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How Whitening Works

Course Number: 657


The growing array of tooth whitening product options – with varying efficacy, safety, cost, and differences in application methods and settings – elicit patient queries. Understanding tooth color etiology, the relative strengths and limitations of treatment options, and patient goals is important for effective guidance. Whitening can sometimes be achieved solely using OTC products with optimal abrasivity and/or chelant technology, such as specially-formulated toothpastes and rinses to aid in the removal and prevention of surface level extrinsic stains. Intrinsic tooth discoloration, however, requires oxidative technologies (e.g., peroxides, chlorites, peroxy acids) to achieve whitening via chemical reactions with stain components that decolorize teeth internally. Peroxide has the longest record of proven safety and efficacy; hydrogen peroxide is the most commonly used whitening agent today.

The efficacy and tolerability of bleaching products is contingent upon the agent’s concentration, dose, and contact time. Retention is imperative for effectiveness and varies by delivery system. Higher levels of bleach concentration and dose produce greater whitening more rapidly, but this must be balanced with the potential for teeth sensitivity and soft tissue irritation. For example, the innovation of at-home adhesive whitening strips with ‘controlled dose’ applied bleach at higher concentration allowed for optimal results while maximizing tolerability.

The specific bleaching agent’s delivery vehicle also impacts the intraoral reactivity and results. In-office treatments utilize short-term, high-concentration peroxide for maximum whitening, but with frequent sensitivity. Prescribed/OTC home use mouthguard/tray-based systems typically produce good results, they are dependent on fit and bleach concentration may similarly bring adverse effects. Professionally-applied Whitening Emulsions™ systems are a new two-phase technology, leave-on treatment formulated with a hydrophobic carrier to stop saliva from washing out the peroxide. Strip-based systems for home use have shown favorable tolerability with proven whitening efficacy. Paint-on systems and whitening pens are convenient, though they may be hindered by a lack of sustained retention for meaningful efficacy. Whitening toothpastes containing low levels of hydrogen peroxide can generate some benefit, but are again limited by the allowable concentration and contact time.

When evaluating clinical research claims for whitening products/treatments, keep in mind that some are related solely to extrinsic stain removal. Additionally, studies utilizing more objective measurements (e.g., digital imaging versus shade guides) are more likely to represent accurate whitening results.