Читать книгу Orthodontic Treatment of Impacted Teeth - Adrian Becker - Страница 57

Most impacted lower second molars are tipped mesially and therefore need to be tipped distally in order to clear the distal aspect of the first molar. Only the occlusal surface of the second molar need be exposed; a button can be bonded in the second molar’s central groove and a sectional equipped with a compressed NiTi super‐elastic open‐coil spring (Figure 3.8a, b). This is hooked onto the button and placed in the slots of the self‐ligating Snaplink^TM tube on the first molar and the premolar brackets. As the spring expands, the sectional wire will slide distally taking the second molar with it, to clear the first molar. If there is not sufficient wire remaining mesial to the first premolar to enable complete alignment of the second molar, the first premolar bracket can be debonded.

Fig. 3.8 (a) Sliding mechanics with a NiTi open‐coil spring threaded over a 0.016 in. stainless steel sectional for freeing a mesially tipped lower second molar. (b) The hook on the distal end of the sectional is fixed to the button. A 360° helix is used as a stop for the NiTi spring.