The article below was sent a few days ago by the UK NPWA. The PFPC received 14 letters in 2001 from people who developed hypothyroidism after having received glass ionomer fillings. In four cases complete thyroid panels were done, revealing normal TSH, elevated Total T4, and reduced Free T3 levels.


The following feature article appears in "Dentistry", 7 February 2002. "Dentistry" is a popular dental magazine with a national circulation.


Tony Lees presents the case against glass ionomers

Carolyn Smith is a well educated, intelligent woman. She has a degree and takes a keen interest in environmental matters. She is concerned about the safety of mercury amalgams and water fluoridation. So, when, last year, she needed dental treatment, she was very relieved when her dentist placed a tooth coloured filling and not a toxic mercury filling. She would not have consented to a mercury filling as she is unwilling to have any toxic material placed in her mouth.

Some days after the filling session, Carolyn began to feel unwell; she developed a constant headache, her stomach was upset, she had a marked thirst, her teeth ached and she felt short of breath. She suspected that the filling that she had received might be the cause of her problems and asked her dentist what he had used to fill her tooth. Her dentist replied that a glass ionomer (GI) filling had been placed. These fillings are known to release fluorides and other substances. So, Carolyn consulted a doctor who specialises in fluoride intoxication and who was of the opinion that her symptoms were consistent with sub acute fluoride toxicity and recommended magnesium and calcium supplements to absorb as much of the fluoride as possible until she could get the filling replaced. This treatment eased her symptoms but she was not free of problems until her dentist removed the glass ionomer filling and substituted with a composite.

Carolyn's unfortunate experience led her to ask two questions:

1 Are GI fillings toxic?
2 Has my right to informed consent been violated by having a toxic substance implanted into my mouth without my knowledge or consent?


Glass ionomer fillings, cements and fissure sealants were first used in dentistry in the late seventies and are now very widely used. GI powder is manufactured by heating glass powder with cryolite (sodium aluminium fluoride) which acts as a flux. Cryolite is a potent pesticide and is used extensively on fruit and vines in the USA. Californian wine often contains between 2 to 3 parts per million of fluoride due to the use of cryolite. Cryolite unfortunately leaks out of GI fillings, which provides a leakage of not just fluoride but aluminium, fluoride, lead and arsenic. Also released are complicated aluminium fluorosilicates which are known to be able to pass the blood brain barrier and are implicated in the aluminium and silicon deposits found in the brains of victims of AlzheimerŪs Disease. (US Federal Register, 2000).

The cytoxicity of GIs has been studied by Lonnroth (2001). The results show: Žall freshly cured GIs released aluminium and fluoride concentrations far above what is considered to be cytotoxic.Ū Some released 215 ppm aluminium and 112 ppm of fluoride. One brand of GI showed 100 ppm of lead. Fraschini of the University of Perugia (1998) showed that in some GI products the arsenic concentration was five times the maximum permissible IOC/FDI content. The IOC/FDI standards are internationally agreed standards for maximum permissible arsenic levels. Arsenic is a very potent carcinogen and these elevated levels are very disturbing. The US Government has recognised the importance of reducing arsenic levels and, in November 2001, President Bush signed an order reducing the maximum permitted level in drinking water from fifty parts per billion to ten parts part per billion. It should be noted that the GI with the most arsenic contain ten parts per million, one thousand times over the new permitted water limits.

Lewis Nix (1996) of the Medical College of Georgia found that all GIs tested cause significant increases of labelling of DNA. This labelling of DNA normally indicates mutagenicity and possibly carcinogencity. Most cryolite is manufactured from fluorspar rock which may be the source of the arsenic contamination. The lead and silica probably derive from the glass component of GI products.

Cryolite has been implicated in cancer studies. A study of cryolite workers in Denmark (Grandjean, P, Olsen, JH, Jensen, ON, Juel, K, 1992) showed that there was a marked excess death rate for respiratory cancer. It can be safely assumed that there is a risk of toxicity to any patient who has had GI filling, cement or fissure sealant, which leak fluoride, aluminium, arsenic, lead and fluorosilicates.

I have always had a problem with GIs because of their tendency to leak. It is a very poor advertisement for a filling which ideally should be watertight and inert. I suspect that a clever salesman has turned this disadvantage into a selling point; they leak fluoride so they must be good. This selling point has now been taken up by manufacturers of composites. One can now buy them with added fluoride guaranteed to leak, sorry release, fluoride and other noxious elements. Look through a current dental supplies catalogue to see how many manufacturers boast that their fillings release fluoride. It has got to the stage where some manufacturers are deliberately adding fluoride to composite fillings which were originally designed not to leak. It could be said that manufacturers of dental filling materials are using fluoride as a therapeutic agent to remineralise the margins of their fillings. This means that fluoride is being used as a drug because this is attempting to effect bodily change. Composites with added fluoride should be categorised as pharmaceutical products not medical devices, so are these fillings strictly legal?


Carolyn was understandably rather angry that without her consent she had received a cytotoxic filling. She maintains that her informed consent was not obtained for the placement of a toxin-releasing filling in her mouth. She recognises that her dentist had acted in good faith throughout but was obviously ignorant of the composition of the GI fillings and has not been properly warned, either by the manufacturers or by the licensing agents, The Medical Devices Agency (a Government body), as to the toxic properties of these licensed medical devices.

Carolyn contacted her local Councillor, her MP, the Minister of Health, the shadow Minister and the Lib Dem spokesman on Health. Many letters ensued as she pressed her point home: ŽI have been denied my right to be fully informed about what is put into my mouth by a dentist.Ū

After many months of correspondence she received a reply to her assertion from Roberta Wallis of the Department of Health Policy Directorate. "We recognise that you have raised an important issue around consent to treatment. The Government agrees that patients should have the same opportunity to give informed consent to dental treatment as they have with other forms of medical treatment. There may be some differences, in that a programme of dental care may comprise different types of treatment, but it should be still possible for the dentist to discuss the procedures involved with the patient. We are shortly to issue all dentists with a laminated single sheet comprising twelve key points on consent. It covers the legal framework, the position of children, the information that should be provided and refusals of treatment. It is intended that the guide should be kept in an accessible place in the surgery so that all members of the dental team may be aware of their obligations. I hope this will provide some reassurance on the issue of informed consent to treatment." This letter was dated 23 July 2001 and, at the time of writing this article, we have yet to receive the promised Ministry guidance.

This case brings to the fore the growing argument about safety and consent. An American environmentalist asked me, žWhat is the fascination the dental profession has with toxic substances? Your fillings are often contaminated with well known toxins mercury, aluminium, lead, arsenic and fluoride just to name a few.

It seems to me that as a profession we ought to adopt a much more precautionary principled approach to our patients and the materials we choose to implant into the oral cavity. More and more patients are asking searching questions about mercury and, increasingly, fluorides. We are treating a more educated and aware population. It is no longer possible to assert that the dentist knows best, especially if the dentist is not aware of the toxicities of dental materials and is also told by the dental hierarchy that Žfluorides are safe and effectiveŪ even though 48% in the water fluoridated areas exhibit dental fluorosis and 12% are Žof aesthetic concernŽ. (The University of York Review into Water Fluoridation 2000).

The profession should know that fluoride ingestion in the UK is increasing alarmingly. There are many sources - air pollution, water, food, pesticide residues, fertiliser residues, drugs and an increasing exposure from dental sources such as glass ionomers, toothpastes, mouth rinses and topical fluorides etc.

American fluoride toothpastes carry a poison warning. Fluorides are cumulative poisons; they collect in bone and severely damage the body in later life. I believe that the dental defence societies and insurance companies will find it increasingly difficult to defend dentists against uninformed consent cases.

The Government has recognised that Ždental fluorosis is a manifestation of systemic toxicityŪ (Baroness Hayman reply to written question on dental fluorosis, 1999). We must also recognise this fact and start limiting the amounts of fluorides and other toxic materials that we use and prescribe for our patients.


Toxic synergistic action between fluoride and aluminium in drinking water. (4 December 2000). Federal Register, Vol.65 No.233. Substances nominated for National Toxicology Programme and testing. United States of America.

Lonnroth EC, Dahl JE. (2001) Cytoxicity of dental ionomers. Acta Odontal Scand 2001 Feb 59 (1):34.

Eramo S, Fraschini M, Lomurno G, Polimeni A. (1998) Tests on ionic release from glass-ionomer cements. Minerva Stomatol 1998 Jul-Aug; 47 (7-8): 299-302.

Lewis J, Nix L, Schuster G, Lefebve C, Knoernschild K, Caughman G (1996) Response of oral mucosal cells to glass ionomer cements. Biomaterials June; 17 (11): 1115-20.

Grandjean P, Olsen JH, Jensen OM, Juel K. (1992) Cancer incidence and mortality in workers exposed to fluoride. J Natl Cancer Inst. Dec 16-84 (24): 1903-9.

Tony Lees qualified in 1961 in Bristol and works in general practice. He is a director of the National Pure Water Association, which campaigns against water fluoridation. He has been researching fluorides for about eight years. He is also the director of a dental manufacturing company.