Dental Material Lecture 1

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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)

Color (correct)

Thermal conductivity (correct)

Branding

Solubility (correct)

All dental materials have ideal physical and mechanical properties.

False

What are the required characteristics of a dental material?

Non-toxic, non-irritant, not produce allergic reactions, and not be mutagenic or carcinogenic. Signup and view all the answers

The linear coefficient of thermal expansion is the change in __________ for a temperature change of 1 Cº.

length per unit length Signup and view all the answers

What effect can mismatched thermal expansion of filling materials and tooth structure have?

It can cause pressure on the pulp or lead to microleakage. Signup and view all the answers

Which material has the largest coefficient of thermal expansion?

Polymers Signup and view all the answers

What is 'dimensional stability' in dental materials?

The ability of a material to maintain its dimensions after setting. Signup and view all the answers

Which of the following is a property of restorative dental materials?

Absorption of fluids Signup and view all the answers

What is bio-compatibility in the context of dental materials?

The ability of a material to elicit an appropriate biological response in a given application in the body. Signup and view all the answers

Acrylic materials can be made with various shades of __________ to look like normal gum.

pink Signup and view all the answers

Metals are generally poorer heat conductors than non-metals.

False Signup and view all the answers

What happens to some restorative materials if they dissolve in the mouth?

They may release toxic substances. Signup and view all the answers

Match the following dental materials with their properties:

Gold = Has a coefficient of thermal expansion of 1410^-6 cm/cm.Cº Acrylic resin = Has a coefficient of thermal expansion of 7610^-6 cm/cm.Cº Water = Density of 1 gm/cm³ Composite = Solubility of 0.01 Mg/mm² Signup and view all the answers

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.