06 Bleaching of Discoloured Teeth / orthodontic courses by Indian dental academy

BLEACHING OF DISCOLORED TEETH

Contents

Introduction

History

Causes of Tooth Discolouration

Bleaching Materials

Mode of Supply

Chemistry of Bleaching

Bleaching Techniques

o Non-vital bleaching

o Vital bleaching

Conclusion

References

BLEACHING OF DISCOLORED TEETH

INTRODUCTION:

Discoloration of anterior teeth is a cosmetic problems that is often the

patient’s primary concern. Although restorative procedures are available,

discoloration can often be corrected totally or partially by a more conservative

approach i.e. bleaching, which is relatively simple to perform and less expensive.

HISTORY:

A professional response to the unrelenting quest for white teeth dates back

at least 2000 years.

First century Roman physicians maintained that brushing teeth with urine,

particularly Portuguese urine, whitened teeth.

In the 1300’s, 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 tooth whitening procedure

in which teeth were gently cleaned with a mixture of honey and burnt salt to which

some vinegar was added, which was considered authoritative for nearly 300 years.

The introduction of clinical procedure of vital tooth bleaching was done by

Chapple in 1877, who used oxalic acid as the bleaching agent.

The first mention of peroxide as a bleaching agent was in 1884 by Harlan,

which he called hydrogen dioxide.

1

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 fluoride stain.

Although not regarded as the bleaching agent, it is capable of removing the stains

as it dissolves the surface of teeth.

In 1918, Abbot found that the bleaching action of hydrogen peroxide could

be greatly enhanced by the addition of heat and light.

In 1937, Ames proposed the combination of 5 parts of 100% H2O2 with

1part of ether activated 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 caused by fluoride

In 1966, the use of HCl combined with H2O2 was advocated by McInnes for

the stains caused by fluoride.

Non-vital bleaching was introduced by Garretson in 1895 who applied

chloride to the tooth surface but could not achieve very good results.

In 1958, Pearson reported the use of superoxol sealed within the pulp

chamber. He found that within 3 days, the oxygen releasing capacity of the

solution had whitened the experimental teeth to some extent.

In 1967, Nutting and Poe refined this method and termed as “walking

bleach” where they packed a mixture of 30% H2O2 and sodium perborate in the

pulp chamber for 1 week.

In 1989, Haywood and Heymann introduced a technique for bleaching vital

teeth which they called Night guard vital bleaching. In this technique, the use of

2

Carbamyl peroxide was introduced which was placed in a molded tray, which the

patient places over his teeth for hours at a time.

In 1992, Rembrandt introduced whitening tooth pastes and enzyme based

dentifrices.

In 1994, Light activation of the bleaching agents was introduced which

further led to activation of bleaching agents by argon laser, CO2 laser and plasma

arc.

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

From 1995 till date a variety of concentrations of bleaching gels containing

remineralising agents, fluoride and peroxide free chemicals have been available.

Etiology of Tooth Discolouration:

The etiology of tooth discolouration may be extrinsic or intrinsic or both.

Extrinsic stains Intrinsic stains

1. Diet related

2. Bacterial strains

3. Medications

4. Habits

1. Pre-eruptive

a) Alkaptonuria

b) Amelogenesis imperfecta

c) Fluorosis

d) Erythroblastosis foetalis

e) Porphyria

f) Tetracycline staining

g) Jaundice

2. Post eruptive

a) Age

b) Pulpal necrosis

c) Intrapulpal haemorrhage

d) Dentin hypercalcification

e) Iatrogenic discoloration

3

- Remnants of pulpal tissues

- Intra canal medicaments

- Obturating materials

- Restorations

1. Amalgam

2. Pins and posts

3. composites

Extrinsic Stains:

These are caused by the daily intake of substances such as food and

beverages or the use of tobacco products. These substances tend to adhere to the

enamel’s hydroxyapetite structure and here by discolor the teeth or reduce the

whiteness of teeth. Over a period they may penetrate the enamel layer and

gradually give rise to intrinsic discolorations.

Nathoo’s Classification:

1. N1 type dental stain or direct dental stain: Coloured material binds to the

tooth’s surface and causes discoloration. The color of chromogen is similar to

that of dental stain.

2. N2 type dental stain or direct dental stain: Colored material changes color after

binding to the tooth.

3. N3 type dental stain or indirect dental stain: Colourless material or a pre-

chromogen binds to the tooth and undergoes a chemical reaction to cause a

stain.

4

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 coffee immediately after orange

or grape juice is a common cause of external discoloration.

Black current juice or cola drinks act by both etching and staining the tooth

simultaneously.

2. Bacterial Strains:

Chromophilic bacteria frequently seen in the deciduous or mixed dentition

can cause a dotted or black-line stain. It has been documented that this type of

bacteria is associated with lower-than normal caries rates and the removal may

result in recolonization of the oral cavity by a more cariogenic flora.

3. Medication:

Chlorhexidine acts in reducing plaque formation by disturbing the pellicle

matrix formation, which attracts more extrinsic strains not readily removed by

tooth brushing.

4. Habits:

Smoking marijuana may produce characteristic linear, green

circumferential rings at the cervical margins. Smoking tobacco causes a yellow-

brown discolouration especially 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 posterior teeth.

5

Intrinsic Stains:

These are stains within the matrix of enamel and dentin caused by the

deposition or incorporation of substances within these structures. These stains may

be caused during the developmental stage i.e., pre-eruptively or after the eruption

into the oral cavity.

1. Pre-eruptive discolorations:

a. Alkaptonuria:- Also known as phenylketonuria or ochronosis. It is a recessive

genetic disorder resulting in dark brown pigmentation of the permanent teeth.

b. Amelogenesis imperfecta:- It affects both primary and permanent dentition and

can be further subdivided into hypomaturtion, where the enamel is chipped off

from the underlying dentin. Hypocalcification; where the thickness of enamel

is normal but is soft in consistency and completely abrades soon after eruption,

which results in a tooth with crown that ranges in appearance from a dull

opaque white to a dark brown. In addition, these teeth are usually rough and

pitted. Hypoplastic, where the enamel is quiet thin, smooth, hard and yellow in

appearance, with occasionally pitting.

c. Dentinogenesis imperfecta:- Usually affects the primary teeth more seriously

than the permanent dentition. The clinical crowns appear reddish-brown to

gray opalescent. Often the enamel is friable and breaks off soon after eruption.

The exposed softened dentin then rapidly abrades away.

d. Fluorosis:- Black and McKay first reported this condition in 1916. The

optimum concentration of fluoride in the drinking water for the dental

development is 1ppm. When the intake approaches 2ppm, noticeable white

spots occur in the enamel, when it approaches 3ppm, patchy brown

6

discolouration of the enamel occurs. Higher concentrations than this can result

in pitting and anomalies in the enamel formation. The high concentration of

fluoride is believed to cause a metabolic alteration in the ameloblasts which

results in a defective matrix and improper calcification. The teeth can be

affected by fluorosis from the second trimester in utero through age 9.

e. Erythroblastosis fetalis:- This is a blood disorder of the neonate which might

discolor the teeth from brown to greenish-blue. This condition is usually self-

treating and the staining resolves as the child matures.

f. Porphyria:- In this condition, the haematoporphyrin pigment creates a

characteristic reddish-brown discolouration of the teeth known as

Erythrodontia. More commonly seen in the primary dentition than the

permanent dentition. The colouration is dispersed throughout the enamel,

dentin and cemetnum and fluoresces red under ultraviolet light.

g. Tetracycline staining:

The tooth discolouration caused by incorporation of systemic tetracycline

was first reported in 1956 by Schwashman and Schuster. Since, it crosses the

placental barrier can affect both the 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 of the tooth forming

tetracycline orthophosphate.

The clinical appearance of tetracycline-stained teeth ranges from light

yellow to dark grey bands. Usually the darker shades are confined to the gingival

1/3rd of the teeth and the lighter shades will often be located exclusively in the

incisal 1/3rd.

7

When the tetracycline stained teeth are exposed to sunlight, they gradually

turn to shades of dark grey or brown. Cohen and Parkin’s suggest this as the

reason why labial surfaces of the incisors darken while the molars remain yellow

for a longer period of time. Studies have shown that further exposure of such teeth

to various light sources such as sunlight, incandescent or ultraviolet lights

produces a subsequent lightening of the tetracycline stain. It has been postulated

that tetracycline incorporated into hydroxyapetite, when oxidized by light

produces the red quinone product 4, 12 anhydro-4-oxo-4-dedimethylamino

tetracycline (AODTC). Continued photooxidation of AODTC photolyses or

bleaches the red quinone. Addition of diluted H2O2 yields an irreversible bleaching

of the red quinone.

The severity of tooth discolouration depends on four factors associated with

tetracycline administration.

1. Age at the time of administration: Anterior primary teeth are susceptible to

discolouration by systemic tetracycline from 4 months in utero through 9

months post partum. Anterior permanent teeth are susceptible from 3

months post partum to 8 years.

2. Duration of administration: Severity is directly proportional to the length of

time the medication was administered.

3. Dosage: Severity is directly proportional to the administered dosage.

4. Type of Tetracycline:

a. Chlortetracycline (Aureomycin): Gray-brown

b. Dimethylchlortetracycline (Ledermycin): Yellow stain

c. Doxycycline (Vibramycin): Does not cause stain

8

d. Oxytetracycline (Terramycin): Yellow stain

e. Tetracycline (Achromycin): Yellow stain

Jordan and Boksman has classified the tetracycline staining as follows:-

a) Primary staining: Light yellow or light grey, slight but uniformly

distributed without banding.

b) Secondary staining: Darker or more extensive yellow or grey staining

without banding.

c) Tertiary staining: Severe staining characterized by dark grey or blue

discoloration, usually with banding.

Minocycline Staining:

It is found that Minocycline, a semisynthetic derivative of tetracycline

stains the teeth of adolescents who were being given the drugs for severe acne.

Minocycline, although combines poorly with calcium, has the ability to chelate

with iron and form insoluble complexes.

Some minocycline stains may be responsive to bleaching while others with

severe banding may require veneers.

b) Jaundice:

Bluish green or brown staining of primary teeth is seen in children who

suffered severe jaundice during infancy. These stains are the result of postnatal

staining of the dentin by bilirubin or biliverdin.

9

2. Post-eruptive discolorations:

a) Age:

In older patients, colour changes in the crown occur physiologically as a

result of extensive secondary dentin formation, thinning and optical changes of the

enamel. Food and beverages also have a cumulative discolouring effect because of

the inevitable crack, crazing and incisal wear of the enamel and underlying dentin.

In addition, amalgam and other coronal restorations that degrade over time cause

further discoloration. Bleaching would be more effective in older patients with

smaller pulps and generally tend to be less sensitive.

b) Pulpal Necrosis:

Bacterial, mechanical or chemical irritation to the pulp may result in tissue

necrosis and release of disintegration by products that may penetrate tubules and

discolour the surrounding dentin. The degree of discolouration is directly related

to how long the pulp has been necrotic. The longer the discolouration products are

present in the pulp chamber, the greater the discolouration.

c) Intrapulpal haemorrhage:

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

disrupted coronal blood vessels, haemorrhage and lysis of erythrocytes. Blood

disintegration products, presumably as iron sulfides permeate 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.

10

Sometimes, mainly in young individuals the tooth remains discoloured even if the

pulp responds to vitality.

d) Dentin hypercalcifiation:

It is the extensive formation of tertiary or irregular secondary dentin in the

pulp chamber or on canal walls, which may occur following certain traumatic

injuries which did not result in pulpal necrosis. In such cases, temporary disruption

of blood supply occurs followed by partial destruction of odontoblasts. These are

replaced by undifferentiated mesenchymal cells that rapidly form irregular dentin

on the walls of the pulp lumen. As a result, the translucency of the crowns of such

teeth gradually decreases, giving rise to a yellowish or yellow-brown

discoloration.

e) Iatrogenic Discolourations:

1. Remnants of pulpal tissues:-

Pulp fragments remaining in the crown, usually in the pulp horns, may

cause gradual discoloration. Therefore, the pulp horns must be opened up and

exposed during access to ensure removal of pulpal remnants and to prevent

retention of sealer at a later stage.

2. Intracanal medicaments:-

Several intracanal medicaments are liable to cause internal staining of the

dentin. Phenolics or iodoform based medicaments sealed in the root canal and

chamber are in direct contact with dentin sometimes for longer periods, allowing

penetration and oxidization. These compounds have a tendency to discolour the

dentin gradually.

11

3. Obturating materials:

It is a frequent and severe cause of single tooth discolouration. Incomplete

removal of obturating materials and sealer remnants in the pulp chamber, mainly

those containing metallic components, often results in dark discoloration.

4. Restorations:

a) Amalgam:-

Silver alloys have severe effects on dentin because of the dark coloured

metallic components that can turn the dentin dark grey. When used to restore

lingual access preparations or a developmental groove in anterior teeth as well as

in premolars, amalgam may discolour the crown, such discolorations are difficult

to bleach and tend to rediscolour with time. Replacing the amalgam restoration

with an esthetic restoration usually corrects the problem.

b) Pins and Posts:

Metal pins and prefabricated posts are sometimes used to reinforce a

composite restoration in the anterior teeth. Discolorations from inappropriately

placed pins and posts is caused by a metal seen through the composite or tooth

structure. in such cases, coverage of the pins with a white cement or removal of

the metal and replacement of the composite restoration is indicated.

c) Composites:

Microleakage around composite restoration causes staining. Open margins

may allow chemicals to enter between the restoration and the tooth structure and

discolour the underling dentin. In addition, composites may become discoloured

12

with time, affecting the shade of the crown, which needs to be replaced with a new

well sealed restoration.

Bleaching Materials:

The most commonly used bleaching agents in dentistry are hydrogen

peroxide, sodium perborate and carbamide peroxide.

Hydrogen Peroxide:

It is a clear, colourless and odourless liquid. Higher concentrations of these

solutions must be handled with care as they are thermodynamically unstable and

may explode unless refrigerated and kept in a dark container. Because of its

ischemic effect on skin and mucous membrane it resembles a chemical burn. 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.

Sodium perborate:

It is a stable white powder. When fresh, it contains about 95% perborate

corresponding to 9.9% of the available oxygen. It is stable when dry and

decomposes in the presence of acid, warm air or water.

3 types of sodium perborate preparations are available, Monohydrate,

trihydrate and tetrahydrate. They differ in oxygen content, which determines their

efficacy. Commonly used preparations are alkaline, their pH depends on the

amount of hydrogen peroxide released and the residual metaborate. It is used for

intracoronal bleaching, more easily controlled and safer than concentrated

hydrogen peroxide solutions.

13

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 a bleaching agent it breakdowns to

hydrogen peroxide.

Previously used only for extracoroanl bleaching.

Lee et al (2004), found that carbamide peroxide had very low levels of

extraradicular diffusion of peroxide in the presence of cemental defects. Therefore,

it could be an alternative to the other intracoronal bleaching agents. 35%

carbamide and 35% H2O2 were more effective than Na perborate after 7 days.

Enzymes:-

There are certain enzymes which are found to have a considerable

bleaching efficiency on both extrinsic and intrinsic stains. These enzymes are

obtained either from plants or microorganisms. These enzymes are effective either

without peroxides or with very little % of peroxides (0 to 1%).

1. Laccases – act on the molecular oxygen and yield hydrogen peroxide

without any need for hydrogen peroxide. They are obtained from fungi E.g.

Mycelipthora thermophila. These enzymes are found to be effective against

intrinsic stains.

2. Oxidases – act on the molecular oxygen and yield hydrogen peroxide. E.g.

L-amino acid oxidase – Trichoderma harzianum, glucose-oxidase –

Aspergillus species, Xylitol oxidase – Streptomyces species. They are

found to be effective against extrinsic stains.

14

3. Peroxidase:- Act on hydrogen peroxide and yield water. These enzymes

require very little % of hydrogen peroxide for their action. They are

obtained from plants e.g. Horse radish peroxidase or from microorganisms.

E.g. Haloperoxidase from Curvularia species. They are found to be

effective against both extrinsic and intrinsic stains along with Laccases.

Mode of Supply:

Hydrogen peroxide:-

Solution: Various concentrations of hydrogen peroxides are available, but 30% to

35% stabilized solutions are the most commonly used. They can be used either

alone or mixed with sodium perborate.

Gel: Also available in the form of Silicon dioxide gels containing various

concentrations of hydrogen peroxide (6 to 38%). Recently introduced is the

Opalescence xtra boost which contains 38% hydrogen peroxide for quicker results

and which does not even require light activation (Syringes).

These gels are also available in preloaded disposable whitening tray where

the concentration of hydrogen peroxide is about 9%. It is available as Tres white

from ultradent which consists of a delivery tray (outer tray with handle) and a

disposable adaptive tray (inner tray without handle). The inner tray consists of a

gingival barrier gel on the border of the tray and 9% H2O2 gel inside the tray. Both

the trays are centered on the arch and lightly pressed into place, the outer tray is

then removed and the inner tray is adjusted. It is advised to wear 30 to 60 min/7-

10 days.

15

Teeth whitening strips:- These are flexible pieces of plastic or polyethylene that

have been coated on one side with a thin film of hydrogen peroxide gel. The idea

of the teeth whitening strips was to reduce the thickness of the peroxide gel.

The thickness of the bleaching gels on the whitening strips is about 0.2mm

while that of a paper is 0.1mm. It is ½ to 1/5th quantity compared to the tray

bleaching.

The concentration of the hydrogen peroxide gels on the whitening strips

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 strips for 14 days and 10% gel strips for 7

days.

Disadvantage:- The length of the strips is small so that they adapt only to the

anterior teeth.

Adverse effects:

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

2. Sensitivity

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 packed into the pulp chamber.

Carbamide peroxide:

The most common mode of supply is in the form of gels, which are

supplied in syringes. It is available in various concentrations ranging from 3 to

16

45%. However, popular commercial preparation contain about 10% carbamide

peroxide with a mean pH of 5 to 6.5.

Leonard et al. studied the use of different concentrations of carbamide

peroxide for bleaching teeth and found that lower concentrations of carbamide

peroxide take longer time to whiten teeth but eventually achieve the same result as

higher concentrations, which may cause increased sensitivity.

Bleaching preparations containing carbamide peroxide usually include

glycerine or propylene glycol, sodium stannate, phosphoric or citric acid and

flavour additives. Some preparations contain carbapol, a water soluble polyacrylic

acid polymer as a thickening agent which prolongs the release of active peroxide

and improves shelf-life.

Enzymes:-

These enzymes either alone or in combination with peroxides are added to

the mouth washes or tooth pastes. Their concentration ranges from 0 to 20% with

0 to 1% of peroxides if used.

Chemistry of bleaching:

Bleaching is a chemical process, which occurs mostly by the oxidation

during which the organic materials are eventually converted into carbondioxide

and water. The most commonly used bleaching agent is hydrogen peroxide which

requires the least time for the desirable action.

In the bleaching process, the oxidizing agent i.e. the bleaching agent has

free radicals with unpaired electrons which it gives up and becomes oxidized,

17

whereas the reducing agent i.e., the substance being bleached accepts the electrons

and becomes reduced.

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 is acid, has reduced breakdown and extended shelf life.

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 bleaching process. In

order to promote the formation of perhydroxyl, the hydrogen peroxide needs to be

made alkaline.

Optimum pH – 9.5 to 1.8 at which ionization.

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

H + HO2 (Higher percentage of stronger free radical)

This reaction results in greater bleaching efficacy in the same time as at

other pH levels. Thus, H2O2 is most effective between pH of 9.5 – 10.8. In the

presence of decomposition catalysts and enzymes the H2O2 ionises as follows.

2H2O2 2H2O + O2

Where no free radicals are produced and the bleaching is ineffective. Some

of these enzymes may be present in the mouth. Therefore, it is important to make

the teeth free of debris and dry when applying the bleaching agent.

18

Bleaching action on tooth surface:

When applied on the tooth, hydrogen peroxide diffuses through the organic

matrix of the enamel and dentin. The radicals released from H2O2 have unpaired

electron which make them extremely electrophilic and unstable and thus will

attack the organic molecules to achieve stability, generating other radicals. Such

reactions lead to the formation of simpler molecules that reflect less light.

During initial bleaching process highly pigmented carbon-ring compounds

are opened and converted into chains which are lighter in colour. Existing carbon

double-bond compounds, usually pigmented yellow are converted into hydroxyl

groups which are usually colourless. As these processes continue the bleached

material continually lightens. A point is reached at which only hydrophilic

colourless structure exist. This is the material’s saturation point. Lightening then

slows down, if the bleaching process is still continued, it begins to break down the

carbon back bones of proteins and other carbon-containing materials. Compounds

with hydroxyl groups are split, breaking the material into yet smaller constituents.

Loss of enamel becomes rapid, with the remaining material being quickly

converted into CO2 or H2O.

Sodium perborate:-

Sodium perborate when mixed with water decomposes to form sodium

metaborate and hydrogen peroxide releasing O2. When mixed with superoxol it

decomposes to form sodium metaborate and water releasing O2. The oxidation is

slow and is active over a long period of time.

19

Carbamide peroxide chemistry:

Carbamide peroxide used as bleaching agent breaks down into H2O2. 10%

carbamide peroxide produces 3.6% H2O2.

CH2 N2O H2O2

NH3 H2O2

CO2

Then, the ionization of H2O2 is the same.

Carbamide peroxide products contain either a carbopol or glycerine base.

The carbopol base slows the release of H2O2, but this does not change the

efficiency of the bleaching treatment. It is slightly acidic to extend the shelf-life.

BLEACHING TECHNIQUES:

Before carrying out the bleaching process, it is important to assess the type

of stain. Certain extrinsic stains can be removed by regular intense mechanical

brushing with cleaning agents containing abrasives or surfactants. However, the

intrinsic stains cannot generally be removed by such processes.

Basically bleaching techniques are:-

1. Non-vital

a. Walking bleach

b. Thermocatalytic

c. UV light photooxidation

2. Vital

a. In-office

b. Night guard

c. Over the counter

20

1. Non-vital bleaching:

These procedures are carried out for endodontically treated teeth.

Indications:-

a) Discolouration of pulp chamber

b) Dentin discolouration

c) Discolourations not amenable to extracoronal bleaching

Contraindications:-

a) Superficial enamel discolourations

b) Defective enamel formation

c) Severe dentin loss

d) Presence of caries

e) Discoloured composites

f) Extensive restorations

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

common.

1. Radiographic assessment of the status of the periapical tissues and the

quality of endodontic obturation. If the obturation is inadequate, the tooth

should be retreated prior to bleaching.

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

replaced.

3. Evaluate the tooth colour with a shade tab by taking photographs at every

appointment.

21

4. Orabase or vaseline should be applied to the gingival tissues, followed by

isolation with rubber dam which should fit tightly at the cervical margin of

the tooth to prevent possible leakage of the bleaching agent onto the

gingival tissues. Opal dam can also be used.

5. Remove all restorative material from the access cavity, expose the dentin

and refine the access. Verify that the pulp horns and other areas containing

pulp tissue are clean.

6. Remove the obturation material to just below labial gingival margin.

Orange solvent, chloroform or xylene on a cotton pellet may be used to

dissolve sealer remnants.

7. Next is the application of the barrier material. This is one of the most

important step as the improper location, material and the shape of the

barrier material could lead to external cervical resorption.

Placement of barrier:

Many studies have suggested using the labial cementoenamel junction as a

guide for barrier placement. However, cementoenamel junction is not level, but

rather curves in an incisal direction on the proximal sides of the tooth. Therefore,

placement of a flat barrier leaves the proximal dentinal tubules unprotected; this is

the site where cervical resorption begins. Therefore, care should be taken to

protect the proximal dentinal tubules by the location and shape of the barrier. To

determine the location of the barrier, three periodontal probings are made with a

custom “transfer periodontal probe”. This is a periodontal probe carefully curved

to match the labial contour of the tooth. First, a labial recording is made, followed

by mesial and distal. These probings are made to determine the position of the

22

epithelial attachment from the incisal edge of the tooth. The internal level of the

barrier will be placed 1mm incisal to the corresponding external tubules that lead

from the pulp chamber apical to the epithelial attachment so that the internal

bleaching agents are confined to the access cavity. By subtracting 1mm from each

of the three probings a template is created for the location and shape of the barrier.

Positioning the palatal portion of the barrier equal or coronal to the barrier’s

proximal height protects the palatal cementoenamel junction without

compromising the esthetic results. The resultant shape of the barrier from the

facial view is a “bobsled tunnel” and from the proximal view resembles a “ski

slope”.

In cases with gingival recession, the root would not be completely bleached

using the cemetnoenamel junction guideline as a reference. Instead, a more

biologically critical and esthetically essential landmark is to relate the barrier to

the epithelial attachment.

Number of material such as IRM, Zinc phosphate, zinc polycarboxylate,

GIC and cavit have been used as the intracoronal isolating barrier material where

light cured GIC and cavit have shown more promising results compared to the

others.

Walking Bleach:

1. In this technique, a mixture of sodium perborate and inert liquid such as water,

saline or anaesthetic solution or even H2O2 can be used but preferably lower

concentrations are placed in the pulp chamber. Studies have shown more

23

number of external cervical resorption 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 sodium tetraborate with water was quiet effective.

Timpavat et al. found the bond strength to be better with Naperborate +

H2O. Excess liquid from sodium perborate should be removed by tamping with

a cotton pellet.

2. Excess bleaching paste from the undercuts in the pulp horns should be

removed and the access cavity should be sealed with a temporary filling

(Preferably IRM) which should be at least 3mm.

3. Rubber dam should e removed and the patient should be informed that

bleaching agents work slowly and significant lightening may not be evident for

several days.

4. Patient should be evaluated after 2 weeks and the procedure should be repeated

if necessary.

Thermocatalytic:

This technique involves placement of the oxidizing agent, generally 30% to

35% H2O2 in the pulp chamber followed by heat application either by electric

heating devices or specially designed photoflood lamps for 5min. this process

should be continued until the desirable results are achieved. Should not be

repeated for more than 5-6 times. Care should be taken that the temperature of the

heating device does not exceed 114F. Lamp unit should be 13 inches away from

patient. Metal clamps should not be used. Recall the patient in a week to assess the

colour after rehydration. Repeat the procedure, if necessary.

24

Potential damage by this method is the external cervical root resorption

caused by irritation to the cementum and periodontal ligament. Therefore,

application of highly concentrated H2O2 and heat during intracoronal bleaching is

questionable.

Photo-oxidation:

In this technique, 30% to 35% of H2O2 solution is placed in the pulp

chamber on a cotton pellet followed by exposure to the curing light for 20-30 sec.

For plasma arc or laser 3-5 seconds of exposure time is sufficient. If the bleaching

gels are used they have to be expressed into the access cavity and onto the labial

surface of the tooth and should be exposed to the curing light from both the sides.

Adverse effects:

1. External cervical root resorption:- It is one of the most commonly noticed

complication with intracoronal bleaching using hydrogen peroxide. It is

asymptomatic and is generally noticed during routine examination. The exact

cause of this response is not fully understood, although a number of

mechanisms have been postulated.

a) In 10% of all teeth, the cemento-enamel junction is defective or 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.

b) Internally applied 35% H2O2 may directly contact periodontal membrane

may passing through patent dentinal tubules or lateral canals or accessory

foramina.

25

c) Bleaching agents may infiltrate between the gutta-percha and root canal

walls. They could then communicate with the periodontal ligament through

dentinal tubules, lateral canals or apex which can cause resorption

anywhere along the length of the canal.

d) Heat application while using high concentrations of H2O2 may enhance

external cervical root resorption.

e) 35% H2O2 mixed with sodium perborate can lower the pH in the

periodontal membrane, which may increase the likelihood of cervical

resorption.

f) Previous traumatic injury may act as a predisposing factor.

2. Chemical burns:- 35% H2O2 is caustic and may cause chemical burns and

sloughing of the gingiva. Therefore, when using such solutions the soft tissues

should always be protected with Vaseline or orabase and rubber dam or with

opal dam.

3. Coronal fracture:- Increased brittleness of the coronal tooth structure,

particularly when hat is applied, is also thought to result from bleaching. This

may be due to dessication of the dentin and enamel. This was noticed clinically

but has not yet proven conclusively.

Suggestions for safer bleaching:

1) Verification of adequate endodontic obturatiion – This provides an

additional barrier against damage by oxidizers to the periodontal ligament

and periapical tissues.

2) Protect the oral mucosa by Vaseline or orabase.

26

3) Effective isolation by opaldam or rubber dam. Use of interproximal wedges

and ligatures may provide a better seal.

4) Use of protective barriers – In most of the clinical reports of the post

bleaching cervical root resorption protective barrier was not used. The

barrier of adequate thickness should protect the dentinal tubules and

confirm to the external epithelial attachment.

5) Acid etching should be avoided as it does not enhance the bleaching

process, but causes undesirable periodontal ligament irritation.

6) Avoid strong oxidizers.

7) Avoid heat.

8) Recall the patient periodically and examine clinically and radiographically.

Post bleaching tooth restoration:

Permanent restoration of the tooth is essential for long-term successful

bleaching. Coronal microleakage especially that of lingual access restoration and a

leaking restoration may lead to rediscolouration. Therefore, a composite

restoration is advised as early as possible. This should be planned 1 or 2 weeks

after complete removal of the bleaching materials. This time period is for the

elimination of residual peroxides.

The use of catalase for 3 min has been proposed for the removal of residual

peroxides where adequate bonding can be acquired.

In case of thermocatalytic or photooxiation bleaching, it has been advised

to pack Ca(OH)2 paste in the pulp chamber for a few weeks prior to placement of

27

final restoration to counteract acidity caused by bleaching agents and to prevent

root resorption.

Vital bleaching techniques:

There are various techniques for bleaching vital teeth depending on the

degree of staining.

1. In-office or Power

2. Mouth guard or Night guard or At-home

3. Over-the counter

1. In-office:

Indications:-

1. Light enamel discoloration

2. Mild tetracycline discoloration

3. Endemic fluorosis discoloration

4. Age related discoloration

Contraindications:

1. Severe dark discolorations

2. Severe enamel loss

3. Proximity of pulp horns

4. Hypersensitive teeth

5. Presence of caries

6. Large/ poor coronal restorations

28

Techniques:-

1. Familiarize the patient about causes of discoloration, procedure to be

followed and the treatment outcome.

2. Make radiographs to detect the presence of caries, defective restorations

and proximity to pulp horns.

3. Evaluate tooth colour with shade tabs by taking photographs at all the

appointments.

4. Apply Vaseline or oraseal and then isolate with rubber dam by using waxed

dental floss or wedgets for additional sealing. Avoid using metal clamps, as

they are subjected to heat.

5. Do not inject a local anesthetic.

6. Position protective sunglasses over the patient’s and operator’s eyes.

7. Clean the enamel surface with pumice and water.

8. For the darkest or most severely stained areas acid etch with 35%

phosphoric acid for 5 to 10 seconds and rinse with water for 60 seconds.

9. Place a small amount of 30 to 35% H2O2 solution into a dappen dish. Apply

the H2O2 liquid on the labial surface of the teeth using a small cotton pellet

or a piece of gauze. Bleaching gel can also be used instead of solution

which can be better controlled.

10. Apply heat with a heating device or light source. The temperature should be

controlled that the patient does not feel any discomfort, usually between

125F and 140F (52C to 60C). Rewet the enamel surface with H2O2 as

necessary. If the tooth becomes too sensitive, discontinue the bleaching

29

procedure immediately. Do not exceed 30 min even if satisfactory results

are not obtained.

Heating can be carried out by thermostatically controlled electric heating

device or a stainless steel instrument such as Woodson No.2 heated over flame.

There are different light sources available for photo-oxidation conventional

bleaching light. This supplies energy to enhance the bleaching action of H2O2 by

adding heat. The heat causes more vigorous release of oxygen and facilitates the

dissolution of pigments. It is slow and often uncomfortable for the patient.

Tungsten-Halogen curing light:

These curing light provides heat and stimulates the initiation of the

chemical reaction by activating the light sensitive chemicals in the bleaching

agent. This is a time consuming process (i.e., 40 to 60 sec per application per

tooth).

Argon laser:

It emits a visible blue light. The action it is to stimulate the catalyst in the

chemical. There is no thermal effect with this. It is easy to use and is best for

removal of initial dark stains, such as those caused by tetracycline. However, it

becomes less effective as the teeth whitens and when there are fewer stain

molecules.

Carbon dioxide laser:

It emits invisible infra red light. They interacts directly with the catalyst-

peroxide combination. It removes the stains regardless of the tooth colour. It emits

heat and can enhance the bleaching effect initiated by the argon laser.

30

Xenon plasma arc light:-

It is a non-laser, high intensity light which produces a great deal of heat;

therefore, it can be applied only for a brief 3 sec period. The action is thermal and

stimulates the catalyst in the chemical. Although it is very fast, there is a greater

potential for thermal trauma to the pulp and surrounding soft tissues than with

other light sources.

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. This does not produce heat.

11. 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 then remove the rubber dam. Do

not rinse with cold water since the sudden change in temperature may damage

the pulp or can be painful to the patient.

12. Dry the teeth and gently polish them with a composite resin polishing cup.

13. Treat all the etched and bleached surfaces with 1.1% neutral sodium fluoride

gel for 3 to 5 min.

14. Inform the patient that cold sensitivity is common, especially during the first

24 hrs and advise to use a fluoride rinse daily for 2 weeks.

15. Recall the patient after 2 weeks and evaluate the effectiveness of bleaching by

sing the same shade tab used pre-operative assessment. Repeat the procedure if

necessary.

31

Adverse effects:-

1. Post operative pain:

A common immediate postoperative problem is pulpalgia characterized by

intermittent shooting pain. It may occur during and after the bleaching session and

usually persists for between 24 and 48 hrs. The intensity of pulpalgia is related to

the duration and temperature of the bleaching procedure. Therefore, shorter

bleaching periods are recommended. If long term sensitivity to cold develops,

topical fluoride treatments and desensitizing tooth pastes should be used to

alleviate these systems.

2. Pulpal damage:-

Extra coronal bleaching with hydrogen peroxide and heat has been

associated with some pulpal damage. Although no significant irreversible effects

on the pulp have been found, these procedure should be carried out with caution

and not in the presence of caries, areas of exposed dentin or in close proximity to

pulp horns. Defective restorations must be replaced prior to bleaching.

3. Dental hard tissue damage:

Hydrogen peroxide causes morphologic and structural changes in enamel,

dentin and cementum and reduces the micro-hardness of these structures. These

changes may cause dental hard tissues to be more susceptible to degradation and

to secondary caries formation. Therefore, teeth should be well polished after the

bleaching procedure.

32

4. Mucosal damage:

Ulceration and sloughing of the mucosa may be caused 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. The

associated burning sensation is extremely uncomfortable for the patient and can be

treated by extensive water rinses until the whiteness is reduced. In more severe

cases, a topical anesthetic, limited movements and good oral hygiene aid healing.

Application of protective cream or catalase can prevent mot of these

complications. Vitamin E oil can also be applied immediately after contact.

Night guard vital bleaching:

Indications:-

1. Superficial enamel discolorations

2. Mild yellow discolorations

3. Brown fluorosis discolorations

4. Age-related discolorations

Contraindications:-

1. Severe enamel loss

2. Hypersensitive teeth

3. Presence of caries

4. Defective coronal restorations

5. Allergy to bleaching gels

6. Bruxism

7. Pregnant and lactating

8. Smoking

33

Technique:-

This technique has been widely advocated as a home bleaching technique

with a wide variety of materials. Numerous products are available, mostly

containing 1.5 to 10% hydrogen peroxide or 10 to 15% carbamide peroxide, that

degrade slowly to release hydrogen peroxide. Carbamide peroxide products are

the more commonly used at home bleaching agents.

1. Familiarize the patient with the probable causes of discolouration,

procedure to be followed and the expected outcome.

2. Carry out thorough oral prophylaxis

3. Assess the colour of the teeth with a shade tab by taking photographs at all

the appointments.

4. Make alginate impressions of both the arches. Cast the impression by

taking care not to incorporate voids or drags in the impression. Apply

approximately 0.5mm thickness of block out material to the desired labial

surfaces to provide reservoir spaces in the tray. It should be 1 to 15mm

short of the gingival margin and should not extend onto the incisal edges

and occlusal surfaces. Extending the block-out material onto the incisal

edges or occlusal surfaces can cause the margins of the tray to open upon

occluding or the tray to impinge on the soft tissues. Cure the block-out

material on each tooth for 20 to 40 seconds. Now heat the tray material on

the vacuum former unit until it sags approximately 2 ½ inches, then adapt it

to the cast and allow it to cool. It is then trimmed with a scalpel or elastic

knife approximately 0.25 to 0.3mm occlusally from the gingival margin

34

facially and lingually in a scalloped manner. The tray is then placed on the

cast and the extensions are checked. Now gently flame polish the edges one

quadrant at a time with a torch. While still warm, hold the periphery of each

segment firmly against the model for 3 sec with a water-moistened finger.

Otherwise, after trimming the tray with scalpel a rubber wheel in a

micromotor can be used to smoothen the rough edges.

5. Insert the mouth guard to ensure proper fit. Remove and apply the

bleaching agent in the space of each tooth to be bleached. Reinsert the

mouth guard over the teeth and remove excess bleaching agent.

6. Familiarize the patient with the use of bleaching agent and wearing the

mouth guard. The procedure is usually performed 3 to 4 hrs a day and the

bleaching agent is replenished every 30 to 60 min. Some clinicians

recommend wearing the guard during sleep for better long-term esthetic

results. The duration of wearing the mouth guard and replenishing the

bleaching agent depends on the severity of staining, concentration of the

bleaching agent and the manufacturer’s instructions.

7. Instruct the patient to brush and rinse their teeth after meals. The guard

should not be worn eating. Inform the patient about thermal sensitivity and

minor irritation of soft tissues and to discontinue use of the guard if

uncomfortable.

8. 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. If complications occur, stop the

treatment and re-evaluate the feasibility of continuation at a later date.

35

Rediscoloration with this technique is not more frequent than the other

technique.

Adverse effects:

1. Systemic effects: Controlled mouth guard bleaching is considered relatively

safe. However, accidental ingestion of large amounts of these gels may be

toxic and cause irritation to the gastric and respirator mucosa. Bleaching gels

containing carbopol are usually more toxic. Therefore, it is advisable to pay

specific attention to any adverse systemic effects and to discontinue treatment

immediately if they occur.

2. Dental hard tissue damage:- In vitro studies indicate morphologic and chemical

changes in enamel, dentin and cementum associated with some agents used for

mouth guard bleaching.

3. Tooth sensitivity: Transient tooth sensitivity to cold may occur during or after

mouth guard bleaching. In most cases, it is mild and ceases on termination of

treatment. Treatment for sensitivity consist of discontinue the use of mouth

guard for few days or the reduction of wearing or the use of desensitizing

agents.

4. Mucosal damage:- Minor irritations or ulcerations of the oral mucosa have

been reported to occur during the initial course of treatment. Possible causes

are mechanical interference by the mouth guard, chemical irritation by the

bleaching agent and allergic reactions to gel components. In most cases,

readjustment and smoothing the borders of the guard will suffice. However, if

tissue irritation persists, treatment should be discontinued.

36

5. Damage to restorations: Some in vitro studies suggest that damage of

bleaching gels to composite resins may be caused by softening and cracking of

the resin matrix. However, there are few other studies which did not find any

significant adverse effects on either surface texture or colour of restorations.

Generally, if composite restorations are present in esthetically critical areas,

they may need replacement to improve colour matching following successful

bleaching.

It has also been reported that both 10% carbamide peroxide and 10% hydrogen

peroxide may enhance the liberation of mercury and silver from amalgam

restorations and may increase exposure of patients to toxic byproducts.

Coverage of the amalgam restorations with a protective layer of dental varnish

prior to the bleaching gel application may prevent such hazards. Unpolished

restorations corrode more.

6. Occlusal disturbances:- Typcially, occlusal problems related to the mouth

guard may be mechanical or physiologic. From a mechanical point of view, the

patient may occlude only on the posterior teeth rather than on all teeth

simultaneously. Removing posterior teeth from the guard until all of the teeth

are in contact rectifies the problem. From a physiologic point of view, if the

patient experiences TMJ pain, the posterior teeth can be removed from the

guard until only the anterior guidance remains. In such cases, wearing time

should be reduced.

Studies have found that At-home bleaching for 2 weeks is more effective

than in-office bleaching 3 times at 3 different appointments.

37

Leonard et al. studied the desensitizing agent efficacy during whitening in

an at-risk population and suggests that the use of an active 3% KNO3 and 0.11% F

desensitizing agent for 30 min prior to whitening may decrease tooth sensitivity

when compared with placebo in a population at risk for tooth sensitivity.

Gamze (2003) had suggested that 10 gm of Carbamide peroxide/ day can be

considered as a safe dose for the prevention of systemic effects in a person / day

can be considered as a safe dose for the prevention of systemic effects in a person

of 70 kg wt.

Alternative Techniques:

1. Acid-pumice technique:-

a) In this technique, 18% HCl is mixed with fine flour of pumice to make a

thick paste.

b) This paste is applied to the enamel surface with a piece of wooden tongue

blade or crushed orange wood stick. Exerting firm pressure, the paste is

worked into the enamel surface with a swirling motion for 5 seconds. The

enamel surface is then rinsed for 10 seconds with water.

c) The paste is re-applied until the desired lightening is achieved.

d) The thick paste of sodium bicarbonate and water are applied to neutralize

the surface.

e) Polish with a fine fluoride prophylaxis paste and superfine aluminium oxide

composite resin polishing discs.

f) Apply 1.1% neutral sodium fluoride gel for 4 min.

38

This technique can be used in combination with the night guard bleaching

using lower concentration bleaching agents.

2. McInne’s technique:-

This technique uses a combination of 5 parts of 30% H2O2, 5 parts of 36%

HCl and 1 part of diethyl ether. The solution is applied directly to the stained areas

for 1 to 2 minutes with cotton applicators. While the surface is wet, a fine cuttle

disc is run over the stained surfaces for 15 seconds. This process is repeated until

the desirable results are achieved, during subsequent appointments.

3. Macro abrasion:

This technique can be combined with night guard vital bleaching to achieve

better results. In this technique the severely dark stains are removed with diamond

points, followed by finishing with carbide burs and polishing by using the

composite polishing disc. Further lightening is achieved by night guard bleaching.

C) Over-the-counter:

Many home bleaching products are available over the counter or through

mail order, radio and television advertisements. This approach is not

recommended as overuse and abuse are a concern.

These systems include

Tooth pastes – AP-24, Rembrandt

Mouth rinses – Crest

Tooth brushes – Spine brush pro whitening

Dental floss – Super smile

39

Teeth whitening strips – Crest

Chewing gums – Brits smile, Happy dent

Pain on varnish – Vivastyle

Brite smile stick or pen

Tooth brushes:

Certain powered tooth brushes are available which are said to remove the

extrinsic stains mechanically. E.g. Spin brush pro-whitening.

Paint on varnish:-

Applied with a brush. On application it contains 6% carbamide peroxide.

Once, it is dried the concentration increases.

Insoluble in saliva and remains on teeth for 20 min. subsequently removed

with a tooth brush.

Advantages:-

1. Can be applied exactly wherever it is needed.

2. Contains D-panthenol – Provitamin

3. Noticeable after 7 days

Chewing gums:

Brite smile, Happy dent

Supersmile whitening floss:

It is the world’s first floss treated with Calprox (not waxed) to safely

whiten between teeth and baking soda for fresher breath. Removes stubborn stains

and odour causing plaque under the gum.

40

Calprox is a clinically proven whitening agent which gently dissolves the

protein pellicle, removing stains and plaque in the process.

Boil and Bite:-

1. Boil a pot of water and then submerge the mouthpiece into it for 5 to 15

sec. Mouthpiece begin to wilt.

2. Place the mouthpiece into the mouth and press against the front of your

teeth with your fingers an the back of your teeth with your tongue. Let it

cool.

3. Remove the mouthpiece from the mouth and cut the handle.

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

1) 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.

2) 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 after 14 days of use.

Increased bristle density, concave polishing strips and new cup shaped

pattern designed to enhance the retention of dentifrice at the brush-tooth surface

interface.

41