Ask most dentists how often you should brush and you are likely to get the same answer: twice daily. But why? What makes brushing two times daily the magic number? What if you are susceptible to cavities, should you be brushing more often? Why do some people get cavities despite brushing religiously, while others never get cavities even when they skip days? There are myriad questions surrounding tooth brushing, some of which I will answer here, others I will save for future articles. In this article I plan to address brushing frequency, and when you should be brushing.
What Dentists Learn
Full disclosure, I only attended one dental school, so my experience is based entirely on the dental education I received. I don’t know about you, but before attending dental school I imagined rows of dental students lined up in neat little rows practicing tooth brushing on little dolls. I figured things like brushing frequency would be studied, memorized, and regurgitated ad nauseum. I mean, how many things does a dentist really need to know, right? In my mind, dental school looked a lot like elf school in Rudolf the Red Nosed Reindeer. Maybe that’s because Hermey wanted to be a dentist. If you’ve never seen that movie, just know that elves are mostly bad people who step on dreams and ostracize anyone who is different. And hey, Santa wasn’t all that nice either.
Now that we’ve thoroughly explored the childhood influences on my decision to become a dentist, let’s get back to the topic at hand. How often should you brush? In general, I advise my patients brush twice per day. But, patients who have a high caries (cavities) index should brush more often. What is a high caries index? Well, there are a number of ways to measure your susceptibility to caries, one of the more common methods is using an index called DMFT which stands for Decayed, Missing, and Filled Teeth.
Decayed Missing and Filled Teeth (DMFT)
The DMFT index is as straightforward as you might guess. We tally all of the teeth in your mouth that have decay, are missing, or have fillings. Assuming the average healthy American adult has 28 teeth, we look at how many of those teeth need or have needed dental treatment. If I find so many teeth have been treated that it’s easier to count the few that haven’t, then that person has a high DMFT. In that way, it is relatively easy to quickly ascertain your oral health status.
DMFT is a useful tool, but it may not paint a complete picture. Missing from the DMFT is the temporal relationship to past dental treatments. For example, some patients had extensive dental work in their teenage years, but haven’t had a cavity since. It is important to consider how recently patients have needed dental treatment when assessing their overall dental health.
Additionally, there may be other factors that lead to things like tooth loss that have nothing to do with oral hygiene. For example, a patient who was assaulted, played hockey, or was involved in a car accident may be missing many teeth. The factors that led to those forms of tooth loss are unrelated to the bacteria that typically causes cavities. So, we shouldn’t consider those lost teeth when making recommendations about tooth brushing frequency. There is no reason to increase how often you brush if you lost multiple teeth as a boxer.
When to Brush More Often
So far we’ve discussed reasons not to brush more often. And I’ve said that most people need to brush twice daily. But what factors could lead someone to need to brush more often? Below is a non-exhaustive list of reasons:
- Orthodontic treatment, whether braces or invisible aligners
- High DMFT score with recent fillings or cavities
- A highly acidic and/or high sugar diet
- Systemic factors such as diabetes or pregnancy
- Medications or diseases that cause dry mouth
One of the most overlooked factors leading to a sudden increase in cavities is dry mouth. Often, patients will take a blood pressure medication and notice that their mouth is dryer than usual, but think nothing of it. A year or two later, they suddenly experience a huge increase in the number of cavities. They may not make the connection to the blood pressure medication, the dry mouth, and the increase in cavities. Hopefully, your dentist will ask the right questions, or notice the sudden changes and seek to get to the bottom of it. In such cases brushing more often is helpful, but it may not be enough. Additional measures should be taken as well.
Another factor I see occasionally is patients who have developed an autoimmune disorder like Sjögrens Syndrome. Symptoms of Sjögrens include dry mouth and dry eyes. If you experience these symptoms along with a sudden decline in oral health, discuss Sjögrens with your dentist. If your dentist suspects Sjögrens, they will likely refer you to your PCP or a rheumatologist for further evaluation.
When Should I Brush?
We’ve established that you should brush twice daily unless you have reasons to brush more often. I never recommend anyone brush less than twice daily. But, a more difficult question is when should you brush? Some dentists will argue that you should brush before meals, and others will argue that you should brush after meals. The answer with currently available knowledge seems to be that it depends. When you should brush actually varies on an individual basis.
One the one hand, brushing after a meal removes the sugar that leads to cavities. But, brushing when there are acids on the teeth following a meal may lead to brushing away tooth enamel. So, the advice to brush before or after a meal depends a lot on your dietary habits and your oral health history. Below are some suggestions that are largely based on my professional judgment because there is scant evidence to support my recommendations:
| Factors | Recommendations |
|---|---|
| High sugar diet, acidic foods and/or acid reflux | Brush before meals |
| High sugar diet, non-acidic foods and no acid reflux | Brush after meals |
| Low sugar diet, acidic foods and/or acid reflux | Brush before meals |
| Low sugar diet, non-acidic foods and no acid reflux | Brush after meals |
| Pregnancy with vomiting | Avoid brushing for 30 minutes after vomiting |