Properties of Dental Materials- Terminology

You must know the properties of the materials used in dentistry to understand its function and how and why it works in oral cavity. It also helps in manipulating it. The main properties you should know about are following:

• Stress
• Strain
• Elasticity Modulus
• Elastic Limit
• Thermal Expansion
• Hygroscopic Expansion
• Setting Expansion

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Annealing: Annealing is a process of heating and cooling of metal in a controlled manner. It is done/designed to produce desired properties in a metal. it is typically done to make the metal softer, increase ductility, stabilise the shape and improve/increase the machinability. When we talk about annealing of gold foil, it typically is done to remove surface contaminants just before the condensation.

Dental Anatomy and Terminology

Anatomy of the tooth and surrounding tissues

Enamel: This is the hard, calcified substance that makes the surface of a crown of a tooth.

Dentin: This is the calcified tissue that forms the major part of a tooth. In the crown of the tooth, the dentine is covered by enamel. The pulp
chamber of the tooth is surrounded by dentine.

Pulp: This is the organ at the centre of a tooth that contains blood vessels, connective and neural tissue, and cells that produce dentine-odontoblast. Blood vessels and neural tissue enter the tooth from the apex of the root.

Gingiva: This is the marginal part of the gum that surrounds the tooth where it emerges from the deeper, supporting tissues.

Periodontal ligament: This is the ligament that connects a tooth, by its root, to the supporting bone.

Cementum: This is the calcified tissue on the surface of the root of a tooth, which provides attachment for the periodontal ligament.

Fissure: It is a naturally occurring crevice in the enamel.

Crown: This is the part of the tooth that is visible and is above the gingival margin.

Root: This is the part of the tooth below the gingival margin; it is connected through cementum on its surface and the fibres of the periodontal ligament to the supporting bone.

Dental numbering system

There are numerous dental numbering systems to identify teeth and their maturity. The most commonly used system in Australia is the Federation Dentaire Internationale (FDI) system (see Figures). When communicating with a dentist, identify which numbering system is being used.

The FDI numbering system divides the mouth into quadrants. The first number indicates the quadrant and whether it is a primary or secondary tooth. The second number indicates the tooth; tooth numbering begins at the central incisor and counts backward to the molars.

Using the FDI numbering system, for adults, the quadrants are numbered as:

1. patient’s upper right is quadrant 1 
2. patient’s upper left is quadrant 2 
3. patient’s lower left is quadrant 3 
4. patient’s lower right is quadrant 4

For primary teeth in children, the quadrants are numbered as:

1. patient’s upper right is quadrant 5 
2. patient’s upper left is quadrant 6 
3. patient’s lower left is quadrant 7 
4. patient’s lower right is quadrant 8

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Ref: Therapeutic Guidelines 2019