Bleaching teeth with carbamide peroxide in a custom tray is an exciting service to offer patients and a tremendous adjunct to restorative dental treatment. One of the side effects noticed when bleaching teeth is that the use of 10% carbamide peroxide applied nightly in a custom-fitted tray is effective to remove plaque, reduce caries bacteria and elevate pH on elderly patients for successful long-term oral hygiene care.
As the population of the world ages – and is living longer and keeping more of its teeth – there is a greater number of people who have received good dental care in their younger years, but are now faced with difficulty in maintaining those restorations and existing teeth in their later years. Dentists have experienced the frustration of rampant root surface caries around crown margins or in virgin teeth as these patients age. This caries phenomenon seems to be associated with a reduction in salivary flow due to ageing, increased side-effects of medications, and a decline in health.
There is also a loss in manual dexterity and the ability to perform routine oral hygiene care. Even if these patients have access to care from a general dentist, their ability to clean at home around hemi-sected molars, under pontics for fixed partical dentures, or interproximally around gingival recession or periodontally involved teeth is compromised, and often results in caries between dental appointments. This mechanical disadvantage is further complicated by the tendency of these patients to use sugar-containing breath mints due to salivary flow loss, and the resultant effect on the caries index.
What is needed is a simple, inexpensive mechanism to apply to better clean the teeth. Rather than mechanical means alone, a chemotherapeutic approach is needed. Typically, fluoride in a tray has been used for this population. However, clinical experience has indicated this is not very effective.
Chlorhexidine can also be used, but the staining is a detriment to use. Interestingly enough, 10% carbamide peroxide can be used alternately with chlorhexidine to remove those stains (Addy et al, 1991).
Although 10% carbamide peroxide is generally associated with tooth whitening, the material was originally used as an oral antiseptic for gingival healing (Haywood, 1992). It was being applied in a tray for wound healing when the tooth whitening side effect was discovered (Haywood, 1991). Carbamide peroxide 10 and 15% has been has been classified by the United States Food and Drug Association as category 1, which means there are sufficient data to demonstrate that these agents are safe and effective for use in the oral cavity as oral antiseptic agents (Haywood, 1993, Dental Product Spotlight, 2001). Persons now involved in tooth whitening research report a loss of plaque during that time such that their teeth feel ‘squeaky clean’ much like after a prophylaxis. Reports from a century ago cite the use of this material in children with pitted teeth to reduce caries (Atkinson, 1893).
Current research on safety noted that the pH of the saliva and the material in the tray is elevated to about eight in less than five minutes after application, and remains that for the duration of the application (Leonard et al, 1994, Leonard and Austin et al, 1994) (in those studies, two hours). This occurrence is related to the urea in the composition (Firestone et al, 1982, Wainwright and Lemoine, 1950). The pH values are crucial to preventing the formation of tooth decay, since root caries can start when the pH of the mouth is between 6 and 6.8 (Hoppenbrouwers et al, 1986, 1987). A further study has indicated that 10%CP kills one of the two bacteria causing tooth decay (Bentley et al, 2000). Gingival indices in bleaching studies have indicated some improvement in gingival scores (Powell and Bales, 1991), although the patient population involved in bleaching often has a very clean mouth for the onset of treatment. Carbamide peroxide is preferred rather than hydrogen peroxide, since the urea and carbopol in 10% CP allows it to be active up to 10 hours in the mouth, while hydrogen peroxide is only active for 30-60 minutes. (Haywood, 2007).
The tray design used for caries control is a non-scalloped, no reservoir tray, which extends 1-2mm onto the gingival tissue (Haywood 2006, 2007). It should not extend into undercuts to the path of insertion, nor encroach on frenum attachments. The contact with the gingival prevents the washing out of the material, and does not generally cause gingival irritation at the 10% concentration (Leonard et al, 1994). The lack of reservoirs means less material is needed per application. The traditional custom fitted bleaching tray from an alginate impression works well, although there are some options with ‘boil and form’ trays in certain arches (Haywood et al, 2001). The boil and form tray can also be used as a diagnostic test to see if the patient can wear the tray and if the material will be effective.
Carbamide peroxide for caries control has a long history of use, except that the previous attempts did not employ a tray application. Several papers cite the use of 10% carbamide peroxide as a rinse in the form of Glyoxide, in orthodontic patients during three years’ treatment to prevent white spot lesions (Fogel and Magill, 1971). It has also been used in elderly patients as a rinse for oral hygiene (Haywood, 1992). Carbamide peroxide seems to be most effective when some type of container or barrier is used.
The questions of safety to the ingestion have been answered in literature prior to bleaching, as well as current literature (Ritter et al, 2002, European Commission, 2005). Prior to bleaching and even today, 10% carbamide peroxide is used in new born infants, 10 drops in their throat every two hours for seven to eight days, to treat candidiasis or thrush (Dickstein, 1964).
Since carbamide peroxide kills lactobacillus, and chlorhexidine kills strep mutans, one option is to both clean the teeth and destroy the lactobacillus bacteria by wearing the non-scalloped, no-reservoir tray overnight with 10% carbamide peroxide. This can be supplemented by using chlorhexidine rinse for 30 seconds prior to bedtime. In addition to caries control, the 10%CP can control the staining from chlorhexidine.
The only side-effect of this treatment is that the teeth will become white. For most people, this may be a benefit. However, since restorations do not change colour, there can be a mismatch between existing restorations and bleached teeth. Some restorations may need to be replaced due to this colour mismatch. However, the benefit of saving the teeth or, having larger restorations due to caries, may override this concern. Teeth typically whiten to a certain level, then stabilise, even with further treatment. However, it is unknown to what level of whitening the patient will progress, so some patients may have very white teeth over time.
Sensitivity is often associated with bleaching. However, in elderly patients, the pulps have receded such that sensitivity is seldom a problem. The use of potassium nitrate in the bleaching tray for 10-30 minutes has been shown to alleviate this in most patients (Haywood et al, 2001). Additionally, many bleaching products now contain this ingredient, and sensitivity levels have been greatly reduced with the combination of potassium nitrate and a soft tray, as well as by pre-brushing and using a desensitising toothpaste during treatment (Haywood et al, 2005).
This technique is meant to be used for the life of the patient. Studies on bleaching teeth nightly for six to twelve months with tetracycline-stained teeth have indicated no harm to the teeth or pulp with low concentrations of carbamide peroxide (Haywood 1997, Matis et al 2006, Leonard et al 1994).
Additionally, this technique may prove beneficial with oral cancer patients for whom the cancer treatment has reduced the salivary flow, and caries is a problem. It is also used in orthodontic patients to avoid white spot lesions, although the fit of the tray and the amount of material needed makes this option more of a challenge. Typically the ‘boil and form’ trays can be made over the brackets if care is taken.
Summary
Root caries may be minimised by use of carbamide peroxide in a tray overnight to remove plaque, elevate pH and kill bacteria. Long-term use is both cost-efficient and safe. Sensitivity can be treated by potassium nitrate in the tray, pre-brushing with it, and using a bleaching product containing the material. Primarily, the indication for caries control is for ageing patients, those with physical handicaps or patients in nursing homes for which conventional brushing and flossing is not proving effective. The side-effect of whitening the teeth is often less of a problem than the cost and medical challenge of restoring teeth due to root caries.
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• Professor Van B Haywood DMD is a keynote speaker at The World Aesthetic Congress on Friday 12-Saturday 13 June 2009 in London. For further information and to book your places, please call Independent Seminars on 0800 371652 or visit www.independentseminars.com/wac.
