How teeth darken, and the mechanism of whitening.
Teeth can be dark genetically, but otherwise become more yellow with age, and with a diet which is rich in dietary pigments, or as a result of breakdown products of a dead nerve, or filling materials. Fortunately, most discolorations can be removed with professional whitening.
Professional tooth whitening is a process where the tooth discolouration is ‘whitened’ to a lighter shade (and unsightly pigments dissolved) by using gentle peroxide-based gel. This gel is held in a thin film in intimate contact with the front surface of the teeth in closely fitting clear bleaching trays. This removes discolouration by chemical action. The peroxide based gel diffuses through the tooth structure and oxidises large coloured molecules (known as ‘macromolecules’) which are coloured, and breaks these down into smaller colourless molecules. The smaller colourless molecules diffuse out of the tooth. The colour change is ‘permanent’. It is true however that you will continue to enjoy eating the diet you are used to, and over 12-18 months there will be some re-pigmentation of the teeth.
Frequently Asked Questions
Professional Whitening is heavily regulated by the General Dental Council to ensure that patients only use safe and accredited bleaching gels, such as those obtained via a dental practice. Dental Practices typically do not purchase regulated products via the internet, but instead purchase medicines and products via reputatable dental suppliers.
Some online suppliers market products which are damaging to teeth, have too low a pH which causes erosion of dental enamel, and have no desensitiser to limit the dental hypersensitivity that can result from professional whitening. Some peroxide-based gels do not have the active silicates that are present in modern professional bleaching gels that seal the small pores that exist in dentine.
Products need to be:
- peroxide based and not chlorine based
- not require heating to be activated
- all peroxide based products need to be stored in a mildly acidic environment. When ‘activated’ the gel must become slightly basic or as close to pH neutral as possible
- the gel must be as close to neutral pH as possible at mouth temperature when in contact with enamel to minimise surface degradation/softening/demineralisation of enamel
- have a maximium concentration of 6% carbamide peroxide or a maximum concentration of 18% hydrogen peroxide
In any form of medicine it is not possible to give 100% guarantees. Professional tooth whitening is however very predictable and your clinician will have a fairly strong idea on how well your teeth are likely to bleach.
Your dentist will hold a tooth brightness chart (which consists of a number of tooth shade tabs) against your teeth so that a realistic assessment can be made about the likely improvement in colour of your teeth:
There are certain light grey shades, which measure as a C1 or C2 shade against a so-called VITA shade tab. These teeth colours will only whiten marginally. It is important to identify these ‘C ‘shades at the outset to help manage your expectations of professional tooth whitening,
One of the main side effects to professional whitening is dental hypersensitivity. This can be significant. It is important to expect dental hypersensitivity and manage this early with desensitising tooth paste. Any tooth-paste which contains potassiium nitrate or strontium acetate may help relieve dental hypersensitivity.
One product which comes highly recommended is ‘MI paset’. This paste contains a super-saturated amount of amorphous calcium phosphate-tricalcium phosphate and this calms nerve that are inflammed and hot. We would always recommend use of ‘MI paste’ while you professionally whiten your teeth:
An extremely rare side effect that has been reported when using heated gels around cracked teeth or teeth with dead nerves – it is possible to initiate internal root resorption. It must be emphasised that this is rare.
Very little is known about the long term effects of using peroxide based gels on the teeth, however the dental profession feel that use of carbamide peroxide and hydrogen peroxide gels in tooth whitening is safe, and one of the most conservative techniques to significantly enhance the smile.
When your dentist consents you for professional whitening he/she will take you through a detailed assessment of risks, benefits and limitations of professional whitening as this applies to your mouth and your personal professional whitening goals.
There are many claims made about the efficacy of laser assisted tooth whitening. Laser assisted professional whitening techniques are typically undertaken at the chair-side. Laser assisted professional whitening is approximately twice the cost of traditional techniques. The laser assisted technique may speed up the professional whitening process, but is unlikely to achieve a better result than traditional techniques.
The laser adds heat to the professional whitening gel and may activate some gels which have a ‘target chromophore’ added which is a pigment that is activated by the specific laser light used. Use of the laser and the associated ‘photothermal’ effect causes the release of reactive oxygen species (ROS) which affects the breakdown of the peroxide into free radicals, namely perhydroxyl and hydroxyl anions and singlet oxygen. The latter two free radicals are extremely reactive and exist instantaneously but do not persist. They also have the highest oxidising capability, and are formed preferentially when a laser is carefully used with a gel which contains the laser’s ‘target chromophore’.
In our experience after use of laser assisted power bleaching, the patient still needs to take home a kit of ‘home’ bleaching gels for 1-2 weeks.
We also believe that the added heat of in using the laser may bring additional risks of internal root resorption. The laser-assisted power bleaching technique may also cause additional dental hypersensitivity.
Coupled with the added cost, the additional benefits of using a laser are mainly the time saving element.
In cases of extreme ‘makeover’ type professional whitening, should the ‘home’ bleaching gels not provide a sufficient improvement then a laser assisted technique can be considered after the initial sensitivity has waned.
If you would like more information on laser-assisted power bleaching, then please ask for a referral to our Clinical Director, Dr.Raj Wadhwani who has undertaken extensive research in the use of dental lasers and runs the Cambridge Dental Laser Study Club.
The cost of professional whitening can be confusing as different practitioners have different peroxide gel preferences, and the manufacturer costs vary. Typical costs for routine professional whitening are circa £400 – £750 depending on the system used, and also depending on the number of tubes of gel supplied to the patient. At the lower end of professional whitening costs, your dentist will supply you with a finite number of gel tubes to place in your bleaching trays, and you will be asked to purchase additional tubes if you are seeking to improve your professional whitening result. You will be supplied with enough whitening gel to bleach for approximately 2 weeks. Additional tubes are typically supplied at circa £110.00 per set of 4 tubes.
When you pay the upper end of costs, your practitioner will typically review your tooth-whitening goal using the tooth shade brightness tabs, confirm that he/she believes that this is achievable for your teeth, and then will work with that goal in mind over several weeks, and using a more much extensive supply of bleaching gels to achieve your goal over approximately 6 weeks.
When you are quoted for professional whitening, you should clearly explain your professional whitening goals, and confirm if you are seeking a moderate but noticeable improvement which can be achieved quickly typically over 2 weeks, or whether you are seeking a very significant improvement which typically may take 4-6 weeks.
The price will vary depending on the tooth whitening strategy needed to achieve your goals.
The length of time it takes to whiten your teeth depends on the extent and cause of discoloration:
- Generally healthy teeth with minimal dentistry which simply need mild lightening may take 1-2 weeks to brighten
- Very yellow, aged teeth, perhaps with leaking fillings that have greyed out the teeth may require 3-4 weeks, and may also require replacement of dark fillings
- Intensely coloured teeth, such as front teeth which have sustained trauma and have experienced leakage of fillings over time within the tooth may require several weeks of bespoke external and internal professional whitening
Your dentist will give you a time estimate of how long your professional whitening will take. If you need to obtain a certain result for a special occasion, please mention this to your dentist. It is possible to use a strategy to undertake ‘home’ bleaching twice per day to speed up the outcome. Your dentist will also suggest using ‘MI paste’ within your professional whitening tray for 1 hour in the day to minimise hypersensitivity.
Professional tooth whitening does not hurt. The peroxide gels however do cause the nerves of your teeth to become hypersensitive. This is self-limiting and typically calms down a few weeks after completion of professional whitening. The degree of hypersensitivity can be controlled by various desensitising toothpastes which variably contain potassium nitrate, strontium acetate and fluoride. Dentists recommend a product called ‘MI paste’ which is sold in the surgeries and not available ‘off the shelf’.
The long term effects of use of peroxide-based professional whitening gels is unknown however the dental profession is confident that the techniques and materials used carry a wide margin of safety.
Our practice runs bespoke ‘professional whitening evenings’ where a bona-fide discount can be offered to suitable cases. When we have approximately 6 clients who wish to have professional whitening at the same time, we can afford to provide an excellent discount to professional whitening, which in some cases can amount to 50% off for a 2 week course of professional whitening.
Click the link below to sign up for one of our professional whitening evenings. You can either sign-up as a group of friends, or simply sign up yourself as we are likely to have a few clients waiting for the next available professional whitening evening,
Tooth whitening will last for a long time, but longevity of your whitened teeth will depend on the intensity of colorants in your diet, for example un-milked coffee, bolognese, curries, intensely coloured fruits such as blackberries, raspberries and strawberries etc. Our advice is to recommend professional whitening with an annual maintenance regime, much in the same way as you will focus on frequent skin care and hair-care. You will frequently apply emollients, moisturisers and masks to maintain fresh skin and maintain complexion. You will also visit a hairdresser several times per year.
The teeth have to endure more ‘abuse’ than your skin or your hair. Every 6-12 months your should place your bleaching trays and use the whitening gel for 1-2 nights to maintain brightness and bleach out dietary stains that have accumulated. In this way, you will maintain the brightness of your teeth and maintain the result.
You can buy professional whitening ‘top-up’ gels from us which if refrigerated, should last 1-2 years. You should only need a top up and will not need to go through a full course of professional whitening treatment.
Professional tooth whitening may identify other shortfalls in appearance such as discoloured yellow fillings. The greyness of silver fillings may also become more obvious as the natural enamel and dentine is whitened. Unsightly crowns may also become more evident. You may also identify crookedness of individual teeth that you may want to have straightened.
Professional whitening makes you scrutinise your teeth more carefully as you notice the improvement and you may want to discuss other smile enhancement techniques to restore the beauty and radiance of your smile.
Our advice is that the teeth will need a gentle ‘refresh’ annually. As long as you look after your clear bleaching trays, these should last several years. You simply need to purchase some gel, and use these in your bleaching trays for 3-4 days once per year to keep the light colour.
Professional tooth whitening is a safe procedure when carried out under professional supervision. Your dentist will however need to check that all of your teeth are alive, and that there are no cracks in the teeth, otherwise use of the peroxide based gels can result in very rare internal or external resorption of roots.
Treatment results usually depend on the severity of the discolouration. Both vital (i.e. live) and non-vital teeth (e.g. tooth with the nerve removed) can be bleached and may take several visits to complete. The whitening gels are not effective on dental restorations such as amalgam fillings, metal or porcelain crowns, etc., and some of these may need to be replaced
Teeth can discolour for various reasons. The dentist will recommend the best method based on your oral condition after an in-office examination to establish the cause and nature of your tooth discolouration, as well as provide you with more information on the various types of whitening procedures available, duration & frequency of treatment.
From time to time, the practice will offer almost 50% off professional tooth whitening on periodically arranged whitening open evenings. Take advantage of these genuine one-off offers.