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ePaper created 2017-03-17, 13:11:17 | version 1.38.0
clear aligners trends & applications | ite to sharpen the contact point in that location for more efficient transmission of force to the tooth (Fig. 8). The HORIZONTAL The second accent instrument is the HORIZONTAL19–21, 24 and it is primarily used to produce an indent to affect a change in tooth root rotation or torque.18, 24, 28, 29 A horizontal impression into the plastic at the gin- gival margin of the aligners will emphasise the force applied to torque the roots of individual teeth (Fig. 9a). These horizontal indents can also be placed at the right-angle junction of a composite attach- ment and the tooth to enhance the contact, thereby increasing the effectiveness of the intended tooth movement and reducing the risk of lag as the plastic may slip away. Another option is to place horizontal indents at the marginal undercuts of the crown of the teeth to increase the retentiveness of aligners or retainers (Fig. 9b). Common applications: Beating aligner lag and bootstrap mechanics Besides facilitating the typical addition of inter- maxillary elastics for a variety of anchorage supports for tooth movement or intention to alter dentoalveolar compensation (i. e. Class II, Class III, resolving deep and open bites, extraction space closure, etc.19–24, 30–34), a common application for the TEAR DROP and the HOLE PUNCH is establishing bootstrap mechanics.20, 23 For instance, a tooth or teeth may be lagging behind the prescribed move- ment, especially in terms of extrusion—the tooth may not be following along the projected path (Fig. 10). This may be due to in adequate space created adja- cent to each side of the tooth or lack of adequate contact on the tooth or attachment. Initially, Chewies Aligner Tray Seaters20, 23, 35 (an- other of our creations from our private practice; DENTSPLY Raintree Essix) are routinely used at each new aligner to assist in seating them on to the teeth (Fig. 11a), along with instructions to massage the trays into place (use fingers to push the trays on to the teeth as though attempting to stretch them over attachments and undercuts for the first few days). Despite those efforts, an air gap between the incisal edge of the teeth and the plastic may develop (Fig. 11b). It may be that inadequate space has been created prior to extrusion and the interproximal contacts thus cannot pass by each other (consider the widening taper towards the anterior incisal edges) and aligner lag or lack of tracking is the result. In these instances or in anticipation thereof, a bootstrap set-up is prepared.20, 23 This consists of placing bonded buttons on the lingual surface of the offending tooth near the gingival margin by creating clearance for the button in the aligner plastic with the HOLE PUNCH (Figs. 12a & b). On the facial surface of the same tooth there are two options: another but- ton and a hole punch (Fig. 12c). The TEAR DROP is used to create two elastic notches at the mesial and distal gingival embrasure spaces (Fig. 12d). A small-diam- eter orthodontic elastic is then applied to either the teardrop notches or the button on the facial surface of the tooth and stretched over the occlusal surface of the aligner to the lingual button. In this scenario, the elastic is intended to more predictably extrude the tooth into the aligner to the prescribed position. Future view on aligners As demand by patients for more comfortable, hy- gienic and aesthetic treatments increases, the clear aligner market will respond with more advances and alternatives. In addition, orthodontists will learn to better push the envelope of applications by adding adjuncts to improve the effectiveness and ultimately the predictability of treatments with aligners. Much like fixed appliances, the ability to individualise, accent and enhance clear aligner biomechanics reduces the known limitations of aligners and the associated clinical frustrations of the orthodontist. Managing alterations of series of aligner trays in real time (including the use of a Clear Collection prescription form;24 Fig. 13) provides increased flex- ibility in the endeavour towards increased predicta- bility of aligner orthodontic outcomes. More details on the Clear Collection, treatment applications, downloadable publications (including the Clear Collection prescription form) and a series of instructional videos can be found on the Hu- Friedy website._ Editorial note: A list of references is available from the publisher. contact Dr S. Jay Bowman is a diplomate of the American Board of Orthodontics and a member of the Edward H. Angle Society of Orthodontists. At the Association of Orthodontists (Singapore) Congress, he will be presenting a lecture titled “Creative adjuncts for clear aligners: Improving the predictability of aligner treatments”, among others. He maintains a private specialty orthodontic practice in Portage in Michigan in the US. He can be contacted at info@kalamazooorthodontics.com. ortho 1 2017 19