PURPOSE OF THE STUDY AND ACKNOWLEDGEMENTS
Children with malocclusions are frequently treated by means of orthodontic appliances at the age of 10.5-12 years. The years immediately preceding (9-10.5) permit an inspection of the development of the bite while awaiting the eruption of the canines and premolars.
The purpose of the present study has been:
1. To follow over the period 9-10.5 years the growth changes in the facial skeleton and soft tissue pattern that are of interest to the orthodontist.
2. To investigate the incidence of oral habits, oral and nasal breathing, and variations in the soft tissues surrounding the jaws, and any correlations that may exist between these different factors and variations in the bite.
I am deeply indebted to Professor A. Lundstrom, head of the Orthodontic Department of the Royal School of Dentistry, Stockholm, to whom I wish to express my warmest thanks for his criticism and helpful suggestions.
The statistical calculations were carried out by Miss J. Wahl at the Statistical Institution, Stockholm. This study has been supported by grants from the Royal School of Dentistry, Stockholm.