Platinum Use in Dentistry
The name platinum is derived from the Spanish platina, meaning 'little silver'. It is a silvery-white, malleable and ductile noble and heavy metal. There are six naturally occurring isotopes of platinum of which only the least common is weakly radioactive.
Like gold, platinum is very resistant to corrosion and tarnishing and will not oxidise in air no matter how strongly it is heated. However it reacts with some other chemicals such as the halogens, cyanides, sulphur and molten sulphur compounds, heavy metals and hydroxides to form a variety of compounds.
Sources of platinum
Platinum occurs sparingly in the earth's crust usually accompanied by iron, silver and gold and less commonly in nugget form. It is always found with five other heavy metals known are collectively known as the platinum group metals (PGM). These include osmium (Os), rhodium (Rh), iridium (Ir), ruthenium (Ru), and palladium (Pd) which all have very similar properties.
Platinum is mined mainly in South Africa, Russia, and Canada and production has increased steadily over the past few decades to about 155 tonnes a year.
In addition to the platinum found in the earth's mantle, the steady shower of meteorites which bombard the planet may also contain significant amounts of platinum.
Uses of platinum
The most common uses of platinum include jewellery and as a catalyst especially in leaded petroleum. This latter use leads to dispersal in the air that may be higher in garages, tunnels, and in the vicinity of routes of trucking companies. However, the newer generation of catalytic converter emits much less platinum than previous types.
In addition, platinum is used in:
High temperature laboratory equipment
Electrical resistance wires and electrical contact points
Glassmaking for optical fibres, and liquid crystal display glass especially that used for laptops
Chemotherapy drugs and
Medical applications such as various prostheses and pacemaker electrodes.
Platinum in dental alloys
Platinum is often used mixed with other precious metals such as gold and silver and small amounts of non-precious metals in the dental alloys used to make inlays, crowns and bridges. The addition of platinum to such alloys provides strength, stiffness and durability whilst the other alloyed metals provide malleability. Small amounts of other platinum group metals such as ruthenium or iridium are also sometimes added.
The most common application of such alloys is in forming the metal framework onto which porcelain can be bonded to make an aesthetic porcelain-fused-to-metal restoration (PFM). There are two main types of precious metal alloys used for this purpose in dentistry - high gold and low gold alloys.
The high gold alloys are primarily gold alloyed with around 10% platinum and the low gold alloys are composed of lesser amounts of gold and between 50% and 80% palladium. The high gold platinum-containing alloys have been used for many decades. However, a rise in the cost of gold during the 1980s resulted in the introduction of the high palladium, low gold alloys. The low gold alloys have the yellow colour of gold and the physical properties required to thermally fuse with the porcelain at a reduced cost.
Routes of exposure to platinum
Some small amount of platinum will be inhaled daily from the atmosphere and this is estimated to be 6 - 600 pg. Platinum will also be acquired from drinking water and many water supplies have approximately 100 pg/litre of platinum. Foodstuffs including eggs, offal and meats also contribute an estimated 1.4 µg platinum per day for adults.
However, platinum-exposed workers are at significant risk and one UK study found that 57% of platinum refinery workers had symptoms related to platinum exposure which may not be dose related once sensitisation has occurred. In another study one in five workers exposed to platinum dust exhibited skin sensitisation upon testing and other symptoms such as rhinitis and asthma (U. Bolm-Audorff et al. On the frequency of respiratory allergies in a platinum processing factory. Report of the 28th Annual Meeting of the German Society).
And allergy (RAST) and skin prick tests at a South African platinum refinery found that two-thirds of those who tested positive to the skin prick test to platinum salts also tested as being allergic.
The health effects of platinum
On an occupational level, there appears to be little concern about exposure to the metal platinum with most consideration centering around the soluble platinum compounds which are recognised to cause allergies, organ damage, DNA alterations, hearing loss and cancer. Once sensitisation to platinum salts has developed, subsequent exposures to minute concentrations may elicit both immediate and late-onset reactions.
Signs of platinum allergy primarily seen in occupationally exposed individuals include: conjunctivitis, rhinitis, coughing and wheezing, bronchitis, asthma, contact dermatitis and mucous membrane inflammation. Smoking has been shown to be a significant factor in platinum sensitisation in several studies.
In general, autopsies reveal low levels of platinum with deposits collecting in the subcutaneous fat, kidney, pancreas and liver. Finally, a danger of platinum is that it can cause potentiation of the toxicity of other dangerous chemicals in the human body, such as selenium.
The problems posed by the use of platinum-containing alloys in dentistry include:
The development of a platinum allergy or the placement of such an alloy in someone who is already allergic.
The sensitisation of dentists and laboratory staff who are casting, trimming and polishing such metals.
Nearly all metals used in dentistry are alloys which means that they are a mixture of dissimilar metals which are then placed in the moisture of the mouth. This creates galvanic currents between the metals in any given alloy and between the dozens of different metals often used in the mouth. In particular the combination of dental amalgam fillings when combined with the use of other metals in the mouth may lead to enhanced galvanic activity by the amalgam filling and greatly enhanced mercury vapour production.
The placement of any metal restoration may block meridian flows through the teeth and the electrical activity of such metals may also effectively create chaotic electrostimulation of the meridians. This may cause systemic or remote physical problems that are hard to associate with the cause.
Although platinum is fairly unreactive, all metals have the potential to leach ions into the surrounding tissues and associated meridian.
When restorations are cemented into place the immune system is exposed to the causative metal 24/7. There is significant synergy between metals, and between metals and other toxins which may be a hundred fold and which can undermine the immune response potentially leading to diseases such as cancer and autoimmune disease.
When such alloys are drilled either to adjust the bite or in order to be removed both patient and dentist are exposed to an aerosol of particulates.
It is always a advised to be tested for sensitivity to dental materials prior to the placement of dental restorations. Many biological and holistic dentists are now of the opinion that metals should be avoided. For laboratories that test for metal toxicity see the Useful Contacts page.
The Natural Recovery Plan book also addresses the issue of the use of toxic metals in dentistry and suggests a metals detoxification programme using natural means.