When the baby is about 2.5 years old and the baby’s milk teeth have fully erupted, parents need to floss the adjacent surfaces of the child’s teeth, i.e. the gaps, because this is where the milk teeth are prone to decay. Since the bristles of the brush cannot fully enter the space between the teeth of the baby teeth, effective brushing can only clean 70% of the plaque, leaving 30% of the remaining plaque still hidden in the crevices of the teeth, which should be flossed. Proper flossing is a safe and effective way to clean your mouth and can effectively prevent tooth decay without increasing the gap between your teeth. It is recommended that every night after brushing, have your child lie on the couch with his or her mouth open while mom or dad flosses to help clean the food and plaque embedded in the cracks between the teeth.