WHAT ARE THE BIOLOGICAL PROPERTIES OF DENTAL MATERIAL?
It is a primary requirement of any dental material that it should be harmless to the patient and to those involved in its manufacture and handling. Ideally, a material placed into a patient’s mouth should be:
No carcinogenic or allergic potential
It is defined as the ability of a material to elicit an appropriate biological response in a given application in the body.
Whether a material is biocompatible is therefore dependent on what physical function we ask of the material and what biological response we require from it.
ADVERSE EFFECTS FROM DENTAL MATERIAL
- Materials may be capable of releasing substances into a patient’s body that can cause overt toxicity
- Of all the biological responses to materials, the first screening test used for almost all materials is a toxicity test.
- The contribution of dental materials to inflammatory reactions is important because pulpal and periodontal diseases are largely chronic inflammatory responses to long-term infections.
- Some materials, such as latex and nickel, cause allergy directly by activating antibodies to the material.
- Non-allergic inflammatory response = be DOSE-DEPENDENT and reactions are proportional to the amount of the substance.
- Allergic response = individual’s immune system recognizes a substance as foreign, thus not all individuals will react to that substance = DOSE-INDEPENDENT
- Mutagenic reactions results when the components of a material alter the base-pair sequences of the DNA in the cell. These alterations are termed mutations.
- Mutagenicity does not imply carcinogenicity, no dental material has been shown to be carcinogenic.
Latex material is used when dental personnel wear gloves to reduce the risk of disease transmission and during the use of rubber dam.
Latex hypersensitivity is an increasing problem and the reactions vary from localized rashes and swelling to more serious anaphylaxis. Dermatitis of hands (eczema) is the most common adverse reaction.
ii) Beryllium and Nickel
Precautions should be taken to avoid exposure to metallic vapor, dust, or grindings containing beryllium and nickel.
Physiological responses may range from contact dermatitis to severe chemical pneumonitis. Therefore efficient local exhaust and filtration systems should be used when casting, finishing, and polishing these beryllium-containing alloys.
The presence of nickel is of greater importance because it is a known allergen. The incidence of allergic sensitivity to nickel has been reported to be from 5 to 10 times higher for females than for males, with 5% to 8% of females showing sensitivity.
However, no correlation has been found between the presence of intraoral nickel-based restorations and sensitivity.
Two key factors that determine a material’s biocompatibility
A) Biological environment in contact with the material
The key point is that the biocompatibility of the material depends to a large degree on the degradation process. It is determined not only by a material’s composition but also by the biological environment in contact with the material.
B) Surface characteristics
The surface may negatively affect the biological response. A rough surface promotes corrosion. If the corrosion products have adverse effects, then roughness is not desirable.
Roughness may also promote the adherence of bacteria and promote periodontal inflammation or decay in teeth.
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