The oral cavity is frequently exposed to a large number of dental materials. Among these many are sensitizing and irritating to the oral cavity. Therefore, the signs and symptoms of oral disease related to dental materials are also various. The clinical applications of dental prostheses are increasing, and allergies related to the non-precious metal alloys used in dentistry have become a serious problem.
Because of corrosion and mechanical abrasion over time, almost every element can be released from the alloys . Nearly every alloy used in prosthodontics releases ions. In the presence of saliva, dental alloys act as electrolytes, causing electrochemical corrosion, and the released elements can initiate reactions of hypersensitivity. Many reports exist concerning allergies that arise from dental alloys containing nickel, chromium, or cobalt.
In such patients who exhibit allergy to metal alloys, the best and popular option was to replace the metal restoration with all ceramic restorations. Although these all-ceramic restorations have excellent esthetics, chemical stability, and biocompatibility, their mechanical strength is inadequate.
Therefore, another better option for fixed dental prostheses, is the zirconia based material combinations. Zirconia is a white opaque material with high strength. Zirconia is milled using computer-aided design/computer assisted manufacturing devices and veneered with feldpathic/flourapetite ceramic either manually or via the lost-wax and press technique.
Zirconia(zrO2) fulfills the standards for posterior restorations, being a bioinert, non-resorbable metal oxide with a remarkable high strength and toughness, as well as having good chemical and dimensional stability.
Zirconia has been used in dentistry with no reported allergic reactions and has proven to be non-toxic and non-irritating.
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