Like Mother, Like Daughter 

Congenital missing of a lower permanent lateral incisor is fairly common tooth abnormality.  It appears that most tooth abnormalities have genetic tendency.  Missing lateral incisor is no exception.

Normally there are 4 incisors either in upper or lower jaw: 2 central and 2 lateral. But Mrs. Deng has only 3 lower incisors: 2 central (Fig.1,2: #1) and 1 lateral (#2).  In other word, the left lateral incisor is missing for Mrs. Deng.  #3 stands for a canine. There is a big gap behind the left canine.

Mrs. Deng's elder daughter is 10 years old.  She has also a missing lateral incisor, but on the right side (Fig.3,4).  Since there is always an extra space on the side of missing incisor, the right canine has prematurely erupted.  The left canine is still underneath the gums.

Mrs. Deng's younger daughter is 6 years old.  The left permanent central incisor has just erupted (Fig.5: #1).  The baby central incisor (A) has not been lost. B and C stand for baby lateral incisor and canine, respectively.  Luckily X-ray shows that there is no missing of any tooth, incisor or canine (Fig.6: #1,2,3).  Basically, underneath every baby tooth there is a permanent tooth bud.  Every permanent tooth bud is pushing its baby tooth out in due time.

In all, missing lateral incisor has genetic component.  In the next lecture, we will discuss that sometimes we need to treat missing lateral incisor.

Xin Wei, DDS, PhD, MS 1st edition 07/29/2012, last revision 07/30/2012