REVIEW ARTICLE

https://doi.org/10.5005/jp-journals-10062-0188
Journal of Oral Health and Community Dentistry
Volume 18 | Issue 2 | Year 2024

Tooth Discoloration: Treatment and Prevention—Part II

Faiez N Hattab

Department of Cariology and Pediatric Dentistry, Munich, Germany

How to cite this article: Faiez N Hattab, Department of Cariology and Pediatric Dentistry, Munich, Germany, Phone: +49 17665006632, e-mail: f_hattab@hotmail.com

How to cite this article: Hattab FN. Tooth Discoloration: Treatment and Prevention—Part II. J Oral Health Comm Dent 2024;18(2):75–84.

Source of support: Nil

Conflict of interest: None

Received on: 18 April 2024; Accepted on: 17 May 2024; Published on: 19 November 2024

ABSTRACT

Background: Evidence that human dentition differs from normal dentition is the noticeable difference in tooth color, leading people to seek treatment. Tooth discoloration varies widely in appearance, location, severity, and treatment.

Aim: Tooth discoloration is a common dental finding associated with clinical and esthetic problems, affecting both children and adults. The purpose of this review is to provide up-to-date methods for treating and preventing tooth discoloration.

Review results: Depending on the cause, tooth discoloration is mainly classified into extrinsic, intrinsic, a combination of both, and intercategory types (Part I). There are many whitening/bleaching products available with varying in concentrations, application techniques, and levels of success. These include over-the-counter (OTC), at-home bleaching using a custom tray with carbamide peroxide gel, and in-office bleaching using concentrated hydrogen peroxide (H2O2) (power bleaching). Treatment of intrinsic discoloration is more complex than extrinsic discoloration. A careful history is essential to determine the type of discoloration and treatment required.

Conclusion: Understanding the causes and clinical manifestations of tooth discoloration is important for dentists to make a correct diagnosis and appropriate treatment. The nature of the condition and ways to prevent it also need to be explained to the patient. Lifestyle changes and good oral hygiene are the best ways to prevent tooth discoloration. Both clinicians and patients need to pursue a range of treatment options to achieve esthetically pleasing results. Some tooth discolorations are irreversible and require veneers, crowns, composite fillings, etc.

Clinical significance: Increasing public awareness of the appearance of teeth has led people to seek cosmetic treatments to improve tooth color. This review provides comprehensive treatment options and preventive measures based on the cause and type of tooth discoloration.

Keywords: Bleaching, Prevention, Tooth discoloration, Vital and non-vital tooth whitening.

INTRODUCTION

Dental discoloration is an alteration of the natural tooth color. It is a common clinical and esthetic problem that has a significant impact on psychological status, social interaction, and well-being. A smile has been said to be among man’s most important interactive communication skills. The demand for conservative cosmetic dentistry has grown dramatically over the past three decades due to the growing public interest in having whiter, brighter teeth. According to reports, one-third of adults in the United States seek cosmetic dental treatment. Currently, tooth whitening is one of the most popular cosmetic procedures in the dental field, and the global teeth whitening market size is expected to reach US $7 billion in 2024. There are many types of whitening products, with different application techniques and varying degrees of success. For dentists, the management of tooth discoloration presents two challenges. First, they should find out the cause of the stain; second, they should treat it. Tooth discoloration varies in etiology, appearance, location, severity, and firmness in adherence to the tooth surface.1 Depending on the cause, tooth discoloration is mainly classified into extrinsic and intrinsic discoloration and subdivided as a combination of the two and an intercategory (Part I). Most tooth discoloration is extrinsic in nature, caused by the deposition and interaction of chromogens (colored substances or chromophores) with the dental plaque (biofilm)/acquired pellicle/tooth surface. Sources of extrinsic stains include foods, beverages, medications, lifestyle habits, and occupations that can discolor teeth, ranging from yellow to brown. In children, chromogenic bacteria can cause yellow, green, and black stains. There are several factors that enhance extrinsic stain deposition, such as enamel defects, reduced salivary flow, stain adherence to the tooth surface, and age. Intrinsic tooth discoloration occurs within the hard tooth structure during tooth formation and is caused by metabolic disorders, systemic diseases, medications, and also affects teeth after eruption. This type of discoloration may be associated with changes in the enamel structure (such as fluorosis) or chemical changes in the dentin (such as tetracycline). Intrinsic discoloration is more difficult to treat than extrinsic staining.1–4 Treatment options depend on the cause, location, and severity of the discoloration. The terms tooth “whitening” and “bleaching” are sometimes used interchangeably, but they do not always mean the same thing. Whitening is a general term that includes bleaching or non-bleaching techniques, while bleaching is a form of whitening that uses hydrogen peroxide (H2O2) and carbamide peroxide for vital teeth and sodium perborate for non-vital teeth. The purpose of this review is to provide various methods for treating and preventing different types of tooth discoloration.

WHITENING PRODUCTS

There are a variety of over-the-counter (OTC) teeth-whitening products available for self-use, including toothpaste, mouthrinse, strips, paint-on gel, pen gel, chewing gum, and dental floss.5–8 They contain H2O2 or carbamide peroxide (CH6N2O3; CP). Hydrogen peroxide decomposes into oxygen and water, whereas CP decomposes into H2O2 and urea at a ratio of 1:3. decomposes faster than CP and releases three times more nascent oxygen than CP. Most H2O2 bleaching power occurs within 30–60 min, while CP releases about 50% of its whitening effect within the first 2 hours. Urea decomposes into ammonia and carbon dioxide. Over-the-counter whitening products are mainly effective in removing superficial extrinsic stains but are not effective in removing adherent stains. Using OTC whitening products is not a substitute for dentist prescribed at-home bleaching, which involves using a custom tray filled with 10, 15, or 20% CP gel. Whitening products may have side effects such as tooth sensitivity and gingival irritation, depending on the application procedure and concentration of the bleaching agent.

Toothpaste

Whitening toothpastes are increasingly appealing to consumers because they are easy to use, low-cost, and readily available. They account for more than 50% of OTC whitening products’ sales. Different whitening toothpastes have different mechanisms of action. In all toothpastes, abrasives are the most important ingredient for cleaning and polishing teeth.9 Whitening toothpastes contain more abrasives, such as hydrated aluminum oxide, calcium carbonate, magnesium carbonate, dicalcium phosphate, and silica, than conventional toothpastes, without causing undue an abrasive effect on the tooth’s hard tissue in normal use. Some whitening toothpastes contain peroxides, enzymes, citrates, pyrophosphates, and hexametaphosphates to remove more stains and prevent them from reforming. Enzymes in the paste break down the organic stain molecules, while pyrophosphate and hexametaphosphate prevent chromogens from binding to the tooth surface. Some whitening toothpastes contain 1% H2O2 or less others contain sodium bicarbonate (NaHCO3; baking soda). Whitening toothpaste used twice a day for two to six weeks can lighten teeth by one to two shades, but it is not as effective as whitening strips.10,11

Mouthrinses

There are two main types of mouthrinse: Therapeutic and cosmetic. Therapeutic mouthrinse is a popular oral hygiene aid due to its antibacterial, antiplaque, anticaries, and refreshing properties. Chlorhexidine digluconate is the most effective antiseptic mouthwash to date (e.g., Peridex 12%, Corsodyl 0.2%). Mouthrinses that cause tooth discoloration include chlorhexidine, phenolic Listerine, stannous fluoride, and phenolic/essential oil-based. Manufacturers of whitening mouthrinses claim that their products lighten tooth color, prevent stain buildup, and inhibit plaque formation. These rinses contain low concentrations of H2O2 (1–3%, typically 1.5%), sodium hexametaphosphate, potassium sorbate, citric acid, etc. Some mouthrinses contain pyrophosphate, which has a strong affinity for the calcium in hydroxyapatite, thereby reducing adhesion of chromogens to the enamel surface and also acting as an anti-tartar agent. There are conflicting reports on the effectiveness of whitening mouthwashes. An experimental study on tooth specimens showed that the color change achieved by using H2O2 mouthwash for 12 weeks was similar to the color change achieved by using 10% CP home-tray bleaching for 14 days.12 Another 28-day experimental study showed that whitening mouthwash can lighten enamel, but the whitening effect was significantly less than using 10% CP bleach.13 It is recommended to use a whitening mouthwash twice daily for 60s, then rinse thoroughly with water until the gingiva return to their natural pink color. Patients should avoid drinking or eating for 30 min after use. It may take several weeks to see the results. Whitening mouthwash should be used along with regular brushing and flossing.

Strip

Whitening strips are thin, flexible polyethylene strips coated with a gel containing 6% H2O2 or 20% CP and are used to avoid home tray bleaching. The strips are designed to fit over the surfaces of the upper and lower anterior teeth (Fig. 1) and are used twice daily for 30–45 min. Application is done after the strip liner is removed and the gel side of the strip is placed on the teeth, aligned with the gum line, and pressed against the teeth. After use, teeth should be brushed to remove the excess gel and reduce tooth sensitivity. One study showed that using H2O2 strips resulted in significant tooth whitening after 3 weeks and lasted for more than 6 weeks.14 Whitening strips are found to be more effective than other OTC whitening agents, but not as effective as at-home bleaching using 10% CP gel on a custom tray. The good result of using the whitening strips may be related to the increased contact time of the bleaching agent with the tooth surface, making the teeth 3–4 shades lighter than the baseline color.15 Reports show that one-third of strip users have gum irritation and tooth sensitivity. One problem with whitening strips is that the peroxides in them can be inadvertently swallowed.

Fig. 1: Whitening strips

Paint-on and Pen Gels

These whitening products appeared on the market in the early 2000s. These products should be used after brushing the teeth and drying. The paint-on gel (containing 6% H2O2) is applied to the tooth surfaces with a small brush as nail polish (Fig. 2). Once applied, it hardens into an adhesive film in 30 min, followed by rinsing with water after 15–20 minutes. The procedure is applied twice daily for 14 days. Whitening pens (Fig. 3) are filled with 6–12% H2O2, 35–45% CP, or 35% sodium bicarbonate (NaHCO3, baking soda) in gel form. Apply a thin layer of the bleaching gel to each tooth, working in downward strokes 3–5 times, avoiding the gum. Let the gel dry for 10–15 min, then rinse with cold water. As for applying the paint-on gel, the whitening pen is used twice daily for 14 days. Both products provide fewer color changes than whitening strips due to a shorter contact time with the teeth.

Fig. 2: Paint-on gel

Fig. 3: Pen gel

Chewing Gum

The widespread use of chewing gum has stimulated interest in its use as a vehicle for frequent delivery of ingredients, ease of use, and better human compliance. Chewing gum stimulates saliva production and increases buffer capacity, which flushes away debris and bacteria, among other protective functions.16 Whitening chewing gum contains water-insoluble gum base, sodium hexametaphosphate, titanium dioxide, sodium ascorbate, malic acid, citric acid, sodium pyrophosphate, baking soda, and 5% silica particles (e.g., Orbit Gum White). Abrasive-acidic ingredients and other compounds in the whitening gum enhance its ability to remove extrinsic stains and lighten tooth enamel. To be effective, the gum needs to be chewed for at least 12 min, five times a day, for 2 weeks. One study showed that subjects who used whitening gum and brushed their teeth experienced a 25–36% reduction in stain formation compared to subjects who brushed alone. Some of the whitening gum products contain fluoride (F). Fluoridated gums are effective in remineralizing early caries lesions.16,17 A 12-week clinical trial showed that participants who chewed whitening gum four times a day for 15 min after smoking or drinking coffee or tea reduced the formation of new stains by 25% compared with brushing alone.18 Another study showed that chewing gum containing sodium hexametaphosphate (4%) for 12 weeks study reduced stain formation by 33% compared to no-gum use.19

TREATMENT OF EXTRINSIC TOOTH DISCOLORATION

Efficient tooth brushing twice a day helps to remove and prevent extrinsic stains. Using whitening toothpaste is more effective than regular toothpaste. Prior to treatment, a comprehensive dental and medical history should be obtained, including oral hygiene habits, food, beverages (e.g., coffee, tea), tobacco, medications, and other lifestyle habits. Teeth should be carefully examined for stain location and distribution, enamel roughness and defects, caries, plaque, and calculus deposits. Treatment methods vary depending on the type of stain and severity. Many extrinsic stains can be removed by professional prophylaxis, ultrasonic cleaning, air-jet polishing, polishing discs, and enamel microabrasion using acid-abrasive slurry. Extrinsic staining is less likely to occur with effective oral hygiene care.

Dental Prophylaxis

Prophylaxis is an important treatment to remove dental plaque and halt the progression of dental caries and periodontal disease. For years, professional dental prophylaxis involved crown cleaning and polishing using rubber cups, bristle brushes, and prophy paste containing 1.23% APF, xylitol, flavors, and abrasives. Using a pumice-water slurry with a rotating rubber cup for 30 s removes about 3 µm-thick layers of the F-rich enamel layer. The Prophy Jet system uses a jet of air/water/fine powder (e.g., sodium bicarbonate) slurry to effectively remove extrinsic stains and polish tooth surfaces. Many dental offices are replacing their traditional tooth polishing equipment with Prophy Jet dental cleaners. The surface roughness of the enamel can be adjusted with fine/superfine aluminum polishing discs and polishing paste. A study showed that Prophy Jet and rubber cup/paste polishing have equal efficacy in removing plaque and tooth polishing.

Enamel Microabrasion

This is a quick, painless technique that uses a combination of acid dissolution and mechanical abrasive action to remove stains from the tooth enamel. Microabrasion is indicated for mild and moderate fluorosis, post-orthodontic demineralization lesions, round brackets, localized white spot hypocalcification, and enamel irregularities. Traditionally, several techniques have been proposed for removing dental fluorosis stains. In the 1940s, a slurry of 18% hydrochloric acid (HCl) mixed with fine pumice powder was applied to areas of fluorosis using a wooden spatula wrapped in cotton cloth and scrubbed for 10 min. Later, a mixture of 18% HCl and H2O2 was applied with a cotton applicator to the stained area for 5–10 min. Other clinicians used 36% HCl and pumice slurry with a rubber cup on a slow-speed handpiece. A mixture of 37% phosphoric acid and pumice powder has also been used, in which the acid-abrasive slurry is applied for a maximum of 10 × 5 s. Among these techniques, the most commonly used is a slurry consisting of 18% HCl and fine pumice, applied through a rubber cup rotating at a speed of about 1,000 rpm. The microabrasion technique involves the removal of stained or defective enamel to a depth of 50–200 μm, depending on the application procedure and acid concentration.1 Tooth surfaces can be smoothed using Soflex discs, a color-coded system that allows identification of grit sequence. They are available in coarse (brown), medium (blue), fine (yellow), or extra fine (pink). A case in which surface enamel discoloration was treated using an ultra-fine diamond bur and a paste containing weak acid and silicon carbide abrasives, and then smoothed and polished using an F-containing polishing paste on a rotating rubber cup (Fig. 4).

Figs 4A and B: Pre- and postoperative treatment for surface enamel discoloration affecting the maxillary anterior teeth after using a fine-grid diamond bur and a paste containing a weak acid and abrasive, followed by smoothing and polishing to create a glassy enamel surface1

Currently, a low concentration of HCl (6.6%) and fine-grit silicon carbide abrasive paste (e.g., Opalustre®, Ultradent Products Inc.) is used. The paste is applied using a bristle brush cup for three separate applications. A slow-speed handpiece running at 1,000 rpm is employed. The enamel surface is polished with remineralizer GC MI paste, washed and dried, and then coated with neutral F gel (Fig. 5). Enamel microabrasion using an acidic/abrasive system produces immediate and permanent esthetic results with minimal enamel loss of less than 0.2 mm in depth. If necessary, this treatment can be combined with bleaching for better results. Deeper stains, such as those associated with hypoplasia, may not be resolved by microabrasion and can be treated with macroabrasion and restoration.

Figs 5A to J: Enamel microabrasion technique for the removal of superficial stains and irregularities of the enamel. (A) White-yellow stains on the maxillary anterior teeth; (B) A fine-tapered diamond bur is applied to remove the stained enamel; (C) Teeth are isolated with a rubber dam. Abrasive paste (Opalustre®, Ultradent Products) is applied to the enamel surface; (D) Opalustre is applied using a special rubber cup with enclosed bristles at a very slow speed for three separate applications of 30–40 s each; (E) Abrasive paste is removed with water/air spray after each application, then dried with an air syringe; (F) Smoothing and polishing the enamel surface using remineralizer GC MI paste; (G) Application of 2% neutral sodium fluoride gel; (H) Completed acidic/abrasive treatment; (I) The patient then underwent home bleaching using 10% carbamide peroxide gel in a custom-made tray for 3 weeks; (J) Clinical appearance after treatment

Source: Dr Machado LS, et al. Dentistry Today, 2013

Enamel Macroabrasion

This technique is used to treat subsurface enamel discoloration or texture alteration extending to a depth of about 0.3 mm. One way to better visualize the lesion depth is to use transillumination by using light emitting diode (LED) or curing light directed toward the palatal tooth surface. A darker color shows the lesion size. Treatment involves using a 12-fluted carbide bur or a fine-grit diamond bur on a turbine at high speed to remove defects. Some operators use a low-speed round bur to remove deep white spots lesion and hypoplastic stains (Fig. 6). Light and intermittent pressure is applied to avoid unnecessary tissue damage. Adequate air-water spray is used to keep the tooth hydrated and to ease the assessment of stain removal. The enamel preparation is etched with 37% phosphoric acid for 20 min, and the cavity is restored with anterior composite resin. It is good to remember that the thickness of the enamel on the labial surface of the anterior teeth ranges from 0.2 to 0.5 mm at the cervical region, 0.5 to 1.2 mm at the central region, and 0.9 to 1.6 mm at the incisal region. The tooth crown is made up of a variety of colors, with the gingival margin being darker than the incisal edge because the dentin is immediately beneath the enamel.

Figs 6A to I: Enamel macroabrasion for removal of subsurface staining and irregularities of the enamel. (A) White and yellow spots on the central incisors; (B) A round bur in slow speed is used to remove the white lesion and prepare the outline; (C) The preparation is smoothed with a Soflex disc (3M ESPE). Soflex discs are color-coded systems that allow identification of grit sequence. They are coarse (brown), medium (blue), fine (yellow), or super fine (pink); (D) The prepared cavity; (E), Etching with 37% phosphoric acid for 20 min, rinsing, drying, and bonding application; (F) Enamel composite resin opacity is used for restoration; (G) Smoothing the enamel surface using a fine Soflex disc; (H) Polishing with felts and diamond paste; (I) Finishing treatment

Source: Dr Paulo Monteiro, Styleitaliano, 2016

TREATMENT OF INTRINSIC TOOTH DISCOLORATION

Different from the extrinsic discoloration that occurs on the tooth surface, intrinsic discoloration is caused by the incorporation of chromogenic substances into the enamel and dentin either during tooth development or after tooth eruption, resulting in structural and compositional changes of the discolored tissue. Several metabolic, systemic, and genetic disorders can affect the development of dentition and cause tooth discoloration. Certain infections and drugs in pregnant mothers can cause discoloration of the infant’s teeth. Intrinsic staining is usually yellow, brown, grey, or orange. The most common discoloration is enamel fluorosis, which ranges from white spots to brownish-black discoloration caused by excessive intake of F and yellow to gray staining caused by tetracycline administration. A combination of extrinsic and intrinsic can also occur. Surfacing whitening techniques often do very little to correct intrinsic stains. For this reason, intrinsic can be more difficult and time-consuming to treat.

Bleaching Vital Teeth

The ADA has defined the difference between tooth whitening and bleaching. “Whitening is the process of restoring the teeth to their natural color, while bleaching teeth refers to whitening teeth beyond their natural color.”20 Whitening is a general term, while bleaching is a form of whitening. There are many methods of teeth whitening/bleaching, and their application depends on the cause, location, and severity of discoloration. They differ not only in the concentration of the whitening agents but also in the mode of application and efficiency. Over-the-counter whitening products contain lower concentrations of bleach and are not effective at removing internal stains, nor are they effective at removing adherent external stains or completely whitening after microabrasion. Hence, an at-home or in-office bleaching system using higher concentrations of H2O2 and CP is required to achieve the desired results. All bleaching agents and most whitening products produce active oxygen, which degrades and removes stains. H2O2 readily diffuses through the enamel interprismatic spaces, penetrates the dentinal tubules, and reaches the pulp in 5–15 min.21 The degree of H2O2 penetration depends on its concentration and the energy source used to activate the bleaching process. High H2O2 concentrations and intense energy sources may damage the odontoblastic layer beneath the dentin and interfere with the pulp’s cellular metabolism.22 The success of the dental bleaching technique is directly related to the ability of penetration or diffusion of the peroxides into enamel and dentin.

Home Bleaching

It is a popular dental procedure used to whiten teeth. Some patients prefer at-home bleaching because it is relatively inexpensive and causes less tooth sensitivity than in-office bleaching. At-home bleaching consists of a dentist-prescribed 1 or 1.5 mm-thick semi-rigid custom tray made from ethylene-vinyl acetate to be filled with a bleaching gel of 10, 15, or 20% CP (containing 3.6%, 5.4, or 7.2% H2O2) and activated by a blue LED (Fig. 7A). An in vitro study showed that lower concentrations (5%) of CP take longer to whiten teeth but eventually achieve the same result as higher concentrations (16%).22 The current regulations for approval in the United States and Canada suggest that 10% CP is the upper limit of toleration for safety for unprotected use.

Figs 7A and B: Tooth bleaching processes. (A) Home bleaching using a custom tray and a syringe containing the bleaching gel; (B) In-office bleaching. The gums are protected by light-cured acrylic resin

Patient Instructions

  • Insert the tray with the gel in your mouth and lightly tap to ensure that the tray fits snugly to the sides of your teeth. Keep the tray containing 10% CP for 8–10 hours or overnight. For 15% CP: 4–6 hours, and for 20% CP: 2–4 hours. Always follow the manufacturer’s instructions.

  • Use extra care to avoid getting the gel on your gums. Remove the excess gel with a cotton swab or a dry toothbrush. Overfilling the tray may irritate the gums.

  • Remove the tray and use a soft toothbrush to remove excess gel from the teeth. Rinse your mouth twice, and avoid swallowing any mouthwash gel. Wash the tray after use with cold water, and use a toothbrush to remove any residual gel. Place the tray into the storage box and store it in a cool, dry place.

  • Treat for 7–14 days until the desired whitening effect is achieved. If you have tooth sensitivity and gum irritation, reduce the amount of gel in the tray or discontinue treatment until symptoms subside.

  • Avoid staining foods, drinks, and tobacco after each treatment, and continue good oral hygiene.

In-office Bleaching

This type of bleaching is becoming increasingly attractive because the treatment is performed in one session, lasting 45 min to an hour. It is difficult to determine whether the tooth will respond to the first treatment or it may if require further bleaching. This depends on the type of staining, depth, and severity. Color changes can be assessed subjectively using pre- and posttreatment clinical photographs and dental color guides. The procedure involves using 35% or 37% H2O2 (power bleaching) in a photosensitizer gel activated by an LED, halogen lamp, plasma arche, or laser. Some operators use composite light-curing sources. Because H2O2 is caustic to the oral mucosa, a rubber dam or a light-cure resin barrier should be used to protect the gingiva (Fig. 7B). Existing literature suggests that bleaching agents activated by heat or lasers have adverse effects on pulp tissue. The use of heat to speed bleaching is controversial. When using concentrated H2O2, the histological changes in the dental pulp disappear within two months. Some clinicians advocate etching teeth with phosphoric acid before bleaching to increase the enamel permeability to H2O2, but this view is not supported by others. A recent innovation in in-office bleaching is the GC MI Paste Plus® gel, which contains casein phosphopeptide, amorphous calcium phosphate, 900 ppm F, and 35% H2O2. Reports indicate that bleaching can whiten teeth in several shades, depending on the type and severity of discoloration. Some operators use intense light to enhance the bleaching process, but this has not been approved by others. Only natural teeth can be whitened, and existing tooth-colored restorations will not be bleached. Although the bleaching effects intend for long-term, in some cases retreatment may be required after 1–3 years.

Steps in-office Bleaching

First, tell the patient about the benefits and side effects of treatment. Obtain consent. Take tooth color using the dental shade guide and clinical photographs to document the color of the pretreated teeth. Clean the teeth with a fine pumice slurry. Use eye protection and apply Vaseline to the lips.

  • Place a cheek retractor to expose teeth in the esthetic area.

  • Use a self-hardening or light-curing gingival protective resin gel (Fig. 7B).

  • Apply bleaching gel to the labial surface of exposed teeth and leave on for 15–20 min. Apply a fresh gel for one or more additional periods of 15–20 min each. The bleaching process is completed in 45–60 min.

  • Check between each bleach application to determine if enough whitening has been achieved and whether more bleach needs to be applied.

  • Do suction the bleaching gel so as not to splash the caustic gel on the mucous membranes.

  • After treatment, rinse your mouth thoroughly and obtain the tooth shade. Part of the whitening effect is due to dehydration during the bleaching process, which makes the teeth look whiter than their true new color and stay for a few days.

  • Avoid taking coffee, tea, cola, tobacco products, red sauces, and berries for 48 hours after bleaching.

  • Maintain good dental hygiene by brushing and flossing thoroughly. Mild sensitivity to hot or cold liquids may occur. This usually goes away within 1–2 days. If sensitivity persists, take 600 mg of ibuprofen every 4 hours as needed for pain relief.

TOOTH SENSITIVITY AND GINGIVAL IRRITATION

These are the most common side effects of all forms of teeth whitening, but they vary in severity. The higher the concentration of bleach and the longer the bleaching time, the greater the risk of tooth sensitivity and gum irritation. Temporary tooth sensitivity may be due to pulp inflammation caused by peroxide infiltration during the procedure.20,21 A study showed that after at-home bleaching using 15% carbamide peroxide gel, 54% of patients experienced mild tooth sensitivity, 10% experienced moderate sensitivity, and 4% exhibited severe sensitivity for 1–2 weeks.23 Another study showed that patients treated with in-office bleaching experienced more tooth sensitivity than the at-home group within 24–48 hours after bleaching and decreased after 7–10 days. Tooth sensitivity rates were found to be similar for the two bleaching techniques, and there were no significant differences in the sensitivity between the two techniques in the following periods. Approaches to reduce bleaching sensitivity include the use of nonsteroidal anti-inflammatory drugs (e.g., ibuprofen, diclofenac) and desensitizing toothpastes or gel in a tray containing 5% potassium nitrate (KNO3) and 2% sodium fluoride (NaF). Potassium nitrate is an ionic salt that penetrates dentinal tubules and depolarizes nerve conduction. Fluoride blocks the dentinal tubules, preventing the fluid flow in the tubules, which can irritate the nerves in the pulp. Gingival irritation is caused by contact with bleach peroxide during treatment, which can be due to poor-fitting trays or improper application of the protective gum barrier.

Tetracycline Discoloration

Tetracycline and its analogues (aureomycin, terramycin, minocycline, and ledermycin) tooth discoloration are the most resistant to treatment. Teeth most susceptible to tetracycline discoloration are during the formation period (i.e., between the second trimester in utero and 8 years of age). The severity of discoloration depends on the time and duration of administration, dosage, and type of tetracycline.24–26 Currently, the incidence of tetracycline discoloration is 1–6%.24 An earlier study indicated that over one-fifth of American Indian children had discoloration of the dentition due to the ingestion of tetracycline during the years of tooth formation.27 The location of staining in the tooth structure is related to the developmental stage of the tooth at the time of exposure to tetracycline, with dentin being more susceptible to staining than enamel. Tetracycline and analogues cause different staining ranging from yellow, brown, or grey that respond to bleaching at different rates, with grey stains being the most difficult to change. There is a gradual color distribution, from lighter at the incisal edge to darker at the gingival margin, which has the worst prognosis for bleaching. Reports showed that minocycline intake for 1 week can induce intense tooth discoloration.25 Tetracycline discoloration is classified into three grades, namely mild, moderate, and severe, based on stain location on the tooth surface, shape, and intensity, with severe dislocations characterized by a dark stained band across the crown surface (Fig. 8A).24 Bleaching tetracycline staining showed varying degrees of success, depending on the severity and degree of discoloration. Combining in-office and at-home bleaching showed that grade I and grade II tetracycline stains were eliminated completely in two months, while grade III stains were lightened significantly with a reduction in the banding effect.28 Bleaching tetracycline-stained teeth is a conservative, cost-effective and is also a good treatment option if the patient is willing to undergo long-term treatment with gradual color changes (Figs 8B and C).26 Options for treating different types of tetracycline staining include the following:

Figs 8A to C: Tetracycline discoloration. (A) Severe tetracycline staining; (B) The initial clinical presentation of tetracycline staining reveals a banded appearance; (C) After 2 months of overnight bleaching with 10% carbamide peroxide, the incisal edges are responding well, but gingival yellow bands are still evident. The untreated mandibular teeth give an indication of the amount of color change achieved26

  • Tooth bleaching only, using an at-home custom tray with CP gel. Studies have found that 6 months of nightly bleaching with 10% carbamide peroxide is effective in treating tetracycline-stained teeth. More beneficial effects are achieved by combining in-office and at-home bleaching.25

  • Tooth bleaching and composite bonding over discolored areas.

  • Laminate veneers to treat more extensive cases. These veneers are made of ceramic or porcelain. Usually, the facial surface is prepared to provide space for the veneering material.

  • Full-coverage restorations. For decades, severe intrinsic staining has been often treated with crowns, but this supposes the aggressive elimination of dental structure. Currently, several types of all-ceramic systems have been developed to satisfy patients’ esthetic demands.

Bleaching Non-vital Teeth

This is a minimally invasive procedure used to cosmetically treat discolored, non-vital teeth. Intracoronal bleaching of endodontically treated teeth involves the use of sodium perborate (NaBO3) powder or gel with varying oxygen content.1,3 Sodium perborate is mixed with distilled water (2:1 gm/mL ratio) or with 3% H2O2 to form a thick paste. Sodium perborate hydrolyzes on contact with water, producing H2O2 and borate, where the H2O2 decomposes to produce nascent oxygen that degrades and eliminates crown staining. The most common causes of non-vital teeth staining are intrapulpal hemorrhage, pulp necrosis, certain endodontic medicaments, and coronal restorations. Endodontic treatment should focus not only on the biological and functional aspects but also on the restorative materials that may cause discoloration. Corrosion of silver points used in root canal filling can cause black discoloration, whereas zinc oxide-eugenol-based sealers are less likely to discolor. Calcium hydroxide-based sealants such as Sealapex do not cause dentin discoloration because of their limited penetration into dentin.29,30 Formocresol, mineral trioxide aggregate (MTA), Ledermix paste, and amalgam placed in the pulp chamber can cause grey to black discoloration.1,3,29 There are at least two bleaching techniques for endodontically treated teeth: Thermocatalytic and “walking” bleach. In the thermocatalytic process, the old coronal filling material is removed to a depth of 2–3 mm below the cementoenamel junction. The dentin is etched with 37% phosphoric acid for 30 s to remove the smear layer and increase the penetration of the bleaching agent into the dentin. A cotton pellet saturated with 30–35% H2O2 is placed into the debridement pulp chamber and heated with a controlled rheostat or lamp.1 Thermocatalytic can cause cervical root resorption.

Walking bleaching has become the most commonly used technique. It is so called because bleaching is carried out in consecutive appointments. The sodium perborate paste is placed into the debrided pulp chamber, avoiding contact with the enamel margins. A small dry cotton pledget is placed over the paste, and the cavity is sealed with IRM (intermediate restorative material). The process may need to be repeated every 3–5 days (Fig. 9).1,3 After bleaching is achieved, the cavity is restored with a glass ionomer base and composite resin restoration. Opalescence Endo (Ultradent, Inc.) whitening gel contains 35% H2O2 and is available in ready-to-use syringes. Before starting, a glass ionomer should be placed on the floor of the pulp chamber to seal the root canal against H2O2 penetration. The patient comes back after 1–5 days to have the teeth whitening gel removed and the restoration completed. Bleached teeth may experience 4–13% external cervical resorption, which significantly increase with using 30–35% H2O2. Using sodium perborate mixed with water minimizes the possibility of cervical resorption. The recurrence rate for endodontically bleached teeth is 10% after 2 years, 25% after 5 years, and 49% after 8 years.31

Figs 9A and B: Bleaching of non-vital tooth. (A) Pretreatment photograph showing a yellowish-brown discoloration of the maxillary right central incisor tooth resulting from endodontic treatment; (B) Clinical results after three sessions of the walking bleaching technique using sodium perborate paste29

PREVENTION OF TOOTH DISCOLORATION

Most tooth discoloration can be prevented through good dental and lifestyle habits. Understanding the cause of discoloration can greatly help maintain natural tooth color and a healthy smile. Causes include food, beverages, tobacco, environmental chemicals, certain mouthwashes, dental procedures, systemic conditions, dental trauma, poor oral hygiene, and medications. Maintain a consistent dental care routine that includes brushing twice a day, flossing daily, rinsing regularly, and having your teeth checked and cleaned by a dentist or dental hygienist at least twice a year. A professional dental cleaning that uses ultrasonic vibrations can remove stains deposited on dental plaque or calculus. Whitening toothpastes can also remove stained plaque and polish the tooth surface. Protects teeth from trauma and pulp injury. Here are the types of tooth discoloration and how to prevent them:

CONCLUSION

Tooth discoloration is esthetically displeasing, psychologically traumatizing, and socially unacceptable. Causes of tooth discoloration are multifactorial, with discoloration varying widely in type, severity, and treatment options. Discoloration is mainly divided into extrinsic and intrinsic types, a combination of both, and interclass types. Extrinsic tooth stains are incorporated into the dental plaque (biofilm), acquired pellicle, and tooth surface. They can be non-metallic or metallic in nature. Intrinsic tooth discoloration is caused by chromogens during tooth formation or after tooth eruption. Certain medications (e.g., tetracyclines), chemicals (e.g., fluoride), congenital/genetic disorders, and systemic diseases can cause dentition discoloration. There are a variety of treatment options for different types of tooth staining. Most extrinsic stains can be removed by effective tooth brushing, the professional use of prophylactic paste, or an air-jet polishing system. For deeper staining, micro- or macro-enamel abrasion combined with bleaching may be used. Whitening/bleaching treatments include OTC products, at-home and in-office bleaching using H2O2, carbamide peroxide for vital teeth, and sodium perborate for non-vital teeth. Tooth sensitivity and gingival irritations are the most common adverse effects of bleaching. The higher the concentration of the bleaching agent and the longer the treatment period, the greater the risk of tooth sensitivity. Dentists should have a good understanding of the types and mechanisms of stain formation so that appropriate treatment can be administered, as well as explaining to the patient the nature of the staining and prevention.

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