Dental Materials and Properties Quiz
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Questions and Answers

What is the definition of luminescence?

  • The ability of materials to emit sound
  • The ability of materials to absorb heat and dissipate it
  • The property of materials to change shape under pressure
  • The ability of materials to absorb energy and then emit it as visible light (correct)

Which type of dental gypsum possesses the highest expansion?

  • Type II
  • Type I
  • Type V (correct)
  • Type III

What does the 'coefficient of thermal conductivity' (k) represent?

  • The ability of a material to resist force
  • The total energy loss during insulation
  • The time it takes for a material to reach thermal equilibrium
  • The heat quantity passing through a specific thickness of material per unit area at a temperature difference (correct)

What is the significance of the contact angle of water in hydrophilic materials?

<p>It is 0°, indicating perfect wetting (D)</p> Signup and view all the answers

What is characteristic of the Vickers hardness test?

<p>A square-based pyramid pressed under specific conditions (C)</p> Signup and view all the answers

What property of a material allows it to let light pass through it?

<p>Transparency (D)</p> Signup and view all the answers

Which of the following components is primarily used for impression plaster in dentistry?

<p>Plaster of Paris (A)</p> Signup and view all the answers

Which type of dental material is designed to remain in the oral cavity for an extended period?

<p>Basic materials (C)</p> Signup and view all the answers

What does the Rockwell hardness test measure using the HRB scale?

<p>Hardness using a ball indenter (C)</p> Signup and view all the answers

What is the significance of the value in terms of color perception?

<p>Lightness or darkness of color (C)</p> Signup and view all the answers

During the measurement of gypsum setting time, what is the purpose of the Gilmore needles?

<p>To determine initial &amp; final setting time (B)</p> Signup and view all the answers

What type of dental stone is classified as modified α-hemihydrate calcium sulfate?

<p>Type IV dental stone (C)</p> Signup and view all the answers

What occurs at high temperatures resulting in the creation of vacancies in materials?

<p>Random atomic movement (A)</p> Signup and view all the answers

What is the primary component of type IV dental stone?

<p>α-hemihydrate (D)</p> Signup and view all the answers

What is the term used to describe the maximum stress that can be maintained without failure over an infinite number of cycles?

<p>Fatigue strength (A)</p> Signup and view all the answers

What is the definition of 'impact strength' in dental materials?

<p>The energy required to fracture a material under an impact force (A)</p> Signup and view all the answers

Which of the following correctly describes the function of the Vicat needle?

<p>To measure setting time (C)</p> Signup and view all the answers

What are the biological properties of dental materials classified into?

<p>Biologically tolerable, inert, and active (B)</p> Signup and view all the answers

Which of the following best describes the setting time of gypsum?

<p>Can be retarded by changing crystal growth rate (C)</p> Signup and view all the answers

Which factors can influence the fatigue of materials?

<p>Surface roughness and load frequency (A)</p> Signup and view all the answers

Which hardness test is characterized by using a steel ball or diamond cone to measure penetration depth?

<p>Rockwell hardness test (B)</p> Signup and view all the answers

The term 'Knoop hardness' (KHN) refers to what?

<p>The hardness of tooth enamel (D)</p> Signup and view all the answers

What type of materials are classified as electric conductors?

<p>Crystalline materials: metals and alloys (A)</p> Signup and view all the answers

What happens to the setting time when the water-to-powder (W/P) ratio increases?

<p>Setting time increases, strength decreases (D)</p> Signup and view all the answers

Which statement accurately describes 'imbibition'?

<p>The process of absorbing liquids and dimensional changes (B)</p> Signup and view all the answers

What is the term for the specific type of photo-luminescence where materials emit light only during excitation?

<p>Fluorescence (A)</p> Signup and view all the answers

What is the definition of thermal conductivity?

<p>The ability of a material to absorb and transfer heat (A)</p> Signup and view all the answers

Who is known as the 'father of modern dentistry'?

<p>Pierre Fauchard (C)</p> Signup and view all the answers

How many forms of CaSO4 hemihydrate exist?

<p>Two forms: α- and β-hemihydrate (A)</p> Signup and view all the answers

What is the main component of model plaster?

<p>Calcium sulfate hemihydrate (D)</p> Signup and view all the answers

Which test is considered a cyclic test?

<p>Fatigue test (D)</p> Signup and view all the answers

What does the W/P ratio indicate?

<p>Water-to-powder ratio (D)</p> Signup and view all the answers

Which of the following is NOT a type of reflection of light?

<p>Reflected diffuse (D)</p> Signup and view all the answers

Which material is known to be an effective electric insulator?

<p>Polymers (C)</p> Signup and view all the answers

What is meant by the term 'plasticity' in materials?

<p>Permanent deformation under load (A)</p> Signup and view all the answers

Which test measures the initial set of gypsum?

<p>Gillmore needle test (A)</p> Signup and view all the answers

What type of stress is characterized by forces acting in opposite directions?

<p>Tensile stress (D)</p> Signup and view all the answers

Flashcards

Compressive Strength

The ability of a material to resist deformation under a compressive load. Measured in Mega Pascals (MPa) or pounds per square inch (psi).

Ultimate Tensile Strength

The largest load that a material can withstand before breaking under tension. This is measured in Mega Pascals (MPa) or pounds per square inch (psi).

Brinell Hardness

A measure of how hard it is to penetrate a material. It's a measure of resistance to indentation.

Setting Time of Gypsum

The amount of time it takes for the material to fully harden after mixing with water. Measured by the time it takes for a needle to sink to a specific depth in the mixture.

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Auxiliary Materials

Type of dental material used for taking impressions or molds of teeth, mouth, or jaw. These materials are temporary and are removed after setting.

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Laboratory Materials

A material used to create models of teeth, jaws, or other dental structures. These materials are permanent and are used for planning treatment or creating dental appliances.

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Basic Materials

Materials used to create permanent fillings or restorations in teeth. These materials remain in the mouth for a long time.

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Transparency

The property of a material to allow light to pass through it. Materials like glass and acrylic can be transparent.

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Fatigue Strength

The maximum stress a material can withstand for an infinite number of cycles without breaking.

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Specific Heat

The ability of a material to absorb heat. It measures how much heat energy is needed to raise the temperature of 1 gram of the material by 1 degree Celsius.

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Adhesion

A surface attachment process where two materials bond together.

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Conductors (Thermal)

Materials with high thermal conductivity readily transfer heat. They allow heat to flow through them easily.

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Electrical Conductors

Crystalline materials with a high density of free electrons, allowing electrical current to flow easily. Metals and alloys fall into this category.

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Work Time

The time available to work with a dental material before it starts to set or harden.

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Electrical Conductivity

The ability of a material to conduct electricity due to the presence of freely moving electrons.

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Impact Strength

The ability of a material to resist deformation under an impact force. It measures how much energy it takes to fracture the material with a sudden force.

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Setting Time

The time it takes for a material to harden after mixing with water. It's measured by how long it takes for a needle to sink a specific depth into the mixture.

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Imbibition

A material absorbs liquids and expands in volume. This process increases the volume of the material, often happening most rapidly in the first 24 hours.

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Hue

The dominant color of an object. It's determined by the wavelengths of light reflected the most by an object.

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Knoop Hardness

The ability of a material to resist indentation. It's tested by pressing a specific object into the surface and measuring the size of the indentation.

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Technological Process

A process that combines different methods and techniques for treating materials to achieve a desired outcome. It's the overarching strategy for how materials are manipulated.

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What are alginate impression materials used for?

A type of impression material that sets quickly and is used for preliminary impressions, study models, and removable fixed partial dentures.

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What is luminescence?

The property of materials to absorb energy and then emit it as visible light. Two types are fluorescence and phosphorescence.

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What is fluidity?

The ability of a molten metal to flow and fill a channel or cavity. It's essential for creating precise castings.

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What is stress?

The force per unit area. It's a measure of how much force is applied to a specific area.

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What is compressive strength?

The ability of a material to resist deformation under a compressive load. It can be measured in MPa or psi.

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Strength of Materials

The ability of a material to withstand an applied stress without failure. It is a measure of how much force a material can handle before breaking or deforming.

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Ductile Materials

A type of material that can be permanently deformed under load, without breaking. After the load is removed, the material retains its new shape.

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Refraction

Change in the direction of a wave, caused by a change in its speed. For example, light refracts when it passes from air to water.

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Wettability

The ability of a material to be welded by melting and applying pressure. It's about how easily two pieces of a material can be joined together.

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Type IV Gypsum

The specific type of gypsum used for creating dies for fixed prostheses. It's used for making accurate models of teeth for crowns, bridges, and other restorations.

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Melting Temperature

The temperature at which a pure metal, compound, or other substance transitions from a solid to a liquid state. It's the point where the solid and liquid phases are in equilibrium.

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Mohs Hardness Test

The ability of a material to resist plastic deformation or fracture due to friction from a sharp object. It measures how easily a substance can be scratched.

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W/P Ratio

The ratio of water to hemihydrate powder. This ratio is important because it affects the physical and chemical properties of gypsum products, like setting time and strength.

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Study Notes

Dental Materials and Properties

  • Gypsum Use: Used in dentistry for impressions and model fabrication
  • Dental Material Structure: Classified as metals, metalloids, non-metals; amorphous or crystalline
  • Transparent Materials: Includes glass and acrylics
  • Rockwell Hardness: Ball indenter with values ranging from 56 to 60 HRB
  • Density: Mass per unit volume (Density=Mass/Volume)
  • Brinell Hardness: Designated as HB/BHN, with a value of 185 HB
  • Absorption: Material property allowing light to pass through
  • Dental Material Usage Types: Basic (long-term in mouth), auxiliary (short-term), laboratory (extra-oral)
  • Lightness/Darkness (Value): Describes the color intensity relative to a black body
  • Setting Time Acceleration: Achieved using accelerators like K2SO4 and NaCl
  • VITA Shade Guide: A color guide in dentistry; A1 to A4 represent color variation
  • B-Hemitydrate: Formed at 150-200°C for 24-36h under normal pressure
  • Tensile Strength: Maximum load a material can handle in tension before failure
  • Mechanical Testing: Static tests include tensile, compressive, bending and torsion
  • Heat Capacity: Heat required to raise the temperature of a substance by 1°C.
  • Thermal Conductivity: Material property for heat transfer
  • Brinell Hardness Test: Used to determine the hardness of metals and alloys
  • Space Lattice: Regular arrangement of atoms in a solid
  • Vickers Hardness Test: Used for testing hard and brittle materials, like porcelain
  • Fatigue Strength:* Maximum stress a material can withstand over an infinite number of cycles without failure.

Dental Materials and Properties (Continued)

  • Fluorescence: Light emitted by a substance after an excitation.
  • Work Time: Mixing time until it becomes unworkable
  • Electrical Conductivity: Ability of an object to transmit electric current
  • Shore Hardness Test: Used for measuring the hardness of material alloys
  • Impact Strength: Energy to fracture a material under impact force
  • Mirror-Like Reflection: Incident angle is equal to the reflected angle
  • Hue: Dominant color of an object
  • Technological Process: Combining several procedures to treat a material
  • Crystalline Lattice: Structures of atoms in materials: Body-centered cubic or face-centered cubic
  • Polymer Materials: Used in crowns, ceramics, composites, metals, artificial teeth
  • Fatigue of Materials: Factors impacting material strength under repeated loading: surface roughness, surface stress, load value, frequency
  • Imbibition: Process of absorbing liquids resulting in dimensional change
  • Knoop Hardness: A hardness test like the Brinell.
  • Elastic Modulus: Ratio of stress to strain in the elastic region.
  • Forces for Breaking Food Up: Up to ~980,7 N (100 kg).
  • Ductile Materials: Permanent deformation under stress
  • Alpha-hemihydrate: Obtained from type II gypsum
  • Composite Fillings: Developed as fillings starting from 1966
  • Translucent Materials: Partially transparent materials allowing some light transmission
  • Alginate Impression Materials: For preliminary impressions and study models.
  • Types of Crystalline Lattices (Metals): Body-centered cubic and face-centered cubic

Dental Materials and Properties (Continued)

  • Coefficient of Thermal Conductivity: Heat transfer rate through a material.
  • Contact Angle of Water: Measure of materials' hydrophilicity or hydrophobicity
  • Vickers Hardness Test: Used to determine material hardness using a diamond pyramid
  • Elastic Limit: Maximum stress that can be applied to a material without permanent deformation
  • Type II Gypsum Use: For study models

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Description

Test your knowledge on the fundamental properties and classifications of dental materials. This quiz covers topics such as luminescence, thermal conductivity, and hardness tests specific to dentistry. Perfect for dental students and professionals looking to refresh their understanding of material science in dentistry.

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