In 2011 three senior-year dental students at the Sahlgrenska Academy, University of Gothenburg conducted a clinical trial with 38 patients using two over-the-counter tray-based bleaching products. Their supervisors were from the Institute of Odontology, University of Gothenburg and NIOM.
The study was done with the aim to detect any differences in bleaching efficacy and potential side effects of over-the-counter products in use at that time having concentrations below or above 6% hydrogen peroxide (corresponding to about 17% carbamide peroxide). The 6% hydrogen peroxide limit was set by the European Union the same year as the study was conducted, and the EU Cosmetics Directive (76/768/EEC) was adopted by the scandinavian countries a year later. Prior to the enforcement of this directive, consumers did not need a clinical examination before starting a bleaching treatment on their own.
The concentrations chosen were probably too similar to detect any difference. They bleached equally well, and were comparable to using a lower concentration, 10% carbamide peroxide, for a minimum of 15 hours as described in the literature. In comparison, the OTC treatment time was 10.5 hours and was the minimum recommended (by the manufacturers) time for the products. Although the well-known side effects tooth sensitivity and gingival irritation prevailed, several less frequently reported side effects occurred as well. These were e.g. tooth ache and sore throat.
The article also discusses differences in effects between tobacco and non-tobacco users, the use of spectrophotometry versus shade guides, and bias induced when using a visual analogue scale (VAS) for e.g. grading the intensity of an experience.
For further reading, please access the article online for free
Heinisch C, Larsson K, Mattsson J, Karlsson S, Alstad T and Bruzell E. Patient’s Satisfaction and Complications of Over-the-Counter Bleaching Products. Oral Hyg Health 2015, 3:2
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