Questions and Answers
What is the primary objective of studying dental materials?
To formulate standards or specifications for dental materials and to certify products that meet those requirements.
Which of the following properties are important in the study of dental material? (Select all that apply)
All dental materials have ideal physical and mechanical properties.
False
What are the required characteristics of a dental material?
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The linear coefficient of thermal expansion is the change in __________ for a temperature change of 1 Cº.
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What effect can mismatched thermal expansion of filling materials and tooth structure have?
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Which material has the largest coefficient of thermal expansion?
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What is 'dimensional stability' in dental materials?
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Which of the following is a property of restorative dental materials?
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What is bio-compatibility in the context of dental materials?
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Acrylic materials can be made with various shades of __________ to look like normal gum.
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Metals are generally poorer heat conductors than non-metals.
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What happens to some restorative materials if they dissolve in the mouth?
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Match the following dental materials with their properties:
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Study Notes
Dental Materials and Physical Properties
- Advancing dentistry requires knowledge of materials used in treatment and their properties.
- The study of dental materials focuses on physical, mechanical properties, and their manipulation.
Historical Context
- Gold bands and wires were used historically for partial dentures.
- G.V. Black conducted research on amalgam in the 19th century, leading the American Dental Association to establish standards for dental materials.
- Standards ensure dental materials meet safety and performance specifications.
Selection of Materials
- Successful restorations depend on proper selection and usage by dentists.
- Ideal dental materials must be non-toxic, non-irritant, non-allergenic, non-mutagenic, and non-carcinogenic.
Properties of Dental Materials
- Properties are categorized into two main types:
- Physical properties (color, solubility, density, dimensional stability).
- Mechanical properties (hardness, strength).
- No material possesses perfect properties, often with trade-offs.
Color and Aesthetics
- Esthetics in dental materials is paramount; materials need to mimic natural teeth.
- Translucence is essential for restorative materials to allow light interaction similar to natural teeth.
- Denture materials should match the appearance of natural gums, with shades of pink for acrylics.
Thermal Properties
- Linear Coefficient of Thermal Expansion requires matching between filling materials and natural tooth to avoid pressure and leakage issues.
- Materials vary in thermal expansion:
- Tooth: 11*10^-6 cm/cm°C
- Gold: 14*10^-6 cm/cm°C
- Acrylic resin: 76*10^-6 cm/cm°C.
Dimensional Stability
- Ideal dental materials retain shape upon hardening; excessive changes can cause microleakage or pressure on pulp.
- Required expansion of investment materials must compensate for metal contraction after cooling.
Density
- Dense materials can be advantageous for stability; for instance, heavy materials may enhance denture control.
- Gold density: 14 gm/cm³, Acrylic: 1.2 gm/cm³, Chromium/Cobalt: 8.3 gm/cm³.
Solubility and Fluid Absorption
- Restorative materials must remain insoluble in the mouth and should not release toxic substances.
- Water absorption can lead to dimensional changes; materials should ideally have low solubility.
Tissue Reaction
- Some materials may harm living tissue or provoke allergic reactions; biocompatibility is crucial.
- Materials should not promote bacterial growth or infection.
Thermal Conductivity
- Metals generally conduct heat better than non-metals; adverse effects like pulp pain can occur in deep cavities with metallic fillings.
- Thermal insulation is necessary to protect pulp from temperature fluctuations.
Electrical Activity and Corrosion
- Metals may ionize in certain environments; differences in electrode potential can lead to discomfort.
- Corrosion resistance is necessary for long-term durability of materials in the oral cavity.
Adhesion and Cohesion
- Adhesion is vital for materials to bond well upon contact; cohesion refers to the attraction between similar molecules.
Biocompatibility
- Biocompatibility assesses the material's ability to provoke appropriate biological responses.
- A single material might be acceptable in one application (e.g., crowns) but not in another (e.g., implants), highlighting the context-dependent nature of biocompatibility.
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Description
Explore the fundamentals of dental materials and their physical properties in this introductory lecture. This session highlights the importance of understanding basic sciences to enhance dental treatment quality. Gain insights into the various materials utilized in dentistry.
