My son has got 4 teeth now. When do you need to start brushing their teeth?

Most infant foods easily wash off Baby's teeth with just a drink of water after meals. But it's good to introduce a toothbrush (choose a very soft one) as soon as possible, so baby can get used to having it in his mouth. You probably won't need to use the brush to actually clean Baby's teeth until he's eating only table foods (and has a significant number of teeth), at around 18 months. However, you'll want to gently clean your child's teeth with a toothbrush or thimble-like cleaner and some bicarbonate of soda if your toddler has eaten sticky, sugary foods.