Biocompatibility of Aluminum Oxide (Alumina)
Help Desk Technical Bulletin: 05001, 11/14/05
Recently, there has been some attention to the possibility that metallic aluminum is a public health concern. Aluminum oxide, also known as alumina, is a well-proven, biocompatible ceramic that has been used as a dental restorative material for many years. Aluminum oxide is an inert compound of aluminum and oxygen. It is formed by oxidation of aluminum and oxygen to form Al2O3, a non-metal or pure ceramic. In the manufacture of dental ceramics, care is taken to ensure that all the aluminum is converted to the inert alumina compound throughout the manufacturing process. There are no bodily functions that react with the alumina, hence the excellent biocompatibility.
The fact that alumina is a compound of aluminum and oxygen, should not be cause for concern. The properties of the compound differ greatly from the plain components. Table salt, NaCl, is a compound of sodium and chlorine, each by themselves a harmful substance, but together it is something the human body needs in appropriate amounts.
Robert Kelly, DDS, MS, DMedSc, Professor of Oral Rehabilitation, Biomaterials and Skeletal Development at the University of Connecticut Health Center states:
“Two types of dental ceramic contain the aluminum oxide: (1) high strength aluminum oxide; and, (2) tooth-colored dental porcelain.1 Aluminum oxide is the most stable form of aluminum known and it is not soluble in water.2 Since this ceramic is not water-soluble there is no method for raw aluminum to leave the crown to enter the blood or the brain.
Further, the outside surface of aluminum oxide crowns are covered with a thick layer of dental porcelain and the inside is sealed to the tooth with dental cement. In this way the aluminum oxide is hidden from saliva. Dental work containing aluminum oxide simply cannot add aluminum to the diet.”
Aluminum oxide has been used as a dental porcelain pigment for some 60 years and as a ceramic restoration substructure for 25 years. It has a variety of orthopedic uses in hip and knee joints where it has demonstrated excellent biocompatibility for many years. Dental patients should rest assured that dental ceramics composed of aluminum oxide are not a source of soluble metallic aluminum in the body.
- Kelly J.R. (1997). Ceramics in restorative and prosthetic dentistry. Ann Rev Mater Sci 27: 443-68.
- Physical constants of inorganic compounds, in: David R. Lide (Ed.) CRC Handbook of Chemistry and Physics. Boca Raton: CRC Press, 1994.
