COMBINING WHITENING TECHNIQUES AND MINIMALLY INVASIVE TREATMENTS

Linda Greenwall

INTRODUCTION

During the last quarter century, there has been a large increase in the whitening techniques and treatments that are available to patients, which has led to a huge paradigm shift away from the existing philosophy of undertaking mechanical dentistry and towards minimally invasive dentistry. The success of the whitening treatments has shown that enamel treatments and dentin bonding are preferable to cutting healthy tooth structure. There are more opportunities to combine whitening treatments and more techniques for more effective whitening. Combination treatments have been recommended to speed up the whitening process and allow for shorter treatment times. This is also significant when treating single teeth for whitening. Further combinations involve whitening and minimally invasive dentistry (see Tables 15.1 and 15.2).

Types of whitening treatments that can be combined are as follows:

1.  Home and power whitening.

2.  Internal and external whitening or nonvital and home whitening together.

3.  Sectional whitening of specific teeth and full-arch whitening treatment.

4.  Chairside whitening treatments using the patient’s whitening trays (to speed up the whitening process and make the treatment more effective).

5.  Home whitening, microabrasion, and/or resin infiltration.

6.  Home whitening and air abrasion, cleaning, and surface preparation.

Although many stains can be treated successfully with a single agent, some may need to be treated using a combination of approaches. Whitening treatments can be combined in various ways depending on the nature of the discoloration. Table 15.3 shows the different options for different levels of discoloration. When one agent fails to remove a stain completely, or when multiple stains of different origins are present in the same tooth, a combination of whitening techniques can be used. Power whitening can be combined with a home whitening program (Garber et al. 1991). Combinations of whitening agents in different concentrations can be used. The microabrasion technique can be combined with home or power whitening. Teeth can even be brightened using pumice and a 10% carbamide peroxide slurry (Baker et al. 1992). In addition, combinations of increasing concentrations of hydrochloric acid and resin infiltration can reduce the effects of white spots.

It is the aim of this chapter to demonstrate how different whitening techniques can be used in combination by showing various case presentations. A modification of the intracoronal technique will be described.

TOOTH SURFACE AND ENAMEL CONDITIONING

Some patients have extensive staining of multiple origins present on the teeth. Some stains are tenacious, such as the stains derived from smoking. It may be useful to use air scaling or enamel conditioning, cleansing, or air abrasion techniques directly on the surface of the teeth before whitening. The surface cleaning approach will eliminate the extrinsic stains so that the intrinsic stains can be examined and plans made to treat the stain or discoloration. The surface treatment involves the following:

1.  Cleaning the tooth with pumice and Hibiscrub before whitening.

2.  Air scaling to remove some simple stain.

3.  Sylc treatment using the Aquacut machine (Velopex International, London). Sylc powder is applied. This is a bioglass similar to Novamin; it contains calcium and phosphate and is used as a cleansing agent and a desensitizer. These materials can clean, seal, and soothe the tooth in preparation for the whitening treatment.

4.  The surface cleaning and conditioning may help in treating cariogenic white spots and other superficial stains.

WHY COMBINE WHITENING TREATMENTS?

•  To make the whitening program more effective.

•  To motivate patients to continue the whitening program at home.

•  To treat a specific problem such as a single dark vital tooth or a single nonvital tooth.

•  To sequence and stage whitening treatment in a complex treatment plan.

•  To treat difficult stains, such as those caused by tetracycline, which may respond better to a combination approach.

•  To treat stains of different origins that exist in the same tooth such as white spots.

Nonvital whitening is a common procedure and has been used as a technique for over 200 years (Abbot and Heah 2009). The most common tooth to be whitened is the upper central incisor (69%; Abbot and Heah 2009), followed by the lateral incisor (20.4%).

REASONS FOR UNDERTAKING NONVITAL WHITENING

The reasons for nonvital whitening are as follows, according to Abbot and Heah (2009) and Plotino et al. (2008):

1.  Trauma (the most common cause; 58.8%).

2.  Previous dental treatment (23.9%).

3.  Pulp necrosis (13.7%).

4.  Pulp canal calcification (3.6%). Dark-yellow and black teeth require more applications of whitening agent than light-yellow and gray teeth.

5.  Intrapulpal hemorrhage, carious tooth.

6.  Defects on teeth, calcification.

7.  Genetic issues (hyperbilirubinemia, fibrosis of the pancreas, amelogenesis imperfecta, cystic endodontic treatment).

8.  Residual pulp tissue after endodontic treatment.

9.  Endodontic materials (medications, irrigants, root or canal sealer).

10.  Root resorption.

EXPECTED OUTCOME OF THIS TECHNIQUE

The range of expected outcomes for nonvital whitening technique for color modification is as follows:

1.  “Good” (87.1%; study by Abbot and Heah 2009)

2.  “Acceptable” (12.9%)

3.  Unacceptable.

4.  No change (rare)

THE OUTSIDE-INSIDE WHITENING TECHNIQUE: A VARIATION OF THE NONVITAL WHITENING TECHNIQUE

This has also been called internal/external bleaching (Settembrini et al. 1997), patient-administered intracoronal bleaching, and modified walking bleach technique (Liebenberg 1997). The technique combines the intracoronal whitening technique with the home whitening technique. It is used to whiten nonvital teeth in a simple manner and to improve the expected outcomes listed earlier. After barrier placement the access cavity is left open so that the whitening material, which is normally 10% or 16% carbamide peroxide or 6% hydrogen peroxide, can be placed into the pulp chamber while the whitening tray is applied to the tooth to retain the material on the tooth. Whitening can thus take place internally and externally at the same time. The higher the concentration of carbamide or hydrogen peroxide, the higher the concentration will be in the pulp chamber, especially if the tooth has been previously restored (Benetti et al. 2004). This technique is a modification of the sealed-in, intracoronal whitening technique (see Chapter 8) and can be used as an alternative technique. Its simplicity and effectiveness warrant description and discussion.

THE PROCEDURE

1. PREPARATION OF THE BARRIER

The nonvital tooth is prepared in the same manner described in Chapter 8 on intracoronal whitening. It is essential to take a pretreatment radiograph to verify the presence of an acceptable root canal treatment and the absence of apical pathology.

Isolation methods

The tooth can be isolated with a rubber dam in preparation for the meticulous removal of the existing extracoronal restoration; however, use of the dental dam is not mandatory because the whitening material is not caustic (Liebenberg 1997).

Gutta-percha removal

As in the intracoronal technique, the gutta-percha is removed to 2–3 mm below the cementoenamel junction (CEJ). The object of the gutta-percha removal is to provide space for the barrier.

Placement of the barrier

A protective barrier is placed over the gutta-percha to prevent the whitening gel from escaping into the root canal system at the CEJ. Conventional glass ionomer or a resin-modified glass ionomer can be used as a barrier (Settembrini et al. 1997).

Protect the gutta-percha

It has been suggested that a calcium hydroxide plug approximately 1 mm in thickness be placed over the exposed gutta-percha. This prophylactic step aims to maintain an alkaline medium because cervical resorption has been associated with a drop in pH at the cervical level (Liebenberg 1997). A periapical radiograph can be taken at this stage to check that the barrier has been well placed, but this is not mandatory.

2. CLEANING OF THE ACCESS CAVITY

The access cavity is cleaned and any remaining pulp horn constituents are removed. The access cavity can be etched merely to clean the internal surface. It does not enhance the whitening effect. A cotton pellet or pellet of polytetrafluoroethylene (PTFE) tape shaped into a ball is placed into the access cavity to prevent food from packing into it.

3. SHADE ASSESSMENT

The pretreatment shades of both the nonvital tooth and the surrounding teeth are taken and noted in the patient’s record or on the whitening record sheet (see Chapter 4).

4. INSTRUCTIONS FOR HOME WHITENING

The whitening tray is checked for fit and comfort (Zimmerli et al. 2010). The patient is instructed not to bite with the anterior tooth for the duration of the treatment (Carillo et al. 1998). The patient is sent home with the whitening instructions and enough whitening materials to lighten the tooth. The cotton pellet in the access cavity is removed with a toothpick before whitening. The whitening syringe can be applied directly into the open chamber before the whitening tray is seated, or the whitening material can be applied into the tray with extra material in the space for the tooth with the open chamber. The patient is instructed to remove the excess with a toothbrush or paper tissue. After the whitening session, the tooth is irrigated with a water syringe and a fresh cotton pellet is inserted back into the tooth. After a meal, the tooth is again irrigated with water to ensure the absence of debris, and a fresh cotton pellet is inserted.

Alternative technique methods

•  Alternatively, the access cavity is syringed with whitening gel and the rest is placed into the whitening tray in a thick layer and the rest of the tray is seated in the mouth. The access cavity can be replenished every 2 hours to speed up the whitening process.

•  Otherwise the access cavity is filled each evening and the tray is worn overnight

•  Another method is to use the sectional whitening tray with windows cut out for the adjacent teeth so that the lighter adjacent teeth do not whiten too quickly before the darker, nonvital tooth has had time to whiten.

•  Alternatively, the material can be sealed into the access cavity as described in Chapter 8.

5. TREATMENT TIMING

If the patient can change the solution every 2 hours, five to eight applications may be all that it is necessary to achieve the desired lightening. This may take a matter of days (Poyser et al. 2004). The more often the solution is changed, the more quickly the whitening will take place. because the tooth is nonvital, this will not lead to sensitivity.

Nightly application will be slower than twice-daily application.

Daily application: It has been advised that unless the tooth is severely discolored, the whitening agent should be applied during the day so that the lightening can be better controlled.

6. REASSESSMENT OF THE SHADE AND RESULTS

The patient returns in 3–7 days. The shade changes are assessed. If sufficient lightening has occurred, the whitening procedure may be terminated. The longer the tooth has been discolored, the longer it can take for the whitening treatment to remove the discoloration (Carillo et al. 1998). Similarly, the darker the tooth, the longer it will take to lighten. The patient is instructed to return if he or she notices that the shade of the nonvital tooth is fully matching that of the adjacent teeth.

7. SEALING OF THE ACCESS CAVITY

The access cavity is then sealed with a glass ionomer restoration (Zimmerli et al. 2010). Placement of the final composite restoration may need to be delayed for 2 weeks to allow the oxygen to dissipate from the tooth and to allow the strength of the enamel-composite bond to improve (Carillo et al. 1998). If it is not possible to wait 2 weeks to place the final restoration, catalase or sodium ascorbate (Khoroushi et al. 2010) (hydrogel and vitamin C) can be placed into the access cavity using a sponge pledget for 3 minutes (Liebenberg 1997). The catalase acts to remove any latent hydrogen peroxide by promoting the decomposition of hydrogen peroxide into water and oxygen (Rotstein 1993). The use of sodium ascorbate, which is an antioxidizing agent, has reversed or decreased fracture resistance of the nonvital tooth in in vitro studies (Khoroushi et al. 2010).

Cleaning the access cavity first

The access cavity is first irrigated with sodium hypochlorite to flush out any remaining debris. The access cavity can then be cleaned using catalase. The cavosurface margin, the enamel surrounding the access cavity, and the pulp chamber dentin are etched for 15 seconds with 37% phosphoric acid according to a chosen adhesive protocol. Immediate dentin sealing can be used to seal the dentin surrounding the access cavity (e.g., HurriSeal Bisco). Dentin bonding agents are then applied. Acetone-containing bonding agents are preferred in this situation because they have been shown to reverse the effects of whitening on enamel bond strengths. The access cavity is sealed as follows in the next section.

8. RESTORATION OF THE ACCESS CAVITY

•  Glass ionomer restoration as a final restoration.

•  Composite restorations can be placed 2 weeks after completion of the final whitening treatment. A composite restoration involves use of incremental buildups of composite and a flowable composite at the base, over the glass ionomer.

•  Sandwich technique: a condensable glass ionomer restoration can be placed immediately (Settembrini et al. 1997) over the barrier and a cut-back of glass ionomer can be undertaken 2 weeks later. A shallower composite restoration is placed after 2 weeks. The thicker base of glass ionomer can sometimes mask the residual discoloration if the nonvital tooth has not fully whitened to match the adjacent teeth.

9. REVIEW

The tooth should be periodically reviewed and a radiograph taken every 2–3 years to check for any signs of a cervical inflammatory process.

BENEFITS OF THE OUTSIDE-INSIDE WHITENING TECHNIQUE

The benefits of the technique are as follows:

1.  More surface area is available both internally and externally for the whitening agent to penetrate.

2.  A lower concentration (10% carbamide peroxide with neutral pH) of the whitening agent is used.

3.  This technique will, it is hoped, eliminate the incidence of cervical resorption that has been reported with the conventional intracoronal whitening technique, because most of the potential factors for resorption are reduced.

4.  The need to change the access cavity dressing is eliminated because the access cavity is left open. (Previously, the oxygen that was released during the whitening process often dislodged the temporary dressing from the tooth. The oxygen can escape normally and there is no buildup of pressure.)

5.  Treatment time is reduced to days rather than weeks (Liebenberg 1997) if repeated replenishment is used.

6.  The patient can discontinue filling the pulp chamber once the desired color has been achieved.

7.  Use of catalase before placement of the restoration can eliminate residual oxygen.

8.  No heat is required to activate the whitening material.

9.  Treatment is simple and noninvasive, offering an alternative solution for removal of nonvital discoloration.

10.  Maintenance treatment is usually undertaken by performing home whitening in trays rather than opening the access cavity and whitening internally. Maintenance is therefore simple.

RISKS

The risks of the procedure are as follows:

1.  The potential for cervical resorption is reduced but still exists.

2.  Noncompliant patients: the technique is patient applied, so it requires the patient to return to have the access cavity filled. Dentists should be careful in their patient selection and education to ensure that the patient returns to have the final restoration placed (Carillo et al. 1998).

3.  Although some degree of manual dexterity is required by the patient to place the syringe into the access cavity, the patient’s desire to achieve a whiter tooth counteracts this problem.

4.  The tooth could be overwhitened through overzealous application of the whitening material by the patient. However, because a matrix is used to apply and retain the whitening material, the color of the other teeth can be lightened evenly to correct the color mismatch. It is thus essential to have regular reviews at frequent intervals to assess the color change taking place.

5.  Shade stabilization occurs over a 2-week period (a slight rebound darkening can be expected as with all whitening procedures; 1–2 weeks later the shade can shift by one shade darker).

INDICATIONS

The indications for the treatment are as follows:

1.  Treatment for adolescents with incomplete gingival maturation.

2.  A single dark nonvital tooth where the surrounding teeth are sufficiently light. If this is the case, a window can be cut into the tray over the adjacent teeth to help the patient identify where to place the whitening agent. An oversized provisional crown form (Wahl 1992) can be used where there is difficulty retaining the whitening tray (Carillo et al. 1998).

3.  All nonvital indications.

OTHER OPTIONS FOR NONVITAL TEETH

Nonvital teeth can be whitened using the whitening tray at home with 10% carbamide peroxide in a closed-chamber technique (Türkün 2004). This may take longer than with a vital tooth because of the nature of the discoloration and the hemosiderin-stained dentin. The benefits of this technique are that instead of removal of an existing sound restoration, the whitening material is applied to the tooth via the whitening tray (Frazier 1998). This technique may be the treatment of choice when providing a touch-up treatment or a maintenance whitening treatment several years after the initial whitening treatment.

The choice of which whitening agent to use depends on the nature of the discoloration and the severity of the existing discoloration. Previous reports of cervical resorption after internal whitening noted more problems when heat was applied to the tooth and when the tooth had been previously traumatized before revitalization. To avoid cervical resorption, it may be prudent to avoid high concentrations of hydrogen peroxide and heat.

See also Table 15.4.

COMBINATION OF POWER AND HOME WHITENING TREATMENTS FOR GENERALIZED DISCOLORATION

This approach is very commonly used to motivate patients to comply with the home whitening protocol and continue whitening at home. Normally one or two power whitening in-office sessions are undertaken. The patient is then given the home whitening instructions, the tray, and enough material to continue the whitening process at home.

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