In 2005 I started a PhD in physical chemistry with the title ‘Sonochemical analysis of the output of ultrasonic dental descalers’. In 2011, I was finally awarded my PhD and able to call myself a doctor!
Ultrasonic descalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the descaler. The spatial distribution of cavitation around three designs of descaler tips and under three load conditions has been observed using sonochemiluminescence from a luminol solution and compared with the vibratory motion of the tips in a water bath, characterised by scanning laser vibrometry. The type of cavitation was confirmed by acoustic emission analysed by a ‘Cavimeter’ supplied by NPL.
Surface profilometry and SEM of eroded hydroxyapatite pellets was performed to quantitatively study the erosion caused by a descaler tip in both contact and non-contact modes. Densitometry was used to study the erosion of black ink from a glass microscope slide, and determined that under the majority of conditions, no erosion was demonstrated via cavitation, by descalers operating in non-contact mode, although significant erosion was demonstrated with the tip in contact with the slide.
There is a PDF version of my thesis, as held at my university, available for download. Be warned that the PDF contains many large images, and is therefore over 150 MB in size, so will take some time to download. I will publish a git repository of the LaTeX source shortly.