2479 Effect of Dentin Exposure on Tooth Whitening and Penetration of Bleaching Agents into the Pulp Chamber
R.H. WONG1 , R. PATABI CHETA RAMAN, and S. KANAGASINGAM, 1 Faculty of Dentistry, Kuala Lumpur, Malaysia
Objectives: Clinically, teeth with exposed radicular dentin may experience increased sensitivity to bleaching agents. This laboratory study is aimed at comparing the quantity of hydrogen peroxide entering the pulp chamber of teeth with and without exposed root dentine using 10% carbamide peroxide bleaching gels. Bleaching efficacy was also assessed. Materials and methods: Forty six roots of freshly extracted human premolars were amputated 3mm apical to the cementoenamel junction. They were divided into 4 experimental groups (n= 10) and a control group of 6 teeth. An acetate buffer was placed into each pulp chamber before the tooth was exposed to the bleaching agents at a controlled temperature of 37oC for 30 minutes. The buffer solution was then reacted with a leucocrystal violet and horseradish peroxidase. The optical density of the resultant blue color was measured by a UV-visible spectrophotometer (Shimadzu UV 160A) at a wavelength of 596 nm A standard curve was used to determine the amount of hydrogen peroxide present. Tooth color changes were also detected by a Dataflash 100® spectrophotometer.
Results: The measured amounts of hydrogen peroxide were 0.5398 ± 0.480 and 0.327 ± 0.097 µg for Vivastyle™ with and without exposed root dentine respectively. In Opalescence™, the amounts were 0.459 ± 0.187 and 0.427 ± 0.121 µg for teeth with and without exposed root dentine respectively. The quantity of hydrogen peroxide present was not statistically different (p>0.05) with or without exposed dentin. There was also no correlation between tooth whitening measured quantitatively and the quantity of hydrogen peroxide entering the pulp chamber
. Conclusions: The amount of hydrogen peroxide leaching into the pulp chamber from bleaching gels is not significantly affected by a 2mm exposure of root dentin. Seq #257 - Biocompatibility of Dental Materials; Pulp Capping 11:00 AM-12:15 PM, Saturday, 28 June 2003 Svenska Massan Exhibition Hall B