I brush and floss, but I still get cavities! Why?

Written by Laura Ellefson, DMD May 19 • 3 minute read

Most people grow up learning some basics about cavities and how to avoid them: “Just brush twice a day, and don’t forget to floss!” Yet, it seems as though many unlucky people follow all of their hygienist’s advice to the letter and still wind up with a load of fillings. Why? As a dentist, I’ve heard too many times a patient say “I just have bad teeth.” They sound discouraged and willing to give up all together. But hold on. Maybe there are more factors out there that contribute to cavities and, maybe there’s something we can do about it! This post will summarize the gist of what’s explained in a book we’ve been reading and discussing in our office lately called "Why Me?" by Dr. V. Kim Kutsch, DMD. Future posts will dive into some of the more important concepts more deeply. If you’d like to read it yourself, the book makes for a good, nerdy poolside read this summer. (Click here to read a free copy online  or visit our office for a free copy)



First, a little science about cavities and how they develop. On everyone’s teeth there is a personalized layer of bacteria and microbes called a biofilm. Your biofilm becomes plaque and tartar if it builds up too much, and we keep the amount of it under control with good brushing and flossing. In healthy mouths it’s a well-balanced mix of good bugs and bad bugs that live with us. However, when the biofilm gets off balance problems, like cavities, can develop. The biofilm’s behavior is directed by pH levels. The lower the pH the more acidic it is. In more acidic conditions the good bacteria don’t fare very well, but the bad bacteria do just fine and take advantage of the situation. The bad bacteria will multiply like crazy and before we know it can outnumber the good bacteria and create an off-balanced unhealthy biofilm on our teeth.

So, what happens to our teeth when they’re covered with this unhealthy biofilm? Acids pull the minerals out from our enamel creating microscopic holes. Without its minerals, our enamel is vulnerable to being invaded by the bad bacteria in the unhealthy biofilm. The bad bacteria move into the little holes in our enamel, set up shop and create their own little acidic environments to keep it going, making the hole bigger, and eventually, it becomes a cavity that we (your caring dentists) can spot during an exam. Basically, the pH level in our mouths determines the state of our enamel.



Good news! We have built-in protection that can help our teeth and that is our own saliva. Spit contains lots of good things that can neutralize the pH and replace the lost minerals back into enamel. Without our saliva, our teeth would become quickly decayed even with the best hygiene efforts. Many medications can cause most cases of​ dry mouth, but mouth breathing, smoking, stress, and genetics can also cause decreased saliva.

To help protect your teeth, consider your diet as the biggest contributor to acidic conditions. Anything acidic will directly weaken your enamel. Anything with simple carbohydrates will break down into sugars that the bacteria eat and turn into acid by-products. That’s why sugar is bad for our teeth – it results in more acid. If you’ve had something acidic or starchy to eat or drink try rinsing your mouth with a water-baking soda solution to help neutralize. Products containing xylitol can help stimulate more salivary flow, and fluoride is always our knight in shining armor to help strengthen enamel. For tasty snacks that are actually good for our teeth, please check out my previous blog post here.

I’ll further explain these common reasons that affect our pH levels and more about what we can do about it in subsequent posts. Keeping good oral hygiene with regular brushing and flossing is very important, but awareness of how our natural biofilm can be altered by acidic conditions and result in tooth decay is the bigger picture. With this knowledge of a patient’s risk factors we can intervene and help prevent cavities before they start. How cool is that?


Recent Articles

I brush and floss, but I still get cavities! Why?

Most people grow up learning some basics about cavities and how to avoid them: “Just brush twice a d ...

Snacks Your Teeth Will Love!

Snacks Your Teeth Will Love!I know we all crave a bag of chips or a candy bar now and then, but our ...


Connect With Us


Contact Us

Ready to come in for an appointment?
Contact us today!

Dr. Laura Ellefson & Dr. Kasia Marelich

We are dedicated to excellence in family and cosmetic dentistry, specifically prevention, crown & bridge, veneers, implants and teeth whitening. Located in Santa Rosa, California, the office serves patients throughout Sonoma County including neighboring cities such as Healdsburg, Windsor, Sebastopol, Rohnert Park and Petaluma.

Site Developed by