Objective. This study was undertaken to determine the potential of dental adhesive products to induce mucosal irritation based on their ability to damage the blood vessels of the chorioallantoic membrane (CAM) in fertilized hen’s egg.
Material and methods. Twenty-seven dental adhesive products (total 36 solutions) covering the four adhesive concepts, etch and rinse with two or three steps procedure and self-etch with one or two steps procedure, were evaluated using the hen’s egg test–CAM method (HET–CAM). The blood vessels on the CAM of a fertilized hen’s egg were used as the test system, and severity of the irritation was based on an assessment of the reaction of the blood and the blood vessels to the test chemical during 5 min of exposure. Three specific end-points – coagulation of blood, lyses of blood and rupture of blood vessel – were evaluated and their time-points for appearance noted.
Results. Coagulation of the blood was the most frequent injury, and was observed within less than a minute’s exposure in 25 of the 36 tested solutions. Seventeen of the solutions were rated as moderate irritants and 16 as strong irritants. The type and severity of reaction could not be linked to the type of solvent (water, ethanol, acetone) nor to the presence of 2-hydroxylethyl methacrylate (2-HEMA) in the products.
Conclusions. Most dental adhesives damage the blood vessels of the CAM, indicating irritant effects on mucous membranes

Potential of dental adhesives to induce mucosal irritation evaluated by the HET-CAM method
Dahl JE.
Acta Odontologica Scandinavica 2007; 65: 275-283.