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Phase I and Phase II Treatment

Many new patients ask us what Phase I and Phase II treatment are.  This is understandable since when most of today’s adults had braces there was no such thing as Phase I and II treatment.  It’s only been in the last 10-15 years that this “split phase” treatment has been popular.

The easiest way to understand Phase I and II treatment is to first understand that a correct bite requires 2 things:  Correctly aligned teeth and correctly aligned jaws.  Incorrectly aligned jaws, resulting in overbites, underbites, etc. can be corrected provided the jaws are still growing.  This occurs up until around age 12-13.

Aligning the teeth requires that all the permanent teeth be erupted. That usually occurs around age 12-13

 So if a patient has crowded teeth and incorrectly aligned jaws, it’s virtually impossible to achieve them both in a single phase of treatment of a reasonable length, because the window of opportunity for the one closes just as the other opens. Instead, we prefer to work on jaw growth sometime between 7 and 10 years old.  This is called Phase I.

We can then wait until after all the permanent teeth have erupted before aligning the teeth.  This is the Phase II part. If a patient has crowded teeth, but correctly shaped jaws, we don’t do a Phase I.  We wait until all of the teeth are erupted and do a single phase of treatment.


Elastics are used to move all the upper teeth against all of the lower teeth.  If Dr. Trosien has asked you to use elastics, it is very important that you are able to wear them.

“Triangle” elastics are used to close the bite down in front. They hook up to the farthest forward hook on the upper and the farthest forward 2 hooks on the lower.

“Class 2” elastics are used to pull the upper teeth back against the lowers (to correct an overbite).  They hook up to the farthest forward hook on the upper and the lower molar hook.

“Class 3” elastics are used to pull the lower teeth back against the uppers (to correct an underbite).  They hook up to the farthest forward hook on the lower and the molar hook on the upper.

Front desk at Trosien