In Office Bleaching – Procedure And Its Side- Effects

in office bleaching

In office bleaching and other bleaching methods are the simplest and inexpensive way to whiten the teeth and improve your smile. Other treatments include crown, veneers, macroabrasion and microabrasion. Crown and veneer involve the removal of a natural tooth material and placing a prosthesis over the prepared teeth. These treatments are also comparatively more expensive than bleaching. 

Tooth whitening treatments are typically categorised based on the place where the procedure takes place. In-office bleaching is the most effective way to achieve the satisfactory results as it is supervised by an experienced health professional.  

In office bleaching is a 1-hour procedure, using 30-35% Hydrogen Peroxide. Some systems may require light as a catalyst. 

On exposure to light, the hydrogen peroxide degrades into hydrogen free radicals and oxygen. A catalyst is something that boosts the rate of a reaction. So if the hydrogen peroxide gives off free radicals at a faster rate, the teeth will whiten faster.  Moreover, the light improves whitening results by up to 26%.

When do you need an in office bleaching       

Extrinsic staining is far more common than intrinsic or internal staining. Extrinsic stains are those that stick to the surface of the tooth or penetrate the very outer layers of enamel.

A majority of staining is caused by the interaction of pigments from food and drinks with the plaque covering the enamel. For instance, an increase consumption of coffee, coke, tea or red wine can stain the teeth.

The stains penetrate the microscopic cracks and fissures of the teeth and cannot be removed by toothbrushing or dental cleanings. These stains respond well to bleaching treatments. 

Things you need to know before the treatment 

  • The first step before proceeding with bleaching is to establish a realistic expectation from the treatment. For instance, older patients whose teeth are somewhat grey will not whiten as well as the pale teeth in younger patients because the enamel layer progressively gets thiner with age allowing the grey dentin to appear through enamel. 
  • Also previously placed composite restorations/fillings will not whiten along with the teeth and will mismatch once the desired shade of natural teeth is reached.
  • A common complication of whitening treatments that may arise along the way is sensitivity. 

Before the procedure

  • The x-ray of all the teeth is taken to check if they are healthy and there is no tooth decay or periodontal disease. 
  • An electric pulp testing is performed on the front teeth to see if they are vital.
  • You will be given a consent form to fill and inform you about all the necessary information about the treatment and its complications.
  • The dentist may take your pictures before the treatment to compare the effectiveness of the treatment later on.

Preparing the patient for tooth whitening

The first step is to obtain a starting shade using a shade guide. The teeth are now cleaned using pumice and a prophy cup to remove any plaque that may be covering the teeth.

Next, a opal dam barrier may be placed along the gum margins and cured for 30 seconds and some dentists place a rubber dam that covers the gums and only exposes the teeth.  The barrier or rubber dam is placed to protect the soft tissue damage or burn from the high concentration of the whitening agent used.

Most of the systems in in office bleaching use high concentration hydrogen peroxide (30- 35%) and if comes in contact with the gums, it temporarily turns the area of contact white. This colour change will usually last for a few hours before the original colour returns. However, it is important to know that hydrogen peroxide has mutagenic or cancer-causing properties, therefore, the dentist takes extra care to keep this from occurring.


Now you are ready to begin the teeth whitening procedure. Most systems use three sets of a 15-minute application of the 30-35% hydrogen peroxide gel. A 0.5-1mm of gel is applied on the front teeth and the teeth may put under a light for 1 hour. Some systems are chemically activated and don’t require light. The saliva is suctioned periodically as it collects. 

After every 15 minutes, the hydrogen peroxide gel is rinsed off, a fresh batch is applied and the procedure is repeated. After one hour the gel is removed, the teeth are rinsed and the tooth shade is checked. 

You will be shown before and after shade so you can more easily see the changes. This procedure can be repeated as many times as required to gain the maximum whitening result.

In office bleaching can be combined with at home bleaching to enhance the effectiveness of treatment.

How does hydrogen peroxide works?

Hydrogen peroxide is an oxidising agent. It penetrates into the teeth and dissociates into free radicals (hydroxyl ions, perhydroxyl anions, perhydroxyl radicals, superoxide anions) and oxygen molecules.

The free radicals attack the organic discoloured molecules in the spaces between inorganic salts and breaks them apart. As oxygen molecules spread, teeth whitens. 

How long does the whitening treatment lasts?

The dentist can not guarantee you on how long does in office bleaching treatments last. However, the longevity of the results depends on your habits and dietary factors.

The frequency of consumption of foods and drinks that cause staining is directly related to the discolouration of the teeth.

For instance, a patient who is a habitual coffee drinker and takes 5-6 cups and one or two glasses of red wine throughout the day, their teeth whitening results are less likely to last longer than six months. Furthermore, smokers are also likely to get the stains faster depending upon the number of cigarettes smoked per day.

In patients with no such habits, a whitening treatment can last up to 3 years.

Side effects 

The most common side effect, by far, of in office bleaching procedure is tooth sensitivity. This problem affects upto 75% of whitening patients. 

The intensity of dental sensitivity after bleaching is directly related to the concentration of the bleaching agent and the length of application time. The intensity is higher during the first 24 hours and can persist upto to 5 days.

Whitening gels also contain potassium nitrate and potassium fluoride, that provide a more comfortable experience. Potassium nitrate helps relieve sensitivity fast and has an affect that lasts up to 24 hours. Fluoride provides relive from sensitivity by increasing hardness of enamel. 

You may be instructed to take ibuprofen or naproxen to prior to whitening to prevent post-treatment sensitivity. The sensitivity is due to the temporary sensitivity of the pulp tissues. If patient has already anti-inflammatory meds in their system the pulpal inflammation is lessened and so is the sensitivity. 


In office bleaching is an effective and inexpensive method of whitening teeth. High concentration of hydrogen peroxide (30-35%) is applied on the front teeth for 15 minutes and is rinsed after that. It is repeated multiple times in one or several appointments to get the desired results.

Tooth sensitivity is a common side effect of in office bleaching due to use of high concentration of hydrogen peroxide.

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