Teeth whitening

By applying the most advanced technologies, modern dentistry these days can offer you a great variety of safe methods to have your teeth whitened. In fact, to get a brighter smile sometimes just a professional oral hygiene procedure is enough: the accumulated pigmented plaque is removed from the dental and interdental surfaces and the natural tooth colour is restored. Quite often, however, a teeth whitening (bleaching) procedure will be necessary to meet your expectations.

Tooth discolouration and its causes

A child’s deciduous teeth are whiter than an adult’s teeth, thus white teeth are usually associated with youth. With age our teeth become darker; they acquire a yellowish tint or may become stained. The colour of our teeth changes because of the stains which appear on the tooth surface or due to some changes in the tooth structure itself. There are a number of factors causing stains to appear and they are usually classified into three groups:

• extrinsic;
• intrinsic;
• age-related.

Extrinsic stains are mostly caused by excessive coffee and tea drinking or consuming dark-coloured foods. Smoking or chewing tobacco leads to tooth discoloration as well. Poor oral hygiene is another major contributor. Extrinsic stains can be easily removed during a professional oral hygiene procedure whereas stains which have already penetrated into the enamel or the dentin can be removed only during the teeth whitening procedure.

Stains which have already reached the deeper layer of the tooth – the dentin – are called intrinsic ones.

They usually develop during tooth formation, because of antibiotics (tetracycline) taken or the excessive exposure to fluoride in the childhood. Although such stains cannot be removed during the professional hygiene procedure, they can be bleached. The outcome of the whitening procedure will greatly depend on the type of the stain and the form of severity.

Age-related stains are extrinsic ones, not deeply penetrated into the enamel or the dentin. Such teeth usually have a yellowish tint and are easy to be whitened.

Tooth colour is the most important factor while trying to predict the outcome of the whitening procedure.  Yellowish teeth respond best to bleaching whereas brownish or greyish teeth tend to be less responsive.

Safe teeth whitening using modern technologies

Since time immemorial humans have been looking for various ways to have their teeth whitened.However, they usually did more harm than good. Modern technologies offer teeth whitening procedures without damaging the tooth structure.

Hydrogen peroxide was first used for teeth whitening in 1884 and since then it has remained the most effective whitening substance due to its low molecular weight which enables it to penetrate through the enamel into the dentine without damaging dental tissues. As pigment substances penetrate into the deeper layers of the enamel and dentin, attempts were made to increase the absorption and penetration of hydrogen peroxide. In 1918 Dr. Abbot first used a very intensive light to accelerate the teeth whitening process. By doing this, he laid the foundations for the in-office teeth whitening procedure.

The chemical teeth whitening mechanism

Teeth whitening is an oxidation-reduction process where oxidising agents – hyper active and freely moving free radicals – easily penetrate into the material we want to bleach.

Plaque – an organic substance accumulating on the surface of the teeth – may hinder the oxidation reaction and enzymes change this reaction by significantly reducing the number of free radicals. As a result, the teeth whitening process slows down.  Thus, in order to achieve the desirable teeth whitening effect, it is crucial to have your teeth cleaned prior to the whitening procedure. So, a professional oral hygiene procedure should be the first step before having your teeth whitened. After the professional cleaning the natural colour of your teeth will be seen and accurately measured. Then the most appropriate teeth whitening method for you will be selected.

In the teeth whitening process it is vital to notice when the saturation point has been reach. After that the teeth will not become any whiter as all the pigmented compounds will have been broken down by then. If the oxidation-reduction process goes on and the procedure is not stopped in time, the organic structures of the dental enamel and dentin will be damaged. It may happen if teeth are being bleached without a dentist’s consultation or if the instructions are not followed regarding the whitening duration and/or frequency or the teeth whitening products.

Consultation before undergoing teeth whitening

Before having your teeth whitened, consultation with a dentist is of paramount importance. During the consultation not only will the causes of the discolouration be identified, but you will also be advised whether in your particular clinical case teeth whitening would be appropriate or another kind of treatment would have a more beneficial effect.

During the consultation your dentist will assess your smile according to the criteria of the aesthetic smile, for instance, how many teeth are visible while smiling, whether or not you have any aesthetic gum defects (e.g., an irregular gum line, too much of the gingiva is seen while smiling, etc). After having your teeth whitened, such defects may become even more noticeable. Therefore, in order to create an attractive smile, additional correction procedures may be required.

If the necks or roots of your teeth are exposed, during the whitening procedure your teeth may become sensitive. Thus, it would be better to have your teeth whitened in the dentist’s chair rather than at home as the necks of the teeth will be protected by applying some special material before the bleaching procedure. Tooth sensitivity could also be caused by old defective fillings or crowns. Attention should be paid to the fact that areas around tooth roots get whiter more slowly than tooth crowns so some places may remain darker.

Every case is special so professional consultation is highly recommended before having your teeth whitened.

During the consultation you will also learnwhich teeth whitening method would be the most suitable for you taking into consideration your overall oral health, expectations, budget and lifestyle and what outcome you could expect after the teeth whitening procedure.

Who should avoid teeth whitening?

• There have not been sufficient clinical studies conducted to prove that teeth whitening is safe for pregnant or nursing women, so they are advised to postpone the procedure. As far as children and teenagers are concerned, the same recommendation should be followed.

• Moreover, if the gingiva covers too much of the tooth surface (also known as the gingival smile), the teeth look short and after having them whitened, the irregularity of the smile will become even more obvious. After the teeth whitening procedure the irregularities of the gum line become more visible as well. Thus, in such cases the gingival line recontouring procedure is recommended prior to teeth whitening

• In some cases periodontal or endodontic treatment may be more necessary than teeth whitening. Dental traumas causing discoloration (it does not matter whether the pulp remained vital or not) could be an example. If your isolated teeth are darker because of the previously received endodontic treatment, internal tooth whitening will be recommended additionally.

Zoom teeth whitening

Zoom is chosen by those who wish the optimal and fastest result possible. It is a safe and effective procedure.

The main benefit  of  the  Zoom teeth whitening treatment is its suitability for certain conditions where other teeth whitening methods are less effective.

Zoom teeth whitening might be the best solution for those who:

• Wish a quick and effective result during one visit which lasts only 1.5 hours. In comparison, using customised trays at home, you may need up to 10 – 14 days and 2 in-office visits in case of laser whitening;
• Have teeth of darker shades. Pigmented enamel stains which have appeared because of smoking or excessive coffee drinking respond to Zoom treatment really well. Even one procedure might make your teeth up to 5-8  shades lighter according to the Vita Shade Guide;
• Have tetracycline stained teeth which have a greyish uneven shade. You might need up to 6 months to have such teeth whitened at home using trays following the prescribed protocol. Results achieved by a laser teeth whitening procedure may not meet your expectations;
• Wish to restore the same colour to their teeth in the case of fluorosis, that is to get rid of different tiny white specks or streaks that can be seen on the surface of the enamel. The Zoom system is the best option in this case.
• Wish to mask the translucent edges of enamel, which are greyish and the teeth look greyish too. The whitening Zoom material is enriched with minerals which together with the whitening components penetrate into the deeper layers of enamel and this way mask the colour unevenness.

At-home teeth whitening

If you opt for the at-home teeth whitening method, during your first visit to the dentist impressions of your teeth will be taken and customised mouth trays will be made. The trays should be filled with a 10-22 % solution of carbamide peroxide. Carbamide peroxide reacts with water and forms hydrogen peroxide in your mouth.  It takes longer for carbamide peroxide to whiten teeth, but it is safer for home use as carbamide peroxide has about one third of the strength of hydrogen peroxide. Owing to these characteristics carbamide peroxide is the most popular teeth whitening agent used while correcting discoloration with bleaching trays.

On average, bleaching trays are worn either for 2-4 hours during the day or left overnight. Usually, a teeth whitening course takes 10 days.

Laser teeth whitening

Laser teeth whitening is one of the most advanced, effective and safest teeth whitening methods available to date. Due to the laser’s monochrome characteristics and the special gel you will have your teeth whitened in a safe, speedy and effective manner in one or two visits.

Before whitening teeth, the Vita Shade Guide is used to determine the current colour of the teeth. To protect the gums against hydrogen peroxide, a special protective coating is placed on them. This material is also applied to the tooth surface if tooth necks are exposed, the enamel has been damaged, etc. During the procedure a solution of 25 – 45 % hydrogen peroxide is applied to the tooth surface which is activated by laser. Laser beams speed up the chemical oxidation reaction and the teeth bleach faster.

LaserSmile™ (Biolase, USA) uses one of the most advanced teeth whitening technologies called TCIA^TM (Target Chromophore In-Phase Accelerated-Activation). LaserSmile™ laser energy is absorbed by special particles contained in the bleaching material, which accelerates the breakdown of hydrogen peroxide into free radicals by 38 %, thus, the procedure time is reduced. Moreover, the bleaching material is in contact with the teeth only for 16 – 32 minutes, therefore, the risk to damage tooth tissues is significantly reduced too. In addition, laser whitening is safe, because when the bleaching material is laser activated, no heat is emitted so the teeth are less sensitive and the risk to damage the pulp is lower.