Inclusion Criteria:

- complaints of xerostomia (visual analogue scale)

- at least 6 months after radiotherapy of the head and neck region including all
salivary glands with at least 50 Gy

- objective hyposalivation / xerostomia (at rest < 0,25 ml saliva per minute,
stimulated < 0,1 ml saliva per minute)

- patient must have given written informed consent

Exclusion Criteria:

- prior radiotherapy was an intensity modulated radiotherapy

- prior hyperbaric oxygen therapy after radiotherapy

- conditions which might be an additional risk for the treatment with hyperbaric oxygen
such as spontaneous pneumothorax within the last two years, surgery of the eardrum or
the middle ear, acute infection of the upper airways, not adequately treated
epilepsy, concurrent radio- or chemotherapy, hereditary spherocytosis, psychosis,
lung emphysema, asthma, severe COPD, prior surgery of the thorax, pace maker

- myocardial infarction within the last 6 months

- drug therapy which might induce xerostomia

- known intolerance or hypersensitivity to Wrigley's Freident®

- pregnancy or breast-feeding women (for women aged less than 60 years a pregnancy test
is mandatory)

- women of childbearing potential with unclear contraception. The following
contraceptive methods are recommended: combined oral contraceptives or
progesterone-only pill, hormone-dispensing or copper intra-uterine system, hormone
patches, long-acting injections, vaginal ring

- treatment with other investigational drugs or participation in another clinical trial
within 30 days prior to enrollment

- refusal of cooperation or consent