Contact stomatitis and dermatitis to nickel and palladium

17 subjects were tested epicutaneously with 22 materials, including Ni, Pd, Cr and Co. 5 subjects with a positive allergic skin reaction to Ni were tested with a pure metallic nickel plate 3 X 5 mm, which was attached to the buccal side of one lower premolar. These 5 subjects all developed local allergic contact stomatitis on the mucosa of the cheek adjacent to the metal plate. This was confirmed histologically. The same oral test with pure metallic palladium gave no reaction in subjects with a positive patch test. A control group gave no reactions to the metal plates. Allergic contact stomatitis was diagnosed with the help of both clinical and histological examinations.