Most common unfavourable sequelae of serial extraction:
Early extraction of the buccal teeth and uprighting of incisors can result in deepening of the bite. This can be corrected with bite plane.
Ref: textbook of orthodontics gowrishankar 2nd edition page 533
Disto-axial inclination of canine
Residual space at the extraction site
Mesio-axial inclination of second premolar
Increase in overbite