More about expansion versus extraction treatment.  I prefer to treat cases in a non-extraction manner whenever possible.  If the patient does not display posterior crossbites we must be careful to not overly expand the maxillary arch into buccal crossbite.  If the lower arch needs, and will withstand, some expansion I will expand the upper arch slower in hope that the occlusion with "drag" the lower posterior teeth along.  Severe mandibular crowding may necessitate premolar extraction treatment so that we do not flare the lower incisors labially and out of the alveolar bone.  This can lead to future boney and gingival dehiscence and periodontal problems.  Over the next few Weekly Tips we will discuss how lip appearance, class II and class III occlusion, overbite and upper/lower tooth size discrepancies affect extraction decisions.