Chapter 3 Dental materials.
Dental Definitions:
Abrasion Resistance: The ability of a dental material to withstand wear and tear from mechanical forces, such as chewing or brushing, without losing its integrity.
Bending: A type of deformation where a material is subjected to a force causing it to bend or curve, often measured to assess the material's resistance to deformation under load.
Biologic Properties: The characteristics of dental materials that affect their interaction with biological tissues, such as biocompatibility, toxicity, and the potential for causing allergic reactions or inflammation.
Chemical Properties: The behavior of dental materials when exposed to various chemicals or environments, including their resistance to acid attack or corrosion and how they react with saliva or food.
Coefficient of Thermal Expansion: The rate at which a material expands or contracts in response to temperature changes. Important for dental materials to ensure they don’t cause discomfort or damage to the tooth structure.
Color: The visual appearance of a material, important for aesthetic dental restorations like composites and ceramics, where the material must match the natural tooth color.
Compression: A type of stress that results in the material being squeezed or compacted. Materials used for fillings and crowns must resist compressive forces from biting and chewing.
Creep: The slow, permanent deformation of a material when subjected to a constant stress over time, such as in dental amalgam under continuous pressure from biting.
Density: The mass of a material per unit volume. Dental materials with higher density typically exhibit greater strength and durability.
Elastic Deformation: The reversible change in the shape of a dental material when a force is applied, meaning the material returns to its original shape when the force is removed.
Elastic Limit: The maximum stress a material can withstand while still returning to its original shape once the stress is removed. Beyond this point, permanent deformation occurs.
Elasticity: The ability of a material to return to its original shape after the removal of a deforming force.
Fatigue: The progressive failure of a material when it is subjected to repeated stress cycles, such as the forces that occur during chewing.
Force: The external power or pressure exerted on a material, which can cause deformation or stress, essential in evaluating dental material strength.
Fracture Toughness: A material's ability to resist crack propagation when subjected to stress. Crucial for dental materials like ceramics, which are prone to fracture.
Galvanic Shock: A sharp, sudden pain caused when two dissimilar metals in dental restorations create an electric current in the mouth, often caused by fillings or crowns in contact with each other.
Goldilocks Principle: Refers to the idea that dental materials need to have properties that are "just right" — not too hard or too soft, not too resistant or too flexible, to provide optimal function and comfort.
Hardness: A measure of a material's resistance to indentation, scratching, or abrasion. Harder materials, such as enamel or dental porcelain, are more resistant to wear.
Heat Capacity: The amount of heat a dental material can absorb without significantly changing its temperature, important in materials used for restorations, to prevent thermal damage to the tooth.
Heat of Fusion: The amount of heat required to change a material from a solid to a liquid state without changing its temperature, important in materials like dental wax used in impression taking.
Heat of Vaporization: The amount of heat required to change a material from liquid to gas, important in dental materials like those used in sterilization processes.
Load: The amount of force applied to a dental material or structure, such as the forces from chewing or the pressure from a dental restoration.
Mechanical Properties: The characteristics that define how a material responds to various forces, including tensile strength, elasticity, and hardness. These are critical in selecting materials for dental restorations.
Modulus of Elasticity: A measure of a material's ability to resist deformation when subjected to stress. Higher values indicate stiffer materials.
Percolation: The movement of fluids (like saliva or beverages) between the interface of the dental restoration and tooth, which may lead to discomfort, tooth sensitivity, or leakage.
Permanent Deformation: Irreversible changes in the shape or structure of a material after stress has been applied, exceeding the elastic limit.
Physical Properties: Characteristics of a material that can be observed or measured without changing the material’s composition, such as color, density, or hardness.
Plastic Deformation: The permanent distortion of a material when the applied stress exceeds the material's elastic limit, leading to a change in shape.
Poisson's Ratio: The ratio of the lateral strain to the axial strain in a material when it is stretched or compressed. It is used to understand the material's deformation in response to stress.
Proportional Limit: The stress point beyond which a material no longer behaves elastically and starts to deform plastically.
Resilience: The ability of a material to absorb energy when deformed elastically and then return to its original shape after the force is removed.
Shade Guides: Tools used to compare and match the color of dental restorations with the natural color of the surrounding teeth for aesthetic restorations.
Shear: A type of stress where two opposing forces act parallel to each other, causing deformation. Dental materials like composites must resist shear forces in the mouth.
Solubility: The ability of a dental material to dissolve in a liquid, such as saliva. Low solubility is often desirable in materials like dental cements.
Specific Heat Capacity: The amount of heat required to raise the temperature of a unit mass of a material by one degree Celsius. Important in preventing thermal damage during dental treatments.
Strain: The deformation of a material due to an applied force. It is often expressed as a percentage of the original shape or size.
Stress: The force per unit area within a material that arises from externally applied forces, internal forces, or changes in temperature.
Stress Concentration: The localized increase in stress that occurs at a point in a material, such as a crack or defect, which may lead to failure or fracture.
Stress Relaxation: The decrease in stress under a constant strain over time, commonly seen in materials like rubber or certain dental polymers.
Tension: A force that stretches a material, leading to elongation. Dental materials must resist tension when used in applications like braces or dental wires.
Thermal Conductivity: The ability of a material to conduct heat. Materials with low thermal conductivity, like composites, are used in restorations to prevent temperature sensitivity.
Torsion: A twisting force applied to a material. Dental wires and orthodontic appliances must be able to resist torsional forces without failure.
Toughness: The ability of a material to absorb energy and deform without breaking, important for materials like dental composites and metals used in crowns.
Ultimate Compressive Strength: The maximum compressive stress a material can withstand before failure. This is an important property for dental materials that are subjected to biting forces.
Ultimate Strength: The maximum stress a material can withstand before breaking. It is a key factor in determining the suitability of materials for dental restorations.
Ultimate Tensile Strength: The maximum stress a material can withstand while being stretched before breaking, relevant for dental materials like wires or braces.
Vapor Pressure: The pressure exerted by a vapor in equilibrium with its liquid or solid form. This property is important when considering materials used for impression taking or sterilization.
Viscosity: The measure of a material's resistance to flow. Dental materials like impression materials and sealants must have a specific viscosity to ensure ease of use and accurate impressions.
Water Sorption: The ability of a material to absorb water, which can affect the strength, color, and longevity of dental materials.
Wetting: The ability of a liquid to spread over a surface, important in ensuring good adhesion between dental materials and tooth structure.
Yield Point: The stress at which a material begins to deform plastically, marking the transition between elastic and plastic deformation.