Most common unfavourable sequelae of serial extraction:
Disto-axial inclination of canine
Residual space at the extraction site
Mesio-axial inclination of second premolar
Increase in overbite
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