It is normal for newly erupted front teeth to appear saw-shaped on the edge. It will be naturally grinded and smoothened after a period of time.
Photograph of lower incisors appearing saw-shaped on the biting surface.

This is a transitional period called the "Ugly Duckling" stage Usually, when the upper canines on both sides erupt, the front teeth will straighten and the gap will close up.
Photograph of two upper incisors flaring out with a gap in between.

Commonly, the deciduous tooth will become loose by itself. The tongue will push the permanent front tooth forward into position. Gradually, the deciduous tooth will exfoliate by itself. The permanent tooth will align itself into normal position. Therefore, it usually do not need to remove the deciduous tooth in this kind of situation.
Photograph of lower permanent incisors erupted behind the deciduous incisors.

Since permanent teeth are bigger than deciduous teeth, and jawbones are not yet completely developed in children, the newly erupted permanent teeth may not have enough room to align properly and they look crowded. However, we usually cannot determine whether the permanent teeth will have a good alignment until all the deciduous teeth are exfoliated and replaced by permanent teeth. If you have any queries, please ask your dentist for further advice.
Photograph of lower incisors that are not well aligned.

Generally speaking, we cannot be sure whether the tooth alignment is irregular or not until all the permanent teeth have replaced the deciduous teeth and the development of jawbones have stabilized. Then, we could decide whether an orthodontic treatment is needed.

You don't need to worry since the timing of tooth transition varies between different individuals. If you have any queries regarding tooth transition, you may consult your dentist.

Related topics:
Queries on Tooth Transition (PDF Leaflet)
Two sets of teeth in a lifetime (PDF Leaflet)

Last revision date: 18 January 2012