4. The purpose of the investigation was to examine the effects of the Tweed
edgewise technique on mandibular growth and rotation. It employed 36 Class II
Tweed edgewise patients, all of whom had 4 bicuspids extracted during the course
of treatment. Pre-treatment (time 1), post-treatment (time 2) and post-retention
(time 3) records of these patients were matched by age, gender, malocclusion,
and treatment interval to untreated controls from the Bolton-Brush Growth Study
Center, Cleveland. The cephalograms of the two samples were traced, digitized
and analyzed by descriptive cephalometric analysis. Analysis was directed
toward an analysis of the increments of change (for various cephalometric
measurements) between time 1 and time 2, time 2 and time 3, and, overall,
between time 1 and time 3. The table below has the results of the paired t-tests
comparing the amount of change (between time 2 and time 3) in 3 cephalometric
measurements in the treated group vs the controls. Please interpret the results
Groups Paired t-test
Variable
ANB -0.4 0.1 0.0 0.1 0.4 0.2 -1.7
Co-Gn 3.2 0.4 1.4 0.4 1.8 0.5 3.8**
Overjet 0.4 0.2 -0.4 0.2 0.7 0.2 3.3**
*p<0.05; **p<0.01
Treated Control Difference t-value Mean SD Mean SD Mean SD
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