Crowding or overlap of permanent teeth happens when the size of the permanent teeth exceeds the length the jaw bone that is going to support the teeth. Naturally, there should be gaps between the primary teeth in the front to allow for the wider permanent front teeth to have sufficient space to erupt. In the back of the mouth, the primary molars are often wider than the permanent premolars that replace them. However, when there is a mismatch between the size of teeth and the space available for them, the permanent teeth erupt in an incorrect position or in severe cases they get stuck (i.e. – impacted) in the bone.
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Crowding: Dental crowding can be managed in various ways. In children, crowding can be managed by using a space maintainer to preserve space, extraction of teeth as the teeth erupt, or expansion of the upper jaw bone. In adults, crowding can be managed with extraction of one or more teeth, surgical jaw expansion, dental arch expansion, or slimming of the teeth.
Space Maintainer: It is very important to take care of primary teeth and repair them if they have cavities. Early loss of primary teeth or loss of their width due to cavities or fractures may lead to space loss for the permanent teeth. Your orthodontist will use space maintainers to preserve the space of the missing baby teeth until the permanent teeth erupt. In this case, the last two primary molars are present in the left image. Counter intuitively, the baby teeth are bigger than the adult teeth. Using a space maintainer at the right time saves the space difference between the baby and adult teeth. There was very little room for the lower canine teeth in the first image and it appeared as though permanent teeth would need to be extracted. The second image on the right shows that the canine teeth almost fit in the arch and permanent teeth do not need to be extracted.
Early Serial Extraction: Your orthodontist can measure the space available in the jaws and estimate the size of the permanent teeth to determine if there will be sufficient space for all teeth to erupt. In cases of severe crowding (lack of space of 8-10 mm per side), your orthodontist may elect to have some of the primary teeth extracted in sequence to guide the eruption of permanent teeth. When baby teeth are extracted (the teeth marked with “x”) the adult teeth naturally straighten with the extra space made from the extraction of the baby teeth.
In this case, there wasn’t sufficient space for all of the permanent teeth. Primary teeth and the first premolar teeth were extracted in sequence to allow the remaining permanent teeth to erupt into a much better position in the mouth.
The pictures below show how permanent teeth erupted naturally after the strategic sequential extraction of the primary teeth and the first premolars. This was done without even using braces or any other orthodontic appliances! If orthodontic treatment were done now – it is very simple, quick, and much less costly than if nothing were done as the teeth were growing in to the mouth. Also, the stability of the alignment is much better when the teeth grow in straighter. Much less need for life long retainers. When indicated, there is so much value from extracting teeth as they grow in.
Late Serial Extraction: In this case, the sequence of eruption meant that the first premolar teeth were extracted sequentially to prevent impaction of the permanent canine teeth and allow them to naturally erupt in a proper location. In the previous case, baby and adult teeth were extracted at the same time. Generally, the extraction of premolar teeth only, can be done in the dental office with local anesthetic. Extraction of baby and adult teeth is more involved and can be a minor surgery. However, the value of the extractions far outweighs the challenge of extracting the teeth and sometimes it is recommended for the child to go to sleep and have the teeth extracted.
Like the previous case, this was done without using any braces or orthodontic appliances!
Upper Jaw Expansion: Using an upper jaw expander to widen the upper jaw bone can help create more space for teeth to erupt when properly timed. A thorough evaluation of the upper and lower jaw sizes is needed. The upper jaw can only be expanded as much as the lower jaw will allow. The lower jaw bone is the foundation for the width of the dental arches. The lower jaw bone can not be expanded since there are no areas of growth. Lower teeth can be tipped outwards, but generally, this is not recommended since it can cause gum and bone loss and is not a stable change to the position of the teeth and the teeth. The teeth are more likely to quickly crowd again if a retainer isn’t judiciously worn.
Shaving the Teeth: Minor crowding and overlap of teeth can be corrected with braces or Invisalign by flaring the front teeth forwards or reducing their width (interproximal reduction or IPR for short).
When there is just too much dental crowding and all other options have been explored – extractions will be indicated. If extractions are recommended – there are reasons they have been prescribed.
It is simply that the jaw bones are not big enough to accommodate the teeth.
The lower jaw can not be expanded and increased in size. If the teeth do not fit the lower jaw – extractions will be indicated. If you are told that the lower jaw will be expanded – this can only be done surgically and in very rare cases. Expanion of the lower jaw is tipping of the teeth outwards and is not widening of the jaw bone. Lower dental expansion may be warranted in some cases, when the teeth are tipped inwards. However, if the teeth are not tippped in, dental expansion in the lower arch is notoriously unstable and leads to dental replapse and can cause significant recession.
Expansion of the upper jaw can be done without surgery and is actually widening the jaw bone. This type of expansion if much more stable and an effective mean is making space. But don’t forget – the lower jaw is the limit to upper jaw exansion. The jaws have to match and this is why crowding in the lower arch will indicate extractions.
Lower Incisor Extraction: Sometimes extraction of one tooth is all that is needed to aid in the alignment of the teeth. In this case a lower incisor was extracted and Invisalign was use to align the teeth.