Table of Contents
- 1 The different forms of dental bleaching
- 2 How we make bleaching trays in the office
These are over-the-counter preparations that have a low concentration of carbamide peroxide. These toothpastes will work to brighten your teeth if you are a very
good brusher, brush many times a day, and have a lot of patience. In the years since these toothpastes have been on the market, I have seen only one person who achieved real results using whitening toothpaste only. They are very useful, however in maintaining the whitening achieved by using trays and strips.
Bleach releasing disposable strips (Crest Whitestrips):
These are strips of plastic designed so that they will adhere to the teeth. They are applied and worn for several hours like the trays described above. The carbamide concentration in home bleaching strips is only 7% to 14% while professionally prescribed take-home bleaches come in either 22% or 32%. Thus it takes a lot longer to get the same results using over the counter bleaching strips than it does using professionally prescribed bleaching solutions in trays. The main advantages to the strips is that no impressions need to be taken to make trays, and the strips do not apply pressure to the teeth which may increase the sensitivity of the bleaching process. A number of my patients have tried them. Some have had good results. The major problems I have heard about with the strips is that they do not adhere very well to lower teeth, and they are too short to bleach all the upper teeth that show when the patient smiles.
This type of system is available only through your dentist. The bleaching material can only be bought with a prescription and must be applied using the custom trays that the dentist or his hygienist makes for you. The agent is carbamide peroxide and it comes in concentrations between 10% to 35% with 15% being the most popular for professional take-home bleaching. Because of the high concentration of the agent, and the close approximation with the teeth made possible by the trays, this system produces very good results in anywhere from one half to one hour per day over the course of a week. A drop of agent is placed in each tooth indent and the trays are placed in the mouth for 30 minutes to an hour maximum. The carbamide peroxide penetrates the enamel into the dentin and effectively bleaches the teeth.
Post-bleaching tooth sensitivity is a frequent complaint, but it is transient and generally lasts no more than 24 hours. The use of high fluoride concentration toothpaste (5000 ppm) such as that found in the prescription toothpaste PreviDent used prior to, and throughout bleaching effectively reduces the sensitivity. Alternatively, the use of a 5000 ppm fluoride gel for 5 minutes in the bleaching trays after each bleaching session can also reduced sensitivity. The patient can also use amorphous calcium phosphate products (MI paste by GC America) either in the trays for 3 minutes, or as a dentifrice twice daily.
Professionally supervised at-home treatment has the highest dentist satisfaction rate of all bleaching methods offered with 94% being either very satisfied or satisfied with the results.
Some offices offer a quick start bleaching procedure in which a concentrated peroxide gel is placed on the teeth and allowed to remain in place while “activated” with a light source. Treatments like this tend to be faster, but they require a lot of chair time which means that they are likely to be expensive. Prior to the introduction of at-home tray-bleaching techniques, this was the only form of bleaching offered to the public. The tray method can achieve the same or better results, (albeit over a greater length of time) with the added benefit of total patient control of the degree of bleaching desired. They can use the trays as long as they want, and keep them around for touch-ups later.
A technique sometimes used in dental offices to remove stains that penetrate to a very shallow depth (a few microns) into the enamel of teeth is called microabrasion. It is used mostly for isolated brown or white discolorations on individual teeth. The technique involves rubbing a slurry of 11% to 18% hydrochloric acid and silicone carbide abrasive into the areas of discoloration. The slurry is burnished into the discolored areas on individual teeth for about 10-15 minutes using a hand instrument. This technique will often remove enough enamel from the tooth surface to eliminate, or reduce the intensity of the stain. Studies have shown that about 2/3 of patients are satisfied with the results. The major advantage of microabrasion is that it affects only the stained areas of the teeth, and the patient gains an esthetic advantage during the course of one relatively short visit to the dentist.
In-office bleaching systems use a gel made with a 35% solution of hydrogen peroxide rather than the carbamide peroxide used with trays or strips in the take-home systems. The hydrogen peroxide gel is much stronger than the carbamide peroxide solutions used in take-home systems, and it must be applied by dental staff because of the potential to harm it could do to other oral tissues surrounding the teeth. These strong hydrogen peroxide solutions offer very effective tooth bleaching in about two hours on their own, however most dentists speed up the process by using a heat or light source to liberate more oxygen from the gel faster than would happen without the light or heat source. Manufacturers of these solutions have managed to cut the time down to about one hour, or in some cases even to a half hour if the light or heat source is used to accelerate the process. On the other hand, retail light bleaching kits that come with a flashlight-like device that illuminates the tray (sold on TV, and recently in big-box merchandise stores) are no more effective at whitening the teeth than using the low concentration bleach that is sold with them without the light. They are simply gimmicks. Stick with the Crest White Strips or go to a dentist for the real thing.
The first step in bleaching involves a thorough examination, X-rays and cleaning. Bleaching diseased teeth is like painting a rusted out old car. The owner walks away thinking he has a new car, but finds out soon that he is no better off than before. It is not ethical for a dentist to perform an esthetic procedure like bleaching in the presence of curable disease!
It is important to be aware that fillings, including white fillings in the front teeth do not whiten with bleach. Therefore, if you have any composite fillings in your front teeth, they may have to be replaced after the bleaching process since the shade of these fillings was chosen to match the teeth as they were before bleaching. In practice, this is not always necessary.
The second step is taking impressions of the upper and lower teeth so models can be made to fabricate the bleaching trays. The major problem with impressions is that people who gag may have a difficult time. The key to having impressions taken is to be sure to breath only through your nose. If you breath through your mouth during this procedure, you will have gagging problems. I usually tell my patients to practice by opening their mouths wide, and humming, being sure that all the sound is coming out of their nose. When performing this feat, the back of the tongue blocks off the throat, and since the impression material cannot go any further down the throat than that, the gagging reflex is suppressed. (This is really the same thing that happens when you are chewing food which is why gaggers generally have no problems eating. You will notice that when chewing food, you can hum at the same time.)
Finally, you get your trays and the bleaching kit, and go home and begin the process. The instructions vary slightly according to the type and manufacturer of the bleaching kit, but you generally wear the trays anywhere from several hours several times a day, to overnight for as long as you want to keep the process up.
The results you can expect from all of the over-the-counter methods are never as good as you can get with prescription dental bleaching methods. The reason for this is that the dentist can provide prescription strength bleach and custom bleaching trays that fit your teeth tightly and keep the bleach in undiluted contact with the teeth for long periods of time. Neither bleaching strips nor the stock trays provided in the over-the-counter bleaching systems have either of these advantages.
The advantage to the availability of the dental bleaching agents through sources such as the home shopping network is that once you finish a prescription bleaching regime, your custom trays remain in your possession indefinitely, and touchups, or continued bleaching can be done using the prescription custom trays and the relatively less expensive bleaching agents available from commercial sources.
The retail light bleaching kits that come with a flashlight-like device that illuminates the tray (sold on TV, and recently in big-box merchandise stores) are no more effective at whitening the teeth than using the low concentration bleach that is sold with them without the light. Click here to see why.