LATEX
The most common allergy is latex, as used in gloves and rubber dams. Often people have developed these allergies after being in contact through their occupation e.g. nurses (gloves), car spraypaint booth operators (rubber masks).
To take care of these patients, we have non-latex gloves (Nitrile), non-latex rubber dams, and non-latex instrument sheaths available.
LOCAL ANAESTHETICS (LA)
Some patients state an allergy to local anaesthetics. These cases need a careful evaluation, as true allergies are very rare nowadays.
Most dental LAs have adrenaline added to them to help the numbness work better. The adrenaline can give patients a quickening of their heart for a few minutes, and this may cause an anxious patient to faint. For these patients, a non-adrenaline based LA is available. This is not an allergy.
Rashes, blotches, or itchiness of the body indicate a true allergy. However, there has never been a documented case of an allergy to the LA ingredient alone. It has always been one of the additives:
- In the past, a common allergy-causing ingredient was methyl paraben. This is no longer used in dental LAs.
- Multiple-use vials of plain local anaesthetics contain a preservative, methylhydroxybenzoate. These are not used in dentistry, but may be used by a medical practitioner. Dentists use single-use cartridges and do not need this ingredient.
- All LAs with adrenaline contain a preservative, sodium metabisulfite. This is the cause of allergies to dental LAs.
There are LAs that contain no preservatives, and can be safely given without testing. However, it is very wise for patients who have had an allergic reaction in the past to undergo proper testing and determine the true cause. Then, whenever you need an LA in the future, be it from a dentist, doctor, or emergency department at a hospital, you will able to have definitive proof of the exact nature of your allergy. Royal North Shore Hospital has an Intensive Therapy Unit which will do this for you. Alternatively, you may make an appointment with a private specialist allergist.
Dental LA preservative-free choices:
- Citanest 3% with Octapressin
- Plain Xylocaine 2%
- Plain Citanest 3%
- Plain Carbocaine 3%
- Plain Mepivicaine 3%
AMALGAM
Allergies to amalgams are very rare, but possible. The allergy does not have an effect throughout all the body, but shows up as a reddened area on the cheek next to the amalgam filling. This reddened area may persist even after the amalgam has been removed. The allergy occurs as a reaction to the mercuric oxides that form on the surface of the filling.
The release of mercury compounds from amalgams is of an inorganic form (i.e. not combined with carbon). As such, they are easily excreted from the body and do not have any harmful effects. They do not accumulate in the body. Amalgam fillings have no effect on your health. In fact, it would be illegal to claim that a person’s health could be improved by the removal of amalgams.
Organic mercury compounds (i.e. combined with carbon), e.g methyl mercury, is often found in food sources, especially fish products. However, even in predominantly fish-eating countries such as Japan or Iceland, people do not build up dangerous levels that can cause illness.