9. If after two days the tooth color has attained a result which the patient is happy with, restoration of the tooth can take place. If another bleaching process is needed within the foreseeable future, a restoration should be made through which access to the pulp chamber can be gained in the future.
Walking Bleach
The first four steps are identical to those for power bleaching.
5. Place the bleaching agent in the pulp chamber.
6. Close the opening with a Cavit or an IRM restoration. Patients must be informed that the bleaching agent present in the pulp chamber releases gases, which could cause the temporary restoration to fall out.
7. The bleaching agent remains in the tooth for between two days and one week.
8. Repeat the process.
9. Restore the tooth.
Internal bleaching should not be repeated more than four times, because the inner tooth structure becomes weakened, increasing the risk that a crown fracture may occur.
73 Bleaching nonvital teeth
The bleaching agent is placed in the pulp chamber.
74 External bleaching
In addition to internal bleaching of the nonvital tooth, all teeth can simultaneously be given an external bleaching with a bleaching tray.
Courtesy of Ultradent Prod. Inc.
Long-term Results
In 1989 Haywood began a scientific study of the bleaching procedures. In 1994, he presented the long-term results of 300 patients.
Seventy-three percent of the patients were satisfied with the bleaching results after three years. Only a few noticed a slight darkening of the teeth. A total of 3% of the patients required a regular follow-up bleaching. No patient reported postoperative sensitivity, gingiva irritation, or had had a tooth fracture. Teeth of patients with an orange-brown discoloration were brightened by about 3.3 shades on the Vita color scale guide, and this result was confirmed after three years.
A survey among dentists by the CRA (Christensen 1997) showed that:
91% of the surveyed dentists bleach teeth
79% were very satisfied with the result
12% were disappointed
62% observed tooth hypersensitivities in 10.7% of all cases
45% said that 5.6% of the patients had gingiva irritations
2.1% recognized systemic troubles in 0.2% of the cases
18.8% had not registered any side effects
75 Before start of bleaching treatment
The patient's smile before treatment began.
76 After bleaching treatment
A follow-up picture after bleaching treatment was completed.
Courtesy of Ultradent Prod. Inc.
How Long Do Bleached Teeth Remain White?
After approximately one year, patients should give their teeth a slight after-bleaching. The original tooth color returns slowly over a time period of one to four years if no after-bleaching is carried out. The slow darkening process of the teeth depends on the original color. Light-yellow color changes do not come back as quickly as gray colors. In the case of younger patients the color change is retained longer than with older patients. It must therefore be clear to the patient that after-bleaching may occasionally become necessary. Because of that, the bleaching tray should be stored in a safe place.
Special whitening toothpastes support the bleaching process very greatly and should be used at regular intervals. Normally, patients who have their teeth bleached are well aware of their teeth and return regularly to the dental hygienist. Tooth-color can thus be reassessed and after consultation with the dental hygienist a schedule for after-bleaching can be outlined. It is quite difficult for the patient to properly notice the slow change in tooth color. Here, the guidance of a dental hygienist can be very helpful.
Micro Abrasion Method
Micro abrasion is indicated for solid color spots found in the uppermost tooth surfaces. Such color inclusions do not disappear through bleaching.
History
At the beginning of the 20th century, Black already described the micro abrasion procedure using hydrochloric acid. In 1984, McCloskey used pumice mixed with 18% hydrochloric acid to remove color changes on tooth surfaces. Six years later the Primier company brought the product Prema (Primier Enamel Micro Abrasion) onto the market. Prema consisted of pumice mixed with 10% hydrochloric acid. Micro abrasion can be combined with bleaching.
Treatment Planning
Superficial color changes (white spots, fluorosis, and slight tetracycline discolorations) can be removed with the micro abrasive procedure. Hydrochloric acid is a very aggressive liquid. Electron microscopic studies have shown that 18% hydrochloric acid removes approximately 10μm enamel (7–22 μm) in five seconds. Because of this, the micro abrasive procedure should only be used for short time intervals (five seconds). A maximum of five repeated applications should not be exceeded.
77 Status before micro abrasion therapy and bleaching
In the case of micro abrasion therapy, pumice and an approx. 15% hydrochloric acid solution are used to remove the outermost enamel layer. In addition to this treatment, external bleaching can be carried out.
78 Result of treatment
Result achieved after completed micro abrasion therapy. An external bleaching treatment was conducted simultaneously.
Materials
Rubber dam, Dappen dish, 12-18% hydrochloric acid, pumice, sodium bicarbonate, fluoride paste, and possibly a bleaching gel.
Treatment Procedure
1. Perfect isolation with rubber dam: If this is not sufficiently tight, it should be additionally sealed by means of a ligature or liquid rubber dam. Patient, dentist, and dental assistant should all wear goggles.
2. Apply the acid: Mix 12–18% hydrochloric acid with pumice. This mixture is then placed on the tooth regions that are discolored. Now this paste is distributed for five seconds over the surface of the tooth with an extra slow contra-angle handpiece and a rubber polishing cup, with which the area is lightly polished. After completion, all of the hydrochloric acid-pumice mixture is immediately rinsed away with thorough suctioning, and afterwards the tooth color is checked.
3. Repetition: This process can be repeated up to a maximum of four times. However, if no drastic improvement can be seen after two to three applications, the treatment should be stopped.
4. Polishing and fluoride treatment of the teeth.