Influence of patient age and sex on orthodontic treatment: evaluations of Begg lightwire, standard edgewise, and straightwire techniques.

The nature of the planned orthodontic correction--primarily skeletal or dental--ought to be influenced by the age and the sex of the patient. Jaw growth should contribute more in younger adolescents and faster-growing boys, and the correction should be primarily dental in patients with little growth potential. Influences of age and sex were studied in 154 Class II Division 1 young people between 10 and 18 years of age at the start of treatment. Variations among 3 orthodontic techniques, Begg lightwire, standard edgewise, and straightwire, were also examined. The Johnston method of cephalometric analysis was used to partition changes into their skeletal and dental components. Analysis of covariance was used to identify changes because of patient age, patient sex, and treatment technique. Technique differences were localized to 2 areas: (1) less root torquing in the Begg group that left the maxillary incisors more upright than in the other groups and (2) more mesial molar crown tipping in the straightwire group because of using preangulated brackets. The patient's age had the greatest influences on (1) translation and mesial crown tipping of the molars (both changes were larger in younger patients) and (2) mandibular growth, which was greatest in younger patients and declined linearly with age. Forward movement of the maxillary molars was greatest in young patients, but this was exceeded at all ages by mesial translation of the lower molars, thus providing a net improvement in molar relationship. Linear growth was greater in males for all facial dimensions, but the sex difference of consequence was the large forward growth of the mandible that contributed significantly to the sagittal correction in boys but not in girls. One would not expect the effects of age and sex to be large because there is so much individual variation in the malocclusions and tempos of growth. Still, the present study shows that these factors produce readily measurable and systematic influences on the nature of the skeletodental correction.