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What is density defined as in dental biomaterials?
What is density defined as in dental biomaterials?
Which of the following is a mass-related property relevant to dental materials?
Which of the following is a mass-related property relevant to dental materials?
How does thermal conductivity affect dental materials?
How does thermal conductivity affect dental materials?
What is the co-efficient of thermal conductivity (K) used to measure?
What is the co-efficient of thermal conductivity (K) used to measure?
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Why is low density important for the retention of upper dentures?
Why is low density important for the retention of upper dentures?
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What impact does high thermal conductivity have on amalgam fillings?
What impact does high thermal conductivity have on amalgam fillings?
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Which property is NOT categorized under thermal properties of dental materials?
Which property is NOT categorized under thermal properties of dental materials?
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What occurs at a lower rate in materials with low thermal conductivity?
What occurs at a lower rate in materials with low thermal conductivity?
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What is metamerism defined as?
What is metamerism defined as?
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Which of the following describes an isomeric pair in color matching?
Which of the following describes an isomeric pair in color matching?
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Which shade guide consists of 20 tabs including four bleach shades?
Which shade guide consists of 20 tabs including four bleach shades?
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What is the purpose of a dental shade guide?
What is the purpose of a dental shade guide?
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Which method involves holding shade guide teeth next to patient teeth for matching color?
Which method involves holding shade guide teeth next to patient teeth for matching color?
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What distinguishes the VITA SYSTEM 3D-MASTER shade guide from others?
What distinguishes the VITA SYSTEM 3D-MASTER shade guide from others?
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What does a chairside colorimeter do?
What does a chairside colorimeter do?
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What is the primary characteristic of the VITA Classical shade guide?
What is the primary characteristic of the VITA Classical shade guide?
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Which characteristic of laser light describes the uniformity of wavelength among all photons?
Which characteristic of laser light describes the uniformity of wavelength among all photons?
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What is the term for the degree of saturation or strength of a color in the Munsell color system?
What is the term for the degree of saturation or strength of a color in the Munsell color system?
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What clinical application of lasers is primarily used for the removal of soft tissues?
What clinical application of lasers is primarily used for the removal of soft tissues?
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In the context of color vision, what is primarily responsible for detecting colors in the retina?
In the context of color vision, what is primarily responsible for detecting colors in the retina?
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What term describes the condition when a restoration appears too bright due to a mismatch in value?
What term describes the condition when a restoration appears too bright due to a mismatch in value?
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Which process is associated with the joining of high fusing alloys in laboratory applications of lasers?
Which process is associated with the joining of high fusing alloys in laboratory applications of lasers?
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What dimension of color refers to the amount of greyness in a given color?
What dimension of color refers to the amount of greyness in a given color?
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Which factor is important for accurate color matching of dental restorations?
Which factor is important for accurate color matching of dental restorations?
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What property of metals contributes to the need for less prolonged heating during casting in dental applications?
What property of metals contributes to the need for less prolonged heating during casting in dental applications?
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What effect may occur due to gold or amalgam restorations having high thermal diffusivity?
What effect may occur due to gold or amalgam restorations having high thermal diffusivity?
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What is the definition of thermal diffusivity?
What is the definition of thermal diffusivity?
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What type of reflection occurs when light hits a smooth surface?
What type of reflection occurs when light hits a smooth surface?
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Which of the following correctly describes refraction?
Which of the following correctly describes refraction?
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What is the significance of having a polished surface in dental restorations?
What is the significance of having a polished surface in dental restorations?
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What defines the refractive index of a medium?
What defines the refractive index of a medium?
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What is scattering in the context of light interaction with matter?
What is scattering in the context of light interaction with matter?
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What is the clinical significance of matching the coefficient of thermal expansion (α) between restorative materials and teeth?
What is the clinical significance of matching the coefficient of thermal expansion (α) between restorative materials and teeth?
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Why is the melting temperature of metals and alloys important in dentistry?
Why is the melting temperature of metals and alloys important in dentistry?
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What does specific heat refer to in the context of dental materials?
What does specific heat refer to in the context of dental materials?
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What happens when there is a breakage of the marginal seal between filling and cavity wall?
What happens when there is a breakage of the marginal seal between filling and cavity wall?
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What does the term 'heat of fusion' refer to?
What does the term 'heat of fusion' refer to?
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What effect does high thermal conductivity in metallic denture base materials have on patients?
What effect does high thermal conductivity in metallic denture base materials have on patients?
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What is the property of a material that allows light to pass with little distortion so that objects can be clearly seen?
What is the property of a material that allows light to pass with little distortion so that objects can be clearly seen?
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Which of the following is essential to avoid crazing in dental materials?
Which of the following is essential to avoid crazing in dental materials?
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Which property of a material prevents the passage of light entirely?
Which property of a material prevents the passage of light entirely?
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What does the coefficient of thermal expansion (α) signify?
What does the coefficient of thermal expansion (α) signify?
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What phenomenon occurs when materials emit light immediately after being excited?
What phenomenon occurs when materials emit light immediately after being excited?
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Which color of materials absorbs all light colors but reflects its own color?
Which color of materials absorbs all light colors but reflects its own color?
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What type of light is often used to produce fluorescent light in dental applications?
What type of light is often used to produce fluorescent light in dental applications?
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Which property of dental materials enhances the brightness and appearance of human teeth?
Which property of dental materials enhances the brightness and appearance of human teeth?
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What are restorative materials and dental porcelains formulated with to enhance their properties?
What are restorative materials and dental porcelains formulated with to enhance their properties?
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How does phosphorescence differ from fluorescence?
How does phosphorescence differ from fluorescence?
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Study Notes
Dental Biomaterials I - Lecture 5: Physical Properties of Dental Materials
- Physical properties are based on the laws of physics, describing mass, heat, light, electricity, energy, force, and other physical phenomena.
- Mechanical properties are a subgroup of physical properties focused on force.
- This chapter provides foundational knowledge to prepare for more detailed discussions on how these properties describe specific dental materials.
Mass-related Properties: Density
- Density is the mass per unit volume of a material.
- Units include gm/cm³ and pound/in³.
- Low density materials are important for denture retention.
- During casting, low-density alloys require higher pressure to fill mold cavities.
Thermal Properties
- Thermal Conductivity: The material's ability to transfer heat. Heat transfer occurs at a lower rate in materials with low thermal conductivity than those with high thermal conductivity.
- Coefficient of Thermal Conductivity (K): Measures the rate of heat transported across a unit cube when one face is hotter than the other.
- Thermal Coefficient of Expansion (α): Measures the change in length per unit length of a material for a 1°C change in temperature.
- Melting and Freezing Temperatures: Temperatures at which a material changes from solid to liquid or vice-versa. Important in casting alloys and selecting investment materials.
- Heat of Fusion: Amount of heat required to convert 1 gram of a substance from solid to liquid state.
- Specific Heat: Amount of heat in calories used to increase the temperature of 1 gram of a substance by 1°C. Metals have low specific heat, non-metals have high specific heat.
- Thermal Diffusivity: Rate at which a material converts from non-uniform temperature to thermal equilibrium (uniform temperature). High thermal diffusivity in gold/amalgam restorations can lead to thermal shock due to high thermal conductivity and low specific heat.
Optical Properties
- Optics: The science of studying light, sight, vision (including color).
- Restorative dentistry requires knowledge of light/color principles to restore natural tooth color and appearance.
- Nature of Light: Light is a beam of photons. Color is the wavelength of light.
- Production of Light: Light can be produced thermally e.g. sun, hot metal) electrically (e.g. by passing electric current through gas), or chemically (e.g. fluorescence, phosphorescence).
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Interaction of Light and Matter:
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Reflection:
- Specular reflection occurs when light bounces off a smooth surface in one direction (e.g., mirrors).
- Diffuse reflection occurs when light bounces off a rough surface in multiple directions.
- Refraction: Change in the direction of light beams when they pass into a different medium.
- Scattering: When light rays passing through a medium are obstructed by inclusions. This results when introducing opacifiers or air bubbles in certain dental materials.
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Reflection:
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Transparency, Translucency, Opacity:
- Transparency: Materials allowing light to pass through without distortion (e.g., glass).
- Translucency: Materials letting some light pass through but scattering/reflecting the rest (e.g., tooth enamel, porcelain).
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Opacity: Materials preventing light passage (e.g., most casting materials).
- Black materials absorb all colors, white materials reflect all colors, and colored materials absorb other colors (except for the color reflected).
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Luminescence: Occurs when the wavelength of the emitted light is longer than the exciting light (e.g., fluorescence, phosphorescence).
- Fluorescence is immediate emission, while phosphorescence lasts after excitation ceases.
- Clinical Significance of Luminescence: Sound teeth emit fluorescent light when exposed to ultraviolet radiation, this is also used in materials to enhance whiteness.
- Laser: Light Amplification by Stimulated Emission of Radiation. Lasers are produced by exciting atoms or compounds via high-energy stimulation and have unique properties like monochromatic, incoherent, and collimated light beams. Usage ranges from oral surgery to laboratory work, like welding and sintering applications.
- Clinical Significance of Lasers: Important for oral surgery because of coagulation properties, removal of carious lesions, composite curing, endodontic work and procedures where hydroxyapatite filling materials may be needed.
- Color Matching (Shade Guides): Guides used to match the color of natural teeth, ensuring artificial restorations possess similar color and esthetics. VITA Classical, Chromoscop, and Vitapan 3D Master Shade Guides are discussed in terms of their construction and applications in shade selection. Different methods are available for shade matching: photocolorimetry, and chair-side colorimeters.
Color Definition and Dimensions
- Color perception is categorized into hue, chroma, and value, as described by the Munsell system.
- Hue: Dominant wavelength (color name).
- Chroma: Saturation/intensity of a color.
- Value: Luminous reflectance, or lightness/darkness.
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Description
This quiz covers key concepts from Lecture 5 of Dental Biomaterials I, focusing on the physical properties of dental materials. Topics include density, thermal conductivity, and the mechanical properties of materials relevant to dentistry. Prepare to test your understanding of how these physical properties apply to practical dental applications.
