Teeth Whitening

The normal colour of permanent teeth is grayish yellow, grayish white or yellowish white. This is usually determined by the thickness of enamel, thickness and colour of underlying dentine and the pulp. Alterations in this colour may be physiologic or pathologic, intrinsic or extrinsic. Generally the colour is more yellowish in fair skinned persons and more whitish in dark skinned persons.Elderly persons also have more yellowish teeth.
Extrinsic discolurations may be due to tea, coffee, fluoride, smoking , bacteria, etc., wheras intrinsic stains maybe due to genetic conditions like amelogenesisimperfecta , due to tetracycline class od antibiotics, jaundice, pulp necrosis, remnants of restorative materials, etc.
Since esthetics is the primary consideration of patients, a discolured tooth or teeth especially in the anterior region definitely causes many patients asking for treatments to “whiten” or”brighten” the teeth. This is commonly referred to as tooth bleaching. Bleaching is a procedure defined as lightening of the colour of the tooth through the application of a chemical agent (mostly acidic) to oxidize the organic content of the tooth.Most common bleaching agents used are: Hydrogen Peroxide (H2O2) 5%-35%, Sodium Perborate (Used inside the pup chamber, called as “walking bleach”), CarbamidePeroxide.Nowadays Laser tooth whitening using zoom bleaching is gaining a lot of poularity , wherin a laser beam activates the bleaching agent thus speeding up the reaction, enabling faster and better results. Teeth whitening is ideal for people who have healthy, unrestored teeth (no fillings) and gums. Individuals with yellow tones to their teeth respond best. But this cosmetic procedure is not recommended for everyone

tooth whitening / bleaching techniques

1.Intracoronal bleaching (bleaching of root canal treated teeth from within the tooth/ non-vital bleaching)-

a. At home (walking bleach)- In this the bleaching agent is placed inside the pulp cavity and sealed. The effect starts after 24 hours. The patient should return 3-7 days after the treatment to assess the change in colour.
b.In- office or thermocatalytic bleach- In this technique cotton pellets soaked with 30% H2O2 are placed inside the pulp cavity and activated by light and heat. Several 5-6 minute exposures are applied to the tooth.

2.Extracoronal bleaching (from external surface) or vital tooth bleaching

a. In-office vital bleach- 35% H2O2 is directly applied to the outer surface of the tooth, in the form of gels, followed by activation with heat, visible light or laser light.Lasers principally work by activating the catalyst of the bleaching agent, which releases nascent oxygen. About 30-60 mins are required at each visit . To get dramatic results several visits may be required.This is also a more expensive procedure.It may reduce the shade 3-5 times lighter than the original shade.
b. At-home vital bleach –It involves the use of custom made polymerized resin trays with 10% carbamide peroxide incorporated into them. The patient is instructed to place enough bleaching agent into the trays cover the outer surfaces of the teeth, after which excess bleaching material is wiped away.The tray should be worn for 4 hours for every session, following which the patient should thoroughly rinse off the teeth.
Results can be seen as early as 2-4 days or may take 6-12 months.

3.Whitening Toothpastes
All toothpastes help remove surface stains, because they contain mild abrasives. Some whitening toothpastes contain gentle polishing or chemical agents that provide additional stain removal effectiveness. Whitening toothpastes can help remove surface stains only and do not contain bleach; over-the-counter and professional whitening products contain carbamide peroxide or hydrogen peroxide that helps lighten the color deep in the tooth.

4.Over-the-Counter Whitening Strips and Gels
Whitening gels are clear, peroxide-based gels applied with a small brush directly to the surface of your teeth. Instructions generally call for twice a day application for 14 days. Initial results are seen in a few days and final results are sustained for about four months.
Whitening strips are very thin, virtually invisible strips that are coated with a peroxide-based whitening gel. The strips are applied twice daily for 30 minutes for 14 days. Initial results are seen in a few days and final results are sustained for about four months.

5.Whitening Rinses
Among the newest whitening products available are whitening rinses. Like most mouthwashes, they freshen breath and help reduce dental plaque and gum disease. But these products also include ingredients, such as hydrogen peroxide, which whiten teeth. Manufacturers say it may take 12 weeks to see results. You just swish them around in your mouth for 60 seconds twice a day before brushing your teeth. However, some experts say that rinses may not be as effective as other over-the-counter whitening products. Because a whitening rinse is only in contact with the teeth for such a short time — just two minutes a day compared to 30 minutes for many strips — it may have less of an effect

Adverse effects of tooth bleaching

  • Tooth sensitivity
  • Enamel damage/erosion
  • Irritation or chemical burns o the gums

Contraindications of tooth bleaching

  • Severe enamel loss
  • Hypersensitive teeth
  • Night grinding habit
  • Presence of dental caries
  • Presence of restorations or fillings
  • Allergy to bleaching agents.