Written by Raymond Nakamura
Once upon a time (before the Internet), Raymond earned his doctorate studying the hydrodynamics of sand dollars. Nowadays he rents his brain at raymondsbrain.com for writing, cartooning, and thinking, when he is not washing the dishes, walking the dog, or helping his daughter with homework. Follow him on Twitter @raymondsbrain.


Created date

Wednesday, April 17, 2013 - 10:33am

How do Ultrasonic Teeth Cleaners Work?

My dental hygienist seemed to be spending more time spraying my teeth than scraping them, so I decided to check up on this. Turned out she was using an ultrasonic tooth scaler. I decided to poke around a bit to find out more.

Dog Eared
Ultrasound is sound above the limit of human hearing, around 15,000 Hertz (Hz, vibrations per second). Supposedly, the Beatles included some ultrasound on their Sgt. Pepper's Album to drive dogs crazy.

Applications
On a more practical level, difference frequencies of ultrasound can be used in all kinds of applications, from scanning a developing baby, to controlling pets, to cleaning teeth.

Good Vibrations
Ultrasonic tooth scalers use transducers that convert electricity into mechanical energy using materials like quartz crystals or specialized ceramics that change shape with electricity (piezoelectric) which generate up to 50,000 vibrations per second or by changing magnetic fields (magnetostrictive) which go up to 25,000 vibrations per second.

Under Pressure
These vibrations produce microscopic high and low pressure areas. This results in cavitation, which might sound bad for cavity prone teeth, but it means the formation of bubbles filled with water vapour rather than air. The vibration stretches and compresses these tiny bubbles until they implode and release a burst of heat and pressure. This energy loosens stuck particles, but it happens on a tiny scale with enough water as coolant so I don't notice this tempest in my tooth spot.

I find it more pleasant to have my teeth cleaned this way and less with the scraping, but ultrasound may add extra wear on metal implants, so it might be worth discussing the pros and cons of this technology with your dentist or hygienist.

Comments

please help me, how do

please help me, how do vibraitions clean teeth

I just had my teeth cleaned

I just had my teeth cleaned an hour ago by this method. I was expecting this cleaning to be painful. It was completely short of that. This was way better than the old fashioned scraping method. This makes me want to go back to the dentist routinely.

I also asked for ultrasonic

I also asked for ultrasonic method for tooth cleaning. Is the best method. the results are visible right away.

And for all we know it could

And for all we know it could be causing all kinds of microscopic damage to our cells. Ultrasound obviously has weird and unpredictable effects on biology, I'm afraid I'll have to stick with the old scrapers for the time being.

The high pitch sounds are

The high pitch sounds are overwhelming -- much worse than the 15,750 Hz I could hear from the horizontal oscillators on old TV sets back in the 1950s and '60s. They should provide soundproof headphones when doing this.

Your claim of being able to

Your claim of being able to hear 16kHz is one thing, but your claim of being able to hear the ultrasonic frequencies of dental scalars is something that no human being has ever demonstrated.

If you're under the age of 39

If you're under the age of 39, apparently 15khz is clearly audible. The human ear is capable of hearing frequencies ranging between 20hz and 20khz with the upper frequencies being less audible with age. I just did a quick search for 15khz tone and came across a video that played a 15khz sinewave. I could clearly hear it but maybe that's because I am under 39 years of age.

The average range of human

The average range of human hearing is approximately 20Hz-20,000Hz, with younger people being able to hear higher frequencies than older people. I'm 34 and I can still hear 20,000Hz. A train station installed anti-loitering devices a few years ago that played annoying, high-pitched frequencied that "only teenagers" could hear. They ended up removing them because they were annoying people in their thirties. I can also hear the sound of the picture tube in CRT TVs. I can tell if a CRT TV is on somewhere around me even if it's muted and I can't see it.

The ultrasonic scaler tips

The ultrasonic scaler tips are autoclavable. This means they are put in a sealed pouch and go through a sterilizer that reaches a certain temperature and pressure regulated by the government.

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