Role of tiny bubbles in teeth cleaning identified

The formation of tiny bubbles around the head of ultrasonic scalers, used by dentists to remove built-up plaque, is key to the cleaning process of teeth, researchers, including one of Indian-origin, have found.
Scientists from University of Birmingham in the UK observed the bubble formation, or cavitation, of water around the head of the scaler using high speed cameras.
They compared scalers of differing power and head shape to quantify the patterns of cavitation.
A Satelec ultrasonic scaler, operating at 29 kilohertz with three different shaped tips, was studied at medium and high operating power using high speed imaging at 15,000, 90,000 and 250,000 frames per second, and the tip displacement was recorded using scanning laser vibrometry.

"Removing dental plaque and calculus, that is the build-up of what we know as tartar or hard plaque, is a big part of maintaining oral health and a regular occurrence in dental check-ups. These findings will help us to understand how to make the tools as effective as possible," said Damien Walmsley from University of Birmingham.
Researchers were not only able to show that cavitation occurred at the free end of the tip, but that it increases with power, and the area and width of the cavitation cloud varies for different shaped tips.

They believe that the methods developed in the study will help to test new instrument designs to maximise cavitation, with the aim of designing ultrasonic scalers that operate without touching the tooth surface. By doing so, the process of teeth cleaning at the dentist would become both less painful and more effective.

"Other studies we have done, using electron microscopy, have shown that removal of plaque biofilm is increased when cavitation is increased. Putting the pieces together, we can therefore say that altering the shape and power of these commonly used tools make them more effective, and hopefully, pain-free," said Nina Vyas from University of Birmingham.
The findings were published in the journal PLOS ONE.