Teeth Whitening. Techniques, Indications and Care

Dentin is primarily responsible for determining the natural color of teeth, but factors such as enamel thickness, translucency, mineralization, and color also contribute. Enamel may carry subtle blue or pink hues, which combine with the underlying dentin’s shades that vary from yellow to brown, creating diverse natural color variations. However, any changes in dentin or enamel during development, while teeth are erupting, or after teeth have emerged can alter light transmission, resulting in discoloration (change in color).

Teeth whitening is a non-invasive method to enhance aesthetics, making it highly appealing to both dentists and patients. Modern whitening techniques rely on hydrogen or carbamide peroxide, activated through heat, light, or chemical processes. Whitening agents can be applied externally or also internally if teeth are non-vital. The goal is to bleach the chromogens within the dentin, so those staining agents are destroyed, so that the tooth’s base color is effectively altered.

Enhance your dental expertise with our comprehensive course, "Teeth Whitening: All The Techniques." Learn modern, safe, and effective teeth whitening methods to offer your patients brighter smiles. Whether in-office or at home, you’ll gain the skills to confidently select the best whitening approach for any clinical case. Join now and elevate your practice with cutting-edge techniques!

Achieving optimal whitening results requires a thorough examination in order to understand the causes of tooth discoloration, which range from lifestyle habits like smoking to pathological processes in the pulp and periodontium. 

Tooth discoloration is categorized into extrinsic and intrinsic discoloration, each requiring different approaches for treatment.

Extrinsic discoloration:

• occurs due to surface factors: pigments, dental plaque, smoking, medications (e.g., chlorhexidine, fluoride), and metals
• these chromogens (staining agents) remain on the tooth's surface and can often be removed through professional cleaning

Intrinsic discoloration:

• results from systemic conditions or diseases affecting the tooth's internal structure, typically dentin
• such stains cannot be addressed with regular hygiene and require advanced whitening techniques
• internalized discoloration involves external chromogens penetrating the tooth structure through defects and are embedded in the tooth’s structure, often in the dentin

Other types of discoloration are localized (affecting one or a few teeth) or generalized, as well as prenatal (due to genetic conditions or maternal health during pregnancy) or postnatal. 

Prenatal causes include:

• enamel hypoplasia
• fluorosis
• tetracycline exposure during tooth development

Postnatal causes can include:

• trauma
• pulp diseases
• improper endodontic treatments, often resulting in devitalized staining

With teeth aging, such changes as enamel thinning, cracks, and secondary dentin formation cause teeth color changes to be more yellow and transparent. 

Modern advancements in dentistry have made teeth whitening a highly effective solution, provided a thorough analysis of the patient’s needs and contraindications is conducted.

Indications for Teeth Whitening:

• Uneven tooth color among neighboring teeth.
• Age-related discoloration.
• Genetic yellow or gray shades in younger patients.
• Staining from food, tobacco, or fluorosis.
• Tetracycline-induced discoloration.
• Post-trauma or devitalized tooth discoloration.
• Pre- and post-restorative treatment to match restoration color with the natural teeth.

Contraindications for Teeth Whitening:

• Unreasonable patient expectations or unwillingness to replace existing restorations.
• Patients under 16 years of age.
• Pregnancy or breastfeeding.
• Severe systemic conditions.
• Conditions like imperfect amelogenesis or dentinogenesis.
• Allergic reactions to whitening agents.
• Severe sensitivity, enamel cracks, or exposed dentin.
• Large restorations, crowns, or veneers in the aesthetic zone.

Whitening Techniques:

1. Professional (In-Office) Whitening: Usually brings faster results and is suitable for those patients who are unable to use home systems due to time constraints or oral conditions (e.g., bruxism, TMJ disorders). High-concentration peroxide agents (25–50%) are used with activators like heat, light, or laser to enhance effectiveness. Proper evaluation of the root canal seal, barriers between the canal and whitening agents for devitalized teeth, and effective isolation and protection of soft tissues are crucial.
2. At-Home Whitening: By using lower-concentration agents (3–6% hydrogen peroxide or 10–22% carbamide peroxide) applied via custom-made trays is considered to be a cost-effective solution. This method is flexible, accommodating both day and nighttime schedules, but it requires compliance.
3. Combination Whitening: Blends in-office and at-home techniques for enhanced results in complex cases.
4. Deep Bleaching: Involves nightly use of custom trays with carbamide peroxide for 14 days, followed by an in-office session with hydrogen peroxide.

Mechanism and Activation Methods for Teeth Whitening

Such staining agents as chromogens, either accumulating on the surface of the teeth (extrinsic) or embedded within their structure (intrinsic) cause tooth discoloration. Chromogens are large organic compounds containing double bonds in their chemical structure. Whitening these chromogens involves releasing free radicals from peroxide-based agents, which penetrate the tooth's hard tissues and alter the chemical structure of the protein matrix. Free radicals break down complex carbon rings into long linear chains and convert double bonds into single bonds.

This chemical transformation reduces the absorption of light, enhancing its reflection and refraction, resulting in a brighter tooth appearance. The goal of whitening is to maximize light reflection from the brightened dentin.

Modern whitening systems are typically based on applying substances containing hydrogen (H₂O₂) or carbamide peroxide combined with activation methods. Hydrogen peroxide serves as a potent oxidizer, releasing free radicals, reactive oxygen molecules, and peroxide anions. The activation process can be enhanced by increasing the temperature, applying light (wavelengths of 480-520 nm), or using a laser. An alkaline pH (>6.2) optimizes the reaction, increasing the release of perhydroxyl radicals (HO₂), the most reactive agents for whitening. However, when the pH drops below 5.2, hydroxyl radicals can affect the mineral components of enamel, leaching calcium and phosphate ions and risking enamel demineralization.

Non-Activated Whitening

One advantage of chemical reactions without external activation is the lack of thermal impact on the tooth, reducing the risk of pulp damage and sensitivity. Additionally, it eliminates the need for expensive equipment, lowering procedure costs. However, this method is considered more time-consuming for reaching better results.

Laser Whitening

With the introduction of lasers, laser whitening was supposed to bring faster and more effective results, particularly for severe discolorations like staining induced by tetracycline or fluorosis. Even though effective, laser whitening can sometimes cause higher rates of sensitivity during and after the procedure. Its high cost and the tendency of some systems to dry out the teeth also pose challenges.

Light-Activated Whitening

Light activation is widely regarded as one of the most effective methods because it enhances the speed and stability of the results. Popular systems use light for accelerating the breakdown of hydrogen peroxide, minimizing exposure time and reducing potential enamel damage. Shorter application times also help reduce the risk of sensitivity.

This method delivers prolonged and stable results, which are a key consideration for patients. The energy from light sources enhances the reaction by transferring kinetic energy to atomic oxygen, allowing it to penetrate pigmentation zones more effectively. The choice of light source is critical, as powerful lights can minimize exposure time while maintaining safety and comfort.

LED Technology in Whitening

LED (Light Emitting Diode) systems are a popular choice for light-activated whitening. Operating in the blue spectrum (450-500 nm), LED lights are energy-efficient, long-lasting, and safe. Unlike lasers, they do not produce UV radiation or significant heat, greatly reducing the risk of sensitivity. These systems are simple, affordable, and capable of targeting multiple teeth simultaneously, making them a favorite for quick and effective whitening.

Recommended Protocol for Teeth Whitening

Preparation Phase

Before starting the teeth whitening procedure: 

1. Identify the causes of discoloration and record them in the patient’s file. A thorough evaluation of the patient’s complaints, medical history, and oral examination is essential
2. Discuss potential solutions (e.g., whitening, or such restorations as veneers, crowns) and agree on a treatment plan.
3. Conduct a thorough evaluation, including assessing tooth vitality, enamel-dentin junction integrity, and sealing any exposed areas with glass ionomer cement.
4. Each tooth slated for whitening must be assessed for vitality, decay, cracks, gum recession, exposed dentin, and other dental tissues defects. X-rays are recommended to identify periapical pathology, evaluate pulp size and vitality, and predict potential sensitivity.
5. Capture pre-treatment photos under natural lighting using a color shade guide for documentation.
6. The preparation phase includes a professional cleaning to remove dental plaque and calculus.

Patient Consultation

Before whitening a detailed discussion with the patient is a must.A lack of information and unfamiliarity with the procedure often lead to skepticism about teeth whitening among patients. The dentist must educate the patient about the process, potential complications, preventive measures, and realistic outcomes.

Managing patient expectations is essential, as whitening effectively treats surface stains, age-related discoloration, and post-trauma staining, but may not produce optimal results for congenital or acquired discoloration (e.g., fluorosis, tetracycline staining) or heavily restored teeth. Patients seeking “dazzling white” teeth should be guided to expect a “refreshed appearance” or a “brighter shade” instead.

Communication is a key! It builds trust, ensures patient satisfaction, and enhances treatment outcomes. Learn how to create a more effective and enjoyable professional relationship with our course “Patient Communication and Dental Office Management: Protocols, Clinical Tips, and Strategies”. Master the art of strong communication and learn the necessary skills for explaining procedures, benefits, and risks in a way patients can understand and be encouraged to cooperate!

Additionally, patients should be informed that the color stabilizes about 2 weeks post-treatment, often appearing slightly darker due to natural enamel rehydration following dehydration during whitening. Existing composite restorations, veneers, or crowns will not change color and may require replacement to match the new shade. Highly translucent teeth may remain grayish post-whitening, which should be discussed beforehand.

Once the patient understands the process, limitations, and expected outcomes, they should provide informed consent by signing the treatment plan.

Post-Whitening Recommendations

To maintain whitening results following instructions are to be given to the patients:

• Brush twice daily, floss regularly, and schedule professional cleanings.
• Avoid foods and drinks with staining potential (e.g., red wine, coffee, tea, soy sauce, berries, and artificially colored beverages) for seven days post-treatment.
• Refrain from smoking.
• Inform patients that touch-up whitening sessions may be necessary depending on diet, oral hygiene, and smoking habits.

If sensitivity occurs, recommend desensitizing toothpaste and remineralization therapy. Allow 2 weeks between whitening and restorative treatments to stabilize tooth color and ensure proper bonding of materials.

Complications and Prevention

The most common side effects of whitening are temporary tooth sensitivity and soft tissue irritation. Sensitivity occurs due to the lowering of pH during whitening, leading to enamel demineralization and increased dentinal tubule fluid movement, consistent with Brännström’s hydrodynamic theory.

To minimize these effects:

• Use desensitizers before whitening for patients with a history of sensitivity.
• Apply remineralizing gel post-whitening to restore enamel strength.
• Opt for non-heat-activated methods for internal whitening of non-vital teeth to prevent root resorption.

Composite restorations may become rougher, lose microhardness, or darken faster post-whitening. Delaying restorative work for two weeks post-whitening allows residual hydrogen peroxide to dissipate, improving adhesive bonding.

Composite restorations do not whiten like natural teeth. If they are discolored or poorly matched, the teeth may appear uneven after whitening, compromising the aesthetic outcome. Moreover, damaged or improperly sealed restorations can allow whitening agents to seep into underlying tooth structures, leading to irritation, sensitivity, or even pulp damage. By addressing restorations before whitening, dentists can achieve safer, more predictable, and aesthetically pleasing results –that is why we want to invite you to join our course “Composite Restorations: Science-Driven Approach” and deliver exceptional results for your patients! Explore cutting-edge techniques for anterior and posterior restorations, adhesive protocols, and material analysis to master every step of the restorative process. Learn to create minimally invasive and durable restorations using the latest layering and photoactivation techniques.

Adhering to proper techniques, selecting the right products, and incorporating remineralization steps are essential for ensuring a safe and effective whitening process while minimizing adverse effects.