Write the next sentence in the following story.

How to keep teeth white while smoking
Brush your teeth.
Although this is important for everyone's dental health, tooth brushing is especially important for keeping a smoker's teeth white. Brush your teeth twice to three times a day, being sure to brush for at least two minutes each time.
Use a whitening toothpaste if you would like to get an extra level of whitening action. Smokers tend to have poorer oral health and a higher risk of periodontal disease, so it's important to focus on keeping your mouth healthy.