Got some questions about teeth whitening?
This section has the answers to your questions!
Most stains on teeth (extrinsic stains) or in the mineral structure of the tooth (intrinsic stains) are organic by nature. These staining substances, often called chromophores, deposit on top of and inside teeth through smoking and the consumption of foods and beverages.
The US Food and Drug Administration (FDA) makes a distinction between:
- Tooth Whitening: treatment that restores the natural shade of the tooth, removing the stains on the surface of the teeth by using cleaning and polishing agents.
- Dental Bleaching: treatment that can bleach teeth beyond their natural shade, removing pigments and stains in the dental structure by means of oxygen radicals.
Unfortunately, the terms “bleaching” and “whitening” are often used as synonyms.
Commercial bleaching products designed for home use include gel, chewing gum, mouthwash and toothpaste.
In general, the toothpastes made specifically for bleaching achieve this objective by removing and preventing the formation of extrinsic (surface) stains.
The key ingredient in bleaching toothpastes is an abrasive substance to which other ingredients with chemical or optical effects are added.
Dental bleaching is a common treatment in the dental sector.
To change the intrinsic shade of a tooth, the bleaching agents must spread inside and through the enamel, reaching and penetrating the enamel-dentin interface and interacting in the underlying dentin with the chromophores (staining substances), pigments and ions that change the shade of the tooth.
Basically, all dental bleaching techniques use hydrogen peroxide (H2O2) as the active principle: either directly or through the decomposition of other chemical substances, like carbamide peroxide.
The H2O2 released generates different radicals or ions depending on the pH value, the temperature, the effect of light, in addition to the presence of co-catalysers and metallic reagents. These different types of oxygen have oxidative and reductive properties that break up the bonds of staining molecules or reduce the coloured metallic oxides, making them colourless.
Because abuse or improper use of hydrogen peroxide (H2O2) can have a negative effect on the surface morphology and on the permeability of enamel and dentin, EU Council Directive 2011/84/UE of 20th September 2011 has limited the use of bleaching and whitening products based on hydrogen peroxide.
Only dentists and dental hygienists can use and supply products that contain or release between 0.1% and 6% hydrogen peroxide (H2O2), while the products that contain or release up to 0.1% H2O2 can be freely sold.
Products with H2O2 concentrations of more than 6% are not allowed as cosmetics, but are admitted as medical devices in different European countries.
In addition to limiting the sale of products containing H2O2, the directive has also established that dental bleaching treatments cannot be applied to anyone under 18 years of age.
There are three approaches to dental bleaching:
- Professional in-office bleaching generally uses gel, applied directly on the teeth, that contains or releases more than 25% hydrogen peroxide. These treatments last from 30 minutes to about one hour. In some cases, the activation is accelerated by heat or by light. The soft tissues must be protected.
- Professional home bleaching uses a gel with a relatively low concentration of H2O2, and specifically less than 6%. The gel is applied on the teeth using personalised trays made by the office and worn during the night for at least 2 weeks.
- In the European Union the products freely sold to consumers can contain only very low levels of a bleaching agent (gel that contains or releases less than 0.1% hydrogen peroxide) and are self-applied on the teeth using rubber trays, strips and varnishes. They must be applied two times a day for at least 2 weeks.
Along with professional teeth bleaching carried out in the dental office, there are also procedures carried out in non-professional environments (non-dental contexts such as kiosks in shopping malls, spas, beauty centres, etc.) and over-the-counter products available directly to consumers with a H2O2 content of less than 0.1% or without hydrogen peroxide.
These teeth bleaching or whitening products can be applied with preformed or adaptable trays using a brush or strips and often use lights to heat the gel and have to be repeated frequently (30-60 days).
However, there is no scientific study that supports the effectiveness of whitening/bleaching products that release or contain H202 concentrations of less than 0.1%.
Effective and safe teeth bleaching requires a correct diagnosis of the problems related to bleaching and teeth stains. This diagnosis can be carried out only by a professional, i.e., a dentist or dental hygienist.
In terms of side effects dental sensitivity caused by bleaching is the most commonly mentioned adverse reaction.
To limit the risk of dental sensitivity, almost all bleaching products on the market – except for BlancOne®– include desensitizing and remineralizing agents.
At concentrations of more than 10%, hydrogen peroxide is potentially corrosive for the mucous membranes and the skin, causing damage to tissue and a burning feeling. In these cases, proper barriers are needed to protect the gums during the bleaching procedure.
Even using concentrations of less than 6%, gum irritation is frequently associated with the extended home use of bleaching trays.
The results of a teeth bleaching procedure depend on the type of stain, the initial tooth shade and a person’s age. In some cases, the original shade can be restored simply through a professional teeth cleaning session (extrinsic stains).
Professional dental bleaching can greatly improve the appearance of even heavily stained teeth. However, some stains do not improve with bleaching:
- Teeth with tetracycline stains and teeth subjected to root canal therapy cannot be bleached effectively with H2O2 concentrations of less than 6% and may require several treatment sessions.
- Inorganic stains (e.g. grey stains following the release of metal from amalgam fillings) do not react to bleaching.
- Bleaching cannot change the colour of the materials used for restorations and prostheses (composites, resins, ceramic, etc.).
If calcifications are present (white spots) in the tooth structure, the bleaching process may highlight such stains.
The key factors that affect the effectiveness of hydrogen peroxide-based bleaching products are concentration and time.
Higher concentrations lead to quicker results than lower concentrations. However, by extending treatment times, the effectiveness of products containing lower concentrations should be similar to that for products with higher concentrations.
The use of high concentrations of H2O2 and extended times may play an important role in the processes that lead to immediate bleaching results that are, however, temporary.
In fact, it will produce an unnatural and short-lived white that will disappear when the teeth rehydrates.
In addition, dehydration significantly increases the risk of sensitivity.
“Power bleaching” or light-accelerated bleaching uses the thermal effect of light energy to accelerate the bleaching process in the dentist office, using lower concentrations over shorter times.
Different types of lights (halogen, LED, plasma) are used for this procedure, generally with a blue light, i.e., the most effective wavelength to trigger the hydrogen peroxide reaction.
It should be pointed out however that there is no evidence that light in itself can activate the bleaching gel.
In fact, light-based activation – without photosensitising agents – is based exclusively on heating the gel.
The heat is then conveyed from the gel to the surface of the tooth which dehydrates it significantly, greatly increasing the risk of sensitivity.
Real light activation of bleaching gel can be induced only by incorporating photosensitising agents.
Light activation uses light energy (photons) to accelerate the break-up of hydrogen peroxide into oxygen. The light energy, consumed by the photosensitisers, does not generate heat, preventing tooth dehydration and sensitivity.
Exception is made for some bleaching gels with light activators activated by special and expensive lasers: up to today, no system has been able to light activate a bleaching gel using traditional light sources (multiple wavelengths) and low-power LEDs.
BlancOne® technology for the first time has created real light-activated teeth bleaching using the lights normally used in dental offices, overcoming the concentration-time paradigm of traditional bleaching treatments.
The dentist uses a shade guide to determine the shade of teeth. This shade guide represents the natural shades of teeth, dividing them by shade (A-D) and intensity (1-4).
For bleaching, the shade guide is reorganised from the darkest shade (C4) to the lightest (B1).
Therefore, if through bleaching the shade changes from A 3.5 to A1 it means that the teeth were bleached by 10 shades.
Recently, with the evolution in professional dental bleaching white shades darker than B1 have been achieved, for which shade guides have been introduced that include 3 additional shades of white besides the 16 natural shades of the VITA Classic guide.
Shade guides have been specially developed for bleaching in the USA where many of the traditional bleaching treatments come from. These shade guides have 29 shades and cannot be compared to the Classic VITA guide used in Europe.
When talking about bleaching shades, it would be important to know what reference shade guide is being used.
The duration of the shade of white achieved after bleaching depends a lot on personal habits.
For example, it tends to last less for smokers than for non-smokers and the same is true for those who usually drink tea and coffee.
Recalling that the shade will no longer return to the one prior to bleaching, over time there will still be a certain regression depending on personal habits and dental hygiene practices (professional and home).
Once the initial treatment is completed in the office, the best way for your smile to remain white is to follow a maintenance program (at home and/or in office). Ask your dentist or dental hygienist for the best solutions to meet your needs.
Conventional bleaching treatments generally require a diet based on white foods on the days following the treatment, while also avoiding smoking, coffee, tea, etc. This is recommended to avoid pigmenting the enamel which becomes dehydrated during the bleaching process.
Because the BlancOne® bleaching treatments do not dehydrate the enamel and do not induce sensitivity, they don’t require a special diet after completing the treatment. It will not be necessary to change your habits.
Normally, it is recommended to refrain from smoking after a bleaching treatment because smoke interacts with the bleaching active principles.
With the BlancOne® bleaching treatments it is recommended not to smoke for a couple of days. If that is just not possible, it is recommended to blow the smoke out through the nose for a couple of days after the treatment since the interaction occurs with the smoke that is breathed out.
Besides being harmful to your health, smoking will also reduce your bleaching effects over time.