forms the framework for other ingredients, providing strength to the porcelain.

A clay component that acts as a binder in ceramic mixtures, providing opaqueness, mouldability, and shape retention during firing.

Added to ceramic mix to improve its strength and act as a crack stopper.

A measure of the change in length per unit of original length when a material is heated or cooled by 1 Kelvin.

A type of mechanical bonding achieved by interlocking ceramic with micro-abrasions present on the surface of metal.

A bonding mechanism generated by the difference in COTE between porcelain and metal. It creates compressive forces that enhance the bond.

Weak attractive forces based on the mutual attraction of charged molecules that contribute to the initiation of chemical bonding between porcelain and metal.

A strong bonding mechanism involving the reaction between the oxides in the opaque layer of porcelain and oxides on the surface of metal.

The ability of a material to resist scratching or abrasion.

The ability of a material to resist wear and tear over time, often measured by its resistance to abrasion.

A type of bond failure in metal-ceramic restorations where no oxide layer forms on the metal surface, often due to surface contamination or improper cleaning.

This fracture type is most commonly observed in gold alloys and occurs when the ceramic breaks away from the metal due to a weak bond between the two materials.

This failure occurs when the ceramic breaks away from the metal substructure at the junction, often due to stress concentration or improper metal preparation.

A common type of failure in base metal alloys, characterized by excessive oxide layer formation on the metal, leading to a weak bond with the ceramic.

This failure is characterized by a thick oxide layer forming on the metal substructure, weakening the bond with the ceramic. It is most likely to occur in joints of bridges rather than crowns.

Sharp angles and pits on the metal surface can concentrate stress and weaken the bond between the metal and ceramic.

The metal framework must be sufficiently thick to prevent distortion and flexing during porcelain firing.

The intended junction between the metal and ceramic should be smooth and at a 90-degree angle for optimal bonding.

Occlusal contacts should be placed away from the metal-ceramic junction to prevent stress concentration and delamination.

Proximal contacts in anterior restorations should be placed lingual to the contact area for better esthetics and stress distribution.

The process of creating an oxide layer on the metal surface for chemical bonding with porcelain.

The removal of hydrogen gas from the metal during casting to prevent air bubbles that weaken the bond.

A controlled oxide layer is essential for strong bonding. It is formed by heating the metal substructure to a specific temperature.

Excess oxide can weaken the bond between the metal and ceramic, often leading to cohesive failure within the oxide layer.

A layer of opaque porcelain is applied to mask the metal substructure, provide the basic shade, and initiate the bond with the metal.

A technique for applying porcelain to a metal coping where porcelain is first applied to the most convex portion of the tooth, then carefully extended to other areas.

A specialized type of porcelain used to create a base for dental restorations. It masks the underlying metal and creates a natural-looking foundation.

The process of building up porcelain layers to form the tooth's structure.

A technique where a porcelain layer is carefully lifted from a die (dental mold) to create a smooth, precise shoulder on the crown.

The porcelain layer that forms the visible part of the tooth, giving it its natural shape and appearance.

A porcelain layer that forms the internal structure of the tooth, mimicking the dentin layer.

Applying a layer of dentin porcelain over the opaquer, extending it both gingivally and facially.

The process of packing porcelain powder tightly to create a dense, solid structure.

The reduction of excess liquid in the porcelain mixture during build-up.

The final step in the porcelain build-up process, where the crown is carefully shaped and contoured to match the original tooth.

Thin, transparent porcelain that is applied after the main porcelain layers to create a smooth, glossy surface.

The process of creating a glossy surface on the porcelain crown through heat treatment.

A type of glaze applied to the crown to improve its appearance and provide a protective layer.

The process of polishing the porcelain surface after the glaze is applied, to achieve a smooth and shiny finish.

The ability of porcelain to shrink when fired, making it essential to compensate for this shrinkage by creating a slightly larger form during the build-up process.

A process of converting glass into a partially crystalline material, involving two stages: nucleation and crystallization.

The process of making a material more resistant to cracking or breaking by creating tiny, evenly distributed crystals within the material.

A key component in glass-ceramics responsible for forming the glass matrix, providing stability and strengthening the porcelain.

A binder in glass-ceramics, providing opaqueness, moldability, and shape retention during firing.

A component in glass-ceramics that enhances strength by acting as a crack stopper.

A phenomenon that occurs when porcelain is overfired, causing it to become milky or cloudy due to recrystallization.

A process used to smooth and polish porcelain restorations, particularly in small areas like proximal contacts.

A technique for modifying the shade of porcelain using stains, often used to lighten dark shades.

A type of ceramic with a high glass content that mimics the optical properties of enamel and dentin. Commonly used in veneers.

A type of ceramic with improved mechanical properties due to the addition of crystalline fillers. Often used for restorations that require greater strength.

A type of ceramic composed entirely of crystals, providing high strength and toughness. Less commonly used in dentistry due to its opacity.

The difference in COTE between porcelain and metal causes compressive forces in the porcelain, leading to a stronger bond with the metal.

Interlocking ceramic with micro-abrasions in the surface of metal, enhancing bonding through a mechanical grip.

Weak attractive forces based on mutual attraction of charged molecules, contributing to the initiation of chemical bonding in PFM.

A strong bonding mechanism involving the reaction between oxides in the opaque layer of porcelain and oxides on the surface of metal.

A controlled oxide layer must be formed on the metal surface to allow for chemical bonding with porcelain.

The metal substructure should be sufficiently thick to prevent distortion and flexing during firing to ensure a strong bond.

Sharp angles or pits on the veneering surface can cause stress concentrations and weaken the bond.

Occlusal contacts should be placed away from the metal-ceramic junction to prevent porcelain delamination.

Hydrogen release during firing can create air bubbles, weakening the bond between porcelain and metal.

The most common type of fracture with gold alloys, occurring due to a lack of oxide layer or surface contamination.

A common failure in base metal alloys caused by over-production of the oxide layer.

A process that removes excess water from a dental porcelain powder during the build-up process, allowing for proper condensation and shaping.

A technique used to shape and condense dental porcelain powder by applying pressure with a vibrating instrument, creating a smooth and dense restoration.

A technique used to remove excess water from dental porcelain powder by using a flat spatula to spread the powder across a moistened porcelain slab.

A technique where a brush is used to remove excess water from dental porcelain powder by utilizing capillary action – water moves up the bristles.

A technique where dental porcelain powder is layered to create the inner core of a crown, mimicking the shape of the tooth's dentin.

A technique where dental porcelain powder is layered on top of the dentin build-up to recreate the enamel layer of the tooth.

The process of adding more porcelain to the incisal edge of a dental restoration to compensate for the shrinkage that occurs during firing.

Noble alloys contain trace elements like tin, gallium, indium, and zinc, which form oxides. These alloys are less prone to oxidation compared to base metal alloys.

Base metal alloys readily oxidize, meaning they react with oxygen, forming a layer of oxide. This oxidation process needs to be carefully controlled during the preparation of dental restorations.

After oxidation, most alloys require air abrasion with 50μ Al2O3 to remove the oxide layer. This is essential because excess oxide weakens the bond between the metal and porcelain, leading to cohesive failure within the oxide layer.

Opaque porcelain is the first layer applied to the metal substructure. It masks the metal color, provides the initial shade and creates a strong bond between the metal and the porcelain.

The composition of opaque porcelain includes insoluble oxides like tin oxide, titanium oxide, zirconium oxide, cerium oxide, rubidium oxide, barium oxide, and zinc oxide. These oxides scatter light, making the porcelain opaque.

The first layer of opaque porcelain is applied as a thin wash using a brush. This layer wets the metal surface and doesn't need to completely mask it.

The coping is dried in front of a preheated porcelain furnace to prevent rapid steam formation. Steam can disrupt the porcelain structure during the firing process.

The second layer of opaque porcelain masks the metal. It should be thin (0.3 mm) and applied by gently vibrating the coping to condense the porcelain and remove excess water.

The glass rod technique uses the pointed end of a glass rod to apply opaquer to the oxidized metal. Start from the most convex portion and work towards the interproximal areas.

Sprayed opaquers are available in different shades and offer a convenient way to apply the opaquer. Examples include AEROpaque and Enamellite LLC.

The direct lift technique involves applying shoulder porcelain to the facial shoulder with a brush, extending 2-3 mm onto the metal coping. This creates a strong shoulder for the final restoration.

Dentin porcelain is mixed with distilled water and applied over the opaquer with a stable brush. This builds the bulk of the tooth structure, starting from the gingiva and working facially.

Condensation of ceramic is the process of packing porcelain powder close together, creating a dense and durable structure.

The shoulder porcelain is dried in front of the furnace and fired under vacuum at a temperature 30°C higher than the body and enamel porcelain. This ensures proper sintering and creates a strong bond between the porcelain and the metal.

If small openings are detected at the margin after firing, more shoulder porcelain can be added. The die should be seated firmly and any excess porcelain removed and smoothed.