MEDICAL MATTERS Dr Muiris HoustonThe Irish Dental Association held its annual scientific conference in Limerick recently. One of the topics discussed was the issue of dental bleaching: the practice of chemically treating teeth to make them whiter.
It is generally agreed that bleaching of the teeth is the most effective and least expensive way to provide patients with a whiter smile. Not surprisingly, given increased aesthetic demands, requests for teeth whitening have risen.
According to Dr Martin Kelleher, consultant in restorative dentistry at Guy's, King's and St Thomas's Dental Institute in London, dental bleaching has revolutionised restorative dentistry.
"As evidence continues to emerge of the beneficial, biological outcome of bleaching rather than traditional, aggressive and destructive techniques, this style of treatment will become the mainstay of many general dental practice teams," he says.
Dr Kelleher points out that, in general, patients will choose and put a higher value on the least damaging treatment available. "By using bleaching and bonding, many of the traditional difficulties of loss of teeth or irregular teeth can now be solved in an innovative but practical and sensible way."
Dr Van Haywood, professor of oral rehabilitation at the School of Dentistry, Medical College of Georgia, and Dr Harald Heymann are the acknowledged fathers of dental bleaching.
According to Dr Haywood, while teeth cleaning helps avoid gum disease and tooth loss, the primary reason motivating most patients to have their teeth cleaned is to have a healthy smile.
In an interview published in the Spring issue of the Journal of the Irish Dental Association, he says: "I have seen the example of youths with poor oral hygiene and discoloured teeth making dramatic changes in their brushing in order to obtain bleaching for whiter teeth."
How is bleaching carried out? Carbamide peroxide is routinely used as a 10 per cent solution and placed in a customised tray that the patient wears at night. In-surgery bleaching with 35 per cent hydrogen peroxide usually takes two to six visits but does not necessarily result in a greater shade change than the at-home technique.
A 10 per cent solution of carbamide peroxide is made up of 3.5 per cent hydrogen peroxide and 6.5 per cent urea. As well as providing long-term stability and a method of time release for the hydrogen peroxide, the urea helps to kill off bacteria in the mouth.
While it is not clear what the peroxide actually does to the tooth to change its colour, extensive research has shown that the chemical does not damage the tooth's hardness or cause problems to its pulp.
Home bleaching can take from two to six weeks treatment. For some people, the process may take only a few days.
The results last for between one and three years. However, a study involving a 10-year follow-up of patients found that 40 per cent still felt their teeth had maintained the same whitened colour and did not need further treatment.
It is recommended that patients wear the tray with the bleaching material overnight. Although half of the carbamide peroxide is taken up in the first two hours, it takes the rest of the night to absorb the remainder. Some people find the chemical causes tooth sensitivity. The answer to this lies in the use of potassium nitrate - an ingredient found in desensitising toothpastes - in the tray.
In addition to wearing the tray at night, patients are asked to keep a log of the number of hours they wear it. If they experience sensitivity, which is not eased by the use of desensitising toothpaste, they should contact their dentist. Otherwise, they carry on with the treatment until the teeth colour has reached the point where it matches the whites of the eyes.
In terms of cost, the bleaching and bonding of upper and lower teeth is in the region of €300. Dr Gerry Cleary, a Dublin dentist who also spoke on the topic in Limerick, says the new technique is particularly helpful for people who have sustained discoloration secondary to the use of an antibiotic called tetracycline.
Prof Leo Stassen, a consultant oral and maxillofacial surgeon at the Dublin Dental Hospital and St James's hospital in Dublin, discussed the dilemma of whether to remove wisdom teeth versus when to observe at the Limerick meeting. While wisdom teeth are the most likely to become impacted, resulting in pain, guidelines from the National Institute of Clinical Excellence in the UK have clarified the indications for removing such teeth. If someone has untreatable decay, has developed an abscess or osteomyelitis (infection of the bone underlying the tooth) or develops a cyst, then removal of the wisdom tooth is the treatment of choice.
This column would like to deal with other dental issues in the future, so if readers have a particular dental topic they would like covered, I would be grateful if they could email their suggestions to the address below. I must express my appreciation at the outset to the President of the IDA, Dr Michael Galvin, for facilitating my research for this item.
Dr Muiris Houston is pleased to hear from readers at mhouston@irish-times.ie - he regrets he cannot answer individual queries.