Introduction
Study objective
Subjects
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congenitally missing or extracted lower second premolars or lower first molars,
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therapy by orthodontic molar protraction without maxillary counterbalance extraction, and
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completed treatment with a lingual appliance (Incognito, 3 M Top Service für Lingualtechnik, Bad Essen, Germany).
Valid N | Mean age (Y) | SD | Minimum | Maximum | Median | |
---|---|---|---|---|---|---|
Females | 15 | 16.74 | 2.19 | 13.417 | 20.99 | 16.34 |
Males | 12 | 16.29 | 1.28 | 14.845 | 19.73 | 16.14 |
All Groups | 27 | 16.54 | 1.82 | 13.417 | 20.99 | 16.14 |
Herbst | 15 | 16.43 | 1.63 | 14.798 | 20.57 | 16.14 |
TAD | 12 | 16.68 | 2.11 | 13.417 | 20.99 | 16.39 |
All Groups | 27 | 16.54 | 1.82 | 13.417 | 20.99 | 16.14 |
Methods
Protraction mechanics
Documentation
Statistical and methodological error analysis
Ethical approval
Results
Composition of groups
Treatment-related features
Velocity of molar protraction (in mm/month)
Valid protraction sites (N) | Mean protraction distance (mm/month) | SD | Minimum | Maximum | Median | |
---|---|---|---|---|---|---|
Herbst | 22 | 0.51 | 0.19 | 0.17 | 0.89 | 0.51 |
TAD | 14 | 0.35 | 0.15 | 0.17 | 0.63 | 0.33 |
All Groups | 36 | 0.45 | 0.19 | 0.17 | 0.89 | 0.45 |
Effect | p-value |
---|---|
Method (Herbst; TAD) | 0.008 |
Site location (right/left) | 0.8 |
Interaction Method * Site location | 0.2 |
Valid subjects (N) | Mean mm/month | SD | Minimum | Maximum | Median | |
---|---|---|---|---|---|---|
Herbst | 15 | 0.53 | 0.19 | 0.19 | 0.89 | 0.46 |
TAD | 12 | 0.36 | 0.15 | 0.18 | 0.63 | 0.34 |
All Groups | 27 | 0.45 | 0.19 | 0.18 | 0.89 | 0.34 |
Discussion
Assessment method
Null-hypothesis
Clinical effectiveness and occlusal side-effects
Velocity of protraction
Conclusion
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The use of a Herbst appliance as an anchorage reinforcement provides increased anchorage control, as protrusive forces of the appliance are effective in cancelling the distalizing side-effects of protraction forces.
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Therefore, Herbst-reinforced space closure was found to be faster and judged to be more reliable compared to TAD anchorage.
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Patients requiring simultaneous space closure by molar protraction and correction of distal occlusion may benefit from using Herbst appliances for anterior segment anchorage reinforcement rather than TAD anchorage.