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.