INTER – TRANSITION STAGE [ 9 – 11 ]
 Anomaly — ugly duckiling stage (9 – 11 years) *** v.imp
o — midline diastema (SCA)
 Erupting — canines
 Distoangular axial inclination of maxillary incisors!
 Rx – wait till canines erupt completely – 11 years
 After that — ortho Rx.

SECOND TRANSITION STAGE
 Erupting — C, 1st PM and 2nd PM
 3, 4, 5, 7
 Anomaly — anterior deep bite

 LEEWAY SPACE — primary Molars > permanent Molars
 it is the space deference between the combined mesiodistal width of the C,D & E teeth and that of their successors ( 3 ,4 and 5 ) which is
 1.9 mm in maxilla & 3.4 mm in mandible.
 — This space is utilized for primary occlusion to
permanent occlusion
 — late mesial shift
o Maxilla — 0.9 mm
o Mandible — 1.7 mm