Written by Daniel L. Zedeker, DDS Tuesday, 30 April 2002 19:00
In today’s society, white teeth send a message of youth, health, and success. White teeth are associated with being attractive, and the desire to appear healthy and attractive is one of the driving forces behind the aesthetic revolution in clinical dentistry. The importance of the dentition to an attractive appearance has been recognized for centuries. The Incas placed gems in teeth as a sign of beauty. There is evidence that urine was used as a whitening agent in first century Rome.1 Today we have safe and effective methods for improving patients’ smiles without the need for tooth reduction. Whitening is the number one requested procedure for people aged 40 to 60.2
|Figures 1 and 2. Before and after use of professionally dispensed whitening treatment. Both color and brightness are improved. Reprinted with the permission of Colgate Oral Pharmaceuticals.|
There are currently three types of systems for whitening. Each system is capable of yielding positive results (Figures 1 and 2):
(1) Professionally dispensed
•Typically a tray system or self-applied strips
•10% to 25% carbamide peroxide.
•Using light or laser activation
•Application of higher concentrations of hydrogen peroxide (30% to 50%). These systems may also be used for endodontically treated teeth.
(3) Over-the-counter/direct-marketed materials
•Dentifrices or tray systems
The primary active agent used in at-home whitening systems is carbamide peroxide. Concentrations vary from 5% to 25%, with 10% to 20% being the most commonly used. According to Lopes et al2 there are no adverse effects on enamel microhardness or surface morphology using a 10% carbamide solution. By comparison, using a 3% hydrogen peroxide solution can have an adverse effect on both enamel hardness and surface morphology. One consideration is that the pH of different systems varies significantly. The lower pH gels can be associated with tooth surface erosion.3
It has been demonstrated, however, that a 10% carbamide peroxide with a pH of 6 increases the pH of saliva during the first 15 to 20 minutes of application.4
Technical advances have occurred over a short period of time. These chemically based whitening systems offer significant advances over crown and bridge or other operative techniques. Initially, whitening techniques used light as a heat source to activate the hydrogen peroxide. The development of tray systems allowed the teeth to be exposed to the whitening materials for extended periods of time. These systems demonstrated marked improvement compared with the light activated systems.
Currently, it is quite common for dentists to use a combination of systems to achieve the desired result in different patients. Recently, self-applied adherent strips that do not require a custom fabricated tray have been introduced.5 Furthermore, there are now products for whitening one or a few teeth. Some of these products—designed for discolored endodontically treated teeth—use 38% hydrogen peroxide. It is necessary to place a glass ionomer liner on these teeth at the CEJ to prevent internal resorption.
External energy whitening systems were the basis of the first tooth whitening systems. Various lights (intense pulse light systems, plasma arc lamps, or polychromatic light) used with hydrogen peroxide gels can achieve excellent results. The typical time for treatment is 30 to 45 minutes with lasers as opposed to 60 to 90 minutes that other systems may require. The clinician must decide which type of whitening procedure should be used for each individual patient. Considerations include patient availability, patient desire for immediate results, bruxism, hyperactive gag reflex, TMJ dysfunction, cost, patient dexterity, and patient compliance. Also to be considered are frequency of use and length of treatment. Contraindications include pregnancy and mothers who are nursing, cervical abrasion, pulpal involvement, and failing restorations.
Tooth sensitivity and gingival irritation are the most common side effects of whitening treatments.6 These are more common with in-office procedures.7 There are products available which contain fluoride or potassium nitrate and can be used to reduce sensitivity. The hypersensitivity may also be corrected by reducing the concentration of the whitening material or the exposure time. There are several clinical studies that demonstrate that hypersensitivity is only temporary and will resolve in a short period of time.8 Furthermore, the tissues may be affected by poorly fitting trays that impinge on the tissue, or if excessive amounts of whitening gel are added to the trays.
White et al9 described the effects of different chemicals and concentrations on enamel surface hardness. Teeth were exposed to various concentrations of hydrogen peroxide (5.3% to 6.5%) or carbamide peroxide (10% to 20%) for 70 hours. Surface hardness testing revealed no decreases in hardness, and confocal laser scanning microscopy measurements showed no effects on the enamel surface or subsurface prism architecture. Lopes et al2 demonstrated that the enamel surface microhardness may actually increase after whitening treatment. Donly et al10 reported the effectiveness of whitening in children with white spot (fluorosis) lesions. He used a 10% carbamide peroxide tray system and a 6.5% hydrogen peroxide strip system to camouflage the discoloration. They showed significant blending of white spots with the newly whitened tooth surfaces.
|Table. Extrinsic Vs Intrinsic Staining|
Using a whitening system is generally very simple. The first step is to determine what type of staining is involved. Staining can be extrinsic or intrinsic (Table).
Tooth whitening is based on oxidation of the organic compounds in enamel and dentin. This eliminates the color emission from the organic compounds. Several products use additives that increase viscosity, allowing more effectiveness of the whitening material. Some products use stabilizers to extend the action of the carbamide peroxide.
When considering tooth whitening, the dentist must manage the patient’s expectations. This can be very challenging when the staining is more intense. Treatment planning consists of:
(1) Clinical examination of the teeth, including radiographs, to determine:
•Presence of caries
•Tooth fractures and crazing
•Restorations in need of replacement.
(2) Determination of the health of the periodontium and presence of plaque and calculus.
(3) Informing patients of the goals of treatment and limitations. (Composite and porcelain restorations will not change shade.)
There should be an office protocol for whitening. This protocol should include careful recording of the baseline shade. The tooth shade to be achieved should be discussed. The treatment protocol and follow-up care should be reviewed. The whitening procedures should be accomplished prior to any definitive restorations. A 2-week time span is needed for the color of the whitened teeth to stabilize prior to placing permanent restorations.
When first introducing whitening as a clinical procedure, many offices start with a staff meeting during which complementary whitening can be offered to staff members. This often results in enthusiastic staff members who discuss the results with patients. Furthermore, many manufacturers provide brochures and posters for in-office promotion, and several manufacturers advertise the procedure to consumers. Whitening services can be incorporated into a hygiene recall program. Hygienists often have excellent rapport with patients and can easily determine if the patient is a good candidate for tooth whitening. In summary, tooth whitening services can be easily incorporated into office routine. These services provide advantages to the dental office environment.
1. Panatic C. Panati’s Extraordinary Origins of Everyday Things. New York, NY: Harper & Row; 1987.
2. Lopes GC, Bonissoni L, Baratieri LN, et al. Effect of bleaching agents on the hardness and morphology of enamel. J Esthet and Restor Dent. 2002;14:24-30.
3. Shannon H, Spencer P, Gross K, et al. Characterization of enamel exposed to 10% carbamide peroxide bleaching agents. Quintessence Int. 1993;24:39-44.
4. Leonard RH Jr, Bentley CD, Haywood VB. Salivary pH changes during 10% carbamide peroxide bleaching. Quintessence Int. 1994;25:547-550
5. Gerlach RW, Zhou X. Comparative clinical efficacy of two professional bleaching systems. Compendium. 2002;23:1A, 35-41.
6. Haywood VB, Leonard RH, Nelson CF, et al. Effectiveness, side effects and long term status of nightguard vital bleaching. J Am Dent Assoc. 1994;125:1219-1226.
7. Nathanson D. Vital Tooth Bleaching: Sensitivity and Pulpal Considerations. J Am Dent Assoc. 1997;128(Suppl):41S-44S.
8. Li Y. Biological properties of peroxide- containing tooth whiteners. Food Chem Toxicol. 1996;34:887-904.
9. White DJ, Kozak KM, Zoladz JR. Peroxide interactions with hard tissues: effects on surface hardness and surface/subsurface ultra structural properties. Compendium. 2002;23:1A, 42-48.
10. Donly KJ, Donly AS, Baharloo L, et al. Tooth whitening in children. Compendium. 2002;23:1A, 22-28.
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