The objectives of this study are to perform tests and questionnaires. All samples will be non-invasive.
Evaluation of metallic taste (MT) occurrence with a specific questionnaire. In a single patient, MT occurrence may vary according to the time of the study.
1. Oral media modifications 1.1- Salivary functions: basal and stimulated salivary flow will be determined. Immediately after collection, both salivary samples will be stored at -80°C. Twice a year frosted samples will be delivered to the Centre des Sciences du Goût et de l'Alimentation in Dijon, France) by a special transporter. Biochemical analyses of saliva will consist of analyses of candidate markers: malondialdehyde, metabolites (uric acid), ions (Mn2+ and Zn2+), enzymatic activities and key proteins involved in the salivary peroxidation (catalase, superoxide dismutase). All the technics are already validated.
1.2- Quantification of fungiform papillae in dermatoscopy. The objective of the dermatoscope is placed on the tongue and a snapshot of a predefined surface area will be recorded on both sides of the tongue. The density will be estimated according to an automatic method from the snapshots.
1.3- Trapping of nasal scents To assess the presence of volatile odorous compounds induced by the oral lipoperoxidation, the nasal scents of the patients will be harvested by a Tenax® trap positioned at the exit of nostril. The operation will be performed without any stimulus, after an iron sulphate mouthwash (artificially inducing MT) and after treatment with lactoferrin mouthwash (chelating agent). The traps will be hermetically closed and sent to the Centre des Sciences du gout et de l'Alimentation in Dijon for analysis by gas chromatography/mass spectrometry. These tests will be performed after psychophysical tests not to distort their results.
2. Psychophysical tests. 2.1- Psychophysical tests of taste intensity will be carried out with two aqueous solutions (one neutral, the other sapid) of each taste (salty, sweet, sour, bitter and umami) and iron sulphate. The solutions will moisten 0.5 cm-diameter filter paper discs that will be deposited on the tongue. For each taste, patients will have to indicate the disc with the strongest and least strong taste. Four locations on the tongue will be tested: one for the territory of the facial nerve (anterior tongue), one for the glossopharyngeal nerve (tongue base), repeated on both sides.
2.2- Efficacy of a lactoferrin mouthwash to attenuate the sensation of MT. Omur-Ozbeck et al. showed that a lactoferrin mouthwash completely attenuated an artificially-created MT by an iron sulphate mouthwash. For the investigator's patients, in case of spontaneous presence of a MT or after having artificially created it by the iron sulphate mouthwash, a lactoferrin mouthwash will be proposed and its efficacy to attenuate the MT will be evaluated.
2.3- Psychophysical olfaction tests (European Test of olfactory Capacities ETOC from Thomas-Danguin T et al. Rhinology 2003;41:142-51) This test is constructed from odours contained in vials. It is made up of 16 series of 4 vials. In a series, only one of the four vials contains an odour. The patients must first find the vial which, among 4 contains the odour (test of detection) then in the vial chosen identify the odour (test of identification) among 4 alternatives proposed in the form of 4 verbal labels.
3. Impedancemetry Measurements of the spontaneous presence of a current in the oral cavity and the resistivity of the oral mucosa will be carried out by application of an electrode on the back of the tongue. This procedure is painless.
4. Evaluation of food intake by patients weighing, an analogic visual scale and of food pleasantness by MT specific questionnaire.
5. Characterization of quality of life through general EORTC QLQ30 and HNC-specific EORTC HNC35 quality of life questionnaires.
