In 1918 Abbot reported the use of a high intensity light that generates a rapid rise in the temperature of hydrogen peroxide, accelerating the chemical bleaching process. This combination continues to be the basic protocol for power bleaching.
The main problems associated with power bleaching are:
• It can require multiple visits to the surgery
• It can be expensive
• Dehydration can cause a false interpretation of the actual shade change
• The use of stronger hydrogen peroxide concentrations can cause an increase in hypersensitivity.
However, despite these disadvantages, many patients prefer power bleaching to home bleaching because of its immediate whitening results. Also, since the whole procedure is under the control of the dentist, less compliance is needed on the patient’s side.
To boost patient satisfaction with whitening techniques, it is up to our profession to provide more convenient and effective whitening procedures with safe and rapid results.
In order to improve the traditional power bleaching technique, several modifications have been proposed:
• Compressive bleaching technique
• Ozone machine for power bleaching
• Deep bleaching technique
• Sealed bleaching technique.
In 2000, Paul Miara suggested that power bleaching could be made more effective by compressing the 35% hydrogen peroxide gel onto the tooth using a bleaching tray and sealing its edges with light-cured resin to prevent soft tissue irritation. The advantage of this technique is that it influences the flow of oxygen ions into the tooth surface.
Julian Holmes and Edward Lynch have proposed the use of an ozone machine to enhance the whitening effect. This is as ozone possesses strong oxidising power.
In 2003, Rod Kurthy introduced the deep bleaching technique, which combines power bleaching with home bleaching. During this procedure the teeth are first primed for better whitening and whitened with a high intensity light. Finally, it’s coated with a clear and glossy protective layer to maintain the colour for a long time.
The sealed bleaching procedure was developed to solve the common problems encountered during conventional power bleaching techniques. During these procedures the gingiva is protected with a resin barrier and a high concentration hydrogen peroxide, or carbamide peroxide, gel is placed onto the labial surface of the teeth. Light activation to enhance the whitening procedure can be used but is not essential.
According to the instructions of many manufacturers, the bleaching gel should be replenished several times during the one visit to maximise the whitening results.
During conventional power bleaching the author found that many patients complained of nasal discomfort, which might have been caused by some volatile agents irritating the mucosa. Replenishing the material several times during the one visit because the material has dried out is time consuming and inconvenient for the patient, the dental team and also increases expenses.
By placing a 45mm by 15mm sized square of low density polyethylene wrap onto the power whitening gel, a sealed environment is established to prevent evaporation and the drying out of active agents and maintain the flow of oxygen ions into the tooth. The advantages of this technique are that discomfort, due to evaporation of volatile agents, can be avoided and thus power whitening can be performed in a safer way.
It can be used with any power whitening agent on the market and also with lower concentrations of hydrogen peroxide gels. This will still produce fast and effective whitening results, but with a decreased percentage of hypersensitivity.
The clinical procedure of sealed power whitening is as follows (Figures 1-8):
1. Thorough prophylaxis of teeth to be bleached
2. Placement of lip retractor, protective eyewear and resin barrier onto gingiva
3. Application of power whitening agent
4. Placement of tooth whitening cover
5. Photoactivation of whitening gel-selective
6. Removal of power whitening agent after 40min
7. Placement of neutral sodium fluoride gel for 5-10min
8. Removal of resin barrier and neutral sodium fluoride gel.
For optimum results, the sealed bleaching procedure should be repeated two or three times per arch at an interval of one week and, if possible, combined with home bleaching (Figure 9). Studies are currently under way to support the effectiveness of the sealed bleaching technique.
Goldstein RE. In-Office bleaching: where we came from, where we are today. J Am Dent Assoc Suppl. 1997; 128:11S-15S
Greenwall LH. Bleaching techniques in restorative dentistry, Martin Dunitz, 2001
Kurthy R. Deep bleaching
Kwon SR. Color atlas of tooth whitening, Daehan Narae Pub., 2006
Holmes J., Lynch E. Uses of Ozone in the general dental practice: Integration into General dental practice, Part 2
Miara P. An innovative chairside bleaching protocol for treating the stained dentition: initial results. Pract Perio Aesth Dent 2000:12/7:669-78