This is a classic example of risk vs. benefit. The benefit: - avoidance of OsteoRadioNecrosis (ORN) because of extractions due to dental caries, which could translate into having your jawbone removed.

The risk: - the items mentioned in the study.

Certainly this is something that needs to be watched. I have used presciption strength flouride for the last couple of years with no other problems or side effects.

And how did they separate this from the side effects of chemotherapy? Chemo is hell on the gastrointestinal system and does a number on the stomach lining.

Common sense is required here as is stated in the study. DO NOT SWALLOW it, use it sparingly. The stuff I use is a foam that I place in custom fit dental trays. A 1/2 hour after I remove the trays, I rinse whatever residue is left.

I can see where this could be a bigger issue with people with dry mouth

There is no doubt that excessive flouride is toxic, so are too many MacDonalds hamburgers! In a recent study published on the ACS site the colon cancer rate is 50% higher for those eating more than 3 ozs. of red meat a day (about a MacDonalds hamburger patty).

From all I have been able to read on this so called study it is based on the conclusions of the study of ONE patient. This is not a true double blind scientific study with a large number of subjects, a control group and a wide range patient demographics. It is merely a white paper that should lead to further scientific research to validate what I believe to be a hypothesis (I am not challenging it's accuracy). If I have missed something please enlighten me. An abstract of the study parameters is listed below.

"Abstract:

Background. High-concentration topical fluorides are used commonly to prevent caries in patients with compromised salivary function due to irradiation and chemotherapy.

Case Description. The authors describe a 50-year-old man with previously treated cancer who was using tray-applied topical fluoride gel. He complained of gastric symptoms, difficulty in swallowing, leg muscle soreness and knee joint soreness. A computed tomographic scan revealed thickening of the esophageal walls. An upper endoscopy revealed abnormal motility. The motility test indicated high-amplitude peristalsis and hypertensive lower esophageal sphincter, and urine testing indicated high levels of systemic fluoride. The patient's fluoride regimen was altered, and within a short period his urinary fluoride levels returned to normal and his symptoms resolved.

Clinical Implications. Clinicians prescribing home-applied high-concentration fluorides need to be cognizant of the symptoms of fluoride toxicity, carefully monitor the patient's compliance with the treatment regimen, and adjust the dosage or mode of application to control the total ingested dose of fluoride."

Here is a reference to oral complications from the NCI: http://cancerweb.ncl.ac.uk/cancernet/302904.html