The HET–CAM test (hen’s egg–chorioallantoic membrane test) was used to evaluate the irritative potential of dental adhesive agents used to improve the clinical quality of resin-based restorations. The dental adhesives were of the multilayer type, represented by either two separate liquids each for prime and bond or one-liquid systems (prime and bond) used for both applications. The chorioallantoic membrane of 9-day-old fertilized eggs was exposed to 15 different brands of dental adhesives consisting of 12 different primer agents, 20 different bonding agents and three prime and bond. During 5 minutes the exposed membrane was examined for haemorrhage, lysis and coagulation, and the time to the first appearance of the effects was recorded. An irritation score was calculated, and the agents were classified as non-irritants or slight, moderate or strong irritants. The most common reaction was coagulation of blood vessels in the chorioallantoic membrane, and the mean detection time for coagulation was less than 100 sec for 20 of the proprietary solutions. All prime and bond, nine of 12 primers and six of 19 bonding agents were classified as strong irritants. The remaining primers and four bonding agents were classified as moderate irritants. The remaining bonding agents were classified as slight irritants (six products) and non-irritants (three products). The results show that adhesive agents have an irritative potential and that care must be taken when using adhesive agents to avoid accidental spill to patient mucosa or the operator’s skin.

Irritation of dental adhesive agents evaluated by the HET–CAM test
Dahl JE
Toxicology in vitro April 1999, 13; 2: 259-264