Dental Materials and Biomaterial Science
- Jeff Davies
- Dec 16, 2015
- 2 min read
There are a few properties regarding the strength of a material that are important to remember when considering composites and what material is suitable for a certain procedure. Three variables exist: Compressive, Tensile, and Shear. These are often defined to as the point on the stress-strain curve at which fracture can occur. Of coarse, different materials will have different properties as a pro and con. The definition for these terms are:
Compressive strength: Pressing. Stress required to fracture a material when forces are applied opposite and toward each other.
Tensile strength: Pulling. Forces are applied opposite and away from each other.
Shear strength: Sliding. Forces are applied opposite and toward each other but at different positions.
While strength is important, dimensional change plays an important role. Dimensional change can be termed as the expansion and contraction of a material, thermal expansion. When the change in expansion of the restoration doesn't match the change in expansion in the tooth, you are left with leakage of fluid between the two. Percolation is the term used to denote the intermittent exchange of fluid and can result in the marginal decay that is so commonly seen.
Composite matches up similarly with both enamel and composite. However, it may be too weak for some larger restorations. Elastic modulus measures the rigidity of the material. Basically, the higher the elastic modulus, the stiffer the material will be. Enamel is the most rigid then followed by amalgam, then composite, then dentin. Yield strength is the measure measurement of the point right before permanent deformation takes place. Yield strength and elastic modulus follow the same strength patterns. In order to replicate nature, its important to understand the biomechanical properties that they have. Biomimetics strives to match these values.
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