essay 17 - restorative materials - types, indications, medico-biological and mechanical requirements

what are the types of restorative materials?

• direct restorative biomaterials (placed directly into the cavity)

• indirect restorative biomaterials (fabricated outside the mouth)

describe direct restorative biomaterials (placed directly into the cavity)

• while in a moldable stage, the material can be adapted to the tooth structure and shaped to recreate normal anatomic contours. This process is called direct restorative dentistry because it is accomplished directly in the intraoral environment

— Amalgam: strong, durable, but unesthetic

— Composite resin: esthetic, adhesive, suitable for anterior and posterior use

— RMGI: bonds chemically to dentin, fluoride release, used in Class V or high caries risk

describe indirect restorative biomaterials (fabricated outside the mouth)

If there is extensive loss of tooth structure, the restorative materials must provide better stress distribution characteristics and be bonded more carefully to remaining tooth structure. in most cases, this requires the use of materials that cannot be made fluid for direct use. these materials must be fabricated into a restoration outside of the mouth and cemented or bonded in place

• Metal alloys (e.g gold, Co-Cr): durable, precise fit

• Ceramic s (e.g feldspathic, zirconia): high aesthetic, brittle

• Indirect composites: better physical properties than direct ones

• Composite for temporary indirect restoration (cemented with zinc oxide eugenol)

Medico-Biological requirements (requirements a dental material must meet to be safe for the body)

• biocompatibility (non-toxic, non-irritant)

• resistance to bacterial leakage

• chemical stability in the oral environment

• no interference with pulp healing

mechanical requirements

• high compressive (resist being pushed, squeezed, or crushed) and tensile (resist being pulled apart or stretched) strength

• wear resistance

• dimensional stability

• good adhesion or retention

• polishability (for aesthetics)