Dental Education Lecture: Ugly duckling

Sometimes the upper adult front teeth appear never to come out in a 7 year old kid (Fig.1), while the bottom 4 adult front teeth are present for a while (*).  If you look more carefully, the upper front teeth are underneath the gums (arrows: -->), just like flower buds that are going to blossom.  The problem is that the gums are too thick in the bottom (arrowheads: >) to let the teeth break through.  Occasionally, we need to make small windows surgically in the thickened gums to invite the teeth to come out (Fig.2). In two weeks, the front teeth are in the business (Fig.3).  In another fourteen days, they make more appearance, but the mom wonders why they are so crooked with a large space between them.  Don't worry.  This is temporary.  As these two front teeth continue to grow, the space becomes narrow (Fig.5) and finally closes when the adult lateral incisors (7, 10 in Fig.6 ) erupt. 

When the front teeth (8,9 in Fig.7) are just coming out, their roots are being pressed inward by the lateral incisors (7,10).  The axes of the front teeth approximate each other at the root end (Fig.8), creating the space at the crown end.  As the lateral incisor are out, they press the crown of the front teeth, changing the axes of the front teeth and closing the space (Fig.9).  Another phase of ugly duckling comes to an end.

Xin Wei, DDS, PhD, MS 1st edition 11/15/2009, last revision 06/14/2010