Irritation Testing of Dental Adhesives

Dental adhesives that improve the bonding between the tooth and the restoration are extensively used. The techniques employed for placement of dental adhesive agents may result in accidental exposure to adjacent oral soft tissue of the patient. Objective: To determine the potential of dental adhesive agents to evoke irritation of oral mucous membranes. Method: The hens’ egg test – chorioallantoic membrane (HET-CAM) was used to establish the agents’ ability to cause immediate damage to the blood vessels of the chorioallantoic membrane of fertilised eggs. The type of injury observed during the five minutes exposure were rupture of the vessels, coagulation within the vessels and haemolysis of the vessels. An irritation score was calculated as an average of two experiments in triplicate based on the time of appearance of the different types of damage. Positive (0.1 M NaOH) and negative controls (saline) were included. Six commercially available agents marketed as “single-component”, “one-step” or “self-etch” adhesives were randomly selected from the Scandinavian market: Adper Prompt L-Pop (3M ESPE) (A), ANA Single Bond (Nordiska Dental) (B), Gluma One Bond (Heraeus Kulzer) (C), ONE-STEP (Bisco Ltd) (D), Syntac Single-Component (Vivadent) (E), Xeno III (DENTSPLY DeTrey) (F). Products A and F also contained etching constituents whereas the etching component was separate for the other products and not included in the testing. Results: Irritant reactions were observed for all of the tested dental adhesives. The irritation score for the different products were as follows: A: 8.1, B: 11.9, C: 18.1, D: 9.5, E: 13.7, F: 8.1. Two of the products (A and F), the so-called “self-etch” adhesives, were rated as moderate irritants (irritation score between 5 and 8.9) and the other four as severe irritants (irritation score between 9 and 21). Conclusion: Inadvertent spill of adhesive agents may result in local damage to oral soft tissue.