After teeth-scaling last Thursday, it was found I had a cavity. A big hole in the pesky back tooth. 

I have a cavity. That is shameful. Especially I use dental floss on a daily basis. But I learned that it is not so useful if I do not know how to floss my teeth properly. The kind doctor asked the nurse to show me how to do it after the teeth-scaling. I want good teeth and I must floss in a right way then I can remove plaque under the gum line. A valuable lesson.