Sonochemical characterisation of ultrasonic dental descalers

• Ultrasonic descaling instruments used in dentistry have been characterised by sonochemical methods.
• Terephthalate dosimetry, luminol emission, surface cleaning show differences between different tip designs.
• Cavitation can promote ‘non-contact’ removal of material from a solid surface.
• Computer simulation of the acoustic pressure distributions explains in part the effect of size and shape of the descaler tips.

An ultrasonic dental descaling instrument has been characterised using sonochemical techniques. Mapping the emission from luminol solution revealed the distribution of cavitation produced in water around the tips. Hydroxyl radical production rates arising from water sonolysis were measured using terephthalate dosimetry and found to be in the range of μmol min−1, comparable with those from a sonochemical horn. Removal of an ink coating from a glass slide showed that cleaning occurred primarily where the tip contacted the surface but was also observed in regions where cavitation occurred even when the tip did not contact the surface. Differences in behaviour were noted between different tip designs and computer simulation of the acoustic pressure distributions using COMSOL showed the reasons behind the different behaviour of the tip designs.