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2: Disadvantages of Mechanical Effective Characteristic


Structure of an appliance:
The standard bracket for the lower jaw front tooth department@ with a@ vertical slot is used for upper jaw front tooth department (including cuspids).


Standard labial brackets for mandibular anterior teeth with vertical slots are placed on the six maxillary anterior teeth in such a way that the slots are angled at 45 to occlusal plane. Premolar and molar brackets are placed in a conventional way.



3:Bracket placement:

1.The bracket slots, when placed at this angle, are much closer to the contacts points, facilitating labial tooth alignment.@ In addition, with an enlarge anterior part of the archform, the interbracket distance is increased for ease of control.

2. Anterior retraction at 45 (effectively) delivers both lingual root torque and intrusive forces to the upper anterior teeth, resulting in retraction from the apices and prevention of the bowing effect during anterior retraction.

3.Double overties are not necessary, for the brackets placed at this angle allow for secure seating of archwire into the slots by simple ligation.

4.Each brackets is equipped with a vertical slot to accommodate auxiliaries for ease of rotation control, which is often difficult to accomplish with lingual technique.@ The vertical slots also permit the use of torque auxiliaries from a transpalatal bar to increase lingual root torque (without loosing anchorage).

4.Each brackets is equipped with a vertical slot to accommodate auxiliaries for ease of rotation control, which is often difficult to accomplish with lingual technique.@ The vertical slots also permit the use of torque auxiliaries from a transpalatal bar to increase lingual root torque (without loosing anchorage).
5. No special brackets are required for this approach.
Development of new brackets is unnecessary, because the brackets to use are for the lower jaw front tooth of standard and the use is only for 3 ~3 furthermore.