ABSTRACT
Objective@#To analyze the impact of the activation mode on the results of space closure in the mandibular arch using a double keyhole loop (DKHL) with a typodont model and reverse engineering technique to provide guidance for clinical treatment. @*Methods@#Nine normal mandibular typodont models after leveling were randomly divided into 3 groups, which then underwent three types of DKHL activation for space closure. Each model was assessed at the initial stage and after the warm water bath, and the images were superimposed to measure the displacement of special crown and root mark points. All statistical analysis of the data was performed using SPSS 19.0@*Results@# After equal activation times, the root retraction of anterior teeth and the crown forward position of posterior teeth in groups activated at the distal loop (conditions 2 and 3) were much greater than those in the group activated horizontally (condition 1). Activation between mesial and distal loops (condition 3) induced significant anterior tooth intrusion, together with elongation and buccal inclination of posterior teeth. The displacement of mark points among the three conditions showed a statistically significant difference. @* Conclusion @# The movement of mandibular anterior and posterior teeth could be flexibly controlled through different DKHL activation modes, which should be chosen carefully according to individual conditions.
ABSTRACT
The present study hypothesized that the double keyhole looped archwire plays a positive role for the sake of translatory movement and/or controlled tipping of upper 6 anteriors, and secures anchorage control as well. The purposes of the study were to evaluate the changes in lateral cephalograms during orthodontic treatment with DKHLs and to compare the skeletal & dental changes before- & after-treatment. The materials of this study were lateral cephalograms of 20 adult patients with upper dentoalveolar protrusion both in class I and in class II Division 1 malocclusion. Lateral cephalograms were taken before and after orthodontic treatment with upper 1st bicuspid extraction and DKHLs. The results were obtained as follows: 1. There were no statistically significant differences in skeletal measurement except SNB and PTFH between before- & after-treatment. The major changes were in dentoalveolar region. 2. After treatment, there were statistically significant decrease in dental measurement except interincisal angle. 3. Both upper & lower lip protrusion was decreased. 4. There were statistically differences in upper anterior crown horizontal & root vertical dimension(7.08+/-2.14 mm, 2.38+/-1.15 mm, p<0.01). 5. There were statistically differences in upper posterior dental(both crown & root) horizontal dimension(2.48+/-0.99 mm, 2.05+/-0.91 mm, p<0.01).