Investigation of the Bleaching Agent Effects Using Atomic Force Microscopy

Objectives: Investigation of effects of bleaching agents on tooth hard-structure has been a subject of interest. We performed an extensive quartz crystal tuning fork Non-contact Atomic Force Microscopy (NC-AFM) study to examine these effects at nanometer scale. AFM is a current observation and measurement technique, which can sense very small interatomic forces and also provide atomic resolution. The use of AFM in dental research has rapidly grown because it does not require special specimen preperation that modifies the specimen structure and also by this technique three dimensional surface images can be obtained. Methods: Dentin sections taken from non-carious teeth extracted because of periodontal diseases and embedded in acrilic stents have been polished. Then, these specimens have been examined by NC-AFM in two groups as with and without smear layer. Upon applying 30% and 10% H2O2 solutions, and distilled water+NaPerborate paste for 15 minutes same specimens have been reexamined by NC-AFM. Results: NC-AFM images and depth profiles have demonstrated that the smear layer has to be removed in order to evaluate the effects of bleaching agents correctly. It has been observed that both H2O2 solutions deepen the grooves; their deepening effect increases with increasing concentration. However, distilled water+NaPerborate paste makes specimen surfaces smoother, it even decreases the depth of grooves. Conclusion: Atomic Force Microscopy, in particular quartz crystal tuning fork NC-AFM used in the present study has proven to be very powerful experimental technique, which is capable to provide high resolution and sustainability in the course of a sequential experiment.