Abstract:

BACKGROUND
Bleaching technology has developed very quickly during last years and this is the reason why pharmacology industry has made new products with different concentrations and new systems to accelerate bleaching agent effect at dental office and at home, to answer increasing patients demand. Light and heat enhance tooth bleaching capacity and can be an effective tool combined with bleaching agents at low concentration which avoid soft tissue damage but can produce tooth sensitivity.

OBJECTIVES
To check the effectiveness of a bleaching tooth system with 9% hydrogen peroxide and light and heat at dental office, the degree of sensitivity due to this method, and the simplicity to be applied at a first level by a group of postgraduate students, in a second level by undergraduated students as a simple system with low risks.

MATERIAL AND METHOD
A selection of 17 patients involved in the Esthetic Dentistry Master in the Faculty of Odontology at the Complutense University of Madrid was made.
Patients included had intact upper-anterior teeth from one canine to the canine on the contralateral hemi-arch and had tooth shade A2 or darker.
A group of 12 postgraduate students applied the treatment. They first observed the initial numerical shade values, compared with VITA Classic guide from canine to canine.
A divided mouth model was used for the study, treating one hemi-arch with the Meta-Tray system to apply 9 % hydrogen peroxide activated with light and heat. This device is made of a plastic tray with a light and heat system inside conected to a battery. The other hemi-arch was used as control.
Patient sensitivity was scored by verbal and visual scale.
Statistical Analysis: The Wilcoxon signed ranks test was used to compare differences in tooth shade values between before and after the bleaching and to compare mean post-treatment values between test and control hemi-arches. The S.A.S. (9.1) software package was used for the statistical analyses.

RESULTS AND CONCLUSIONS
Results were compared from one treated hemi-arch with the contralateral as control. Meta-Tray system with 9% hydrogen peroxide groups is capable of lightening tooth shade, specially lateral incisor. The overall mean whitening in shade was 1,85 units for the side treated.
There were no soft tissue damage and no pacient reported sensitivity.
This technique has shown to be applied successfully and safety by postgraduate students and it is a simple method to be used by undergraduate students.

Keywords:

whitening, bleaching agent, hydrogen peroxide, at dental office, at home, light, heat, sensitivity.