Biological Properties Of Dental Materials Question And Answers

Biological Properties Of Dental Materials

Question 1. Describe the biological consideration that is associated with the selection and uses of dental material designed for the oral cavity.
Answer:

The science of dental materials must include a knowledge and appreciation of certain biological considerations that are associated with the selection and use of materials designed for the oral cavity.

Biological Requirement of Dental Materials:

• They should be non-toxic to the body.
• They should be non-irritating to the oral and other tissues.
• They should be non-mutagenic or carcinogenic.
• They should not produce allergic reactions.
• They should be biologically inactive

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Classification of Dental Material from a Biological Perspective:

• Those that contact the soft tissues within the mouth.
• Those which could affect the health of the dental pulp.
• Those that are used as root canal filling materials.
• Those that affect the hard tissues of the teeth.
• Those used in the dental laboratory though not used in the mouth are handled and may be accidentally ingested or inhaled.

Hazards of Dental Materials: There are two types:

1. Chemical hazard.
2. Physical hazard.

Chemical Hazards of Dental Materials :

• Dental cement which is acidic in nature can cause pulp irritation.
• An unreacted monomer can irritate the pulp.
• Phosphoric acid which is used as an etchant can harm the surrounding tissue of the tooth.
• Eugenol can cause irritation and a burning sensation.
• Beryllium use in casting alloys can cause “Berylliosis”.
• Some dental products contain nickel and some patients are allergic to nickel.
• Lead used in elastomeric material causes a hazard.
• Alginate dust while mixing precipitates asthma.
• Mercury is used in dental amalgam, mercury vapor is toxic.

Physical Hazards of Dental Materials: Physical hazards are classified as:

1. Dimensional hazard
2. Thermal hazard
3. Electrical hazard.

1. Dimensional hazard:

• Microleakage: A microscopic space between the restoration and the prepared cavity is called microleakage.
• Microleakage can result in:
  • Secondary caries: The seepage of acids and microorganisms could initiate caries around the margins of the restorations.
  • Stains or discoloration can also develop.
  • Sensitivity: Sometimes, because of microleakage the tooth remains sensitive even after placement of the filling, bacterial growth occurs in between restoration and cavity. Toxic products liberated by microorganisms produce irritation to the pulp.

2. Thermal change: Tooth structure and dental restorations are continually exposed to hot and cold beverages and foods. Instantaneous temperature fluctuation during the course of an average meal may be as great as 85 °C.

• The temperature fluctuation can crack the restorative materials or produce undesirable dimensional changes in them because of thermal expansion and contraction.
• Many restorative materials are composed of metals. Metals conduct heat and cold, patient complaint of sensitivity in the tooth.

3. Electric hazards: Galvanism Another cause for sensitivity is the small currents created whenever two different metals are present in the oral cavity.

• The presence of metallic restoration in the mouth can cause a phenomenon called galvanic action, or galvanism.
• This results from a difference in potential between dissimilar filings in opposing or adjacent teeth.
• These filings in conjunction with saliva as an electrolyte, make up an electric cell.
• When two opposing filings contact each other the cell is short-circuited and the patient experiences pain.