Dental Bleaching

This article will look at the various types of bleaches available and highlight some of the risks associated. The first step in to look at the history of bleaching.
Bleaching like amalgam dates back to 1848. The, in -office bleaching technique was popular in the late 1800’s and early 1900’s.’ Many articles appeared in the dental journals of the time describing popular bleaching fashions. Bleaches were placed on teeth. Lights have been associated with in-office bleaching since the 1800’s. That association was a logical one since we know that heat and light speeds up a chemical reaction.

Many different techniques and materials were tried in the late 1800’s to lighten, first non vital (dead) teeth and then vital (normal live) teeth.
The traditional technique for in office bleaching that we recognise today was described in the early 1900’s in “ Dental Cosmos” a fore runner of the “American Dental Journal”. The clinical observation of the time was that the teeth appeared lighter immediately after treatment but the result faded and it took up to four visits to obtain patient satisfaction. With the advent of the great depression in America, bleaching disappeared from the dental journals until the 1960’s, when there was a brief comeback.
The bleaching phenomena really only took off again in the early 1990’s. The home bleaching technique as we know it today was being practiced as a cheap form of cosmetic treatment in Jacksonville, North Carolina. Local dentists had come up with the idea of putting carbamide peroxide ,which was on the food and drug list as an oral antiseptic, into a tray at night to whiten the teeth. A visiting dentist called Van Haywood , who was a guest lecturer and looking for a research topic, heard of the technique and decided to do some research on the subject. Numerous research papers later the “bleaching industry” is spawned.

There are three forms of bleaching. Over the counter bleaching products ,tray bleaching , and bleaching performed in an in office environment applying hydrogen peroxide and using a dental light.
If you are interested in this treatment , then the first step is to educate yourself about the benefits and the risks involved. The first place to start is to get a dental exam and correct any routine dental problems. There is no point placing a white filling and matching the shade, if the teeth are to be bleached and the shade of the teeth changed. Bleaching doesn’t alter the colour of crowns , white fillings or teeth on a denture. Equally there is no point bleaching teeth that are diseased. One of the side affects of bleaching is sensitivity in teeth. Any underlying problems will be made more problematic. It would be like painting a house, where the roof might be about to cave in.

There are a wide variety of these products, including strips, wraps, trays and paint ons not to forget toothpastes. Some of these will bleach teeth and some will make no difference. The main concern is the lack of a dental exam before bleaching. The European directive is that these products shouldn’t be purchased without an exam and prescription by a dentist. The directive also states that the maximum concentration of hydrogen peroxide should be no more than 0.1% concentration.
There would be concerns that the one size fits all tray, will leak peroxide in to the mouth,as the fit is not custom made to the patient. The toothpastes and paint- ons containing bleach are shown in research to merely remove stain and have no internal affect in changing the colour of the tooth. A concern with these products are complaints of sensitivity in the gum tissues.

Carbamide peroxide is used in tray bleaching. The first step is for the dentist to take an impression and this is sent to a dental lab where a custom designed bleach tray is made. The dentist will take into account the cause of the darkness where if the tooth has had a root treatment or the person is a victim of tetracycline staining, then a higher strength product is used. The material used is carbamide peroxide which is a blend of hydrogen peroxide and urea. A 10% carbamide peroxide has a3.5 % hydrogen peroxide strength. Hydrogen peroxide is active for 30 to 60 minutes whereas carbamide peroxide is active for 2 to 10 hours. Carbamide peroxide increases the ph above 7 and a positive side affect of this is that it kills the bacteria causing tooth decay and periodontal disease. There is no concern for small cavities but a large cavity wouldn’t benefit from having this product getting closer to the nerve.

Normal teeth take 3 days to 6 weeks to lighten, depending more on the individuals tooth response than the product used. For most patients an acceptable result occurs after 4 to 10 days of nightwear. Nicotine and tetraccycline stained teeth could take 1 to 3 months of nightly 10% carbamide peroxide use depending on the severity of stain.

One in office treatment does not yield the same outcome as tray bleaching. The average is 3 in office visits for maximum outcome. The bleaching light used, from all research is shown to have no long term result. It is used as a fancy prop to justify the bill. The initial whitening that appears is down to dehydration of the tooth. The combination of in office and tray bleaching may shorten the time but will increase the bill and the sensitivity. I have problems also with placing a 35%hydrogen peroxide concentration on teeth for half hour periods. Research has shown that some properties of dentine never recover from high doses of hydrogen peroxide, possibly because of the acidic nature of this product. The long term risks with regard to mouth cancers with too much use are also a concern. The research shows that the end result with regard to bleaching is the same regardless of the material, if the time is extended long enough, as the outcome is determined by the tooth rather than the product.

I have never chosen to push dental bleaching. I have always felt that the clinics that went all out to charge large sums for in surgery treatments using hi-tech lights as a dazzling prop to be charlatans. The beauty industry latching on to this treatment I find scary, because they are not qualified to prescribe and perhaps don’t understand the risks. They are also in breach of EU legislation. Since this article was first written, a hairdressing chain in the UK has been sued for practicing dentistry illegally and for providing over strength bleaches.

I received a letter from the medical defence union telling me that I wasn’t covered if I did in surgery bleaching , in the event of a lawsuit. I think it’s interesting that “Smiles Dental” don’t advertise this treatment anymore, even though it was the treatment, it first flogged in a big way.

All the research seems to suggest that tray bleaching using a mild dose of carbamide peroxide is safe and has a few add on benefits of being useful for patients prone to periodontal disease and extensive caries. It has the added beauty that if sensitivity is becoming an issue that you can take a break from treatment for a few days. I would also be be happy that there isn’t an instant result and a little work has to be put in to achieve a nice smile. Only someone who has a real interest will pursue the treatment.
I am happy to provide this treatment with a clear conscience.

Doctor Patrick O’Brien of Monread Dental Practice, Monread, Naas Co Kildare provides a dental bleaching service.

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