通常情况下,刚诞生的婴儿是没有牙的,可是有极个别的婴儿在出生时或出生后两三个月,口里已有乳牙萌出。有迷信思想的人认为这是不祥之兆;也有人认为这样的孩子长大之后,必定性情恶劣。实际上这些认识都是错误的,都是无科学根据的。口腔医学把这种现象称为“诞生牙”或叫乳牙早出。最常见的“诞生牙”是下颌乳中切牙,即下面正中的两个门牙。正常婴儿中发生“诞生牙”或乳牙早出的约为千分之一 Under normal circumstances, the birth of a baby is no tooth, but there are very few babies at birth or two to three months after birth, the mouth has a baby eruption. Someone with superstitious ideas thinks this is ominous; others think that when such a child grows up, he must be in a bad mood. In fact, these understandings are wrong and are not scientifically based. Stomatology calls this phenomenon “birth tooth” or premature deciduous teeth. The most common “birth tooth” is the incisors in the mandibular milk, the two front incisors below. In normal infants occurs “birth tooth” or deciduous early out of about one thousandth