Hereditary and environmental factors in facial development

Abstract

1. 1. Developmental growth expresses itself as local increase of dimensions in an orderly pattern which may be interrupted by disease, intermittent starvation and adverse socio-economic conditions. 2. 2. Developmental growth implies modification of proportions and constant readjustment of parts as well as local dimensional increase. 3. 3. The foregoing principles can readily be demonstrated by experimental interference. 4. 4. Facial growth is subject to the same general influences and interferences as general bodily growth. 5. 5. In early childhood antero-posterior (and transverse) growth is largely controlled by cranial (brain) development. Vertical facial growth is largely determined by bodily respiratory needs. 6. 6. In suitably oriented roentgenograms the developing upper central milk incisor is a useful indicator of comparative facial growth. 7. 7. The incisor travels forward with antero-posterior facial growth and downward with vertical facial growth. 8. 8. Interruption in bodily development in infancy retards anterior progress of face (and incisor) more than vertical progress which is more closely related to bodily size than to bodily maturation. 9. 9. As a rule the increased velocity of growth during convalescence or restoration repairs the defective facial growth but severe disturbance may remain as a permanent defect requiring readjustment of parts and in later chilhood orthodontic treatment.