Tooth whitening is done to correct the discoloration of a tooth. When we talk about discoloration of a tooth, we mean to say that the colour of a tooth has become from its normal white colour to light, light brown to dark brown or from light Gray to dark Gray or to complete black. The discoloration may be of one tooth, or all the teeth may be discoloured. Discoloration of a tooth is caused by several factors. It may be due to deposition of external stains over the surfaces of a tooth, or it may be because of the internal position of certain chemicals into the teeth structure at molecular level during the period when teeth were being formed in the mother’s womb.
External Discoloration of the Teeth
External stains deposited on the surface of the teeth may be due to smoking, drinking tea or coffee or food colorants like turmeric. Poor oral hygiene habits may also lead to the external discoloration of teeth.
Internal Discoloration of Vital Tooth
Tetracycline, excessive fluoride or other medication intake by a pregnant mother during developmental phase of the teeth of the foetus may result in the discoloration of the teeth as a child.
The Internal Discoloration of a Non-Vital Tooth
The discoloration of non-vital teeth is caused by the death of the pulp tissue due to trauma. In such cases, the pulp of the traumatized tooth goes through the death process and becomes necrotic. The necrosis or rotting of the pulp tissues produces Sulphur compounds that give the light brown to dark grey color of that particular tooth.
Procedure of Teeth Whitening
The procedure for teeth whitening depends on whether the tooth is vital or non-vital. These procedures should be performed by a qualified dentist. For common people, teeth whitening kits are available in the market. They can be utilized by anyone with care. The chemicals used for tooth whitening may be hydrogen peroxide or carbamide peroxide.
Technique of tooth whitening for non-vital teeth
It'll be a good idea to wait for at least 2 weeks after the completion of root canal treatment before the start of the tooth whitening procedure. During this time period we should watch for the development of any symptom. If no symptoms arise, then we should proceed for the tooth whitening procedure.
Colour of the tooth should be matched with the shade guide, and it is recorded in the patient’s file.
A successful root canal treatment of the dead tooth should be done. Then only, a tooth whitening procedure should be performed to correct the discoloration of the tooth involved.
The temporary filling material used to fill the access cavity after the root canal obturation should be removed up to 3 millimeters beyond the cervical line.
Then, the remaining root canal filling material is covered by a setting calcium hydroxide paste of 1 millimeter thickness. The walls of the access cavity should be smoothed with the help of a dental bur. During the smoothening procedure, a smear layer develops over the smooth surface of the cavity.
This smear layer should be removed from the walls of the access cavity. This is necessary otherwise the opening of the dentinal tubules will remain blocked, and the tooth whitening chemical will not give its full effect. To do this, 37% orthophosphoric acid is applied over the surface of the access cavity and left for 20 seconds. It is rinsed thoroughly with water and air dried.
A cotton pledged, soaked in hydrogen peroxide or carbamide peroxide is placed inside the access cavity and sealed by a temporary filling material, e.g. zinc oxide eugenol cement.
It is left there for 2-3 or more days and continuously observed. The patient is instructed to report back when the colour of the tooth becomes slightly lighter than the neighbouring tooth, the cotton pledge is removed from the access cavity and a suitable filling is done.
Teeth whitening of the vital teeth
Sometimes, few of us, especially younger ones, think that the colour of their teeth is yellow or Gray, not the white. These days, beauty conscious people seek the help of teeth whitening procedures to lighten the teeth colour and make it look whiter. This is done by “Vital Teeth Whitening Procedure”.
Technique of Vital Teeth Whitening
The original shade of the tooth is noted in the file.
The shade guide is shown to the patient and the desired shade is also noted.
A thorough scaling and polishing is done.
All over the face, petroleum jelly is applied for protection from spill of etchant.
Soft tissues are protected by protecting gel which is supplied by the manufacturer.
The whitening agents are mixed as per manufacturer’s instructions and applied over the labial surfaces of anterior teeth, from canine to canine or from premolar to premolar.
A light source is placed over it to enhance the chemical reaction.
It is left there for the time period specified by the manufacturer.
The whitening gel is washed away after the specified time.
The colour of the teeth are matched with the help of a shade guide.
If needed, the procedure is repeated again and again till the desired colour is achieved.
As a last step, the teeth, after washing away the whitening gal, are coated with a fluoride containing varnish.
The patient is instructed to not eat or drink anything, especially the carbonated drinks for one hour. This period is necessary for remineralization of the enamel by calcium present in the saliva.
Before a patient leaves the dental office, (s)he is advised to avoid eating or drinking foods that may speed up the discoloration of the teeth.
A lot of home kits are available for teeth whitening in the market. They can be used at home by anyone with little care. They are useful for mild to moderate discoloration of teeth.
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