Most teeth whitening processes are designed to have a long-lasting effect. However, relapse is not uncommon, usually due to personal behaviours; and while for some people it is possible to achieve a whiteness that’s several shades brighter than their existing tooth colour, others may only achieve a few shades’ difference. Results can never be the same for any two people.
Another variable is the range of teeth whitening options available today. Over-the-counter products include whitening toothpastes, mouthwashes and strips; and then there are the professional services provided by dental practitioners, such as in-chair whitening and DIY kits for home whitening. Each option can produce differing degrees of permanency.
Your dentist will advise on the degree of whitening, and the process, that’s best for your teeth.
The bleaching that results from any teeth whitening process – whether in-chair whitening or at-home whitening – will last several years. Some rebound of your original tooth colour can be expected from both methods. The most significant relapse occurs initially in the first month, usually in the first 24 hours. Colour relapse is slower between 6 months and 24 months. Even with this relapse, your teeth will probably be lighter than they were before whitening.
It should be noted that not everyone’s teeth are suitable for whitening. Dentists are the only people trained and qualified to make an assessment of your teeth and gums. They will check for any gum recession, sensitivity, tooth decay, existing restorations (e.g. fillings, crowns and veneers) or oral conditions that might act as an impediment, as well as measuring your enamel thickness. They will also assess the cause of your tooth discoloration (e.g. diet or aging).
The procedure of teeth whitening
Tooth whitening is normally achieved by bringing a dental bleach such as hydrogen peroxide or carbamide peroxide into contact with the teeth. This may be done using high concentrations in one visit to your dentist, or by using lower concentrations over a period of weeks at home. At Smile Solutions we do not provide any other methods of whitening, such as charcoal or abrasion.
Studies of at-home whitening effects
One of the longest studies of the effects of teeth whitening assessed participants 9 to 12 years after they had undergone six weeks of overnight home whitening using 10% carbamide peroxide. Of these patients 33% reported no obvious change, 27% reported a slight change and 6% reported moderate to severe change. Remaining participants stated they had already redone the bleach process.
Other studies tend to follow patients for two years, and they perform surveys of patient experiences as well as light/colour measurement with devices. Patient experiences have been shown to vary, while objective measurements with the devices tend to show that lightening persists, but shades of yellow and red can return.
Studies of in-chair whitening effects
Many follow-up studies of whitening treatments performed in the dental chair have also shown that teeth are still lighter two years after treatment but are not as white as immediately after treatment. The general consensus is that use of an activation light can reduce treatment time overall but it does not extend the duration of the whitening.
Studies comparing home and in-chair whitening
The studies that compare at-home and in-chair whitening show a similar rate of colour rebound after the two processes, regardless of the length of initial treatment. This holds true for 45 minute in-chair whitening, 10 day home whitening and 4 week home whitening.
Factors affecting longevity of results
The duration of your results can be affected by your original shade, dental health, previous experience with whitening, diet and smoking.
The main factors that you can control are dental health, diet and smoking. Dental health issues can be identified and prevented with regular check-ups and cleans.
Most studies looking at the effect of drenching teeth in coloured liquids suggest that red wine, cola and tea are worse than coffee for changing the colour of your teeth. Smoking can change the internal colour of teeth, but also (more noticeably) will usually leave an external stain, which can only be removed by dental prophylaxis (performed by a hygienist or dentist).
Maintaining your results
Aside from maintaining your dental health, having a healthy diet, and avoiding smoking, there are some other things you can do.
Touch-ups of in-chair whitening can be performed after a minimum of 12 months or by using shorter courses of home whitening. Additionally, some studies suggest that hydrogen peroxide mouth rinses or whitening toothpastes may recover the whitening effect following staining. As with all dental treatments, it is best to speak with a dentist face-to-face about the suitability of these options in your particular case.
Is it safe?
Whitening is a chemical process that breaks the carbon bonds that give tooth enamel its yellowish tinge. Once these bonds have been broken they no longer reflect the colour yellow and this makes the teeth look whiter.
Whitening is generally safe and when used in the correct way can produce very satisfying results. However, if you choose the wrong treatment – or a suitable treatment is applied incorrectly – then you can risk damaging your teeth.
Some of the side effects of whitening can be damage to and blistering of the gums, tooth sensitivity, and irritation and possibly bleeding in the oesophagus and stomach if the bleaching agent is swallowed. It is also important to know that crowns, veneers or fillings will not change colour after whitening, so you could end up with “multicoloured” teeth. Without professional assessment, it is not possible to rule out any permanent side effects or other risks associated with whitening.
Things to avoid pre and post whitening are smoking; drinking tea, coffee and red wine; eating highly coloured foods; and using mouthwashes. All of these can stain the teeth, reversing the effectiveness of both home whitening and in-chair whitening. Your dentist will advise you when it’s appropriate to resume any of the above (although smoking is to be avoided at all times due to the overall health risks).
Ultimately, the only way to maintain your teeth whitening and general health of your teeth and gums is to see your dentist and hygienist regularly – ideally every six months.