[Orthodontic materials studied in the HET-CAM test for mucosa-irritating effects]

A total of 33 different substances used in orthodontic therapy were investigated for their potential to irritate mucous membranes. As an alternative to animal testing, the HET-CAM test (Hens Eggs Chorioallantois Membrane Test) was employed. The effects of the substances on the vessels of the chorioallantois membrane, such as haemorrhage, lysis, and coagulation, were videotaped and evaluated. When polymerized correctly in accordance with manufacturers' instructions, plastic materials used for removable orthodontic appliances and bracket bonding caused no irritation. Liquid primers for bracket bonding and monomer substances were highly irritating. Etching gels for decalcification of the enamel surfaces were far less irritating than liquid etching substances. Thus, primers should be handled with care; the use of liquid monomers should be avoided in the oral cavity; and etching gels should be preferred to liquid etching substances.