Which toothbrush is best?
In general, a toothbrush head should be small (1" by 1/2") for easy access to all areas of the mouth, teeth and gums. It should have a long, wide handle for a firm grasp. It should have soft nylon bristles with rounded ends so you won't hurt your gums.

When should I change my toothbrush?
Be sure to change your toothbrush, or toothbrush head (if you're using an electric toothbrush) before the bristles become splayed and frayed. Not only are old toothbrushes ineffective, but they may harbor harmful bacteria that can cause infection such as gingivitis and periodontitis. Toothbrushes should be changed every three to four months. Sick people should change their toothbrush at the beginning of an illness and after they feel better.

How do I brush?
Place the toothbrush beside your teeth at a 45-degree angle and rub back-and-forth gently. Brush outside the teeth, inside the tooth, your tongue, and especially brush on chewing surfaces and between teeth. Be sure to brush at least twice a day, especially after meals.

How long should I brush my teeth?
You should brush your teeth at least 2-3 minutes twice a day. Brush your teeth for the length of a song on the radio, the right amount of time to get the best results from brushing. Unfortunately, most Americans only brush for 45-70 seconds twice a day.