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  1. 1. A Comparison of At-Home and In-Office Bleaching By Van B. Haywood, DMD Reprinted from Dentistry Today (2000:19(4):44-53), c2000, Dentistry Today, Inc. Introduction Hydrogen peroxide is very unstable. In-office bleaching of teeth has been in Like the hydrogen peroxide one buys at the use for approximately 125 years, with little drugstore in an amber bottle, it foams and fizzes change in science or technique during that time. as soon as it contacts organic material. One When at-home "nightguard" bleaching using question we must ask when assessing in-office carbamide peroxide was introduced in 1989, it bleaching is, can we leave a high concentration appeared that the in-office approach would of hydrogen peroxide on the tooth long enough quickly become extinct. However, there has to achieve proper color change? This is the been a recent resurgence in in-office bleaching, question that interfered with the popularity of in- primarily due to aggressive marketing of various office bleaching even in its early years. In-office "high-tech" light sources such as lasers and bleaching was never very popular because of plasma arc lights, coupled with claims of the danger to the patient and the dentist, the reducing bleaching time, even to a single office amount of time it took to do it, and the cost to the visit. patient. The danger to the patient is the potential This article will examine at-home and in- for tissue burns from the 35% hydrogen peroxide office bleaching in terms of efficacy, safety and used, which can result from a leaky rubber dam cost, and discuss their clinical indications and or improper isolation technique. There are also contraindications. Advantages and questions about dangers to the pulp related to disadvantages of both techniques will be certain lights used and the heat generated. assessed, and treatment parameters as well as At-home bleaching, when it appeared in coping with side effects will be addressed. This 1989, had the same indications as in-office author bases the following information on a bleaching except that it was much less costly, thorough analysis of the literature combined with and safer to the patient and dentist. The original personal research and clinical experience. at-home bleaching products used a 10 percent solution of carbamide peroxide as the bleaching Mechanism of Action agent, which is basically 3 percent hydrogen The degree of tooth whitening that can peroxide and 7 percent urea. The urea primarily be achieved during bleaching is dependent on acts as a stabilizer to give these products a the concentration of bleaching material used and longer shelf life, slower release of the hydrogen the time that this material has to act without peroxide and other benefits. Thus, both in-office producing side effects. In-office bleaching uses and at-home products use hydrogen peroxide, 35 percent hydrogen peroxide as the "whitening" but they are not identical. The pure form of agent. Many people don't understand that hydrogen peroxide penetrates the tooth more hydrogen peroxide penetrates through the quickly than the pure form of carbamide enamel, the dentin, and to the pulp in a matter of peroxide. The basic mechanism of action is the minutes. Bleaching using either in-office or at- same, but the formulation affects shelf life and home techniques is not mere surface treatment time required for penetration of the tooth. of the tooth, it is causing internal color changes. We are not simply taking out stains that have Efficacy occurred after formation of the tooth, but are Current in-office bleaching technique is changing the inherent color of the tooth. We basically the same as the technique developed typically think of bleaching as an oxidation between about 1880-1916, which uses 35 process, but the bottom line is we don't really percent hydrogen peroxide with rubber dam know what gives a tooth its color, therefore, isolation. The question is often asked, "How long when we change the color we don't know exactly does it take to effectively whiten teeth?" The what we are changing. Bleaching doesn't appear answer is, "You bleach 'till they are white." In to have an effect on hardness or structural other words, every case is different, and the integrity of the tooth, but there is no real amount of time required to achieve the desired scientific evidence regarding what is being result will vary from patient to patient. As noted affected during the color change process. previously, in-office bleaching uses a much higher concentration of hydrogen peroxide than 1
  2. 2. does at-home bleaching, therefore the bleaching problem with in-office bleaching is that you only agent will penetrate the tooth more quickly with bleach the anterior six or eight teeth. It is hard to in-office bleaching. However, the literature place a rubber dam on second molars without it shows us that when using in-office bleaching we leaking during bleaching. Thus, the result will be must count on 2-6 visits with about 45 minutes whiter anterior teeth and darker posterior teeth, application time per visit, with or without using a and many people show their molars when they light, to achieve an effective result. And we must smile. At-home bleaching using a custom tray wait at least one week between visits due to reaches all teeth. tooth sensitivity. This can be a financial burden What about the efficacy of various light for the patient even if the dentist charges a fair sources marketed for use with in-office hourly fee. Also, you must apply the rubber dam bleaching? Here has been this author's each time and hope it doesn't leak. Certainly, challenge for several years to anyone who some patients will experience satisfactory results claims that a light increases in-office bleaching in a single in-office visit depending on the efficacy...publish a paper with proper scientific underlying cause of the discoloration. However, evidence showing that the light makes a this is not the norm. difference. No one has done this. There are only For at-home bleaching expect 2-6 two published papers on the use of lasers in weeks of treatment time. Some patients will bleaching, one showing that lasers are no more achieve desired results in a few days, but most effective than other types of light, and one will take 2-6 weeks, and it is best to tell them to showing that lasers are less effective than 20 expect this. If they finish earlier the dentist is a percent carbamide peroxide with no light. This saint...if it takes that long the dentist is a author has published case reports showing one prophet. Treatment time will be longer for special in-office treatment using a light-activated 35% situations such as tetracycline staining. With hydrogen peroxide material did not achieve the tetracycline staining, at-home treatment may results obtained from at-home bleaching with require 2-6 months, or even longer. In such 10% carbamide peroxide. A light source will cases it is suggested that a monthly fee be speed up an oxidation reaction, but whether this established, and the patient must understand will speed up the color change of a tooth is not that lengthy treatment may be required. This known. Someone needs to conduct a clinical author has experienced severe tetracycline double-blind, evidence-based study , possibly staining cases that required up to 12 months of using a split-arch design, if they wish to prove at-home bleaching treatment, but the results that lights such as lasers or plasma arc are were spectacular. indeed efficacious for bleaching. It would be For some patients who are willing to pay easy to do, but none of the manufacturers have an additional fee, in-office bleaching can be done so thus far. appropriate as a "jump start" technique, where it It should be noted that all of the lights is accomplished while the tray is being used in in-office bleaching are "grandfathered" in fabricated for at-home bleaching. This terms of FDA marketing approval based on their combination approach could shorten the equivalency to the original flood light used with treatment time. Also, if for some reason a patient the Union Broach in-office bleaching product. cannot comply with wearing the custom tray The Union Broach product, which originally used designed for use with at-home bleaching, in- a flood light to generate heat, and the Star Brite office bleaching is a viable treatment alternative. product, which does not use a light source, are Can you achieve as good a result with the only two 35 percent hydrogen peroxide in- in-office bleaching as you can with at-home office bleaching products that are approved by bleaching? You might, but most often you don't the American Dental Association. For at-home because of financial, tooth sensitivity and labor bleaching products, no product that contains considerations. People tend to give up too soon. higher than 10 percent concentration of If the dentist and patient can persevere through carbamide peroxide is approved by the ADA, the number of visits required for effective results, because all of the efficacy, safety and sensitivity then equivalency with at-home bleaching is studies have used 10 percent carbamide certainly possible. As for one-visit "Power peroxide. While many at-home bleaching Whitening" that is the focus of extensive products contain a higher concentration of marketing these days, this author has not had carbamide peroxide, and future literature may any such technique work to the level of what can support their safety and efficacy, this author be achieved with at-home bleaching. Another doesn't use any bleaching product that is not 2
  3. 3. ADA approved. Currently ADA-approved contraindication to bleaching. Patients with products include Opalescence 10% (Ultradent existing tooth sensitivity, or who experience Products Inc.), Platinum and Platinum Overnight sensitivity during bleaching to the degree that it (Colgate Oral Pharmaceuticals), Rembrandt is a real problem, represent a contraindication. Classic 10% (DenMat), NiteWhite Classic 10% While severe tetracycline staining is not (Discus Dental), and Patterson Toothwhitening necessarily a contraindication, these cases are Product. The ADA-approval requires that any difficult to bleach, especially the dark grays and advertising claims have a scientific basis, and blues and if the discoloration is located in the this is important because practitioners are being gingival third, which is the most difficult part of confused by a variety of marketing claims which the tooth to bleach. Patients must be informed are not supported by evidence. that the prognosis for such cases is guarded. Elderly patients often present with Indications for Bleaching gingival recession and roots that are yellow and The clinical indications for bleaching evident to observers. The roots don't tend to teeth are basically the same for both in-office whiten during bleaching, therefore the patient and at-home methods, but the clinician must will be left with white teeth on the anatomical decide which is the best method for a particular crown but yellow roots, so they must be aware of patient situation to achieve the desired result. this. This could be a limitation to bleaching in There are many patients who are candidates for this group. This author doesn't bleach teeth on bleaching, including those whose teeth have pregnant women, although there is no scientific been darkened by aging; people who were born evidence that pregnancy is a contraindication. with yellow teeth; people with stains from We simply do not want the woman to ever think chromagenic foods such as tea and coffee; bleaching caused a problem with her baby. If a people with nicotine stains; those with drug- woman discovers she is pregnant during induced stains such as tetracycline; those with bleaching, we ask her to stop for the same trauma-induced darkening; and people who reason, and also because the bleaching solution have staining from fluorosis, which tends to could possibly exacerbate any pregnancy produce brown and white areas. gingivitis problems she might have. Tetracycline staining, one of the significant challenges for bleaching, is most Tooth Sensitivity Due to Bleaching often associated with people who ingested the There are no studies comparing drug in their younger years, during tooth sensitivity between in-office and at-home formation. However, there are several reports in bleaching. Many companies have no scientific the literature about adult teeth being stained by basis for claims about the amount of sensitivity minocycline, which is the most commonly their products cause. A review of the double- prescribed drug for acne. Teenagers who use blind, placebo clinical trials that have been done this antibiotic may see their teeth change from involving at-home bleaching will show that 55-75 white to a gray coloration by the time they percent of patients in the treatment group will graduate from college. Minocycline is laid down experience some sensitivity, if only for one day. in the secondary dentin, and it is resecreted in The interesting finding here is that the placebo the saliva and soaks into the outside of the groups have 30-35 percent sensitivity without tooth. Minocycline remains the best drug using carbamide peroxide at all, and one study available for acne, so dentists should be aware showed that a group wearing an empty tray had that adults may present with this type of 18 percent with sensitivity. From these data one tetracycline staining. can assume that sensitivity is not just due to the bleaching product, it can also result from Contraindications to Bleaching treatment manipulation of the teeth. Anything Contraindications to bleaching are that places forces on the teeth has the potential mainly due to existing conditions of the patient. to cause sensitivity. Existing crowns or extensive restorative dentistry The clinician can treat sensitivity either where the restorations are tooth-colored, e.g., passively or actively. With at-home bleaching, porcelains or composites, will not change color passive treatment involves adjusting the with bleaching. Bleaching will affect the natural frequency of treatment (every day, or skip a day, teeth, but if replacing existing restorations in etc.) and duration of treatment (1-8 hours per order to match the bleached teeth is a financial day), and the concentration of carbamide burden for the patient, this can be a peroxide. Often, simply stopping treatment for a 3
  4. 4. few days will alleviate sensitivity when treatment bleach, and the single dark tooth presents a resumes. Actively, the traditional way to treat challenge, but is still amenable to external sensitivity was with fluoride or brushing with a bleaching. Brown stains are also more difficult to desensitizing toothpaste. This author and bleach, and will require longer treatment time. colleagues have an abstract with the Brown discolorations are responsive to International Association for Dental Research bleaching perhaps 80 percent of the time. White this year (#3001) where we placed potassium spots, such as may occur in conjunction with nitrate and fluoride in a bleaching tray to treat brown spots in the case of fluorosis, will not bleaching sensitivity in the same manner as change color but will become less noticeable as Jerome treated periodontal sensitivity. Just as the rest of the tooth becomes lighter. hydrogen peroxide penetrates through the Mild and moderate tetracycline stains enamel and dentin and to the pulp, so does are responsive to bleaching if you give them potassium nitrate. Fluoride acts primarily as a enough time, but severe tetracycline stains are tubular blocker, plugging the holes and slowing very difficult. Banded stains are a special down the fluid flow that causes the sensitivity. challenge, and the clinician may have to use Potassium nitrate acts more like an analgesic or bonding to cover a particular band after anesthetic by keeping the nerve from bleaching. Tetracycline comes in about six repolarizing after it has depolarized in the pain different brands, and each brand causes a cycle. Therefore, there are two mechanisms of different color on the teeth. Banded teeth action, one affecting fluid flow and the other a indicate that the patient took different brands of direct effect on the nerve. tetracyclines in a sequence, and each brand laid Several companies provide 3-5 percent down a different color on the tooth. Some of potassium nitrate in a syringe for application in those colors respond better to bleaching than the bleaching tray as needed. Or, one can take others, and the ones that don't respond must be a desensitizing toothpaste that contains 5 covered with bonding. percent potassium nitrate, which is the maximum Remember the axiom, "bleach 'till they approved by the FDA, place it in the tray and are white". Bleaching results depend on the apply it in this fashion for 10-30 minutes. Some individual patient's teeth and the type stain they patients may have a gingival reaction to the have. You can't simply say that bleaching will ingredients in the toothpaste, not to the take one day, or two weeks, or several weeks. It potassium nitrate, and get a tissue burn, will take as long as it takes. Nicotine stains may therefore the clinician may have to experiment take 1-to-3 months to successfully bleach, with various formulations for certain patients. For depending on how long the patient has been patients with chronic sensitivity unrelated to smoking. If you bleach for two weeks and don't bleaching, the toothpaste gives them an OTC get the response you seek, you might be product that they can use whenever they need it, tempted to say this doesn't work. In reality, it is even before a prophy. The syringe materials that likely that the treatment time was inadequate. must be purchased from the companies may be more appropriate for episodic sensitivity The Evolution of Bleaching associated with the bleaching itself. This author We are starting to better understand the provides a free slide presentation on treating different bleaching vehicles or bases, e.g., sensitivity on the internet at glycerin, anhydrous glycerin, several different kinds of glycols, toothpaste bases, etc. We are seeing more sophistication in this area. We are Types of Discoloration and Relative also learning that the way in which the material Bleaching Difficulty releases oxygen may affect sensitivity. We know It is often easier to bleach the teeth of that roughly 50 percent of the peroxide in a older patients because the pulp is small and they bleaching agent is released in the first 1-2 hours, have accumulated a lot of stains that can be and the rest is released over the next 4-6 hours. more easily bleached, including secondary This is why advocates of overnight at-home dentin discoloration due to age. Aging bleaching believe you get the best "bang for the discolorations and tea and coffee discolorations buck" with this technique, with the least amount are very easy to bleach. Teenagers, too, may of sensitivity and most bleaching efficacy in a have yellow teeth, or yellow canines with white single application per day. However, some incisors. These cases also respond well to products release the peroxide more rapidly, and bleaching. Nicotine stains are more difficult to this can have an effect on sensitivity. The future 4
  5. 5. evolution of the science of bleaching will likely notching, that patients could incorrectly blame involve further development of the vehicles and on the bleaching itself if pre-operative the release time of the peroxide. photographs were not taken. Bleaching is just starting to catch on in One problem dentistry may create for Europe, and this may contribute to itself is charging too much for bleaching in an enhancements that we in this country haven't attempt to make a lot of money on a few considered. patients. The national average in 1999 for bleaching was $196 per arch, and this is very The Importance of Dentist Supervision reasonable and fair to both patient and dentist. There are advertisements for at-home As noted previously, for tetracycline stained bleaching products that one can order directly teeth that will require longer term treatment a from a company, with no dentist involvement. monthly fee can be fairly established. The most important thing the dentist offers patients is the initial exam and diagnosis, which Conclusion cannot be done without the patient coming to the Bleaching offers an excellent solution to dental office. So many times people will come to many cases of tooth discoloration, and in this the dentist to have their teeth bleached, and the author's opinion at-home bleaching offers many dentist finds that they need endodontic therapy, advantages when compared to in-office which is why the tooth is dark. Or they have technique. No matter whether at-home or in- internal resorption and need aggressive office methods are selected by the clinician and treatment, or class 3 decay that is dark and patient, both parties must understand that each needs treatment, or restorations that are dark case is different. If the clinician uses in-office and need replacing due to secondary caries. bleaching, the patient should be given the choice Proper examination and diagnosis, including of at-home or in-office bleaching after explaining radiographs, are needed to rule out pathology the fees, treatment times, and number of that will require completely different treatment appointments for successful outcomes. The time from bleaching. required to achieve desired results will vary, and The second service dentists offer is a the patient's expectations in this regard must not custom fitted tray. You can have a loss of be unrealistic. The key is to "bleach 'till they are efficacy of the bleaching material if it is not white". Don't give up too early and switch to properly contained in the tray, and you have an veneers or another less conservative treatment increased risk of TMJ problems or occlusal until bleaching has been given a fair chance. problems, or even orthodontic movement of the teeth, with an ill-fitting tray. Dentists can also ensure quality of product by using an ADA Van B. Haywood, DMD, is Professor, approved product, and by knowing the shelf life Department of Oral Rehabilitation, at the Medical of the product. Some products bought over the College of Georgia School of Dentistry. He was counter or by mail order may not have good co-author with Dr. Harald Heymann of the first quality standards, may have a low pH, or may article in the world on nightguard vital bleaching have a short shelf life. The dentist can monitor in 1989, and in 1997 was co-author of the first any side effects and take immediate action to article on extended treatment of tetracycline- address them. And, the dentist can take before- stained teeth with 10 percent carbamide and-after photographs, which will demonstrate peroxide. He is a 1974 alumni of the Medical changes in color and properly document pre- College of Georgia School of Dentistry. existing conditions in the teeth, such as End 5