Q我儿子已经19个月了,可他才长了4颗牙齿,上下门牙各两颗。周围的孩子还从没见过这么晚出牙的,请问这种情况正常吗?是什么原因导致的?A孩子牙齿的发育萌出是有规律的,但每个人的遗传因素、生活环境及营养状况不同,所以存在较大差异。一般情况下,孩子出生后6个月左 Q My son is 19 months old, but he has 4 teeth, two upper and lower incisors each. Children around have never seen such a tooth out so late, is this normal? What is the cause? A child development of teeth eruption is regular, but each person’s genetic factors, living environment and nutritional status Different, so there is a big difference. Under normal circumstances, the child is left 6 months after birth