Before we get into the details of tooth-whitening, let’s talk about how tooth staining occurs!
A tooth is made up of an inner dentin layer and a hard outer enamel layer, which protects the teeth. When you expose your teeth to food, smoking, coffee, tea etc., another layer starts to gradually form on top of the enamel layer. Basically, the foreign material accumulates to form a pellicle film over the enamel layer.
A dentist can clean away this film, through scaling and polishing. Even brushing your teeth removes some of it — brushing with a whitening (abrasive) toothpaste cleans the tooth in the same way scrubbing with an abrasive pad cleans a dish. “Whitening toothpastes” are designed to work even harder on this layer.
The problem is, as this pellicle layer sits on your teeth for years and years, the foreign material (and stains) gets into the enamel. The enamel layer is made up of hydroxyapatite crystals, which form microscopic hexagonal “rods.” Simply put, enamel is porous, which means staining particles can work their way into the tooth, where you can’t simply clean them away. The deeper stains are basically harmless, but many people find them unattractive.
This is where true tooth whiteners come in. Basically, the whiteners use bleaching chemicals to get down into the tooth enamel pores and set off a chemical reaction (specifically, an oxidation reaction) that breaks apart the staining compounds. This will result in a change in tooth shade, as shown in the images above.
Most tooth whiteners use one of two chemical agents: carbamide peroxide or hydrogen peroxide (the same stuff that will bleach your hair). When used in the mouth, carbamide peroxide breaks down into hydrogen peroxide and urea, with hydrogen peroxide being the active whitening ingredient.
There are a number of different ways of setting off this basic process. Let’s look at the main options:
Clinically Supervised In-Office Whitening
This tooth whitening treatment involves controlled use of carbamide or hydrogen peroxide, tailored to a particular patient. Before the tooth whitening treatment, most dentists clean the teeth,fill any cavities, and make sure the patient’s gums are healthy.
Most in-office systems use 15 to 35 percent hydrogen peroxide gels, sometimes coupled with a high intensity light to speed up the bleaching chemical reaction. Zoom Whitening works the same way, with the added option of adjusting the intensity of the LED light to help reduce any sensitivity during the procedure.
The in-office procedure involves the following:
- Taking impressions (moulds) of your teeth, for a customisedsoft mould to wear later at home. You will need to use this with a thin layer of a take home sensitive relief gel to reverse the sensation of sensitivity and protect the enamel layer.
- Gently cleaning your teeth with the Colgate pro-relief polishing paste which will also provide protection against sensitivity and reduce it.
- Taking a before photograph of the initial shade of your teeth.
- Isolating the gums and soft tissues of the mouth with a barrier to protect from any peroxide burning or damage.
- Applying the hydrogen peroxide gel onto the teeth for 15 minute intervals, rinsing it off after each 15 minute interval, reapplying up to 4 times. The procedure can achieve about four to six shades of whitening within your 2 hour appointment.
- Going through post-operative instructions on how to maintain the new shade and restore the structure of your enamel.
At Home Whitening Treatment
At-home systems will often use 10 to 20 percent carbamide peroxide gels that also contain glycerine, carbomer, sodium hydroxide, water, and flavouring agents. At Argyle Street Family Dentist, we use ZOOM DayWhite home gel of 9.5% concentration. There are always other options, which can be discussed and ordered for you. Our Hygienist will discuss with you how to use it and go through how to maintain the shade and protect your enamel.
The at-home whitening procedure involves the following;
- Impressions (moulds) of your teeth are taken, to make your own custom made mouth tray.
- To administer the treatment, you place a small drop of thegel into each tooth area in the tray.
- Wear it according to the instructions given to you by our Dentist or Hygienist. These instructions vary according to which product you decide to use.
- Most whitening occurs in one to two weeks. In difficult cases, trays may need to be worn for extra weeks.
A combination of in-office and at-home systems can achieve up to 12 to 15 shades of whitening in most patients. At-home systems used alone take a long time to obtain similar results, but will need compliance and following a strict, low stain diet (no smoking, no black coffee, black tea, red wine, dark coloured curries). These procedures are considered safe and effective when monitored by a dentist.
Clinically supervised systems have advantages and disadvantages when compared to over-the-counter tooth whitening products. The main advantage of the supervised system is that our dentist or hygienist can help you determine if tooth whitening should be performed and if it will be effective for you. If you have decayed teeth, infected gums, white spots on their teeth, and multiple tooth coloured fillings or crowns (caps) on the front teeth, you may not be a good candidate for tooth whitening.
We can also help in deciding what type of tooth whitening is required (in-office, at-home or both) and the concentration of the whitening gels. We can monitor and treat sensitivity to the whitening agents and modify the procedure for those who are having difficulty getting optimal results. Finally, we can help you explore other cosmetic dental options such as porcelain or resin veneers, tooth coloured fillings and tooth shaping used with or without tooth whitening.
IS TOOTH WHITENING SAFE?
Most studies confirm that tooth whitening is safe and effective. Whitening gels that contain up to 10% carbamide peroxide (equivalent to 3.6 percent hydrogen peroxide) have not been shownto cause any damage to the enamel of the tooth. Higher concentrations of carbamide and hydrogen peroxide available from the dentist may weaken the enamel, but most of these formulas also contain fluoride and other mineralising will be prescribed to offsetting this potential side-effect and protect the enamel.
If tooth sensitivity or gum irritation occur, it is best to start using the whitening product less frequently, as in every other day instead of every day. Also, reduce the amount of time spent whitening. Prescription mineralising products are also used to treat sensitivity sometimes associated with tooth whitening. Irritation ofthe gums can occur from either the in-office, at-home or over-the-counter tooth whitening systems. Gum irritation is usually mild and reversible, but can be treated with over-the-counter products such as Bonjela or vitamin E oil.