BLEACHING TECHNIQUES

TECHNIQUE FOR BLEACHING PULPLESS TEETH

Intracoronal bleaching of endodontically treated teeth may be successfully carried out many years after root canal therapy and discoloration. A successful outcome depends mainly on the etiology, correct diagnosis, and proper selection of bleaching technique

CASE SELECTION IN CASE OF INTRACORONAL BLEACHING

Which teeth are amenable to intracoronal bleaching?

. Successful bleaching depends upon two important criteria-

1. The root canal obturation must be complete. In order to prevent an endodontic failure, the root canal system must be filled in three dimensions

2. The remaining tooth structure must be intact

The ideal tooth for nonvital bleaching is a discolored tooth with an unrestored crown. If minor restorations are necessary, the tooth should be bleached first. Then the color of the restorative material may be matched to the resulting tooth color. If the tooth requires significant restoration, it should be restored with a porcelain laminate or full crown. When staining is caused by alloy restorations or endodontic sealers containing silver, the bleaching effect is less predictable. These teeth may also be better candidates for crowns or laminates.

The methods most commonly employed to bleach endodontically treated teeth are the walking bleach and the thermocatalytic techniques. Walking bleach is preferred since it requires less chair time and is safer and more comfortable for the patient.

WALKING BLEACH: -

1. Prepare the tooth for bleaching by polishing the enamel surface with a prophylaxis paste to remove any gross surface debris or discolorations.

2. Apply petroleum jelly to the gingival tissues around the tooth to be bleached, for protection against tissue irritation. Superoxol, in contact with the skin or mucous membrane, may cause severe discomfort.

3. Adapt the rubber dam, invert it, ligate it with wax dental floss, and hold it securely in place with a clamp on the tooth to be bleached.

4. Re-establish the access cavity.

5. Remove any gutta-percha root canal filling that extends into the pulp chamber with a hot Weichman No.1 instrument to the level of the crest of the alveolar bone. The remaining root canal filling should be vertically condensed with finger pluggers.

6. Examine the pulp chamber, and remove any residual debris or stains in the pulp horns and along the incisal edge of the pulp cavity with a small, round bur in a slow-speed contra-angle

7. Seal the orifice of the root canal with atleast 1mm Cavit over the gutta-percha, to prevent percolation of the bleaching agent into the apical area

8. Remove the smear layer, and open the tubuli by applying a 25% solution of citric acid or a 30% solution of orthophosphoric acid to the dentinal surface of the pulp chamber. Flush the surface with sodium hypochlorite or water to remove the acid. The smear layer may also be removed by flushing the chamber with alternate solutions of ethylenediaminotetra-acetate (EDTA) and sodium hypochlorite. Dry the tooth with suction.

9. Flush the pulp chamber with 95% alcohol, and dry with air to desiccate the dentin

10. Protect the exposed areas of the patient’s face by draping it and cover the patient’s eyes with glasses .The patient’s clothing should be covered with a plastic apron. The operator should wear gloves to protect his hands

11. Mix sodium perborate powder with Superoxol to a thick paste in a clean dappen dish.

12. Carry the thick paste into the pulp chamber with a plastic instrument. Make sure the entire facial surface of the pulp chamber is covered with the paste.

13. Place a small cotton pellet, slightly moistened with superoxol, over the bleaching paste

14. Seal the access cavity with IRM or zinc phosphate cement. Because the oxygen generated may dislodge the filling, apply pressure with the gloved finger against the tooth until the filling has set

The maximum bleaching effect is attained about 24-hours after treatment. The patient should return in 3 to 7 days, for evaluation of the result. If the shade is too dark, additional bleaching is necessary. If the shade is too light, the tooth should be permanently restored. Generally, 2 treatments, performed about a week apart, are necessary to attain the desired shade, although in some cases a single treatment is sufficient. The advantage of walking bleach technique is that it is safe and effective.

HEAT AND LIGHT BLEACHING

After preparation of the tooth, a loose mat of cotton is placed on the labial surface and another is placed in the pulp chamber of the tooth to be bleached. The loose cotton mats are saturated with Superoxol. The solution is activated by exposing it to light and heat from a powerful light. The tooth is subject to several, usually 6, 5-min exposures. On completion of the bleaching, a pellet of cotton moistened with Superoxol, or Superoxol and sodium perborate, is sealed in the pulp chamber until the following appointment

An alternative to activate the superoxol is the application of a thermostatically controlled electric heating instrument or a stainless steel instrument, such as a Woodson No.2, heated over a flame. Heat and light from a photoflood light aimed directly on the tooth from a distance of 2 ft or more also activate Superoxol. Wisps of cotton, moistened with Superoxol, hold the bleaching agent inside the tooth chamber and on the labial and lingual surfaces of the crown. Superoxol is added to the cotton every 5 min during the bleaching process. The techniques can be used alone or in combination with the walking bleach.

Potential damage by the thermocatalytic approach is external cervical root resorption caused by irritation to the cementum and periodontal ligament. This is possibly attributable to the oxidizing agent combined with heating. Therfore, application of highly concentrated hydrogen peroxide and heat during intracoronal bleaching is questionable and should not be carried out routinely. Other disadvantages of this technique include increased brittleness of coronal tooth structure due to heat and chemical burns to the soft tissues.

EXTERNAL CERVICAL ROOT RESORPTION

External cervical root resorption has been linked to intracoronal bleaching using hydrogen peroxide. The incidence of its occurrence is not rare. Characteristic resorption occurs only at the CEJ.The age of the patient at the time the tooth became pulpless and the presence of a barrier may be as important as the type of bleaching agent and the use of heat during bleaching.

ETIOLOGY: -

A defect can be found between the cementum and the enamel at the level of the cementoenamel junction. Therefore, dentinal tubules communicate between the root canal system and the periodontal membrane. If a tooth becomes pulpless when a patient is young, the dentinal tubules are relatively wide open, since sclerotic dentin can no longer form.

Dentinal tubules are oriented incisally. Bleaching techniques recommend removal of gutta percha 1 to 3 mm apical to the labial CEJ, allowing the bleaching agent to diffuse incisally to lighten the cervical third of the crown. The combination of bleach placed below the CEJ, a young pulpless tooth, and a potential defect at the junction of the cementum and enamel may allow the bleaching agent to diffuse through the patent dentinal tubules into the periodontal ligament below the epithelial attachment. This can initiate the inflammatory reaction that causes external root resorption at the cervical level.

BARRIER: -

The age of the patient at the time the tooth became pulpless and the lack of a bleach barrier appear to be critically important in the cause of external cervical root resorption.

What can be done to control these factors?

Clinicians have no control over the age at which a tooth becomes pulpless, but they have control over the barrier. What is the perfect barrier? Where should it be located? What shape should it take? Which material is best?

Previous studies and techniques have suggested using the labial CEJ

As a guide for barrier placement. However, the CEJ is not level, but rather curves in an incisal direction on the proximal sides of the tooth. A flat barrier leaves the proximal dentinal tubules unprotected; this critical area is the site where cervical resorption begins. The proximal tubules must be protected by the location and shape of the barrier.

BARRIER TRANSFER: -

How is the location of the barrier determined? This step is essential to prevent resorption. 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 recordings. These probings are made to determine the position of the epithelial attachment from the incisal edge of the tooth. The internal level of the barrier will be placed 1mm incisal to the corresponding external probing of the epithelial attachment. This strategy blocks patent dentinal tubules that may communicate with the periodontal ligament apical to the epithelial attachment.

The idea is to block the dentinal tubules that lead from the pulp chamber apical to the epithelial attachment so that the internal bleaching agents stay within the access cavity. By subtracting 1mm from each of the three probings, an internal template is created for the location and shape of the barrier. Positioning the palatal portion of the barrier equal or coronal to the barriers proximal height protects the palatal CEJ without compromising the esthetic results. The resultant shape from a facial view is the “bobsled tunnel” outline. This should be verified radiographically. The outline form from the proximal resembles a “ ski slope”

There is also an esthetic reason for avoiding the CEJ as a guide for barrier placement. In an instance of gingival recession, the root would not be completely bleached using the CEJ guideline as a reference. Instead, a more biologically critical and esthetically essential landmark is to relate the barrier to the epithelial attachment.

After identification and transfer of the level of the epithelial attachment, the barrier may be placed. In preliminary studies, intermediate restorative material, zinc oxyphosphate, and dentin sealants failed to provide adequate bleach barriers. However, carefully placed Cavit or light-cured glass-ionomer cements may offer promise as barrier materials. Research to identify the best barrier material is ongoing.

ULRAVIOLET PHOTO-OXIDATION

This technique applies ultraviolet light to the labial surface of the tooth to be bleached. A 30-35% hydrogen peroxide solution is placed in the pulp chamber on a cotton pellet followed by a 2-minute exposure to ultraviolet light. Supposedly, this causes oxygen release, like the thermocatalytic bleaching technique. Laboratory evidence that photo-oxidation is a cure for tetracycline staining suggests that light alone is potentially a viable treatment for some tooth discolorations. The disadvantage of this technique is that UV light does not penetrate enamel easily. Other sources of higher intensity UV light,

such as deuterium arc sources or UV lasers, may overcome this obstacle, but problems such as high temperature generation, skin and mucosal burns, eye damage, potential carcinogenicity, and structural damage to enamel and dentin have not yet been suitably addressed, making this an unacceptable alternative at this time.

INTENTIONAL ENDODONTICS AND INTRACORONAL BLEACHING

Intrinsic tetracycline and other similar stains are incorporated into tooth structure during tooth formation, mostly into the dentin, and are therefore more difficult to treat from the external enamel surface. Intracoronal bleaching of tetracycline – discolored teeth lead to significant lightening.

The technique involves standard endodontic therapy (pulpectomy, cleaning and shaping, and obturation) followed by an intracoronal walking bleach technique. Preferably, only intact teeth without coronal defects, caries, or restorations should be treated. This prevents the need for any additional restoration, thereby reducing the possibility of coronal fractures and failures. The most discolored tooth should be selected for trial treatment.

TROUBLESHOOTING IN NONVITAL BLEACHING

PROBLEM POSSIBLE CAUSES SOLUTION

1) Color does not improve - Old Superoxol -Obtain fresh SuperoxolWith bleaching - Insufficient bleaching time - Perform additional wal-

-Discoloration requires combi- king bleaches and/or nation bleaching combination bleaching - Defective temporary seal. With heat.

2) Staining from metal – - Silver cone extended into - Remove silver cone or Or silver-containing sealers chamber amalgam.Retreat with

-Amalgam placed in access gutta percha and sealer Cavity - Perform nonvitalblea-

ching with barrier in place

3) Patient tastes walking - Defective seal - Flush all walking Bleach mixture - Too much sodium perborate bleach mix from used tooth and seal - Walking bleach mix too thin properly. -Be sure there is clean, dry tooth structure between the packed Sodium perborate

and the cavosurface Of the access cavity

4) Discolored tooth is next - Dictated by treatment plan - Perform nonvital to implant bleaching with an adequate barrier for safety.

5) Gingival third fails to bleach - Gingival third dentin thicker - Rebleach gingival - Barrier covers gingival third, third only preventing bleaching of this - Remove excess area. Labial barrier while staying 1mm incisal to labial epithelial attachment6) Patient reports stinging - Leakage of bleaching material -Remove rubber dam during bleaching onto tissue and flush area thoroughly

-Use smaller rubber dam and flush area thoroughly

-Use protective gingival seals or Vaseline over Gingival before Rubber dam.-Improve ligation and confine bleaching mater- ials to chamber

7) Discolored tooth has -Inappropriate use of post where - Remove post and endodontic post intact crown is present retreat with gutta percha and sealer

-Use a nonvital bleaching to restore esthetic match.

8)Color relapse - Microleakage in the access cavity - Remove lingual access material, rebleach, and re- pair access with acid-etched, lay- ered, light-cured restorative mate- rials - Be aware of new techniques to re- duce microleak- age

9) Tooth shade is too light - Walking bleach left in too long -Consider access after bleaching - Failure to compare color change restorative mate- during thermocatalytic bleaching rials that will darken the tooth

-Best solution is prevention and better monitor- ing of bleaching process

10) Tooth is discolored -Increased dentin thickness -Perform endodontic due to calcified treatment followed chamber by nonvital bleaching -Make normal access cavity. Place baseand perform nonvital bleaching without endodontic treatment -External bleaching with Superoxol and external heating inst- ment and/or dual- activated bleaching

Paste.

RECOMMENDATIONS FOR SAFE BLEACHING OF PULPLESS TEETH

1) Excellent Endodontic treatmentThis is required to prevent leaking of the bleaching agent through underfilled foramina.

2) Patient HistoryAll published case reports of external cervical root resorption have occurred in patients whose teeth became pulpless before age 25.Patent dentinal tubules appear to be a factor in allowing bleach to diffuse more readily into the periodontal membrane space. No report of cervical root resorption after bleaching with sodium perborate and water has been published. It may be prudent to use this combination when bleaching pulpless teeth in young patients or in teeth that became pulpless before age 25

3) BarrierThe location, shape, and materials of a protective barrier have been discussed. Its presence appears critical in preventing resorption.

4) No EtchEvaluators were unable to distinguish a significant difference between the results of walking bleach procedures carried out with dentinal etching of the pulp chambers and those bleached without etching. Since etching opens the dentinal tubules, having an adequate barrier becomes more important. Should the barrier fail, etching may increase the potential of external cervical root resorption.

5) New Superoxol and Sodium PerborateBleaching agents lose their effectiveness over time. Superoxol may lose about 50% of its oxidizing strength in a 6-month period.

6) Recalls

Resorption has been detected as early as 6 months after intracoronal bleaching. Most cervical root resorption has been detected after 2 years and was often too advanced to salvage the tooth. Early detection improves the possibility of arresting and repairing the problem.

BLEACHING OF VITAL TEETH

The techniques used for bleaching of vital teeth include: -

IN-OFFICE BLEACHING:

Also called as Chairside bleaching.

1) Bleaching using Mc Innes solution

2) Thermo/Photo Bleaching

3) Power Bleaching

DENTIST PRESCRIBED HOME-APPLIED BLEACHING: -

i.e. Matrix bleaching

OVER-THE-COUNTER KITS: -

1) Whitening strips2) Whitening gels3) Tray-based bleaching systems

IN-OFFICE BLEACHING

Teeth that have been discolored as a result of ingestion of a high amount of fluoride, such as 5 ppm in natural drinking water, or consuming tetracycline continuously for a long period of time as for the treatment of cystic fibrosis or other infections during the formative period of the teeth do not respond well to ordinary methods of bleaching In cases of endemic fluorosis (mottled enamel), a solution of anesthetic ether, hydrochloric acid, and Superoxol is used for bleaching. The solution is prepared in a clean dappen dish, as follows:-

1 part anesthetic ether 0.2 ml

5 parts hydrochloric acid (36%) 1.0 ml

5 parts hydrogen peroxide (30%) 1.0 ml

The anesthetic ether removes surface debris, the hydrochloric acid etches the enamel, and the hydrogen peroxide bleaches the enamel. This is the old Mc Innes solution. Due to the deleterious effects of HCL, it has been replaced by 20% NaOH.

The technique for vital bleaching is as follows: -

1) Polish the crown with a prophylactic paste

2) Protect the gingiva with petroleum jelly

3) Isolate the teeth to be bleached with a rubber dam that is carefully inverted and ligated.

4)The solution should be freshly mixed and applied directly to the enamel surface for 5 min at 1-min interval 5)

5)Oncompletion of the bleaching, the solution is neutralized with a baking soda solution and copious irrigation with water.

6) 6)Thebleached surface should be polished with cuttle discs and a prophylactic paste.This procedure may have to be repeated 2 or 3 times before the desired shade is obtained.

Fluoride-stained teeth are difficult to bleach and require longer and repeated sessions to decolorize them. Teeth discolored by tetracycline may also be bleached to some extent with superoxol. Destaining of the yellow color is most successful, whereas brownish teeth are least successfully bleached.

THERMO/PHOTO BLEACHING

This technique basically involves application of 30 to 35% hydrogen peroxide and heat or a combination of heat and light or ultraviolet rays to the enamel surface. Heat is applied either by electric heating devices or heat lamps. The technique involves the following steps:

1. Familiarize the patient with the probable causes of discoloration, procedure to be followed, expected outcome, and possibility of future rediscoloration

2. Make radiographs to detect the presence of caries, defective restorations, and proximity to pulp horns. Well-sealed small restorations and minimal amounts of exposed incisal dentin are not usually a contraindication for bleaching

3. Evaluate tooth color with a shade guide and take clinical photographs before and throughout the procedure.

4. Apply a protective cream to the surrounding gingival tissues and isolate the teeth with a rubber dam and waxed dental floss ligatures. If a heat lamp is used, avoid placing rubber dam metal clamps as they are subjected to heating and may be painful to the patient.

5. Do not inject a local anesthetic.

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

7. Clean the enamel surface with pumice and water. Avoid prophylaxis pastes containing glycerine or fluoride.

8. As an optional procedure, acid etch the darkest or most severely stained areas with buffered phosphoric acid for 10 seconds and rinse with water for 60 seconds. A gel form of acid provides optimum control. Enamel etching for extracoronal bleaching is controversial and should not be carried out routinely.

9. Place a small amount of 30-35% hydrogen peroxide solution into a dappen dish. Apply the hydrogen peroxide liquid on the labial surface of the teeth using a small cotton pellet or a piece of gauze. A bleaching gel containing hydrogen peroxide may be used instead of the aqueous solution.

10. Apply heat with a heating device or a light source. The temperature should be at a level the patient can comfortably tolerate, usually between 52 degree Celsius to 60 degree Celsius. Rewet the enamel surface with hydrogen peroxide as necessary. If the teeth become too sensitive, discontinue the bleaching procedure immediately. Do not exceed 30 minutes of treatment even if the result is not satisfactory

11. Remove the heat source and allow the teeth to cool down for at least 5 minutes. Then wash with warm water for 1 minute and 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. Treat all of the etched and bleached surfaces with a neutral sodium fluoride gel for 3 to 5 minutes.

13. Inform the patient that cold sensitivity is common, especially during the first 24 hours after treatment. Also, instruct the patient to use a fluoride rinse daily for 2 weeks.

14. Re-evaluate the patient approximately 2 weeks later on the effectiveness of bleaching. Take clinical photographs with the same shade guide used in the preoperative photographs for comparison purposes. If necessary, repeat the bleaching procedure.

Photo-assisted dental bleaching has progressed throughout the time mainly on the photo-activator light/heat sources. Initially the activation of the gel was carried out by means of the use of heat sources such as instruments and lamps (Photoflood, Halogen lamps). However, the high penetration of the 35% hydrogen peroxide associated to the increased local temperature caused by the heating source results in increase in tooth sensitivity. Due to this, the techniques used nowadays seek less time for application, less heating and decrease in the post-operative tooth hypersensitivity.

POWER BLEACHING

In this technique, high intensity light, which was used as a heat source, is replaced with conventional halogen units, plasma arc lamps, LED lights, Xe-halogen lights and lasers. There are specific situations, such as single tooth bleaching within an arch, or even small areas on teeth that need to be lightened, where power bleaching is advocated. The dentist here has complete control throughout the procedure and is able to stop when the desired shade is achieved. Very often power bleaching can be used to give a kick start to the lightening process in order for the patient to see immediate results before being encouraged to comply with the home bleaching regimen. Power bleaching works by the permeation of oxygenating per hydroxyl free radicals through enamel micro pores along a diffusion gradient and into the dentine where it oxidizes the stains and thereby bleaches the teeth.

POWER BLEACHING may frequently require more than one visit to produce an optimal result. However, for many patients a single visit is enough to satisfy their aesthetic needs and no further treatment is required. It can also be used on teeth with different stain etiologies, but must be carried out with meticulous care and attention owing to the caustic nature of the 35% hydrogen peroxide used.

ADVANTAGES OF POWER BLEACHING

The main advantages of power bleaching technique are-

The time factor-produces immediate results, which can be used to motivate the patient to continue with home bleaching.

Avoiding problems with home bleaching procedures such as:

- Wearing trays that may cause patients to gag;

- Distaste for home bleaching gel.

DISADVANTAGES OF POWER BLEACHING

Disadvantages of power bleaching include:

The caustic nature of the 35-50% hydrogen peroxide makes isolation and protection mandatory;

More time required, making the procedure more expensive for the patient;

Dehydration of the teeth may occur, thereby giving a falsely lighter shade immediately post treatment.

This last factor can cause further problems with patients perceiving there is color regression or rebound following re-hydration of the teeth. Some manufacturers produce gels that contain 10-20% water, which re-hydrates the teeth throughout the bleaching procedure. Other manufacturers have tackled the problem by using lower concentrations of hydrogen peroxide (15%), which is a water-based solution, thereby increasing the water content by 20%.

However, by far the biggest disadvantage of power bleaching procedure is the caustic nature of the 35-50% hydrogen peroxide used. The need for a meticulous protocol in handling, applying, removal and disposal of these materials is essential.

SAFETY FACTORS IN POWER BLEACHING

Handling of hydrogen peroxide products to avoid the risk of tissue burns to the lips, cheeks, gingiva, and the rest of the face or eyes makes isolation and protection techniques mandatory in the course of power bleaching.

The main safety issue concerning the activating lights used in power bleaching is heat generation and its effect on the pulp. Recent research showed the increase in the intra-pulpal temperature with most bleaching lamps was below the critical threshold of a 5.5 degree Celsius increase thought to produce irreversible damage. The only lamp that produced an intrapulpal temperature increase above this threshold was the laser-based lamp and this was also found to be below the critical temperature once the power output was reduced from 3W to 2W.

Hydrogen peroxide is more widely used as the power-bleaching agent, but the range of concentrations in use today varies from about 17-50%; bleaching times also vary. Thirty-five percent carbamide peroxide yields approximately 10% hydrogen peroxide and is used in certain bleaching systems sometimes known as ‘waiting room bleach’, as the patient wears the custom-made trays full of the material and waits in the waiting room of the surgery. It is available in a powder/liquid combination mixed together to produce a gel or in a ready-made gel to which liquid is added. There are many different combinations available depending on the system or activation method used.

CASE SELECTION/BLEACHING PROTOCOL

Patients that present with decay, periapical lesions or have thermal sensitivity should be treated for these issues prior to the bleaching procedure. It is acceptable for decayed anterior teeth to have the decay excavated and dressed with a temporary glass ionomer filling material until two weeks after the bleaching treatment. This will allow the clinician to shade match the permanent restoration to the new lighter tooth shade and also allow enough time to elapse for dissipation of oxygen free radicals from the tooth which may otherwise compromise the composite bond to tooth.

The use of full mouth periapical radiographs to document the size and vitality of pulps to predict sensitivity levels or check for periapical pathology has been documented. In view of the current ionization radiation regulations and the unnecessary exposure of the patient to high levels of radiation, other forms of vitality testing such as ethyl chloride or electric pulp testers are advised instead. Any teeth that require root canal therapy should have this carried out prior to the bleaching procedure.

Patients should also be made aware that the procedure may need to be repeated or topped up with home bleaching to achieve optimal results, especially if the existing shade is dark or there’s tetracycline staining.

Following the assessment of the teeth, the shade should be agreed with the patient and recorded in the notes. A pre-operative photograph with the shade tab in situ should always be taken under standardized lighting conditions without using the dental operating light, which would washout the shade. After all the relevant explanations, options, limitations and prognosis have been discussed with the patient, a consent form should be signed and the patient should be referred for a hygiene session about a week to ten days prior to the bleaching procedure.

OPERATIVE PROCEDURE

Shade assessment on the day with the teeth wet and dry followed by photographs with shade tab in situ.

External stain removal using pumice/water slurry and a bristle brush or sodium bicarbonate with air abrasion units.

Isolation: there are many forms of isolation that can be used, depending on the type of power bleaching procedure used, or the dentist’s particular preference. Rubber dam is a good method of isolation used in combination with caulking putty beneath it on the gingival area. The teeth should also be ligated with waxed dental floss to prevent seepage of the fizzing hydrogen peroxide solution to the underlying gingiva. The use of rubber dam is contra-indicated when simultaneous dual arch power bleaching is used. Light bodied impression materials used in the past for isolation did not provide reliable protection and have been replaced by the newer paint on dam materials such as Opal dam. These are light cured resin barrier materials that are painted on to the gingiva around and in between the teeth to be bleached. It is essential to ensure that the material covers a wide area of gingiva and mucosa around the teeth and flows interdentally so that it prevents leakage of the hydrogen peroxide to these areas. It may also be advisable to place the material lingually or palatally in interdental areas. The material can also

be used to cover areas that are not intended for bleaching, such as exposed dentine caused by recession or developmental defects.

Soft tissue retraction: cheek and lip retractors are placed to pull these tissues away from the teeth and bleaching gel. There are many products available, some of which have inbuilt suction facility, which is very useful, while others have a tongue guard to prevent the forward movement of the tongue on to the teeth and bleaching gel. Further tissue protection is provided by gauze and cotton wool rolls placed inside the lips and cheeks to keep them away from the gel. Vaseline should be used on the lips to reduce cracking of the lips and prevent them from drying up. A low volume saliva ejector should be placed at the back of the patient’s mouth and the dental chair should be adjusted to allow the patient to swallow comfortably any saliva that is not removed.

Bleaching cycle: power bleaching products would normally be refrigerated and should therefore be allowed to reach room temperature for at least an hour prior to the procedure or be activated by running the syringe under warm water for a few minutes. A fresh mix of gel is mandatory as these products have a very short active time before which the free radicals are depleted; any gel remaining should be disposed of after use. The consistency of some preparations can be altered by varying the hydrogen peroxide liquid content but generally the mix should be creamy and slightly spreadable, similar to that of acid etch gel, so that it can be easily applied using a brush or plastic spatula.

A 2-3 mm layer of freshly mixed gel should be applied to all the labial surfaces of teeth in the smile zone and lipped over to cover the incisal edges and extend slightly lingually or palatally. This should only be done in the absence of exposed dentine caused by incisal wear. The smile zone varies between patients but is commonly from the first or second premolar to its contra lateral counterpart.

Activation with or without a light source depends on the bleaching system used.

The gel is left in place for a length of time dependent on the system and concentration of hydrogen peroxide used, usually about 10 minutes, but can range from 3-20 minutes at a time.

The gel is suctioned off the teeth using high volume suction and the teeth wiped using damp gauze before being lightly dried.

A further fresh mix of gel is now applied to the teeth, activated as before and left in place for the same length of time. After removal of the gel using suction, the teeth are washed with copious amounts of water before light drying. The application and activation procedure is repeated one more time before final washing and drying of the teeth. Therefore contact of the bleaching agent with the teeth is for three 10-minute cycles, often known as passes. Hence, power bleaching procedures usually involve three 10-minute passes, but some systems use three or four 20-minute passes with lower concentrations of hydrogen peroxide, while others use 3-minute passes repeated five times with total bleaching time being 15 mi

After removal of the isolation dam the gingiva and surrounding mucosa are examined for blanching or areas of redness indicating hydrogen peroxide seepage through the isolation. Areas of damage should be thoroughly washed with copious amounts of water before the application of a neutralizing agent, such as vitamin E, usually supplied within the bleaching kits.

Polishing with a diamond polishing paste gives a high luster look to the teeth and further enhances the appearance of the teeth.

Application of a neutral colorless fluoride gel such as Gelkam may help in cases where there was sensitivity experienced during the procedure.

Final shade assessment and postoperative photographs should be taken with both start and final shade tabs in situ.

Patients should be given postoperative instructions. These include:

The use of a fluoride gel or potassium nitrate containing toothpaste in cases that experience thermal sensitivity.

Dietary advice to avoid acidic drinks, fruits, tea, coffee and smoking for 48 hours. It is thought that the oxidizing free radicals are still active within the teeth for a further 48 hours post bleaching.

Shade regression of about half a shade unit tends to occur about a week to ten days post bleaching. Patients should be made aware of this to avoid disappointment.

Top up home bleaching kits should be given to those cases that require further bleaching.

CURING LIGHTS

Various types of curing lights are used to activate the bleaching gel or expedite the whitening effect. Initially, conventional curing lights were used but these were quickly joined by lasers and plasma arc lamps. In addition, some systems are activated by a chemical reaction on mixing two gels, while others utilize a dual activation system

HALOGEN CURING LIGHTS

Curing lights such as Demetron 501 can be used with a number of different systems such as Polar Office or Quick White. Activation is via the lights bleach mode for 30 sec per tooth and, generally, the application involves three 10-minute passes. Some products available, such as Opalescence Xtra are based on a pre-mixed 35% hydrogen peroxide gel that contains carotene, which converts light energy to heat and therefore increases the activation of the hydrogen peroxide by encouraging further breakdown into active free radicals.

PLASMA ARC LAMP

Systems that use these lights are usually based on three 10-minute passes with light activation in whitening mode for 3 sec per tooth performed twice during the pass. Alternatively, a full smile adaptor

is used to illuminate both arches together for the full 10-minute pass with the light switching on and off in 5-sec bursts but giving out lower intensity.

XE-HALOGEN TECHNOLOGY

These systems utilize a full smile illuminator placed a few centimeters in front of both arches to activate 35% hydrogen peroxide gel with the usual protocol being three 10-minute passes. However, the use of a combination of carbamide peroxide (22%) and hydrogen peroxide (38%) for 20-minute passes repeated three times has been recommended, but this protocol must be questioned in terms of possible penetration into the pulp chamber and whether there is any benefit in combining 22% carbamide peroxide, which breaks down into approximately 7.5% hydrogen peroxide.

LASER BLEACHINGLaser Bleaching can be an option for some patients who want dramatic whitening effect. The objective of laser bleaching is to achieve the ultimate power bleaching process using the most efficient energy source, while avoiding any adverse effects. Using the 488-nm argon laser as an energy source to excite the hydrogen peroxide molecule offers more advantages than other heating instruments. Argon lasers emit fairly short wavelengths (488 nm) with higher – energy photons; conversely, plasma –arc lamps, halogen lamps, and other heat lamps emit short wavelengths as well as longer invisible infrared thermal wavelengths (750 nm to 1 mm) with low- energy photons and predictable high thermal character. This high thermal energy can create unfavorable pulpal responses.The argon laser, which emits a visible blue light, is used first to activate the bleaching gel. The blue light will be absorbed by the dark stains and becomes less effective as the tooth whitens because the blue light will be reflected rather than absorbed by the whiter tooth surface. The hydrogen peroxide molecule falls apart into different, extremely reactive ionic fragments that swiftly combine with the chromophilic structure of the organic molecules, altering them and producing simpler chemical chains. The result is a visually whitened tooth surface. Then the Carbon dioxide laser that emits invisible infrared energy is used to achieve deeper penetration leading to deeper, more efficient tooth whitening.

Diode lasers

Both 830 nm and 980 nm wavelength diode lasers can be used for tooth bleaching in combination with 35-50% hydrogen peroxide gel. The gel is produced by mixing the hydrogen peroxide liquid with a powder mainly containing fumed silica and a blue dye. The blue dye absorbs the laser wavelength and heats up to cause the controlled breakdown of the hydrogen peroxide to oxidizing per hydroxyl free radicals. The system is also based on applying 2-3mm of gel to teeth in the smile zone and three 10-minute passes with activation using 1-2 W of laser energy for 30 sec per tooth. It is essential that all present, including the dentist, patient and nurse are correctly protected with eye protective glasses as ocular damage is a real risk with the use of these lasers.

RATE OF REACTIONThe expeditious rate of reaction in laser bleaching makes one major beneficial difference when

compared with other methods of bleaching. Because bleaching has a short history of research and study, a calculated, hard definition of how the chemical rate of reaction operates is in its infancy. Enough research

has been concluded to assure clinicians that laser bleaching using the argon laser, as an energy source with the highly concentrated HOOH is the most efficient method in the tooth- whitening process. These two components-the ideal energy source and high concentration of the bleaching gel- meet all the criteria required for achieving the ultimate rate of reaction. The bleaching process is a chemical reaction composed of different factors that determine the rate of chemical reaction. The increase of the temperature, concentration of the reactants, and intensity of the light in a photochemical reaction are all proportional to the rate of the chemical reaction of the tooth whitening

The Ph value plays an important role in the rate of reaction in the bleaching process as well. Ionization of buffered hydrogen peroxide in the Ph range of 9.5 to 10.8 produces more per hydroxyl HO-2 free radicals. The result is a 50% greater bleaching effect in the same time allotment as other pH levels. The average pH value found in various strengths of hydrogen peroxide is approximately 4. The acidity allows the hydrogen peroxide to have a longer shelf life; however, to achieve efficiency standards, it should be buffered to a much higher pH value with the salt of an alkaline base before being used as an agent for tooth whitening. A thickening agent is added for ease of control and handling.

CHOOSING A LASER FOR BLEACHING

Three dental laser wavelengths have been cleared by the Food and Drug Administration (FDA) for tooth whitening: argon, carbon dioxide, and the most recent 980 nm GaAlAs diode. In February 1996, Ion laser Technology gained FDA clearance for ILT argon (approximately 480 nm) and ILT Genesis 2000 carbon dioxide laser (10,600 nm) with a patented bleaching gel and chemicals for laser tooth whitening. The laser method originally was patented by Yarborough, a dentist and inventor widely credited with introducing some of the presently used tooth-whitening methods to the dental community. Yarborough founded Brite Smile to commercialize laser tooth whitening; Brite Smile was then acquired by ILT. In 1998, ILT changed the process of laser manufacturing, and the company underwent reorganization. The Brite Smile Co changed its protocol in 1999 and currently uses the plasma-arc lamp as an energy source for teeth whitening in their Brite Smile Centers.

Yarborough’s treatment concept for laser bleaching involves the mixture of 50% hydrogen peroxide in a sodium perborate, proprietary powder base. Argon laser energy is used first to remove deep-colored stains, followed by a carbon dioxide laser, which emits the mid-infrared thermal energy that is absorbed rapidly by water and the moist bleaching paste. The bleaching paste is applied several times; the teeth are then cleaned, followed by a final coating of fluoride gel. The carbon dioxide laser then is activated to promote the remineralization of the tooth surface. Caution should be exercised when using the carbon dioxide laser because the characteristic of this wavelength is thermal and well absorbed into water and hydroxyapatite, which are the primary components of enamel.

There is a need for research efforts in laser bleaching. The preferred energy source is argon laser energy. The visible blue light emits a high-energy photon that efficiently excites the hydrogen peroxide molecules to an eigenstate molecular vibration without any thermal. The thermal effect from the carbon dioxide is favorable for its rate of reaction, but the potentially adverse pulpal responses are a valid concern.

The research has focused on the application of the plasma-arc lamp as a curing source for photo initiating a camphoroquinone-tertiary amine-type composite system. Similar to the argon laser, the plasma-arc lamp can provide the high to medium intensity of light needed to reduce curing time and ensure the full polymerization of the composite to gain its proper physical properties. Miller and Louca noted that the Apollo plasma-arc lamp emits a high intensity for 3-second curing cycles; for bleaching cycles, at 820 mW/cm square. Simultaneously the radiometers reading for infrared light shows the 3-second curing cycle to be approximately 50 mW/cm square, and the bleaching cycle is 21 mW/cm square similar to and slightly higher than the halogen curing lamp. Measurement of the temperature rise at the fibreoptic tip on the 3-second curing cycle is approximately 20 degree Celsius; one bleaching cycle is approximately 12 degree Celsius, which is higher than the controlled halogen lamp at 6 degree Celsius. Duret emphasized that using the halogen lamps for 30 to 60 seconds potentially can raise the pulpal temperature from 4 degree Celsius to fourteen degree Celsius, and when using the Apollo plasma-arc lamp for a 4-second bleaching cycle, the pulpal temperature can increase 2.2 degree Celsius. Before using plasma-arc lamps as an energy source for teeth whitening, clinicians must know the proper protocol and be aware of the existence of the infrared and thermal energy.

SAFETY ISSUES IN LASER BLEACHING

There are no compromises when it comes to safety; responsible clinicians must recognize the operational parameters of the energy source selected. The argon-curing laser falls in the class III laser classification; this requires special training for operating the equipment and use of special eye protection with the orange-colored lenses. The eyes are sensitive photoreceptors –everyone in the operatory area must wear these glasses. The intensity of the light used for bleaching must be blocked out with glasses with the proper optical density for specific wavelengths.

One must handle the caustic hydrogen peroxide with extreme caution. The patient should be acquainted fully with the procedure and well protected with a good isolation technique. There are different techniques for isolating the bleaching site, such as the well-ligated traditional rubber dam, painting a gingival barrier, or merely working with lip and cheek retractors. Whatever method the clinician feels the most confident with is acceptable.

A first-aid kit should contain antioxidants such as vitamin E in liquid or capsule form and aloe Vera gel. Even with all isolation techniques in place, a single spilled droplet of hydrogen peroxide or bleaching compound, within seconds, blanches and burns gingival tissue. The patient may express discomfort with body language because the isolation techniques in place may make verbal communication impossible. The clinician should remain calm and apply the vitamin E oil quickly; the symptoms subside within 1 minute.

The clinician must follow the protocol regarding the length of exposure time for the selected energy source, which depends on the intensity of the light and the particular wavelength. The shorter the wavelength, the higher the energy of the photon. Conversely, longer wavelengths carry lower energy with more of the thermal effect of the photon. The general rule for avoiding unfavorable pulpal

responses is 30 seconds per tooth using the argon laser and 10 seconds per tooth for the plasma-arc lamp because its thermal energy is at a higher energy output. Usually, there is a recommended time period for chemical oxidation followed by the light oxidation. Some bleaching compounds give color indication when the redox process has been completed. Toxicologic considerations, such as cytotoxicity or acute systemic toxicity, are much less of a problem with in-office power bleaching than with the at-home tray bleaching because there is no chance for the patient to consume any bleaching gel or have long- term contact or exposure.

METAL HALIDE LAMP

The Zoom light is used with a two part 25% hydrogen peroxide gel in a dual arch technique employing three 20-minute passes followed by the application of sodium fluoride gel.

CHEMICAL ACTIVATION

Systems such as Opalescence Xtra Boost are based on 38% hydrogen peroxide two part gel system. It consists of one syringe, containing hydrogen peroxide that is chemically activated by mixing with the second syringe, containing a unique proprietary activator that increases the Ph to 7 for maximum activation. When mixed together, a supercharged bleaching agent is produced that does not require light activation.

DUAL ACTIVATED SYSTEMS

Hi Lite is a system that contains both ferrous and manganese sulphate, which are chemically, and light activated, respectively, to accelerate the bleaching process to 7-9 minutes.

The system is based on 35% hydrogen peroxide blue gel that is activated using a conventional light-curing unit. After about 2 minutes, the gel changes color to green, following oxidation, and then to cream, before finally becoming chalky colored on complete inactivation. At this point it is removed and a fresh mix is applied, with the procedure being repeated up to six times in one session.

WAITING ROOM BLEACH TECHNIQUE

Thirty-five percent carbamide peroxide is activated by holding the syringe under hot running water for a few minutes prior to use. The gel is placed in the custom-made tray, which is then put in the mouth of the patient where the excess material is removed. The patient is then asked to sit in the waiting room for about 30 minutes to an hour. After this time has elapsed, the patient returns and the gel is suctioned and rinsed off the teeth. The procedure can be repeated 2-3 times more in the one session.

COMPRESSIVE BLEACHING TECHNIQUE

This technique suggests that the power bleaching technique can be made more effective by compressing the gel against the teeth. This is based on the observation that, on decomposition of the power bleaching gel, small bubbles appear in the gel that indicate the release of oxygen ions and, unlike in home bleaching techniques, these ions migrate and a small of them will permeate the enamel. In order to enable the permeation of oxidizing ions through the enamel, the nascent oxygen must be guided under pressure.

The procedure involves the usual isolation and placement of 35% hydrogen peroxide gel, such as Opalescence Xtra, in a custom-made tray, which is put in place and any excess material is removed before the lingual and buccal edges of the tray are sealed with light cured resin material, to prevent any leakage during gel decomposition. Once the edges are sealed, the gel is activated using either a halogen light or a plasma arc lamp. After 30 minutes, the gel and isolation are removed and the teeth are washed, with the procedure being repeated on another occasion, using home bleaching with 10% carbamide peroxide in the interim for maximum results. This technique is relatively new and is undergoing clinical evaluation. Concerns with this technique include the probable penetration of hydrogen peroxide into the pulp chamber after only 15-20 minutes. In addition, there is no proof that the presence of the tray will force the nascent oxygen back into the tooth to enhance the bleaching procedure as hypothesized.

COMBINING BLEACHING TECHNIQUES

Combining different bleaching techniques serves a number of purposes including improving the effectiveness of the whitening procedure, especially when there are stains of varying etiology or cases of tetracycline staining. It is also used to motivate those patients whose compliance levels for home bleaching is questionable. The patient is encouraged by the almost immediate results produced by power bleaching to continue with top-up home treatment to achieve maximum whitening results. It is also desirable to combine techniques in cases where a non-vital tooth is involved or single teeth with multiple stains.

ULTRASONIC TECHNOLOGY

The latest addition to the in-surgery bleaching systems is the SoniWhite Whitening system, which utilizes ultrasonic technology with a 6-7.5% hydrogen peroxide gel in upper and lower trays. The procedure only involves approximately two cycles of 5 minutes but it is thought that the use of the ultrasonic energy indirectly encourages the production of more oxygen-free radicals that permeate through the tooth to produce the whitening effect.

MOUTHGUARD BLEACHING

This technique has been widely advocated as a home bleaching technique, with a wide variety of materials, bleaching agents, frequency, and duration of treatment. This out-of-the-office technique for lightening teeth also has been referred to as matrix bleaching, nightguard vital bleaching, and dentist-prescribed/home-applied bleaching. Numerous products are available, mostly containing either 1.5 to 10% hydrogen peroxide or 10 to 15% carbamide peroxide that degrades slowly to release hydrogen peroxide. The carbamide peroxide products are more commonly used. Higher concentrations of the active ingredient are also available and may reach upto 50%.

Typically, nightguard vital bleaching will attain optimal lightening in approximately 2 to 6 weeks. The rapidity with which the final results are obtained depends primarily upon the daily treatment or exposure times and the degree of discoloration present in the teeth. Bleaching results are dose/time-related. The greater the exposure time for a given concentration, the faster the final results are obtained. Consequently, the bleaching process proceeds more rapidly if daytime wear of the

nightguard is employed in combination with nighttime wear, compared to daytime or nighttime use only.

Most current bleaching preparations intended for nightguard use contain a synthetic polymer thickening agent, Carbopol, which renders the material more thixotropic, resulting in better retention in the nightguard. The addition of Carbopol also slows the rate of oxygen release, extending the duration of the bleaching action. This oxidation-retarding effect makes Carbopol-containing bleaching agents preferred, especially for nighttime use. Daytime use typically consists of 1- to 2- hour applications one to two times a day.

Although predictable outcomes are not absolute, nightguard vital bleaching appears to offer consistently effective results when case selection is optimally determined. It should also be noted that when used together in combination, in-office and nightguard vital bleaching techniques often achieve superior results to those obtained through the use of either approach alone. The advantage of this technique is that it is less costly than in-office bleaching procedures. The disadvantage includes patient compliance.

Nightguard vital bleaching achieves the best results for patients in whom the teeth are yellow, orange, or light musky brown in coloration. Teeth with dark blue-gray staining due to a past history of tetracycline administration do not typically respond well to this technique. Nonetheless, some lightening of tetracycline-stained teeth can be achieved with extended treatment times, especially if combined with in-office bleaching treatments. Nightguard vital bleaching is used for the treatment of brown fluorosis stains. Brownish discolored areas resulting from this etiologic factor respond quite well to this treatment. However, the white opaque areas often found in conjunction with brown fluorosis stains are not resolved. Typically, these “ white spots” become less apparent with bleaching of the tooth in this manner, because the surrounding tooth structure lightens, making the white spots less evident.

Although multiple discolored anterior teeth are treated most easily with this technique, single discolored anterior teeth may be treated as well. If the patient does not wish to lighten all the anterior teeth, the nightguard or bleaching matrix itself may be modified to facilitate bleaching a single tooth. Extended bleaching times may also be required to resolve significant yellow discoloration of single vital anterior teeth, especially if the staining is associated with a history of trauma and calcific metamorphosis of the pulp chamber is evident.

Single anterior teeth that are significantly more discolored may also be treated in conjunction with treatment of all the anterior teeth. The bleaching treatment for the single more discolored tooth is simply extended beyond the time it takes to lighten the other anterior teeth. Once the anterior teeth have been lightened, the remaining darker tooth is bleached by placing the bleaching agent in the single space in the nightguard corresponding to this darker tooth. The adjacent teeth will not be affected by further exposure to the bleaching agent if they already have been optimally lightened.

Nightguard vital bleaching techniques, used singularly or in conjunction with conventional in-office bleaching, can also be useful in restoring teeth to their lighter coloration following years of

exposure to the staining influences of smoking, coffee, tea, and/or other chromogenic foods. Teeth that have darkened in this manner often no longer match adjacent or opposing crowns or other prostheses. This mismatch in color significantly compromises dental esthetics and is frequently considered unsightly by the patient. By bleaching the natural unrestored teeth, the original shade often can be achieved and a match with other existing prostheses obtained. Through this very conservative approach, nightguard vital bleaching can frequently reverse the staining effects associated with the aging process and restore a color match with existing restorations.

This same approach can also be used to salvage an existing anterior prosthesis that is simply too light in shade. Due to economic considerations, many patients cannot afford to replace an existing crown or bridge that, when placed, was too light in shade. Assuming the fit, contour, and occlusal relationship of the prosthesis are otherwise acceptable, the adjacent teeth often can be bleached sufficiently to achieve acceptable esthetics, saving the patient considerable time and expense. Ordinarily all bleaching should be performed prior to the placement of any anticipated anterior restorations or prostheses. Ample time always should be allowed after the bleaching treatment for the bleached teeth to “stabilize” in color prior to pursuing any esthetic restorative treatment.

An interesting future indication for nightguard vital bleaching appears to be in the reduction of the staining associated with chlorhexidine treatments.

Because of the anticariogenic characteristics of carbamide peroxide, custom-made mouthguards or matrices are being examined for the application of this medicament to effect a reduction in root surface caries. Use of this system also is being considered for the treatment of the gingival inflammation associated with gingivitis and acute necrotizing ulcerative gingivitis. However, no definitive conclusions can yet be made regarding either of these potential uses.

Some concern still exists regarding the indications and contraindications for bleaching teeth with existing cervical abrasion or erosion lesions. Nightguard vital bleaching is generally not a problem when bleaching teeth with exposed root surfaces or cervical eroded areas, as long as these areas are not hypersensitive. Hypersensitive teeth are best treated first with a desensitizing agent, such as those that deposit calcium oxalate crystals in the dentinal tubules. Desensitizing toothpastes containing fluoride or sodium nitrate also may be used. Exposed dentinal surfaces in cervical areas are otherwise not at significant risk when using nightguard vital bleaching techniques, because studies show that the peroxide component passes freely through tooth structure. The low molecular weight of the peroxide molecule allows free passage through both enamel and dentin. For this same reason, little concern exists when bleaching teeth with existing potentially “leaky” restorations. These restorations need not be replaced prior to nightguard vital bleaching.

Although nightguard vital bleaching appears to be most safe and effective under normal use, it is not recommended in heavy smokers or users of tobacco products, unless they are willing to refrain from tobacco use during treatment. Although no conclusive evidence is available, studies do suggest that the carcinogenic effects of DMBA, a known carcinogen associated with tobacco products, may be elevated in the presence of oxygenating agents. Furthermore, as is prudent policy for most

drugs, the administration of nightguard vital bleaching agents is not recommended in pregnant or lactating women.

Treatment techniques may vary according to manufacturers’ instructions. The following step-by-step instructions should be used only as a general guideline. The procedure is as follows: -

1. Familiarize the patient with the probable causes of discoloration, procedure to be followed and expected outcome.

2. Carry out prophylaxis and assess tooth color with shade guide. Take clinical photographs before and throughout the procedure.

3. Make an alginate impression of the maxillary and mandibular arch. Care must be taken to avoid incorporating voids in the impression. After disinfecting the impressions and thoroughly rinsing them, casts are poured in stone. The casts are then prepared for the vacuum-forming machine by removing the palate and vestibule. It is customary to treat one arch at a time, allowing one to act as a control for the other. Outline the guard on the model. It should completely cover the teeth. Place two layers of die relief on the buccal aspects of the cast teeth to form a reservoir for the bleaching agent. Fabricate a vacuum-form soft plastic matrix, approximately 2 mm thick, trim with crown and bridge scissors to 1mm past the gingival margins, and adjust with an acrylic trimming bur.

4. Insert the mouth guard to ensure a proper fit. Remove the guard 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.

5. Familiarize the patient with the use of the bleaching agent and wearing of the guard. The procedure is usually performed 3 to 4 hours a day, and the bleaching agent is replenished every 30 to 60 minutes. Some clinicians recommend wearing the guard during sleep for better long-term esthetic results.

6. Instruct patients to brush and rinse their teeth after meals. The guard should not be worn while eating. Inform the patient about thermal sensitivity and minor irritation of soft tissues and to discontinue use of the guard if uncomfortable.

7. Treatment should be for between 4 and 24 weeks. Recall the patient every 2 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 treatment and re-evaluate the feasibility of continuation at a later date. NIGHTGUARD VITAL BLEACHING

PATIENT INSTRUCTIONSNighttime schedule

1) Brush and floss your teeth prior to bedtime.

2) Place 2 to 3 drops or a thin bead of the carbamide peroxide bleaching material into the space of the nightguard corresponding to each tooth to be bleached.

3) Insert the nightguard in the mouth over the teeth. Expectorate the excess bleaching material. Some materials may require wiping excess from tissue with a finger or clean toothbrush, or rinsing with water.

4) Wear the loaded nightguard during the night and remove it in the morning. Wipe or rinse material from the teeth. Aggressive brushing is not indicated or desirable.

5) Clean the nightguard with a toothbrush. Rinse, dry, and store in the retainer box provided for storage of the nightguard.

Daytime Schedule1) Place 2 to 3 drops or a thin bead of the carbamide peroxide bleaching material into the space of

the nightguard corresponding to each tooth to be bleached.2) Insert the nightguard in the mouth over the teeth. Expectorate the excess bleaching material.

Remove excess material from the gingival by wiping with a finger or a toothbrush.3) Replenish the carbamide peroxide bleaching material after 1 to 2 hours, or according to the

manufacturer’s instructions. Repeat applications are possible; however, do not exceed a total wearing time (including any nighttime wear) of approximately 12 hours per day to allow adequate time for tissue recuperation and occlusal stabilization.

4) Do not wear the nightguard during meals. Use normal oral hygiene procedures prior to the insertion of the loaded nightguard.

Clean the nightguard after use with a toothbrush. Rinse, dry, and store it in the retainer box provided for nightguard storage.

OVER-THE-COUNTER KITS

1. Whitening strips: -They are thin, flexible pieces of plastic (polyethylene) that are coated on one side with a thin film of hydrogen peroxide. They are effective only for a color change of 1-2 shades. These strips are positioned across the users teeth and then gently pressed into place so as to ensure maximum contact between the whitener and the surface of each tooth that will receive treatment. Example-Crest white strips.

Whitening strip kits contain two different shapes of strips. Half of the strips in the kit are designed to fit across the users upper teeth and the other half are shaped to fit across the lower teeth. They have to be worn for 30min/day twice daily. The strips coated with 6% hydrogen peroxide are intended to be worn for 14 days. Strips coated with 10% whitener should be worn for a period of 7 days.

The advantage of these strips is that they are less visible when worn thus providing less restriction. No tray is required with these strips. The strip itself is the delivery system for the whitener and it is very thin in comparison to the tray.

Problems documented with whitening strips include the following; -

Short shelf life due to the use of hydrogen peroxide instead of carbamide peroxide.

Uneven whitening by inadequate coverage of the areas between the teeth and close to the gum – line.

Very small coverage area. Because whitening strips are so small, they cover the first 2-3 teeth on either side of the mouth.

Do not whiten the backside of teeth, which is important so that the backside of the teeth do not show through the translucent teeth.

Whitening gel is exhausted within 30 minutes, requiring frequent replacement of the strip.

Cannot be worn while sleeping

As these strips are not custom fit, the gel does not reach all the areas of the tooth such as the areas around the gum line. This combined with a low-strength whitening ingredient results in a disappointing, uneven lightening effect.

2. Whitening gels: -These clear, peroxide-based whitening gels are applied with a small brush directly to the surface of the teeth. Instuctions generally call for application twice a day for 14 days. Initial results are seen in a few days and final results are sustained for about 4 months. The degree of whitening achieved will be very low.

3. Tray-based bleaching systems

The procedure of usage of tray-based whitening system purchased over-the-counter involves filling a mouth guard-like tray with a gel-like whitening solution, which contains peroxide-bleaching agent. The tray is then placed over the teeth and worn for a period of time, generally a couple of hours a day or every day during the overnight for upto 4 weeks and even longer (depending on the degree of staining and desired level of whitening)

The patient should be careful while choosing the over-the-counter. Tray-based whitening product.

The patient should select a kit that allows some customization of the mouthpiece. Some kits come with a mouthpiece that can be molded to some degree. These are better than others that come with a standard, stock mouthpiece.

The patient should get the opinion of others who may have already tried the kit he is considering to use

If at any time the patient experiences a prolonged change in the color of his gums or increased tooth sensitivity to hot or cold foods and beverages, he should stop wearing the mouthpiece and visit the dentist immediately.

The advantage of over-the-counter bleaching products is its less cost. The disadvantage includes no dentist supervision and its abuse potential.

DIFFERENCES BETWEEN IN-OFFICE BLEACHING PROCEDURES AND AT-HOME AND OVER-THE-COUNTER TRAY-BASED BLEACHING SYSTEMS: -

Strength of bleaching agent. Over –the-counter home use products and dentist-supervised at-home products usually contain a lower strength-bleaching agent (from 10% carbamide peroxide-equivalent to about 3% hydrogen peroxide-upto 22% carbamide peroxide). In-office, professionally applied tooth whitening products contain hydrogen peroxide in concentrations ranging from 15% to 43%.

Mouthpiece trays. With dentist-supervised at-home bleaching products, the dentist takes an impression of the patient’s teeth and makes a mouthpiece tray that is customized to fit the patient’s teeth exactly. This customization allows for maximum contact between the whitening gel, which is applied to the mouthpiece tray, and the teeth. A custom-made tray also minimizes the gel’s contact with gum tissue. Over-the-counter whitening products do contain a mouthpiece tray, but the “one-size-fits-all” approach means that the fit will not be exact. Ill –fitting trays can irritate the gum and soft tissue by allowing more bleaching gel to seep onto these tissues. With in-office procedures, the bleaching agent is applied directly to the teeth.

Additional protective measures. In the office setting, the dentist either applies a gel to the gum tissue or uses a rubber shield (which slides over the teeth) before treatment to protect the gums and oral cavity from the effects of the bleaching. Over-the-counter products do not provide these extra protective measures.

Speed of the bleaching process. Dentist-supervised at-home bleaching and over-the-counter bleaching products typically need to be applied every day for 1 or 2 hours or every overnight for up to 4 weeks. In-office bleaching provides the quickest and most effective way to whiten teeth. With in-office bleaching, the whitening product is applied directly to the teeth. These products can be used in combination with heat, a special light, and/or a laser. The light and/or heat accelerate the whitening process. Results are seen in only one 30 to 60 minute treatment. To achieve dramatic results, however, several appointments are usually needed. With laser-enhanced bleaching, however, dramatic results can be seen after the first treatment.

Costs. Over-the-counter bleaching systems are the least expensive option, followed by dentist-supervised home bleaching systems and In-office bleaching procedures.

Supervised versus unsupervised process. Dentist-supervised at-home bleaching and in-office treatment offer additional benefits compared with over-the-counter procedures. First, the dentist performs an oral examination and considers the complete medical history of the patient, which can be helpful in determining how the teeth became discolored and if bleaching is an appropriate course of treatment based on the type of stains and number, type, and location of restorations. The dentist can then better match the type of stain with the best treatment, if appropriate, to lighten those stains. With dentist-supervised bleaching procedures, the dentist

will likely want to see the patient a couple of times to ensure that the patient is following directions, to make sure the customized tray is fitting properly, to inspect your gums for signs of irritation, and to generally check on how the teeth whitening process is proceeding. With over-the-counter bleaching products, the patients are on their own.