Effect of drinking water fluoridation on hearing of patients with otosclerosis in a low fluoride area: a follow-up study.

Fluorine content in bone samples taken from the middle ears of otosclerotic patients was determined. Otosclerotic stapes footplate was found to have a significantly higher content of fluorine than skeletal bone from the meatus. Fluorine contents in footplate and meatal wall samples of otosclerotic patients drinking fluoridated water were slightly higher than those of patients drinking low-fluoride water. In the clinical part of the study, hearing levels of 280 patients with otosclerosis living in an area with low-fluoride water were assessed. In 344 operated ears, the preoperative and long-term postoperative air conduction and bone conduction thresholds of patients drinking fluoridated water did not differ significantly from those of patients drinking low-fluoride water. After a mean follow-up period of 9.6 years, air conduction thresholds of non-operated ears in patients drinking fluoride-poor water were found to be significantly worse than those of patients drinking fluoridated tap water, likewise there were significant differences in bone conduction thresholds at 2 and 4 kHz. Thus, fluoridation of drinking water has a beneficial effect on non-operated otosclerotic ears but has no significant effect on hearing levels of operated ears.