Essential Dental Materials: Properties and Clinical Uses
Dental Materials for Tooth Reconstruction
Materials for rebuilding teeth must be durable (not prone to breaking quickly), resistant to mastication, and aesthetically pleasing, resembling natural teeth.
Pulp Protection and Fillings
Pulp Protective Materials:
- Fluid composites
- Glass ionomer cements
- Calcium hydroxide liners
Types of Fillings:
- Composite Fillings: Made from resin-based materials.
- Amalgam Fillings: Historically used, containing mercury and silver. Often supplied in pre-dosed capsules for mixing.
Types of Chemical Bonds Explained
In chemistry, atoms are held together by chemical bonds. The type of bond formed dictates many of the substance’s properties. Three primary types of chemical bonds are covalent, metallic, and ionic.
Covalent Bonds
In a covalent bond, two bonded atoms share electrons. When the atoms joined by a covalent bond are the same (e.g., N₂, O₂), neither atom attracts the shared electrons more strongly than the other. This is called a nonpolar covalent bond or simply nonpolar.
If the atoms of the covalent
Read MoreKey Metallurgy Definitions
Some significant transformations are induced in steels, such as annealing, generally performed to achieve a smaller grain size and, consequently, improve metal properties.
Anisotropy
Anisotropy is the property of a material according to which certain physical properties, such as elasticity, thermal conductivity, velocity of propagation, and light, vary depending on the direction in which they are examined.
Alloy
An alloy is a system consisting of several elements, of which at least one is a metal, retaining
Read MoreCore Chemistry Concepts: Matter, Atoms, and Reactions
States of Aggregation
Matter exists in different states based on the intensity of forces between particles:
- Solid: Forces of attraction are very intense. Solids are rigid, cannot flow, maintain their own shape and volume, and are incompressible.
- Liquid: Forces are less intense than in the solid state. Liquids can flow, do not have their own shape (taking the shape of the container), maintain their own volume, and are nearly incompressible (often treated as incompressible, though slight compressibility
Chemical Principles: Thermo, Kinetics, Eq
Work
- Isobaric Process: At constant pressure (P = cte)
W1→2 = -PΔV - Isothermal Process: At constant temperature (T = constant)
W1→2 = -nRT ln(P1/P2) - Isochoric Process: At constant volume (V = constant)
W1→2 = 0
Heat
- Specific Heat: c = dQ / (mΔT)
Q = c · m · ΔT
If ΔT > 0, heat is absorbed.
If ΔT < 0, heat is ceded (released). - Latent Heat of Change of State (L): At constant temperature
From solid to liquid: Qf = m · Lf
From liquid to gas: Qv = m · Lv
First Law of Thermodynamics
ΔU = Q + W
Calculating
Read MoreStates of Matter and Phase Changes
Solids
In the solid state, the particles are touching, and the only motion allowed to them is vibration. The particles may be arranged regularly (in which case, the solid is crystalline), or at random (giving waxy solids like candles or some forms of polyethylene, for example).
The particles are held in the solid by forces which depend on the actual substance – ionic bonds, covalent bonds, metallic bonds, hydrogen bonds, or van der Waals attractions.
Liquids
In a liquid, the particles are mainly touching,
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