Any time is a good time to brush, but some times are better times than others. The most crucial times are after eating and in the morning. Brushing immediately after eating, especially if the meal or snack contained processed food and refined sugar. By “immediately,” I mean as soon as possible, but absolutely within four to six hours after any meal. The damage caused by food left in your mouth is directly proportional to how long it is left there.
Brushing in the morning is vital, even if you don’t eat breakfast. You need to break up plaque that formed during the night. Plaque actually forms more rapidly during sleep than during waking hours, because it doesn’t require food to attach its gooey self to your teeth and because most of your body’s natural plaque fighters—your tongue, lips, and saliva—are not nearly so active at night. Even if your bedtime brushing removes all available germ food, the remaining plaque-forming germs continue to do their thing. Therefore, the morning brushing is critical, even if you don’t eat. If you do eat breakfast you can accomplish two goals with a single brushing by brushing after you eat. Otherwise, brush as soon as possible.
Finally, it’s a good idea to brush before going to bed, even if you brushed after your last meal, in order to break up the plaque that has formed since then. Even if you’ve skipped meals or are fasting, never let more than eight hours go by without putting a brush to your teeth. If you do have advanced periodontitis, your hygienist may have you brush more often.