bleeching of discolored teeth

8/3/2019 Bleeching of Discolored Teeth

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BLEACHING OF

DISCOLORED TEETH


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Contents

Introduction

History

Causes of Tooth Discolouration

Bleaching Materials

Bleaching Techniques

Non-vital bleaching

Vital bleaching

Conclusion

References


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INTRODUCTION

Discoloration of anterior teeth is a cosmetic

problems that is often the patients primary

concern. Although restorative procedures

are available, discoloration can often becorrected totally or partially by a moreconservative approach i.e. bleaching, whichis relatively simple to perform and lessexpensive.


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BLEACHING

Defined : as the whitening of a tooth through theapplication of chemical agent to oxidise/reduce theorganic pigmentation in the tooth.

Advantage

Safe procedure

Painless to adults

No tooth reduction required No anesthesia necessary

Least expensive to treatment altenatives


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Disadvantage

Normal tooth colour may be restored

Bleaching can caused discomfort in childrenbecause of their large pulps.

Extended treatment time may be necessary.


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INDICATIONS

Discoloured teeth due to either extrinsic orintrinsic stains.


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Contra-indications to bleaching Patient selection

Patients with emotional or psychologic problem or those with unrealisticgoals do not make good candidates for bleaching.

Dentinal hypersensitivity

These symptoms may be associated with severe cases ofattrision,erosion,abrasion or abfraction .

Suspected or confirmed bulimia

Application of bleaching agent in such cases may result in acute pulpitis.Bulimia patients may require a comprehensive course of restorative

treatment involving veneers and crowns.


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Generalized dental caries and leaking restoration

Use of bleaching agents for such patients who fall in this category maylead to severe, generalized hypersensitivity

Heavily restored teeth

Teeth with visible,tooth colored restorations respond poorly tobleaching because the composite restorations do not lighten andbecome more evident after bleaching.

Teeth with opaque white spots

Teeth slated for bonded restorations or orthodontic bracketing.

Oxygen produced during bleaching remains in the enamel or dentinoxygen interferses with the bonding agent and induses bonding failure.


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HISTORY

A professional response to the unrelenting quest for white teeth

dates back at least 2000 years.

First century Roman physicians maintained that brushing teethwith urine, particularly Portuguese urine, whitened teeth.

In the 1300s, after abrading the enamel with coarse metal files,aquafortis, a nitric acid solution was applied to whiten the teeth.

Guy de Chauliac, in 14th century recommended a toothwhitening procedure in which teeth were gently cleaned with a

mixture of honey and burnt salt to which some vinegar wasadded, which was considered authoritative for nearly 300 years.


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The introduction of clinical procedure of vital tooth bleaching wasdone by Chapple in 1877, who used oxalic acid as the bleachingagent.

The first mention of peroxide as a bleaching agent was in 1884by Harlan, which he called hydrogen dioxide.

In 1888, Taft and Atkinson suggested calcium hypochlorite to be

an effective tooth whitening solution.

In 1916, Kane proposed the use of 18% HCl to the brown fluoridestain. Although not regarded as the bleaching agent, it is capableof removing the stains as it dissolves the surface of teeth.

In 1918, Abbot found that the bleaching action of hydrogenperoxide could be greatly enhanced by the addition of heat andlight.


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In 1937, Ames proposed the combination of 5parts of 100% H2O2 with 1part of etheractivated by heat as the treatment for the

stains caused by fluoride.

In 1939, Younger proposed the use of 30%

H2O2, ether and heat for the stains causedby fluoride.


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In 1966, the use of HCl combined with H2O2 was advocated byMcInnes for the stains caused by fluoride.

Non-vital bleaching was introduced by Garretson in 1895 whoapplied chloride to the tooth surface but could not achieve verygood results.

In 1958, Pearson reported the use of superoxol sealed within thepulp chamber. He found that within 3 days, the oxygen releasingcapacity of the solution had whitened the experimental teeth tosome extent.

In 1967, Nutting and Poe refined this method and termed aswalking bleach where they packed a mixture of 30% H2O2 and

sodium perborate in the pulp chamber for 1 week.


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In 1989, Haywood and Heymann introduced atechnique for bleaching vital teeth which they calledNight guard vital bleaching. In this technique, theuse of Carbamyl peroxide was introduced which wasplaced in a molded tray, which the patient placesover his teeth for hours at a time.

In 1992, Rembrandt introduced whitening toothpastes and enzyme based dentifrices.


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In 1994, Light activation of the bleaching agents wasintroduced which further led to activation ofbleaching agents by argon laser, CO2 laser andplasma arc.

In 1999, Diode laser was introduced as a vector intooth whitening.

From 1995 till date a variety of concentrations ofbleaching gels containing remineralising agents,fluoride and peroxide free chemicals have beenavailable.


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Etiology of Tooth Discolouration

The etiology of tooth discolouration may beextrinsic or intrinsic or both.

Extrinsic stains

Diet related

Bacterial strains

Medications

Habits


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Pipe smoking

Bacterial products

Mouth wash

Tobacco stains Mouth wash


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Intrinsic stains1. Pre-eruptiveAlkaptonuriaAmelogenesis imperfecta

FluorosisErythroblastosis foetalisPorphyriaTetracycline stainingJaundice

2. Post eruptiveAgePulpal necrosisIntrapulpal haemorrhageDentin hypercalcification

Iatrogenic discolorationRemnants of pulpal tissuesIntra canal medicamentsObturating materialsRestorations


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Enamel hypoplasia Trauma Mild fluorosis

Severe flourosis Tetracycline staining Mild tetracycline stains

Dentinogenesisimperfecta

Amelogenesis

imperfecta

Pulpal

heamorrhagicproduct


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Extrinsic Stains:

These are caused by the daily intake of substances

such as food and beverages or the use of tobaccoproducts.

These substances tend to adhere to the enamels

hydroxyapetite structure and here by discolour theteeth or reduce the whiteness of teeth.

Over a period they may penetrate the enamel layerand gradually give rise to intrinsic discolorations.


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Nathoos Classification(for extrinsic dental stain)

N1 type dental stain or direct dental stain: Colouredmaterial(chromogen) binds to the tooths surface and

causes discoloration. The color of chromogen is similar tothat of dental stain.

N2 type dental stain or direct dental stain: Coloredmaterial(chromogen) changes color after binding to thetooth.

N3 type dental stain or indirect dental stain: Colourlessmaterial or a pre-chromogen binds to the tooth and

undergoes a chemical reaction to cause a stain.


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CAUSES OF EXTRINSIC STAINS:

1. Diet:

These stains affects multiple teeth and appears as yellow or brown

stains of varying intensities. Consumption of strong tea or coffeeimmediately after orange or grape juice is a common cause ofexternal discoloration.

Black current juice or cola drinks act by both etching and stainingthe tooth simultaneously.

2. Bacterial Strains:

Chromophilic bacteria frequently seen in the deciduous or mixeddentition can cause a dotted or black-line stain.

It has been documented that this type of bacteria is associated withlower-than normal caries rates and the removal may result inrecolonization of the oral cavity by a more cariogenic flora.


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3. Medication:

Chlorhexidine acts in reducing plaque formation by disturbing thepellicle matrix formation, which attracts more extrinsic strains not

readily removed by tooth brushing.

4. Habits:

Smoking marijuana may produce characteristic linear, greencircumferential rings at the cervical margins.

Smoking tobacco causes a yellow-brown discolourationespecially on the lingual aspects of the teeth.

Chewing tobacco causes a black-brown stain that is most

noticeable on the buccal surfaces of the mandibular posteriorteeth.


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5) Gingival Hemorrhage

Chronic gingivitis may induce staining fromthe breakdown of blood in the gingival sulcus.


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Intrinsic Stains

These are stains which are incorprated within the

matrix of enamel and dentin and are caused by thedeposition or incorporation of substances within thesestructures. These stains may be caused during thedevelopmental stage i.e., pre-eruptively or after theeruption into the oral cavity.

1. Pre-eruptive discolorations:

Alkaptonuria:-Also known as phenylketonuria or ochronosis. It is arecessive genetic disorder resulting in dark brown

pigmentation of the permanent teeth.


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Amelogenesis imperfecta:- It affects both primary and permanentdentition and can be further subdivided into

Hypomaturtion: where the enamel is chipped off from theunderlying dentin

Hypo calcification: where the thickness of enamel is normalbut is soft in consistency and completely abrades soon after

eruption, which results in a tooth with crown that ranges inappearance from a dull opaque white to a dark brown. Inaddition, these teeth are usually rough and pitted.

Hypo plastic: where the enamel is quiet thin, smooth, hard

and yellow in appearance, with occasionally pitting.


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Dentinogenesis Imperfecta:

is a hereditary developmental disturbance of dentin that may be seen

alone or in conjuction with systemic disorder of bone (osteogenesisimperfecta).

This disorder is autosomal dominant .

WITKOP outlined three descriptive classification of this disorder

1.Dentinogenesis imferfecta2.Heriditary with opalescent dentine3.Brandy white isolate.

Usually affects the primary teeth more seriously than the permanent

dentition.

The clinical crowns appear reddish-brown to grey opalescent.


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FluorosisBlack and McKay first reported this condition in 1916.

The optimum concentration of fluoride in the drinking water forthe dental development is 1ppm.

When the intake approaches 2ppm, noticeable white spotsoccur in the enamel.

when it approaches 3ppm, patchy brown discolouration of theenamel occurs. Higher concentrations than this can result inpitting and anomalies in the enamel formation.

The high concentration of fluoride is believed to cause ametabolic alteration in the ameloblasts which results in adefective matrix and improper calcification.

The teeth can be affected by fluorosis from the second

trimester in utero through age 9.


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Erythroblastosis fetalis:- This is a blood disorder of theneonate which might discolour the teeth .This disease inthe fetus or new born results from Rh incompatibilitywhich leads to massive lysis of erythrocytes.

The discolouration ranges from brown to greenish-blue.This condition is usually self-treating and the stainingresolves as the child matures.

Porphyria:- is a metabolic disease.In this condition, the haematoporphyrin pigment createsa characteristic reddish-brown discolouration of the teethknown as Erythrodontia.

More commonly seen in the primary dentition than the

permanent dentition. The colouration is dispersed throughout the enamel,

dentin and cementum and fluoresces red underultraviolet light.


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Tetracycline staining

The tooth discolouration caused by incorporation of systemic

tetracycline was first reported in 1956 by Schwashman andSchuster. Since, it crosses the placental barrier it can affect boththe primary and permanent dentition.

Though the exact mechanism of staining is not fully understood, it

is believed that the tetracycline molecule binds to the calcium ofthe tooth forming tetracycline orthophosphate.

The clinical appearance of tetracycline-stained teeth ranges fromlight yellow to dark grey bands.

Usually the darker shades are confined to the gingival 1/3rd of theteeth and the lighter shades will often be located exclusively in theincisal 1/3rd.


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When the tetracycline stained teeth are exposed to sunlight, theygradually turn to shades of dark grey or brown.

Cohen and Parkins: suggest this as the reason why labialsurfaces of the incisors darken while the molars remain yellow for

a longer period of time.

Studies have shown that further exposure of such teeth tovarious light sources such as sunlight, incandescent or ultravioletlights produces a subsequent lightening of the tetracycline stain.

It has been postulated that tetracycline incorporated intohydroxyapetite, when oxidized by light produces the red quinoneproduct 4, 12 anhydro-4-oxo-4-dedimethylamino tetracycline(AODTC).


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Tetracycline is a bacteriostaticantimicrobial,which was commomly given for

treatment of

Chronic middle ear infection in children

Long term therapy for acne valgarius. Cystic fibrosis

Rocky mountain spotted fever.


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The severity of tooth discolouration depends on four factorsassociated with tetracycline administration.

Age at the time of administration: Anterior primary teeth aresusceptible to discolouration by systemic tetracycline from 4months in utero through 9 months post partum.

Anterior permanent teeth are susceptible from 3 months postpartum to 8 years.

Duration of administration: Severity is directly proportional tothe length of time the medication was administered.

Dosage: Severity is directly proportional to the administered

dosage.


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Type of Tetracycline:

Chlortetracycline (Aureomycin): Gray-brown

Dimethylchlortetracycline (Ledermycin): Yellowstain

Doxycycline (Vibramycin): Does not cause stain

Oxytetracycline (Terramycin): Yellow stain

Tetracycline (Achromycin): Yellow stain


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Jordan and Boksman has classified the tetracyclinestaining as follows

Primary staining: Light yellow or light grey, slightbut uniformly distributed without banding.

Secondary staining: Darker or more extensiveyellow or grey staining without banding.

Tertiary staining: Severe staining characterized bydark grey or blue discoloration, usually with banding.


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First degree tetracycline stains Second degree tetracycline stains

Third degree tetracycline stains


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Minocycline Staining:

It is found that Minocycline, a semisyntheticderivative of tetracycline .unlike tetracycline it ispoorly absorbed in gastroinstestinal track.

Minocycline, although combines poorly with calcium,has the ability to chelate with iron and form insolublecomplexes,forming a yellow grey discolouration .

Minocycline stains may be responsive to bleachingwhile others with severe banding may requireveneers.


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2. Post-eruptive discolorations:

a) Age

In older patients, colour changes in the crown occurphysiologically as a result of extensive secondary dentinformation, thinning and optical changes of the enamel.

Food and beverages also have a cumulative discolouring effectbecause of the inevitable crack, crazing and incisal wear of theenamel and underlying dentin.

In addition, amalgam and other coronal restorations thatdegrade over time cause further discoloration.


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2) Pulpal Necrosis:

Bacterial, mechanical or chemical irritation to thepulp may result in tissue necrosis. Tissue

disintegration by products are then released thatmay penetrate tubules and discolour the

surrounding dentin.

The degree of discolouration is directly related tohow long the pulp has been necrotic.

The longer the discolouration products are present inthe pulp chamber, the greater the discolouration.


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c) Intrapulpal haemorrhage:

It is the most common result of traumatic injury to a tooth, which

results in disrupted coronal blood vessels, haemorrhage andlysis of erythrocytes.

Blood disintegration products, presumably as iron sulfidespermeate dentinal tubules to stain the surrounding dentin, which

tends to increase with time.

If the pulp becomes necrotic, the discoloration usually remains.

If the pulp survives, the discolouration may resolve and the tooth

reverts to its original shade.

Sometimes, mainly in young individuals the tooth remainsdiscoloured even if the pulp responds to vitality.


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d) Dentin hypercalcifiation/calcific metamorphosis

It is the extensive formation of tertiary or irregular secondary

dentin in the pulp chamber or on canal walls, which may occurfollowing certain traumatic injuries which did not result in pulpalnecrosis.

In such cases, temporary disruption of blood supply occurs

followed by partial destruction of odontoblasts.

These are replaced by undifferentiated mesenchymal cells thatrapidly form irregular dentin on the walls of the pulp lumen.

As a result, the translucency of the crowns of such teethgradually decreases, giving rise to a yellowish or yellow-browndiscoloration.


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e) Iatrogenic Discolouration

Remnants of pulpal tissues:

Pulp fragments remaining in the crown,

usually in the pulp horns, may cause gradualdiscoloration.

The pulp horns must be opened up and

exposed during access to ensure removal ofpulpal remnants and to prevent retention ofsealer at a later stage.


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2. Intracanal medicaments

Several intracanal medicaments are liable to cause

internal staining of the dentin.

Phenolics or iodoform based medicaments sealed inthe root canal and chamber are in direct contact withdentin sometimes for longer periods, allowingpenetration and oxidization.

These compounds have a tendency to discolour thedentin gradually.

Idoform induced discolourations tend to be moresevere.


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3. Obturating materials:

It is a frequent and severe cause of single toothdiscolouration.

Incomplete removal of obturating materials and

sealer remnants in the pulp chamber, mainly thosecontaining metallic components, often results in darkdiscoloration.

Such discolouration can be prevented by removing allthe obturating material to a level just cervical to thegingival margins.


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4. Coronal Restorations:Amalgam

Silver alloys have severe effects on dentin becauseof the dark coloured metallic components that canturn the dentin dark grey.

When used to restore lingual access preparations ora developmental groove in anterior teeth as well asin premolars, amalgam may discolour the crown.

such discolorations are difficult to bleach and tend to

rediscolour with time. Replacing the amalgamrestoration with an esthetic restoration usuallycorrects the problem.


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b) Pins and Posts:

Metal pins and prefabricated posts are sometimesused to reinforce a composite restoration in theanterior teeth.

Discolorations from inappropriately placed pins andposts is caused by a metal seen through thecomposite or tooth structure.

In such cases, coverage of the pins with a whitecement or removal of the metal and replacement ofthe composite restoration is indicated.


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c) Composites:

Microleakage around composite restoration causesstaining.

Open margins may allow chemicals to enter between

the restoration and the tooth structure and discolourthe underling dentin.

In addition, composites may become discoloured

with time, affecting the shade of the crown, whichneeds to be replaced with a new well sealedrestoration.

Bl hi M t i l


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Bleaching Materials:

The most commonly used bleaching agents in dentistry are

Hydrogen peroxideSodium perborateCarbamide peroxide.

Hydrogen Peroxide:

It is a clear, colourless and odourless liquid.

Higher concentrations of these solutions must be handled with care as they arethermodynamically unstable and may explode unless refrigerated and kept in a darkcontainer.

Because of its ischemical effect on skin and mucous membrane it resembles a chemicalburn.

It is especially painful if it comes in contact with the nail bed or the soft tissue under the

finger nail.

It can be used for both intra and extra-coronal bleaching.

Ch i f bl hi


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Chemistry of bleaching:

Bleaching is a chemical process, which occurs mostly by theoxidation during which the organic materials are eventuallyconverted into carbondioxide and water.

The most commonly used bleaching agent is hydrogen peroxidewhich requires the least time for the desirable action.

In the bleaching process, the oxidizing agent i.e. the bleachingagent has free radicals with unpaired electrons which it gives upand becomes oxidized, whereas the reducing agent i.e., thesubstance being bleached accepts the electrons and becomesreduced.


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Hydrogen peroxide bleaching:

H2O2 has the ability to produce free radicals i.e.,

H2O (perhydroxyl-stronger free radical) and O.(nasant oxygen-weaker free radical).

In pure aqueous form, hydrogen peroxide

acid

reduced breakdown extended shelf life.

I i ti


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Ionization:-H2O2 H2O + O (Higher percentage of the weaker free radical)

H + HO2 (Lower percentage of stronger free radical)

The perhydroxyl is the more potent free radical in the bleachingprocess. In order to promote the formation of perhydroxyl, thehydrogen peroxide needs to be made alkaline.

Optimum pH 9.5 to 1.8 at which ionization takes place.

H2O2 H2O + O (Lower percentage of weaker free radical)

H + HO2 (Higher percentage of stronger free radical)


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This reaction results in greater bleaching efficacy inthe same time as at other pH levels. Thus, H2O2 ismost effective between pH of 9.5 10.8.

In the presence of decomposition catalysts andenzymes the H2O2 ionises as follows.

2H2O2 2H2O + O2

Where no free radicals are produced and thebleaching is ineffective. Some of these enzymesmay be present in the mouth.

Therefore, it is important to make the teeth free ofdebris and dry when applying the bleaching agent.


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Mode of Supply:

Hydrogen peroxide:-

Solution: Various concentrations of hydrogenperoxides are available, but 30% to 35% stabilizedsolutions are the most commonly used. They can beused either alone or mixed with sodium perborate.

Gel: Also available in the form of Silicon dioxide gelscontaining various concentrations of hydrogenperoxide (6 to 38%).

Recently introduced is the Opalescence xtra boostwhich contains 38% hydrogen peroxide for quickerresults and which does not even require lightactivation (Syringes).


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These gels are also available in preloaded disposable whiteningtray where the concentration of hydrogen peroxide is about 9%.

It is available as crest white from ultradent which consists of adelivery tray (outer tray with handle) and a disposable adaptivetray (inner tray without handle).

The inner tray consists of a gingival barrier gel on the border ofthe tray and 9% H2O2 gel inside the tray.

Both the trays are centered on the arch and lightly pressed intoplace, the outer tray is then removed and the inner tray is

adjusted. It is advised to wear 30 to 60 min/7-10 days.


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Teeth whitening strips:-

These are flexible pieces of plastic or polyethylenethat have been coated on one side with a thin film ofhydrogen peroxide gel.

The idea of the teeth whitening strips was to reducethe thickness of the peroxide gel.

The thickness of the bleaching gels on the whiteningstrips is about 0.2mm while that of a paper is0.1mm. It is to 1/5th quantity compared to the traybleaching.


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The concentration of the hydrogen peroxide gels on the whitening


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The concentration of the hydrogen peroxide gels on the whiteningstrips varies from 6% to 10%.

The teeth whitening strip kit consists of half the strips designed to

adapt the upper arch and half the lower arch.

It is advised to use these strips for 30 min twice a day. 6% gel stripsfor 14 days and 10% gel strips for 7 days.

Disadvantage:- The length of the strips is small so that they adaptonly to the anterior teeth.

Adverse effects:

Gingival irritation: As there is no barrier to restrict these gels.

Sensitivity

H d id i i


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Hydrogen peroxide toxicity

Cervical root resorption after internal (non vital) tooth bleaching.

Increased sensitivity after external(vital) tooth bleaching.

For resorption to occur ,there must be a combination of

Deficiency in the cementum(exposing the dentin)

Injury to the periodontal ligament

Infection(sustaining the inflammation).

HYDROGEN PEROXIDE TOOTH WHITENING


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HYDROGEN PEROXIDE TOOTH-WHITENING(BLEACHING)PRODUCT:REVIEW OF ADVERSEEFFECTS AND SAFETY . BDJ vol 2000 no 7 apr 2006

Hydrogen peroxide in the form of carbamide peroxide iswidely used for tooth whitening (bleaching),both inprofessionallyand in self administered product.

Cervical root resoption is a possible consequense ofinternal bleaching and is more frequently observed inteeth treated with the thermo-cataytic procedure.

Direct contact with H2O2 induces genotoxic effects .

Several carcinogenesis studies indicated H202 might actlike a promotor.

Eff f bl hi h f


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Effect of bleaching on the structure of

enamel

Surface alteration in enamel topographyfollow vital bleaching using hydrogenperoxide.

High concentration of hydrogen peroxide

damage enamel surface intergrity.

Eff f h bl hi h


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Effect of tooth bleaching on tooth

restoration

Bleaching with hydrogen peroxide increase thesolubility of glass ionomer and other cements andreduce the bond strength between enamel and resinbased filling in the first 24 hour.

Hydrogen peroxide residues in the enamel mayinhibit the polymerisation of resin based materialand reduce bond strength.

So ,hydrogen peroxide should not be used prior totreatment with resin based material

Sodium Perborate


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Sodium Perborate:

It is supplied in a granular form, that has to

be ground into a powder before using.

It is either mixed with water or hydrogen

peroxide to form a thick paste and is packedinto the pulp chamber.

When fresh ,it contains 95% perborate .

S di b i bl h d b i


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Sodium perborate is stable when dry,but inthe presence of acid,warm air,or water it

decompses to form sodiummetaborate,hydrogen peroxide and nascentoxygen.

Various forms of sodium perborate


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Various forms of sodium perborate

monohydrate

trihydrate

tetrahydrate

They differ in there oxygen content which

determines the bleaching efficacy.

Commonly used sodium perborate are alkaline and

there pH depends on the amount of hydrogenperoxide released and residual sodium metaborate.

Ch i f bl hi


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Chemistry of bleaching

Sodium perborate:-

Sodium perborate when mixed with water

decomposes to form sodium metaborate andhydrogen peroxide releasing O2.

When mixed with superoxol it decomposes to form

sodium metaborate and water releasing O2. Theoxidation is slow and is active over a long period oftime

Ad f di b


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Advantage of sodium perborate


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Carbamade peroxide:-Also known as urea peroxide, cabramyl peroxide, perhydrol urea,perhydelure, carbamide urea, urea H2O2 and H2O2 carbamide.It is a clear, colourless odourless liquid. When used as ableaching agent it breakdowns to hydrogen peroxide.

Previously used only for extracoroanl bleaching.Lee et al (2004), found that carbamide peroxide had very lowlevels of extraradicular diffusion of peroxide in the presence ofcemental defects. Therefore, it could be an alternative to theother intracoronal bleaching agents. 35% carbamide and 35%

H2O2 were more effective than Na perborate after 7 days.


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Bleaching preparations containing carbamideperoxide usually include glycerine orpropylene glycol, sodium stannate,

phosphoric or citric acid and flavour additives.Some preparations contain carbapol, a watersoluble polyacrylic acid polymer as athickening agent which prolongs the release

of active peroxide and improves shelf-life.


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Carbamide peroxide:The most common mode of supply is in the form of gels, whichare supplied in syringes. It is available in various concentrationsranging from 3 to 45%. However, popular commercialpreparation contain about 10% carbamide peroxide with a mean

pH of 5 to 6.5.Leonard et al. studied the use of different concentrations ofcarbamide peroxide for bleaching teeth and found that lowerconcentrations of carbamide peroxide take longer time to whitenteeth but eventually achieve the same result as higherconcentrations, which may cause increased sensitivity.


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Enzymes:-There are certain enzymes which are found to havea considerable bleaching efficiency on both extrinsicand intrinsic stains. These enzymes are obtainedeither from plants or microorganisms. Theseenzymes are effective either without peroxides orwith very little % of peroxides (0 to 1%).

Laccases act on the molecular oxygen and yieldhydrogen peroxide without any need for hydrogen

peroxide. They are obtained from fungi E.g.Mycelipthora thermophila. These enzymes are foundto be effective against intrinsic stains.


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Oxidases act on the molecular oxygen and yield hydrogenperoxide. E.g. L-amino acid oxidase Trichoderma harzianum,glucose-oxidase Aspergillus species, Xylitol oxidaseStreptomyces species. They are found to be effective againstextrinsic stains.

Peroxidase:- Act on hydrogen peroxide and yield water. Theseenzymes require very little % of hydrogen peroxide for theiraction. They are obtained from plants e.g. Horse radishperoxidase or from microorganisms. E.g. Haloperoxidase fromCurvularia species. They are found to be effective against bothextrinsic and intrinsic stains along with Laccases


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Enzymes:-

These enzymes either alone or in combinationwith peroxides are added to the mouth

washes or tooth pastes. Their concentrationranges from 0 to 20% with 0 to 1% ofperoxides if used.


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Sodium perborate:-

Sodium perborate when mixed with waterdecomposes to form sodium metaborate and

hydrogen peroxide releasing O2. Whenmixed with superoxol it decomposes to formsodium metaborate and water releasing O2.The oxidation is slow and is active over along period of time


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Carbamide peroxide chemistry:Carbamide peroxide used as bleaching agentbreaks down into H2O2. 10% carbamide

peroxide produces 3.6% H2O2.CH2 N2O H2O2

NH3 H2O2

CO2

Then, the ionization of H2O2 is the same.

BLEACHING TECHNIQUES:


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BLEACHING TECHNIQUES:

Before carrying out the bleaching process, it

is important to assess the type of stain.Certain extrinsic stains can be removed byregular intense mechanical brushing withcleaning agents containing abrasives or

surfactants.


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Basically bleaching techniques are:-

Non-vital

Walking bleach

Thermocatalytic

UV light photooxidation

Vital

In-office

Night guard

Over the counter


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1. Non-vital bleaching:These procedures are carried out for endodontically treatedteeth.

Indications:- Discolouration of pulp chamber

Dentin discolouration Discolourations not amenable to extracoronal bleachingContraindications:- Superficial enamel discolourations Defective enamel formation

Severe dentin loss Presence of caries Discoloured composites Extensive restorations

In any of the non-vital bleaching techniques, there are


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y g q ,certain steps which are common.

Radiographic assessment of the status of theperiapical tissues and the quality of endodonticobturation. If the obturation is inadequate, the toothshould be retreated prior to bleaching.

If there are any leaking or discoloured restorations,they have to be replaced.

Evaluate the tooth colour with a shade tab by takingphotographs at every appointment. Orabase or vaseline should be applied to the

gingival tissues, followed by isolation with rubberdam which should fit tightly at the cervical margin of

the tooth to prevent possible leakage of thebleaching agent onto the gingival tissues. Opal damcan also be used.


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Remove all restorative material from the accesscavity, expose the dentin and refine the access.Verify that the pulp horns and other areascontaining pulp tissue are clean.

Remove the obturation material to just below labialgingival margin. Orange solvent, chloroform orxylene on a cotton pellet may be used to dissolvesealer remnants.

Next is the application of the barrier material. Thisis one of the most important step as the improperlocation, material and the shape of the barriermaterial could lead to external cervical resorption.

Walking Bleach:


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Walking Bleach:

In this technique, a mixture of sodium perborate andinert liquid such as water, saline or anaesthetic

solution or even H2O2 can be used but preferablylower concentrations are placed in the pulp chamber.Studies have shown more number of external cervicalresorption cases with the combination of sodium

perborate and 30% hydrogen peroxide. Studies with different types of sodium perborae, water

and H2O2 have shown that the combination of sodiumtetraborate with water was quiet effective.

Timpavat et al. found the bond strength to be better withNaperborate + H2O. Excess liquid from sodiumperborate should be removed by tamping with a cotton

pellet.


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Excess bleaching paste from the undercuts inthe pulp horns should be removed and theaccess cavity should be sealed with a temporaryfilling (Preferably IRM) which should be at least

3mm. Rubber dam should e removed and the patient

should be informed that bleaching agents workslowly and significant lightening may not beevident for several days.

Patient should be evaluated after 2 weeks andthe procedure should be repeated if necessary.

Thermocatalytic:


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Thermocatalytic:

This technique involves placement of the oxidizingagent, generally 30% to 35% H2O2 in the pulpchamber followed by heat application either byelectric heating devices or specially designedphotoflood lamps for 5min. this process should becontinued until the desirable results are achieved.Should not be repeated for more than 5-6 times.Care should be taken that the temperature of theheating device does not exceed 114F. Lamp unitshould be 13 inches away from patient. Metal

clamps should not be used. Recall the patient in aweek to assess the colour after rehydration. Repeatthe procedure, if necessary.


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Photo-oxidation:

In this technique, 30% to 35% of H2O2 solution isplaced in the pulp chamber on a cotton pelletfollowed by exposure to the curing light for 20-30sec. For plasma arc or laser 3-5 seconds ofexposure time is sufficient. If the bleaching gels areused they have to be expressed into the accesscavity and onto the labial surface of the tooth and

should be exposed to the curing light from both thesides.


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Adverse effects: External cervical root resorption:- It is one of the most

commonly noticed complication with intracoronal bleachingusing hydrogen peroxide. It is asymptomatic and is

generally noticed during routine examination. The exactcause of this response is not fully understood, although anumber of mechanisms have been postulated.

In 10% of all teeth, the cemento-enamel junction is defectiveor absent, resulting in a portion of the tooth being devoid of

cementum coverage. 35% H2O2 may denature the dentin,involving a foreign body response by elements in the

approximating gingival tissue causing cervical resorption.


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Internally applied 35% H2O2 may directly contactperiodontal membrane may passing through patentdentinal tubules or lateral canals or accessory foramina.

Bleaching agents may infiltrate between the gutta-percha and root canal walls. They could then

communicate with the periodontal ligament throughdentinal tubules, lateral canals or apex which can causeresorption anywhere along the length of the canal.

Heat application while using high concentrations ofH2O2 may enhance external cervical root resorption.

35% H2O2 mixed with sodium perborate can lower thepH in the periodontal membrane, which may increasethe likelihood of cervical resorption.


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Chemical burns:- 35% H2O2 is caustic and may causechemical burns and sloughing of the gingiva. Therefore,when using such solutions the soft tissues should alwaysbe protected with Vaseline or orabase and rubber dam orwith opal dam.

Coronal fracture:- Increased brittleness of the coronaltooth structure, particularly when hat is applied, is alsothought to result from bleaching. This may be due to

dessication of the dentin and enamel. This was noticedclinically but has not yet proven conclusively.


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Suggestions for safer bleaching: Verification of adequate endodontic obturatiion This provides

an additional barrier against damage by oxidizers to theperiodontal ligament and periapical tissues.

Protect the oral mucosa by Vaseline or orabase.

Effective isolation by opaldam or rubber dam. Use ofinterproximal wedges and ligatures may provide a better seal.

Use of protective barriers In most of the clinical reports of thepost bleaching cervical root resorption protective barrier was notused. The barrier of adequate thickness should protect the

dentinal tubules and confirm to the external epithelial attachment.


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Acid etching should be avoided as it doesnot enhance the bleaching process, butcauses undesirable periodontal ligament

irritation. Avoid strong oxidizers.

Avoid heat.

Recall the patient periodically and examineclinically and radiographically.


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Post bleaching tooth restoration:Permanent restoration of the tooth is essential forlong-term successful bleaching. Coronalmicroleakage especially that of lingual accessrestoration and a leaking restoration may lead to

rediscolouration. Therefore, a composite restorationis advised as early as possible. This should beplanned 1 or 2 weeks after complete removal of thebleaching materials. This time period is for theelimination of residual peroxides.

The use of catalase for 3 min has been proposed forthe removal of residual peroxides where adequatebonding can be acquired.


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In case of thermocatalytic or photooxiationbleaching, it has been advised to packCa(OH)2 paste in the pulp chamber for a few

weeks prior to placement of final restorationto counteract acidity caused by bleachingagents and to prevent root resorption.


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Vital bleaching techniques:

There are various techniques for bleachingvital teeth depending on the degree of

staining. In-office or Power

Mouth guard or Night guard or At-home

Over-the counter

1. In-office:


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Indications:-

Light enamel discoloration

Mild tetracycline discoloration

Endemic fluorosis discoloration

Age related discoloration

Contraindications: Severe dark discolorations

Severe enamel loss

Proximity of pulp horns

Hypersensitive teeth Presence of caries

Large/ poor coronal restorations


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Techniques:-Familiarize the patient about causes of discoloration,

procedure to be followed and the treatmentoutcome.

Make radiographs to detect the presence of caries,defective restorations and proximity to pulp horns.

Evaluate tooth colour with shade tabs by takingphotographs at all the appointments.

Apply Vaseline or oraseal and then isolate with rubber

dam by using waxed dental floss or wedgets foradditional sealing. Avoid using metal clamps, asthey are subjected to heat.


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Do not inject a local anesthetic. Position protective sunglasses over the patients and operators

eyes.

Clean the enamel surface with pumice and water.

For the darkest or most severely stained areas acid etch with

35% phosphoric acid for 5 to 10 seconds and rinse with waterfor 60 seconds.

Place a small amount of 30 to 35% H2O2 solution into adappen dish. Apply the H2O2 liquid on the labial surface of theteeth using a small cotton pellet or a piece of gauze. Bleaching

gel can also be used instead of solution which can be bettercontrolled.


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Apply heat with a heating device or light source. Thetemperature should be controlled that the patient does not feelany discomfort, usually between 125F and 140F (52C to60C). Rewet the enamel surface with H2O2 as necessary. Ifthe tooth becomes too sensitive, discontinue the bleachingprocedure immediately. Do not exceed 30 min even ifsatisfactory results are not obtained.

Heating can be carried out by thermostatically controlledelectric heating device or a stainless steel instrument such asWoodson No.2 heated over flame. There are different lightsources available for photo-oxidation conventional bleaching

light. This supplies energy to enhance the bleaching action ofH2O2 by adding heat. The heat causes more vigorous releaseof oxygen and facilitates the dissolution of pigments. It is slowand often uncomfortable for the patient.


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Tungsten-Halogen curing light:

These curing light provides heat andstimulates the initiation of the chemical

reaction by activating the light sensitivechemicals in the bleaching agent. This is atime consuming process (i.e., 40 to 60 secper application per tooth).


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Argon laser:

It emits a visible blue light. The action it is tostimulate the catalyst in the chemical. There

is no thermal effect with this. It is easy to useand is best for removal of initial dark stains,such as those caused by tetracycline.However, it becomes less effective as theteeth whitens and when there are fewer stainmolecules.


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Carbon dioxide laser:

It emits invisible infra red light. They interactsdirectly with the catalyst-peroxide

combination. It removes the stains regardlessof the tooth colour. It emits heat and canenhance the bleaching effect initiated by theargon laser.


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Xenon plasma arc light:-

It is a non-laser, high intensity light whichproduces a great deal of heat; therefore, it

can be applied only for a brief 3 sec period.The action is thermal and stimulates thecatalyst in the chemical. Although it is veryfast, there is a greater potential for thermaltrauma to the pulp and surrounding softtissues than with other light sources.


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Diode laser light:- It is a true laser light produced from solid-state source. It is

ultra fast taking 3 to 5 sec to activate the bleaching agent. Thisdoes not produce heat.

Remove the heat source and allow the teeth to cool down for

at least 5 min. Then wash with warm water for 1 minute and thenremove the rubber dam. Do not rinse with cold water since thesudden change in temperature may damage the pulp or can bepainful to the patient.

Dry the teeth and gently polish them with a composite resinpolishing cup.

Treat all the etched and bleached surfaces with 1.1% neutralsodium fluoride gel for 3 to 5 min.


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Inform the patient that cold sensitivity iscommon, especially during the first 24 hrsand advise to use a fluoride rinse daily for 2

weeks. Recall the patient after 2 weeks and

evaluate the effectiveness of bleaching bysing the same shade tab used pre-operativeassessment. Repeat the procedure ifnecessary.


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Adverse effects:-1. Post operative pain:

A common immediate postoperative problem ispulpalgia characterized by intermittent shootingpain. It may occur during and after the bleachingsession and usually persists for between 24 and 48hrs. The intensity of pulpalgia is related to theduration and temperature of the bleachingprocedure. Therefore, shorter bleaching periods arerecommended. If long term sensitivity to colddevelops, topical fluoride treatments anddesensitizing tooth pastes should be used toalleviate these systems.


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. Pulpal damage:-Extra coronal bleaching with hydrogen peroxide andheat has been associated with some pulpaldamage. Although no significant irreversible effects

on the pulp have been found, these procedureshould be carried out with caution and not in thepresence of caries, areas of exposed dentin or inclose proximity to pulp horns. Defective restorations

must be replaced prior to bleaching.


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Dental hard tissue damage:

Hydrogen peroxide causes morphologic andstructural changes in enamel, dentin and

cementum and reduces the micro-hardnessof these structures. These changes maycause dental hard tissues to be moresusceptible to degradation and to secondarycaries formation. Therefore, teeth should bewell polished after the bleaching procedure.

Mucosal damage:


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Ulceration and sloughing of the mucosa may becaused when the highly concentrated peroxide

substances come in contact with the mucosa.Generally, the mucosa appears white but does not

become necrotic or leave scar tissue. Theassociated burning sensation is extremely

uncomfortable for the patient and can be treated byextensive water rinses until the whiteness isreduced. In more severe cases, a topical anesthetic,limited movements and good oral hygiene aid

healing. Application of protective cream or catalasecan prevent mot of these complications. Vitamin Eoil can also be applied immediately after contact.

Night guard vital bleaching:Indications:-


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Indications:- Superficial enamel discolorations

Mild yellow discolorations Brown fluorosis discolorations Age-related discolorationsContraindications:-

Severe enamel loss Hypersensitive teeth Presence of caries Defective coronal restorations

Allergy to bleaching gels Bruxism Pregnant and lactating 8. Smoking

Technique:-This technique has been widely advocated as a


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This technique has been widely advocated as ahome bleaching technique with a wide variety ofmaterials. Numerous products are available, mostlycontaining 1.5 to 10% hydrogen peroxide or 10 to15% carbamide peroxide, that degrade slowly torelease hydrogen peroxide. Carbamide peroxideproducts are the more commonly used at homebleaching agents.

Familiarize the patient with the probable causes ofdiscolouration, procedure to be followed and theexpected outcome.

Carry out thorough oral prophylaxis

Assess the colour of the teeth with a shade tab bytaking photographs at all the appointments.


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Make alginate impressions of both the arches. Castthe impression by taking care not to incorporatevoids or drags in the impression. Applyapproximately 0.5mm thickness of block out materialto the desired labial surfaces to provide reservoirspaces in the tray. It should be 1 to 15mm short ofthe gingival margin and should not extend onto theincisal edges and occlusal surfaces. Extending theblock-out material onto the incisal edges or occlusal

surfaces can cause the margins of the tray to openupon occluding or the tray to impinge on the softtissues.

1. Cure the block-out material on each tooth for 20 to40 seconds Now heat the tray material on the


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40 seconds. Now heat the tray material on thevacuum former unit until it sags approximately 2 inches, then adapt it to the cast and allow it tocool. It is then trimmed with a scalpel or elasticknife approximately 0.25 to 0.3mm occlusally fromthe gingival margin facially and lingually in ascalloped manner. The tray is then placed on thecast and the extensions are checked. Now gentlyflame polish the edges one quadrant at a time witha torch. While still warm, hold the periphery ofeach segment firmly against the model for 3 secwith a water-moistened finger. Otherwise, aftertrimming the tray with scalpel a rubber wheel in a

micromotor can be used to smoothen the roughedges.

Insert the mouth guard to ensure proper fit.Remove and apply the bleaching agent in the


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pp y g gspace of each tooth to be bleached. Reinsert themouth guard over the teeth and remove excess

bleaching agent. Familiarize the patient with the use of bleaching

agent and wearing the mouth guard. Theprocedure is usually performed 3 to 4 hrs a dayand the bleaching agent is replenished every 30 to

60 min. Some clinicians recommend wearing theguard during sleep for better long-term estheticresults. The duration of wearing the mouth guardand replenishing the bleaching agent depends onthe severity of staining, concentration of the

bleaching agent and the manufacturersinstructions.

Instruct the patient to brush and rinse their teethft l Th d h ld t b ti


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after meals. The guard should not be worn eating.

Inform the patient about thermal sensitivity and

minor irritation of soft tissues and to discontinueuse of the guard if uncomfortable.

Treatment may be carried out for 4 to 24 weeks.Recall the patient every 2 weeks to monitor stain

lightening. Check for tissue irritation, oral lesions,enamel etching and leaky restorations. Ifcomplications occur, stop the treatment and re-evaluate the feasibility of continuation at a later

date. Rediscoloration with this technique is notmore frequent than the other technique.

Adverse effects:


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Systemic effects: Controlled mouth guard bleachingis considered relatively safe. However, accidentalingestion of large amounts of these gels may betoxic and cause irritation to the gastric and respiratormucosa. Bleaching gels containing carbopol areusually more toxic. Therefore, it is advisable to pay

specific attention to any adverse systemic effectsand to discontinue treatment immediately if theyoccur.

Dental hard tissue damage:- In vitro studies indicate

morphologic and chemical changes in enamel,dentin and cementum associated with some agentsused for mouth guard bleaching.

Tooth sensitivity: Transient tooth sensitivity to coldmay occur during or after mouth guard bleaching


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may occur during or after mouth guard bleaching.In most cases, it is mild and ceases on terminationof treatment. Treatment for sensitivity consist of

discontinue the use of mouth guard for few days orthe reduction of wearing or the use of desensitizingagents.

Mucosal damage:- Minor irritations or ulcerationsof the oral mucosa have been reported to occurduring the initial course of treatment. Possiblecauses are mechanical interference by the mouthguard, chemical irritation by the bleaching agentand allergic reactions to gel components. In mostcases, readjustment and smoothing the borders ofthe guard will suffice. However, if tissue irritationpersists, treatment should be discontinued.

Damage to restorations: Some in vitrodi h d f bl hi


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studies suggest that damage of bleachinggels to composite resins may be caused bysoftening and cracking of the resin matrix.However, there are few other studies whichdid not find any significant adverse effects

on either surface texture or colour ofrestorations. Generally, if compositerestorations are present in estheticallycritical areas, they may need replacement toimprove colour matching followingsuccessful bleaching.


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It has also been reported that both 10%carbamide peroxide and 10% hydrogenperoxide may enhance the liberation ofmercury and silver from amalgam

restorations and may increase exposure ofpatients to toxic byproducts. Coverage of theamalgam restorations with a protective layerof dental varnish prior to the bleaching gel

application may prevent such hazards.Unpolished restorations corrode more.


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Occlusal disturbances:- Typcially, occlusalproblems related to the mouth guard may bemechanical or physiologic. From a mechanicalpoint of view, the patient may occlude only on theposterior teeth rather than on all teethsimultaneously. Removing posterior teeth from theguard until all of the teeth are in contact rectifiesthe problem. From a physiologic point of view, ifthe patient experiences TMJ pain, the posterior

teeth can be removed from the guard until only theanterior guidance remains. In such cases, wearingtime should be reduced.


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Studies have found that At-home bleaching for 2weeks is more effective than in-office bleaching 3times at 3 different appointments.

Leonard et al. studied the desensitizing agent

efficacy during whitening in an at-risk population andsuggests that the use of an active 3% KNO3 and0.11% F desensitizing agent for 30 min prior towhitening may decrease tooth sensitivity when

compared with placebo in a population at risk fortooth sensitivity.


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Gamze (2003) had suggested that 10 gm ofCarbamide peroxide/ day can be consideredas a safe dose for the prevention of systemic

effects in a person / day can be consideredas a safe dose for the prevention of systemiceffects in a person of 70 kg wt.


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Alternative Techniques: 1. Acid-pumice technique:-

In this technique, 18% HCl is mixed with fine flour ofpumice to make a thick paste.

This paste is applied to the enamel surface with a piece ofwooden tongue blade or crushed orange wood stick.Exerting firm pressure, the paste is worked into the enamelsurface with a swirling motion for 5 seconds. The enamelsurface is then rinsed for 10 seconds with water.

The paste is re-applied until the desired lightening isachieved.


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The thick paste of sodium bicarbonate and waterare applied to neutralize the surface.

Polish with a fine fluoride prophylaxis paste andsuperfine aluminium oxide composite resin

polishing discs.

Apply 1.1% neutral sodium fluoride gel for 4 min.

This technique can be used in combination

with the night guard bleaching using lowerconcentration bleaching agents.


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2. McInnes technique:- This technique uses a combination of 5

parts of 30% H2O2, 5 parts of 36% HCl and 1part of diethyl ether. The solution is applieddirectly to the stained areas for 1 to 2 minuteswith cotton applicators. While the surface iswet, a fine cuttle disc is run over the stainedsurfaces for 15 seconds. This process isrepeated until the desirable results areachieved, during subsequent appointments.


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Macro abrasion: This technique can be combined with

night guard vital bleaching to achieve better

results. In this technique the severely darkstains are removed with diamond points,followed by finishing with carbide burs andpolishing by using the composite polishing

disc. Further lightening is achieved by nightguard bleaching.


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Over-the-counter:Many home bleaching products are available over the counter orthrough mail order, radio and television advertisements. Thisapproach is not recommended as overuse and abuse are aconcern.

These systems include

Tooth pastes AP-24, Rembrandt Mouth rinses Crest Tooth brushes Spine brush pro whitening Dental floss Super smile Teeth whitening strips Crest

Chewing gums Brits smile, Happy dent Pain on varnish Vivastyle Brite smile stick or pen


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Tooth brushes:Certain powered tooth brushes are available which are said toremove the extrinsic stains mechanically. E.g. Spin brush pro-whitening.

Paint on varnish:-

Applied with a brush. On application it contains 6% carbamideperoxide. Once, it is dried the concentration increases.

Insoluble in saliva and remains on teeth for 20 min. subsequentlyremoved with a tooth brush.

Advantages:-

Can be applied exactly wherever it is needed.Contains D-panthenol Provitamin

Noticeable after 7 days

Chewing gums:

B it il H d t


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Brite smile, Happy dent

Supersmile whitening floss: It is the worlds first floss treated with Calprox

(not waxed) to safely whiten between teethand baking soda for fresher breath. Removesstubborn stains and odour causing plaqueunder the gum.

Calprox is a clinically proven whitening agent

which gently dissolves the protein pellicle,removing stains and plaque in the process.

Boil and Bite:-


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Boil a pot of water and then submerge the

mouthpiece into it for 5 to 15 sec. Mouthpiecebegin to wilt.

Place the mouthpiece into the mouth andpress against the front of your teeth with your

fingers an the back of your teeth with yourtongue. Let it cool.

Remove the mouthpiece from the mouth andcut the handle.

Squeeze whitening gel and place it for 1-3hrs.


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Tooth pastes:- They contain enzymes that are thought to

help to break down the organic protein

components of the stains. E.g.Rembrandt whitening contaisn citroxain,

derived from papaya

Janina ultrawhite opal contains Bromelain,which is derived from Pineapple.


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Tooth brush:- It is clinically proven that it whitens the teeth

in 14 days. Removes up to 88% of surface

stains tobacco, wine, tea and coffee after14 days of use.

Increased bristle density, concave polishingstrips and new cup shaped pattern designedto enhance the retention of dentifrice at thebrush-tooth surface interface.


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bleeching of discolored teeth

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