The aim of this study was to assess what effect varying the concentration of bleaching agent would have on the response of stained teeth to bleaching. The data was explored further using Discussion 1, which shows a possible exponential relationship between hydrogen peroxide concentration and the number of applications required for an optimal clinical result. This data is also shown graphically in Fig. The number of applications ranged from one for the 35% solution to 12 applications for the 5% solution. Table 1 shows the number of applications required to produce the maximum change in tooth colour with the various concentrations of hydrogen peroxide. Prior to experimental use the teeth were examined for the absence of disease, cracks or other surface defects. It is likely that the enamel of the teeth had matured, since apical closure of the teeth was complete or at an advanced stage. 16 Third molar teeth, extracted from subjects aged between 18 and 30 years, were obtained from the Oral Surgery Department of Bristol Dental School. 16 The aim of this study was to investigate the effect that variations in the concentration of hydrogen peroxide from 5 to 35% had on the tooth whitening process.Įxtracted teeth were stained with a standardised tea solution using the method of Sulieman et al. Recently, a reliable in vitro method that quantitatively assesses the effects of tooth whitening products has been developed. To date, there has been little scientific study of the effect that various concentrations of hydrogen peroxide have during the tooth whitening process. However, all concentrations produced a bleaching effect if used for long enough. 14 A laboratory study has found that a 15% carbamide peroxide solution bleached more quickly than a 5 or 10% solution. 13 Similarly, power bleaching agents using 35% hydrogen peroxide with or without light and/or heat activation has also been shown to be effective. These so called ‘power bleaching’ techniques use concentrated hydrogen peroxide solutions of up to 35%.Ī variety of case reports and small clinical studies have shown that a 10% carbamide peroxide gel used in a bleaching tray at night produces predictable results,4., 5., 6., 7., 8., 9., 10., 11., 12. These penetrate into the tooth to oxidise chromogens present. 3 These are usually applied under rubber dam and a strong light source is applied to the bleaching gel to accelerate the breakdown of hydrogen peroxide into oxygen and per-hydroxyl free radicals. 2 Also available are surgery-based products whose application needs to be supervised by a dental practitioner. This so called night guard vital bleaching technique tends to favour the use of 10% carbamide peroxide. 1 However, contemporary techniques involve the application of hydrogen or carbamide peroxide based gels in a bleaching tray that is worn for up to 8 h each night. The technique of bleaching or whitening teeth was first described in 1877. Over the last decade or so there has been renewed interest in the topic of tooth whitening. Many patients are keeping their teeth for longer but dislike the physiological darkening process that follows the laying down of secondary dentine.
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