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How Whitening Works

Course Number: 657

Key Considerations for the Evaluation of Clinical Studies for the General Practitioner

Don’t be confused by shade claims, look for technical color change.

  • “5 shades whiter in three days”.

  • “95 % reduction in tooth stain”.

  • “Removes 10 years of yellow stains in two weeks”.

The claims for tooth whiteners create a challenge for the dental professional – how to interpret the science and how to counsel their patients. A comprehensive review of methods used in the clinical evaluation of whitening products is beyond the scope of this CE review – however some general principles can be outlined for the professional to assist in recommendations for their patients.

Why is it hard to know what the efficacy of a whitening product truly is? The answer is that clinical studies on whitening are relatively easy to do – patient selection and choice of index can create a seemingly remarkable level of tooth whitening for even an ordinary product with minimal efficacy. In addition, there are no established guidelines for indices used in tooth whitening clinical evaluations.

A few principles can be helpful here:

  • Studies that use stain indices (e.g., Lobene) are often used for efficacy studies of toothpastes and rinses. The high % of stain reductions observed in studies is not indicative of any degree of intrinsic whitening. The % are often obtained by careful patient selection. To be clear, pastes and rinses are effective in reducing surface stains and they are extremely useful in preventing tooth stains from recurring.

  • Use of shade guides can be misleading. The shade guide index is not linear in tooth color and clinician application of shade guides can be problematic at best. Seek research that employs objective digital measurements.

  • The clinical population where efficacy is seen can be very important in determining observed efficacy. Hard-to-treat populations including those with stains from tetracycline, cigarette smoking, or demonstration of whitening efficacy in a population post-prophylaxis, can be relied on to reinforce the efficacy claims of products.