Correlation of vibrometry and cleaning effects in ultrasonic dental instruments

One application of physical acoustics is the development of ultrasonic dental instruments for cleaning purposes including descalers and endosonic files. The vibration characteristics of these instruments have been measured by scanning laser vibrometry, SLV. One possible contribution to the cleaning processes is cavitation and we have been using sonochemical methods to characterize cavitation around dental instruments. For example, significant amounts of sonoluminescence can be produced at the vibration antinodes of the endosonic files and there is good correspondence between regions of cavitation and large vibration. The cleaning efficacies of the files were studied using an irrigant used in endodontics (sodium hypochlorite) to bleach a dye (Rhodamine B). Results showed that ultrasound accelerates the rate of degrdation of the dye. For a range of different file shapes and sizes, there was a correlation between sonoluminescence and Rhodamine B degradation although the chemical effects of each files depended on their design. A comparison of the chemistry with the SLV results should allow the optimization of cavitation production along the endosonic files by modifying their shape to increase the cleaning efficacy for benefit in treatments.