lInitially crowding of deciduous tooth germs
lDec 2nd molars move backward and anterior tooth germs move forward
lAll teeth move bodily outward and upward (mand teeth) or downward (max teeth)
lPerm tooth germs lie in their own bony crypts lingual to or between the roots of dec teeth
lInitially the perm max molars have their occlusal surfaces facing distally, but swing
mesially
lInitially the perm mand molars have their long axes inclined mesially, but swing vertically into
position after mand grows to provide space