Circuit 4, station 5

Teeth bleaching:

What is teeth bleaching
Teeth bleaching, also known as Teeth whitening, refers to a variety of cosmetic dental procedures that aim to enhance the brightness and whiteness of natural teeth. This process involves removing stains and discoloration from teeth using a bleaching agent, such as hydrogen peroxide, carbamide peroxide, or sodium perborate.
Types of stains and discolorations
The causes of tooth staining vary, as does the speed with which they can be removed. Therefore, it’s essential to carefully assess the causes of tooth staining to predict the rate and degree to which bleaching will improve tooth colour since some stains are more responsive to the process than others. There are two main types of tooth discoloration: extrinsic and intrinsic.
Extrinsic stains: Extrinsic stains are caused by the buildup of pigments on the external surface of teeth, often resulting from poor oral hygiene, the consumption of pigmented foods and drinks, and tobacco use. These stains are found primarily in the pellicle, a thin film that forms on teeth due to the interaction of sugars and amino acids or the retention of external chromophores. Chemical analysis of stains caused by pigmented foods reveals the presence of furfurals and furfuraldehyde derivatives resulting from this reaction.
Intrinsic stains: Intrinsic stains are deeper and occur within teeth or enamel defects. They are often caused by ageing, pigmented foods and drinks, tobacco use, enamel microcracks, tetracycline medication, excessive fluoride consumption, severe infant jaundice, porphyria, dental caries, restorations, and thinning enamel. Ageing is a common cause of discoloration as secondary dentin, which is darker and more opaque than the original dentin, forms over time, and the overlying enamel becomes thinner, resulting in darker teeth.
Composition of commercial bleaching agents
Bleaching agents contain both active and inactive ingredients. The active ingredients in most bleaching agents include hydrogen peroxide or carbamide peroxide compounds. The major inactive ingredients may include thickening agents, carriers, surfactant and pigment dispersants, preservatives, and flavouring.
Thickening agents like Carbopol (carboxypolymethylene) are commonly used in bleaching materials, while glycerin and propylene glycol are used as carriers in commercial bleaching agents. Gels containing surfactants or pigment dispersants may be more effective than those that do not. Common preservative substances include methyl, propylparaben, and sodium benzoate, while flavourings like peppermint, spearmint, wintergreen, sassafras, anise, and sweeteners such as saccharin are used to improve the taste and consumer acceptance of bleaching products.
Types of dental bleaching procedures:
Vital Tooth Bleaching
There are three fundamental approaches to bleaching vital teeth: in-office or power bleaching, at-home or dentist-supervised night-guard bleaching, and bleaching with over-the-counter (OTC) products.
• In-office whitening: In-office bleaching involves the use of a high concentration of tooth-whitening agents, such as 25–40% hydrogen peroxide. The dentist has complete control throughout the procedure and can adjust the concentration and duration of the treatment to achieve optimal results. This method is considered the most effective way to achieve fast and dramatic whitening results.
• Dentist-supervised at-home bleaching: Dentist-supervised at-home bleaching involves the use of a custom-fitted tray that is filled with a bleaching gel containing 10–20% carbamide peroxide or 3.5-6 % hydrogen peroxide. The tray is worn for a few hours a day or overnight for a specified period, typically two to four weeks. This method is less expensive than in-office bleaching and may be a better option for individuals who have mild to moderate staining.
• Over-the-counter (OTC) bleaching products: OTC bleaching products are readily available in most drugstores, supermarkets, and online stores. These products typically contain lower concentrations of the active bleaching agent and may be less effective than in-office or dentist-supervised night-guard bleaching. OTC products include whitening toothpaste, strips, gels, and mouthwash. It’s important to note that while these products are readily available, they may not be safe or effective for everyone, and it’s always best to consult a dentist before using any bleaching product.

Bleaching techniques for non-vital teeth
Various techniques are used for non-vital tooth bleaching, such as walking bleach, modified walking bleach, non-vital power bleaching, and inside/outside bleaching.
• Walking bleach: a technique where a bleaching agent is placed inside the tooth and left for several days then removed and replaced as necessary until the desired shade is achieved
• Modified walking bleach: a variation of the walking bleach technique that involves using a heat source to speed up the bleaching process
• Non-vital power bleaching: a technique where a high-concentration bleaching agent is placed inside the tooth and activated with heat or light
• Inside/outside bleaching: a technique that combines both walking bleach and non-vital power bleaching, where the inside of the tooth is bleached first, then followed by external bleaching to improve the overall appearance of the tooth.
Effects of teeth bleaching:
Effects on soft tissues
More potent in-office bleaching agents, such as those containing 30-35% hydrogen peroxide, can potentially cause burns on the soft tissues, turning them white. However, if exposure to the bleaching material is limited in time and quantity, these burns are typically reversible and do not cause any long-term consequences. Rehydration and the application of an antiseptic ointment can quickly restore the tissue’s natural colour.
Systemic effects
Home-bleaching agents, although their concentrations are lower than those used in-office, are a cause for concern for possible adverse effects. In-office bleaching agents are under the control of a dentist. Patients may experience gastrointestinal mucosal irritation, such as a burning palate and throat, and minor stomach or intestinal upsets.
Conclusion
Teeth bleaching is a popular cosmetic dental procedure that can help improve the appearance of stained or discoloured teeth. Different types of stains and discolorations require different bleaching techniques and products. In-office and dentist-supervised night-guard bleaching are the most effective techniques.