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. 

Expansion versus extraction treatment decisions.  I probably get the most questions regarding the decision to expand the arches versus extract permanent teeth.  I'll limit the discussion here to children and adolescents.  Anatomical development finds the mandibular midline suture closed before one year of age while the maxillary midline suture can widened into the teens in many cases.  For this reason significant upper expansion is much more obtainable than the same procedure in the lower arch.  Thus, extraction decisions in many cases are made after carefully reviewing the amount of space needed in the mandibular dentition.  We have to look not only at the amount of crowding present but also the degree of overbite correction, class II or III correction and tooth uprighting necessary.  More on how I make these decisions next week.