Contact allergy is not frequently seen in the oral mucosa. Oral lichenoid reactions in conjunction with dental restorations, particularly amalgam fillings, are among the most common affections. Subjective symptoms such as burning mouth syndrome, could have an allergic component, but the etiology is unclear and complex. Food additives and oral hygiene products can cause oral lesions of allergic nature. Patch testing is the routine diagnostic tool used by dermatologists, though the interpretation of the clinical relevance is crucial.