Increasing Cavitation around Dental Ultrasonic Scalers to Improve Biofilm Removal Efficiency: A High Speed Imaging and Image Analysis Study
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- Ris (Zotero)
- Reference Manager
Dental ultrasonic scalers are used to remove plaque and mineralised deposits from teeth. Cavitation occurs in the cooling water flowing over the tip and may be used to enhance removal of the biofilm. Our research shows that cavitation occurs around the bend of the scaler tip and at its free end. By increasing the amount of cavitation, the instrument can potentially be used in a novel non-contact mode. The metal tip of the scaler will not touch the tooth surface allowing the cavitation to undertake the removal. This non-touch cleaning will reduce the present damage on both teeth and dental implants, which may be damaged by contact with the metal scaler tip. The aim of this study was to modify an ultrasonic scaler tip and image it with a high speed camera to determine the increase in cavitation. An ultrasonic scaler (P5 XS Satelec, Acteon) operating at 29 kHz at the medium power setting was imaged with tip 10P using a high speed camera (Shimadzu HPV1) at 1,000,000 fps. Imaging was done with the tip immersed in distilled water preventing spray from the scaler. The outer edge of the free end of the tip was ground and polished manually (DAP-7, Struers, Ballerup, Denmark) using P500 and P4000 SiC paper until horizontal. These alterations were made to increase the pressure drag, which would create lower pressures and consequently increase the cavitation. Image segmentation was done using a semi-automatic machine learning approach to calculate the area of the cavitation occurring at the free end of the original and modified tips. The mean area of cavitation around each tip was calculated from 102 images. There was a statistically significant difference between the amount of cavitation occurring around the modified and original ultrasonic scaler tip. The area of cavitation around tip 10P was 0.27±0.05 μm2 and the area of cavitation around the modified tip was 0.35±0.07 μm2. High speed imaging also showed that there was cavitation present at the point of the free end in the modified tip but not in the original tip. This will be clinically useful as the point of the tip is the part closest to the tooth surface when in use. These results propose that cavitation from an ultrasonic scaler may be used to remove dental plaque without damaging teeth. This method also has potential to be used to clean dental implants.