About one-third of Americans use electric toothbrushes of some type. Some believe a powered toothbrush cleans better than a manual brush with flossing. Others find them more convenient, or more pleasing in some other way. Electric toothbrushes are a well-established oral hygiene option. Hence, it’s well worth a review of the technology, their safety, and their effectiveness.
The first electric toothbrush was brought to market in 1927 by the Electro Massage Tooth Brush Company, USA. In 1940 a US patent for an electric toothbrush design was granted to Tom Moseley. In 1954 a Swiss Dr. Woog invented the Broxodent design. These three designs drew electrical power through a cord, from wall outlets. Plainly a dangerous setup, especially around water. Interestingly, these early designs were oriented toward people with limitations that made manual brushing difficult or impossible. Superior cleaning for the general population was not a priority for these inventors.
The General Electric Automatic Toothbrush was introduced in 1961. This device was cordless and rechargeable. It looked and worked much like the powered toothbrushes of today. Unfortunately, battery design was (and still is!) lagging behind the rest of the technology. Thus, the primitive batteries in this GE brush were so toxic and dangerous they were sealed into the handle. They couldn’t be changed when their short useful life was over. The whole brush had to be replaced.
Finally, in the 1990s the US and Canada came up with new safety regulations that forced design updates across the board. The electric toothbrush as we now know it was born. Safer and more trouble-free, they were rapidly adopted by the mass market.
TYPES – ROTATING, SONIC, ULTRASONIC
Today’s electric toothbrushes are of three types. All of them use battery power to impart motion to the brush itself. The differences are in the kind of motion and in the speed of the motion.
ROTATING ELECTRIC TOOTHBRUSHES
Rotating designs generally have small, round brushes. The bristles are rotated around a tiny axle, either in complete circles or in half-turns back-and-forth. The source of the motion is an electric motor. It’s transmitted through a gear-and-cam system. The speed is relatively low, around 1,300 -8,800 “strokes” per minute. Some pricier models jazz up the scrubbing action with a high-frequency pulsating movement. The brush itself is the only part of the device that moves.
Rotating electric toothbrushes have low price to in their favor. They’re the cheapest entry to powered brushing. They work to clean and remove plaque by scrubbing, just like a regular toothbrush does. Thus, users can brush the way they learned to with manual toothbrushes. Note that due to the small brush heads, the makers recommend cleaning one tooth at a time.
SONIC ELECTRIC TOOTHBRUSHES
Sonic brushes differ in two ways. First, the motion of the brush head is oscillation, not rotation. There’s no motor inside the handle. Instead, these brushes use exotic components like the piezoelectric transducer, which convert electric current to very high-speed vibration. The entire brush head vibrates, rather than just the brush itself.
Sonic bristles move much faster than simple rotary brushes do. In reality, the term “sonic” with regard to toothbrushes has no scientific meaning. Government and industry definitions vary. Most electric toothbrushes on the market today are termed “sonic”. They vibrate at speeds in the range of 12,000-24,000 movements per minute. That’s 200-400 Hz. By the way, the hum we hear is somewhere around middle C on the piano! Indeed, an audible hum is one of the defining features of sonic toothbrushes.
The brush heads of sonic toothbrushes are generally larger than those of rotaries. Brushing technique is similar, with one twist. Sonic brushes do provide a scrubbing action, like manual and like powered rotary brushes. However, the point of the very high vibration speeds is a different, no-contact cleaning action. Designers believe that the fast vibration produces cavitation or turbulence in the toothpaste and mouth liquids. They intend the turbulence to dislodge debris and plaque even beyond where the bristles are actually touching the teeth. As we noted, some rotary brushes have a high-speed pulsing feature. This borrows from the sonic design, and adds turbulence to the rotary scrubbing.
The idea behind ultrasonic toothbrushes is to ramp up the vibration speed and turbo-charge the no-contact cleaning effect. Here the FDA has set a standard. In order to qualify as an FDA ultrasonic, a toothbrush must oscillate at 1.6 Mhz or more. As noted, sonic brushes vibrate in the 200-400 Hz range. The 1.6Mhz speed of an ultrasonic translates to 192,000,000 movements per minute. The ultrasonic cleaning action is strictly by turbulence.
In contrast to the rotary brushes “souped up” with high-speed pulsation, many ultrasonics are “souped down”. That is, designers add a sonic-range (slower) vibration pattern, which in turn adds a scrubbing action.
The brushing technique with an ultrasonic toothbrush isn’t really brushing at all. Rather, the bristles simply rest on the teeth. Vibration and turbulence do the rest. The user just gently passes the brush head over the surfaces of each quadrant. Top inside, top outside, etc.
EFFECTIVENESS OF POWERED TOOTHBRUSHES
Now we come to the Big Question. Do electric toothbrushes work better than regular ones? Let’s stop for a second and step back. Maybe that’s not really the right question. Maybe what really matters is whether an electric toothbrush will work better for you. That’s not quite the same question.
The difference is in the details. Some research shows that other things being equal, powered toothbrushes have an edge. That is, they are better at reducing plaque and gingivitis. The more recent studies tend to support this finding.
Bottom line, research has produced mixed verdicts comparing manual vs. sonic vs. ultrasonic. It’s chaos. For example, one study of the supposed cavitation effect was unable to find any cavitation. However, there’s no sign at all that powered brushes are less effective than manual. Thus, by going electric, there’s nothing to lose but some money.
THE DEVIL IS IN THE DETAILS
Let’s deal with the mixed research findings. The thing is, in real life beyond studies, other things are not equal. There’s the human factor. Look, if using a powered toothbrush gets a person to brush more often, that’s good for his or her hygiene. Likewise, if buying a new electric brush leads the user to bone up on brushing technique, that’s a plus, too.
On the other hand, there’s also something called “offsetting behavior”. In this case, that would be a new user tending to brush less often or less completely with an electric. In other words, relating to the electric toothbrush as a time-saver. Not good for hygiene. Neither is slacking off from flossing, as if a powered brush makes it unnecessary. That’s not so.
Whether you’re thinking of going electric or are already, tap your dentist’s knowledge to set your policy. You’re an individual human being. Your dentist knows your mouth and knows you. If you opt to stay with electric or move to it from manual, discuss models and how to use them properly. If you’re concerned about technique, look at one of the Bluetooth-enabled models. These provide feedback on brushing technique and keep records to keep you honest.
Then, your next checkup will tell the tale.