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ePaper created 2017-03-17, 13:11:17 | version 1.38.0
| trends & applications clear aligners Fig. 11a Fig. 11b Figs. 11a & b: Chewies Aligner Tray The VERTICAL Seaters were developed as a kind of mini-tooth positioner for patients to clench in specific sites to encourage trays to seat and reduce the development of aligner lag. Controlled rotations of teeth are often difficult to achieve with aligners,20, 25–27 as the computer- generated prescribed movement may not be trans- lated accurately to the tooth. The first of the two accent pliers is called the VERTICAL20, 24 and it is used to gently impress a vertical indent into the aligners in a specific location in the lingual and/or facial plastic for an individual tooth (Figs. 7a & b). Rotating maxillary lateral incisors and canines are often sites of these types of problems.20, 25–27 As an example, the rotated lateral incisors in Class II Division 2 maloc- clusions are dif ficult to correct and typically require that overcorrection be designed into the aligners at the outset. If additional rotation is indicated, an indent can be placed in the plastic at the mesial line angle on the facial surface and the distal line angle on the lingual surface to create some extra force in the form of a rotational couple in a series of align- ers.24 This may preclude the necessity of another round of refinement appliances to achieve the intended goal. If a composite attachment is in place on a specific tooth, the VERTICAL can be used at the right-angle contact of the aligner and the compos- Fig. 12a Fig. 12b Fig. 12c Fig. 12d Fig. 13 Figs. 12a–d: Bootstrap mechanics are designed to extrude individual teeth into clear aligners with orthodontic elastics. (a & b) The HOLE PUNCH is used to cut out a half-moon clearance for a bonded button on the lingual surface of a selected tooth. (c) The TEAR DROP is used to place two elastic notches in the facial margin of the aligner at both the mesial and distal gingival embrasures. An elastic is then stretched from the dual notches, over the aligner, to the lingual button to generate an extrusive force. (d) A second option is to cut a second half-moon in the facial surface, bond a labial button and place the elastic from the labial to lingual surfaces over the aligner. – Fig. 13: A Clear Collection prescription form is completed for each patient to indicate the instruments that will be required to customise each aligner in a series, along with the specific sites where they will be employed on each tooth. 18 ortho 1 2017