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> Dental Bleaching
By sedron | November 10, 2007
What is dental bleaching? How does it work?
For stubborn extrinsic discoloration and intrinsic stain, dental bleaching techniques may be attempted. Tooth bleaching can be performed:
a. externally: termed vital tooth bleaching
b. intracoronally: called non-vital tooth bleaching
Active Bleaching Agents
The bleaching agents used in dentistry are either hydrogen peroxide or its precursor carbamide peroxide. It is NOT the same as the household bleach, hydrogen hypochlorite (NaClO). Some people mistakenly think the “bleaching” term in dental bleaching refers to household bleach and use it to whiten their teeth, which really works by the way but is very dangerous.
Hydrogen hypochlorite is mainly used to remove stains from laundry, toilets, or any inanimated objects, but definitely not tooth stains or body stains. It is a strong oxidizer and is highly corrosive, resulting in damage or burn of the oral mucosa (gum, tongue, soft tissue in the mouth). Repeated trauma can subsequently lead to oral cancers. Ingestion of the solution is another risk to get concerned of. Household bleach actually is not always dangerous as in fact it is the same substance used in the chlorinated water we drink in a certain dilution proportion believed to be safe. It is the concentration that makes it dangerous. To whiten the teeth however, it needs to be in high concentration to achieve its purpose which will also put your health into compromise. However, household bleach does have an application in dentistry; ie, during root canal treatment to disinfect canals and dissolve any remaining necrotic dead pulp tissue. This procedure is done in a confined and controlled environment, where soft tissue and teeth other than the one being worked on are isolated with a rubber dam and high volume suction is turned on to remove excess hypochlorite when the solution is administered. Another application of household bleach is to disinfect dentures that has been infected with candida (a fungal infection); however, this is done extra-orally. As long as the dentures are rinsed thoroughly under water following bleaching, it poses little risks to the oral mucosa.
Both hydrogen peroxide and sodium hypochlorite work similarly; they’re oxidizing agents, producing free radicals that degrade stains during bleaching process. No wonder some people think they’re the same and use hypochlorite to whiten the teeth, which is a no-no. Compared to hypochlorite, hydrogen peroxide is relatively safe, but still should be used with cautions. Free radicals produced in the bleaching reaction are corrosive and can burn skin/oral mucosa/any soft tissues. If hydrogen peroxide is used inappropriately, the gum will be damaged and appear fibrotic and unhealthy white. Dental bleaching should be done best in a controlled and confined environment.
1. Carbamide Peroxide (aka urea hydrogen peroxide; CH4N2O.H2O2)
- most commonly used professional home bleaching agent
- breaks down into ⅓ hydrogen peroxide (active agent) and ⅔ urea when it contacts saliva
- 10% carbamide peroxide releases 3.5% hydrogen peroxide
- was used for many years as an oral antiseptic before it was applied as a gel for home bleaching
2. Hydrogen Peroxide (H2O2)
- most commonly used in-office bleaching agent
- more potent than carbamide peroxide
How does tooth bleaching work?
Tooth bleaching today is based on hydrogen peroxide as the active agent. It may be applied directly or produced in a chemical reaction from carbamide peroxide. Hydrogen peroxide acts as a strong oxidizing agent through the formation of free radicals, reactive oxygen molecules, and peroxide anions. These reactive molecules attack the long-chained (insoluble), dark-colored chromophore molecules and split them into smaller (more soluble), less colored, more diffusible molecules. The free radicals eventually combine to form molecular oxygen and water.
Tooth Whitening 1 | 2 | 3 | 4 |
Topics: Cosmetic Dentistry, Dentistry, Health & Well Being |