Bleaching

Colour of the teeth is determined by the translucency & thickness of the enamel and by the color of the underlying dentin and pulp.

Classification of discolouration

•Extrinsic– These stains are found on outer surface of teeth and are of local origin ex. Tobacco stains and tea stains . These stains can be removed by scaling and polishing.

•Intrinsic- These stains are within enamel and dentin and are caused by the deposition or incorporation of substances with in there structures ex. tetracycline stains

Causes of tooth discolouration

Principle causes are-

•Decomposition of pulpal tissue.

•Excessive haemorrhages causing pulp removal

•Trauma

•Medicaments

•Filling materials

In addition to these causes discolouration can also be seen in systemic disease like congenital porphyria, endemic fluorosis, etc.

Prevention of tooth discolouration

It can be prevented by-

•Proper access cavity preperation that permits removal of all pulpal tissue.

•All traces of blood should be removed by thorough irrigation.

•All strands of the pulpal tissue should be removed before the resin is placed.

•Any defective restoration should be replaced.

•Sealer and obturating material should be removed from the pulp chamber beyond level of 1-3 mm apical to the free gingival margin.

Bleaching Agents

Superoxol is 30% solution of hydrogen peroxide by weight and 100% by volume in pure distilled water. Superoxol can be used alone or mixed with sodium perborate into a paste for use in walhing bleach. When mixed into a paste with superoxol , this paste decomposes into sodium metaborate , water and oxygen.

When seat into the pulp chamber oxidises and discolour these stains slowly. This procedure is called walking bleach.

Procedure for Walking Bleach

•Polish the enamel surface of tooth to be bleached.

•Apply petroleum jelly to the gingival tissue around tooth to be bleached

•Adapt rubber dam

•Restablish the access activity.

•Remove any G.P root canal filling that extends into the pulp chamber to the level of crest of alveolar bone.

•Seal the orifices of root canal with atleast 1mm cavit over the gutta percha to prevent the percolation of the bleaching agent.

•Now remove the smear layer and open the tubule by applying 25% solution of citric acid or 30% solution of orthophosphoric acid to the dentinal surface of the pulp chamber.

•Flush the surface with sodium hypochloride or water to remove the acid.

•Flush the pulpal chamber with 95% of alcohol and dry with air to dessicate the dentin.

•Protect the exposed area of the patients face.

•Now mix sodium perborate with superoxol into a thick paste in a clean dip n dish.

•Carry the thick paste into pulp chamber with plastic instrument.

•Then cover entire facial surface of pulp chamber.

•Place small cotton pellet slightly moistened with superoxol over bleaching agent.

•Finally seal the access activity with ZnPO4 cement.

Maximum bleaching affect is attained about 24 hours after treatment. Patient should be called after 3 days for the evaluation of the result.

Bleaching of Vital teeth

Teeth that has been discolored as a result of ingestion of high amount of fluoride such as 5ppm in natural drinking water or consuming tetracycline for a long period of time do not respond well to ordinary method of bleaching. In cases of endemic fluorosis a solution of anaesthetic ether, HCl and superoxol is used for bleaching. A solution is prepared in clean dip n dish as follows:

1 part anaesthetic ether i.e 2ml

5 part of HCl i.e 1ml

5 part of H2O2 i.e 1ml

Contributor- Dr. Somya Deep Kaur