Oral allergies are underdiagnosed by dental health professionals. Patients with an oral allergy complain of various symptoms such as burning or tingling sensations, with or without oral dryness or loss of taste, or of more general symptoms such as headache, dyspepsia, asthenia, arthralgia, myalgia. The signs of oral allergy include erythema, labial oedema or purpuric patches on the palate, oral ulcers, gingivitis, geographical tongue, angular cheilitis, perioral eczematous eruption, or lichenoid reactions localized on the oral mucosa. There is an increase in the prevalence of oral allergies to metals used in dental materials. Allergy to gold included in dental prosthesis has been well documented since the years eighties. Recently, titanium, used in orthopedic devices and oral implants, considered as an inert material, can induce toxicity or allergic type I or IV reactions. These reactions to titanium could be responsible for unexplained successive failure cases of dental implants in some patients (named "cluster patients"). The risk of an allergy to titanium is increased in patients who are allergic to other metals. In these patients, an evaluation of allergy is recommended, in order to exclude any problem with titanium medical devices. We stress the importance of a multidisciplinary approach to take into account patients with an oral allergy, with participation of specialists from dental and dermatologic fields.