ZENT FLEX TOOTHBRUSH REVIEW
Brushing your teeth with too much force can cause permanent damage to the vital tooth structure. But how much force is too much? The Zent flex toothbrush offers an elegantly simple solution that ensures you always brush with exactly the right pressure.
My initial impression of the idea behind the Zent Flex toothbrush was, “That’s brilliant!” There are similar concepts in electric toothbrushes that beep at you or flash a red light when the user uses too much pressure, but they don’t actually stop the force. We always advise patients to brush gently with a soft-bristled toothbrush. After all, it takes very little pressure to remove dental plaque from the teeth. But in my experience, there are some people who just can’t seem to lessen the pressure they use. The unique design of the clicking joint in the Zent Flex toothbrush may be exactly what they need.
Tooth enamel is the hardest structure in the human body, much harder than bones. It is possible, albeit difficult, to mechanically abrade (gradually wear away) enamel. Enamel abrasion is not our biggest concern with poor brushing technique, though.
There are two serious consequences of an aggressive toothbrushing technique: 1) gum recession, and 2) root abrasion.
Although poor brushing technique is not the primary cause of gum recession, it is certainly a contributing factor in many cases. The gum tissues surrounding the teeth are relatively delicate, so any inappropriate force can cause them to back away from that perceived injury. Gum recession in itself is bad because it is a loss of attachment between the teeth and the underlying jawbone. Gums that have receded do not grow back. Severe gum recession can require gum grafting surgery to repair the defects.
In the consideration of poor brushing technique, a recession is exceptionally bad because it exposes the roots of the teeth, increasing the risk for the second consequence of hard brushing: root abrasion. Root abrasion is much more likely than enamel abrasion because the roots of teeth do not have a protective enamel coating. Instead, the roots are covered in a thin layer of cementum, which is very susceptible to abrasion. Once the cementum is gone, the underlying dentin (the major component of teeth) is exposed, leading to a high risk for cavities and tooth sensitivity. Like gums, cementum and dentin do not regenerate on their own. If severe abrasion occurs, dental restorations might be necessary to repair the defects.
The Zent Flex mechanism of “breaking” the joint at 150g of force is appropriate based on scientific research about the force required to remove dental plaque versus the force that damages dentin. Research supports (and it just makes sense) that increasing force will increase plaque removal. That’s the whole point of brushing: to remove the sticky film of plaque that contains disease-causing bacteria. At some point, though, that increasing force will remove not only the plaque but also the dentin to which it is stuck!
The threshold of 150 grams of force is also an accepted standardized amount for Toothbrushing as the appropriate amount of pressure. We see this in the testing protocols that the American Dental Association uses in its Relative Dentin Abrasivity (RDA) index. They use 150g of force when testing the abrasion potential of various kinds of toothpaste.
The reason dentin is so essential to this conversation is that it contains tiny pores, called tubules, which create a communication between the oral environment and the nerve within each tooth. Chemical or mechanical processes that open or widen these tubules will open that communication, meaning you will be more likely to feel hot, cold, and sweet sensations in the nerve. This study shows that using a lower force when brushing actually helps to shrink those tiny pores, reducing sensitivity significantly.
[Side note: While sensitivity is a more common consequence of open dentinal tubules, we also need to worry about cavities. The open pores in dentin increase the risk for bacterial contamination, and therefore increase the risk for cavities on these exposed root surfaces.]
After using the brush myself, I was surprised to learn that I brush too hard! I am a dentist! Of course, I consider myself to be someone with a great brushing technique. During my first use of the Zentflex, it was hard to stop laughing at myself because the clicking joint broke over and over. I did feel, as I brushed, that I might have been missing areas, which caused me to pay close attention to how thoroughly I was covering the teeth.
The brush itself is comfortable and well-constructed. The bristles feel soft-to-medium-soft. (More importantly, they felt much softer after the clicking joint broke at 150g of force.) As I continued brushing, I noticed that I was gradually altering my technique to keep the joint from breaking, so I think this brush carries great potential for training people in the appropriate amount of toothbrushing force. If this is the only toothbrush you use, I believe that over time you would develop a brushing technique that would not cause the joint to break.
This toothbrush would be a wonderful tool for anyone with sensitive teeth, gum recession, root exposure, or simply a naturally heavy brushing technique. I recommend it for those particular people due to its protective abilities and its training potential. It also has the advantage of being much less expensive than the average electric toothbrushes that promote the same protective functions.
Dr. Lara Coseo
Dr. Lara Coseo, (DDS, FAGD) is a 2004 graduate of Baylor College of Dentistry in Dallas, Texas. Having practiced general dentistry for 13 years, Dr. Lara currently serves as an Associate Professor at Texas A&M College of Dentistry.