Can adult undergo expansion?
Dr. Robert Mason responds:
Yes, adults can be expanded — but — the expansion is primarily the result of tipping the crowns of the teeth labially or buccally, rather than the bodily movement of teeth that occurs under age 16 when the midpalatal suture is cartilaginous. After age 16, the midsagittal suture is totally ossified (turned into bone) whereas previously it was a cartilaginous band traversing the length of the hard palate. . For adult expansion, longer periods of retention are needed to maintain the expansion.
One of the problems with expanding out adults is that, if held/retained for many months out of fear of relapse, the roots of upper molars can poke through the buccal bone that contains them. When a root pops through the alveolar bone, it is called a fenestration, and this is an unspoken problem among those orthodontists who claim that they can expand everyone out and never need to extract. Causing fenestrations is one of many complications from this rigid and inappropriate view that everyone should be expanded and no one should undergo extractions. You can only expand individuals out so far, and relapse in many non-extraction cases is greater than had extractions been done appropriately.
For expansion in children, the cartilaginous suture area widens and then bone eventually fills in following the expansion to maintain the width created. ~ Bob