13The IDA Times Mumbai June 2013

CMYK

CMYK

DeNtal PraCtiCe

Dental Bleaching

Dr. Neeraj MahajanProf. & Head

Dept. of Pediatric & Preventive DentistryGuru Nanak Dev Dental College & Research Institute, Sunam, Punjab

Email: drmahajanneeraj@gmail.com

AbstractBleaching has been scientifi cally proven to be safe and very effective in altering the colour of teeth. Discoloured teeth are up to fi ve times more worrying to patients than crooked teeth. Diagnosis of the causes of discolouration, assessment of patient’s expectations and full discussion with patients about their available options are all important aspects of bleaching. Bleaching is now well established as one of the most important appearance enhancing aspects of modern evidence based clinical practice. The aim of the present article is to review critically the biological aspects of tooth bleaching including effi cacy and side effects of such treatments. In addition, the safety of tooth bleaching is especially addressed.

AimThe aim is to introduce the concept of bleaching, or overview the vital teeth bleaching procedures, and to demonstrate the safety of bleaching technique.

IntroductionBleaching has been scientifi cally proven to be safe and very effective in altering the colour of teeth. Discoloured teeth are up to fi ve times more worrying to patients than crooked teeth. Diagnosis of the causes of

discolouration, assessment of patient’s expectations and full discussion with patients about theira vailable options are all important aspects of bleaching. Bleaching is now well established as one of the most important appearance enhancing aspects of modern evidence based clinical practice. Bleaching in combination with composite or porcelain bonding can produce results that are comparable with favourable and much more destructive and expansive traditional crown techniques. Unlike bleaching, many ofthe alternative more destructive techniques produce negative biological outcomes at considerably greater expense in terms of tooth tissue, time and money .

Bleaching leaves the patients with one of their most important assets, viz., good, clean looking, healthy, attractive enamel. Dentists have sought for years to produce natural looking replacements for the enamel. It is prudent to refl ect that “less is more” in dentistry. The change away from a destructive mechanical approach to a biological, minimally invasive one is to be welcomed. Bleaching in this context, sensibly applied according to scientifi cally validated principles, can reasonably be expected to produce good long term results. This confi dence is based on multiple randomized, double blind, controlled trials.

Tooth discolouration varies in aetiology, appearance, localization, severity and adherence to tooth structure. It may be classifi ed as intrinsic, extrinsic and a combination of both (Halab etal 1999). Intrinsic discolouration is caused by incorporation of chromatogenic material into dentin and enamel during dentogenesis after eruption. Exposure to high levels of fl uoride, tetracycline administration, inherited developmental disorders and trauma to the developing tooth may result in pre-eruptive discolouration. After eruption of tooth, ageing, pulpnecrosis and iatrogenesis are the main causes of intrinsic discolouration. Coffee, tea, orange, tobacco, etc., give rise to extrinsic stain.Scaling and polishing the teeth remove many extrinsic stains.

For more stubborn extrinsic discolouration and intrinsic stains various bleaching techniques may be attempted. Tooth bleaching can be performed externally termed “NIGHT GUARD” vital bleaching orvital tooth bleaching or intracoronally in root fi lled teeth called“Non vital tooth bleaching”.

The aim of the present article is to review critically the biological aspects of tooth bleaching including effi cacy and side effects of such treatments. In addition, the safety of tooth bleaching is especially addressed.

Bleaching Agents

Tooth bleaching is based on hydrogen peroxide as the active agent. Hydrogen peroxide may be applied directly or produced in a chemical reaction from sodiumperborate orcarbamide peroxide. Hydrogenperoxide actsasa strong oxidizing agent through the formation of free radicals, reactive oxygen molecules and hydrogen peroxide anions.These reactive molecules attack long chained dark coloured chromophore molecules and split them into smaller less coloured and more diffusible molecules. Carbamide peroxide also yields urea that theoretically can be further decomposed to carbon dioxide and ammonia. The high ph of ammonia facilitates the bleaching procedure. This can be explained by the fact that in a basic solution, lower activation energy is required for the formation

of free radicals from hydrogen peroxide and the reaction rate is higher,resulting in an improved yield compared with an acidic environment. The outcome bleaching procedure depends mainly on the concentration of the bleaching agent, the ability of the bleaching agent to reach the chromophoremolecules and the duration and number of times the agent is in contact with chromophore molecules.

Current research has demonstrated that the tooth is a semi-permeable membrane, and both hydrogen peroxide and urea (the ingredients of carbamide peroxide) can pass freely through intact enamel to the pulp in fi ve to fi fteen minutes. Other research has demonstrated that the passage through the tooth is rapid, with the dentin changing colour as fast at the pulpal interface as it does at the dento enamel junction. Hence bleaching material enter the tooth regardless of whether there are cracks present in the teeth, and will pass under existing restorations to bleach the entire tooth. When the teeth are being

.....Continued on pg.15

The IDA Times_June_2013.indd 13 5/27/2013 12:15:08 PM

15The IDA Times Mumbai June 2013

CMYK

CMYK

Heals inflamed and bleeding gumsPrevents Plaque formation

Effectively reduces tooth sensitivityNeutralizes acids that cause dental decay

Head Office Address:Peninsula Business Park, Tower “A”, 801, 8th Floor, Ganpatrao Kadam Marg, Lower Parel, Mumbai-400 013.Website: www.jlmorison.in / Contact us: Phone: 91-22-24975031/ 61410300/ Fax: 91-22-2495 0317

customercare@jlmorison.com/

UNDER LICENSE AND ®REGD. TRADE MARK OF

DR. WILD & CO. LTD., MUTTENZ, SWITZERLAND.

The Multi-action toothpaste from Dr. WILD & CO.LTD.,MUTTENZ, SWITZERLAND.

action toothpaste from action toothpaste from action toothpaste from . WILD & CO. WILD & CO. WILD & CO. WILD & CO.L.LTDTD.LTD.L.LTD.L ..,MUT,MUTTENZ, SWITZERLTENZ, SWITZERLTENZ, SWITZERLTENZ, SWITZERL,MUTTENZ, SWITZERL,MUT,MUTTENZ, SWITZERL,MUT ANDANDTENZ, SWITZERLANDTENZ, SWITZERLTENZ, SWITZERLANDTENZ, SWITZERL ..

DeNtal PraCtiCe

bleached, they will get lighter until they reach a “maximum lightness” for that tooth. After that, further treatment will not make the many lighter. Upon termination of bleaching, the tooth colour will relapse about one half shade as the optical qualities return to normal from the dissipation of the oxygen from the tooth that was present during bleaching. After this colour stabilization, which takes approximately two weeks, the teeth will remain colour stable for years.

Nightguard Vital Bleaching

NGVB involves making analginate impression of the patient’s teethand generating a stone cast. This cast is trimmed such that it has novestibule. A thin soft tray material is used along with a vacuum-formingmachine to fabricate a custom-fi tted tray for the patient. The patient applies a bleaching solution (inmost cases 10% carbamide peroxide) in the tray every night,and sleeps with the tray in place for a number of daysor weeks, depending on the discolouration.In comparison, in-offi ce bleaching (also known as chair side teeth whitening), which has existed for over100 years, involves the isolation of the teeth with a rubber dam or paint-on barrier, and application of 25–38% hydrogen peroxide for up to one hour per appointment. The hydrogen peroxide is activated by heat or light. Over-the-counter products also containhydrogen peroxide, in a strip or wrap, which is appliedfor 30 minutes, once ortwice a day.If safety, effi ciency and cost to the patient are considered for the three techniques, NGVB is the preferred method. This technique is supported by many safetyand effi cacy studies, as well as research on long-term stability, its effects on teeth, and ease of use by the patient. While in-offi ce has a long history of use, it is more expansive and generally requires an average of 3 application visits for maximum whiteness.

Tray DesignThere are a variety of tray designs, and the choice depends on the product used, the patients’ concerns or habits, their tooth alignment and their gingival status. Tray designs can be scalloped to follow the free gingival margin, and contain reservoirs or spacers to reduce the tightness of the fi t of the tray.

However, a non-scalloped, no-reservoir tray design is the most comfortable to the patient,

provides the best seal against the gingiva to retain the material, and uses the least material per application for the same result.Generally, reservoirs are not needed to bleach teeth, but their presence will reduce the tightness of the tray and may reduce sensitivity. However, more material is used per application, and more time is required to fabricate the tray. Scalloped trays are not as important now that the softer tray materials are available, and non-scalloped trays provide a better seal and are more comfortable, aswell as being easier to fabricate. However, higher concentrations of peroxide can cause gingival irritation.

A single tooth tray consists of a non-scalloped, noreservoir tray design with the tooth mould removed on either side of the tooth desired to be bleached. If a sticky bleaching material is used, a ‘temporomandibulardisorder’ or ‘TMD’ tray design will only cover the facial surfaces of the teeth and not involve the occlusal contacts of the mouth. Although there are many tray designs, this author prefers the non-scalloped tray with no reservoirs or spacers as fi rst tray of choice.

IndicationsIndications for bleaching include a variety of situations. Teeth can be stained from drinks and food stuff, or be discoloured from birth. NGVB is not only removing extrinsic stains that have become intrinsic, but is also changing the genetic colour of the tooth. Mild yellow and brown discolourations are most responsive, while darker colours take longer, and gingival discolouration is the most diffi cult to resolve. In most bleaching situations, the teeth look very natural after bleaching, with the incisal area normally lighter than the gingival. Canines which may be darker than the traditional half shade from the lateral incisor can be lightened to more closely match the incisor with tray bleaching. This ability to change the colour of the canine is a good indication that the bleaching is changing the genetic colour of the tooth, rather than merely removing stains. As patients age, the teeth become more yellow, both from secondary dentine and from staining. Bleaching will provide a younger appearance to the teeth for anyone over 45 years old.

Bleaching and BondingBleaching and bonding offers a very conservative approach tothe management of discoloured and mal-formed teeth as shown in fi gures 1 and 2. Often,

bleaching makes the teeth light enough that conservative composite restorations can hide the remaining discolouration or complete the tooth shape successfully (Figures 3 and 4). If more aggressive restorations are needed, the patients can now see the benefi ts to their smile from the initial treatment, and is more willing to continue with other treatments. Bleaching often allows the patient to visualize the additional treatment that is indicated but not readily apparent to the untrained eye. A combination of conservative treatments is most cost-effective and preserves the natural enamel of the tooth. All other options are still available should bleaching, aestheticre-contouring, and bonding not provide the desired aesthetic outcome.

Lights and Heating DevicesVarious devices have been developed for the purpose of providing heat and light which claim to accelerate the rate of bleaching. These include:

• Xenon halogen

• Led Light

• Diode lasers

• Plasma Are Lamps

• Composite photo activation unit

Chair Side BleachingThe bleaching gel which usually contains between 15 and 38% hydrogen peroxide is applied to all teeth to be bleached at the same time and left in position for about 15 minutes. The gel should be agitated. Light or heat can be used in an attempt to speed up the process but the benefi t of this is questionable. This gel is washed every 15 minutes, the teeth are dried and new bleaching material is applied.This procedure is repeated three to four times.

Figures 5, 6 and7 represent the chair side bleaching technique.

None of the chair side bleaching systems is more effective than night guard vital bleaching. The main justifi cation for the use of chair side bleaching is immediate results for the patients who are not prepared to tolerate or lack the patience to undertake night guard vital bleaching. It is generally advocated that most teeth are susceptible to bleaching provided that treatment is carried out for a suffi ciently long time. (Haywood 1996, Goldstein 1997, Heymen 1997, Dunn 1998, Leonard 1998). The fi rst subjective change in tooth colour was observed after 2-4 nights of tooth bleaching with 10% carbamide peroxide.To date, none of the systems utilizing “powerful”chair side lights for bleaching have been granted ADA approval, nightguard vital bleaching using 10% carbamideperoxide within a customized bleaching tray remains

the gold standard in dental bleaching. In closing, bleaching or whitening is best performed ina professionally supervised manner, with a proper examination and diagnosis, using appropriate materials for the patient and situation, with a fair fee for service. Ten percent carbamide peroxide in a custom-fi tted tray is generally the safest, most cost-effective whitening treatment available. Other bleaching treatments may be indicated based on patient preference, lifestyle, fi nances, or other limitations, but require informed consent after presenting cost / benefi t and risk / benefi t ratios.

References:1. ADA (1998) Acceptance

programmeguidelines: home use tooth whitening Products Council on Scientifi c Affairs.

2. Barghi. N (1998) Making Clinical decision for vital tooth bleaching : at home or in offi ce Compend cont. edu. Dent 19:831-38.

.....Continued from pg.13

The IDA Times_June_2013.indd 15 5/27/2013 12:15:18 PM

Copyright of IDA Times is the property of Indian Dental Association and its content may notbe copied or emailed to multiple sites or posted to a listserv without the copyright holder'sexpress written permission. However, users may print, download, or email articles forindividual use.