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162 JCO/MARCH 2015© 2015 JCO, Inc.

however, the application of adjuncts is still indi-cated in some cases.

Intrusion

Intrusion of selected teeth33 or dental seg-ments,34 as needed in patients with deep overbites, has been regarded as challenging to perform with clear aligners. In fixed-appliance treatment, mini-screws have been used to assist not only in intru-sion of single posterior teeth for subsequent pros-thetic restorations,35 but in mass intrusion to help close anterior open bites and correct deep over-bites.22,36,37 It seems logical to extend the applica-tion of skeletal anchorage into the realm of clear aligners.

Overeruption of teeth with no opponents is commonly seen in mutilated dentitions. Intrusion of a hypererupted tooth is one way to provide suf-ficient clearance for prosthetic replacement. Mini-screws are ideally suited to such a task, since a variety of forces (elastic chain, coil springs, or elastics) can be applied to predictably guide the programmed intrusion without affecting adjacent teeth, even when using clear aligners (Fig. 8).37,38

Intrusion of multiple teeth to correct deep overbites has been acknowledged as a more chal-lenging and less predictable aspect of clear-align-er treatment.34 The importance of resolving deep

Part 1 in this series of articles (JCO, February 2015) described a number of adjuncts for im-

proving the reliability of Class II treatment with clear aligners. This month, we will demonstrate how to perform certain difficult tooth movements with aligners. Part 3 will conclude the series with a discussion of extraction and interdisciplinary treatment.

One of the most frustrating aspects of clear-aligner treatment has been the unpredictability of tooth movements such as dental extrusion, resolu-tion of rotations, and correction of deep overbites. For example, Chisari and colleagues reported that only 57% of the programmed movement of a sin-gle incisor was actually achieved over an eight-week experimental period.31 Kravitz and col-leagues found only a mean 41% accuracy.32 As treatment progresses, this lag in tooth movement can be compounded, resulting in a “tracking error” that is usually first noticed as an “air gap” between the incisal edges of the incisors and the aligner trays. This situation may spread to other teeth, until the trays no longer fit snugly or the intended tooth movement is adversely affected. Newer plas-tic materials, more accurate digital scans, new attachment designs, and better programming strat-egies for treatment planning (including the neces-sity of overcorrection) have improved the predict-ability of outcomes. As we discussed in Part 1,

S. JAY BOWMAN, DMD, MSDFRANK CELENZA, DDSJOHN SPARAGA, DMDMOSCHOS A. PAPADOPOULOS, DDS, DMDKENJI OJIMA, DDSJAMES CHENG-YI LIN, DDS

Creative Adjuncts for Clear AlignersPart 2 Intrusion, Rotation, and Extrusion

©2015 JCO, Inc. May not be distributed without permission. www.jco-online.com

163VOLUME XLIX NUMBER 3

overbites has become more apparent in recent years with the increasing percentage of adult orthodontic patients—especially those with re-stricted anterior function, resulting in severe enam-el attrition of both the incisal edges and the labial and lingual tooth surfaces.

Recent improvements in aligner program-ming have been designed to assist in leveling the curve of Spee with incisor intrusion and premolar or molar extrusion.39 These include biteplanes molded into the aligner trays behind the upper anterior teeth and bonded attachments used to deliver extrusive forces to the premolars. Since miniscrew anchorage has been highly dependable in correcting deep bites and “gummy smiles”, it has inevitably been applied to similar treatments with clear aligners (Fig. 9).36-38

Rotation and Extrusion

Dental rotations and extrusion of anterior teeth seem to be the least predictable aligner move-ments. Kravitz and colleagues found that extrusion was the least accurate tooth movement in aligner treatment, at 29.6% effectiveness.32 Reasons for these difficulties, along with strategies to improve rotation control, have been proposed by Nicozisis40 and Humber.41 We have incorporated several of their common themes in the following suggestions:

Dr. Bowman is a Contributing Editor of the Journal of Clinical Orthodontics; an Adjunct Associate Professor, St. Louis University, St. Louis; a straight-wire instructor, University of Michigan, Ann Arbor, MI; an Assistant Clinical Pro fessor, Case Western Reserve Uni versity, Cleveland; a Visiting Clinical Lecturer, Seton Hill University, Greens burg, PA; and in the private practice of orthodontics at 1314 W. Milham Ave., Portage, MI 49024; Drs. Celenza, Sparaga, and Ojima are in the private practice of orthodontics in New York City; Anchorage, AK; and Tokyo, re spectively. Dr. Papadopoulos is Professor and Program Director, De partment of Orthodontics, School of Dentistry, Aristotle University of Thes saloniki, Thessaloniki, Greece. Dr. Lin is Clinical Assistant Professor, De partment of Orthodontics and Pediatric Dentistry, School of Dentistry, National Defense Medical University, Taipei, Taiwan, and in the private practice of orthodontics and implantology in Taipei. Dr. Bowman is inventor of the Clear Collection pliers and Aligner Chewies. E-mail him at [email protected]. Dr. Bowman

Fig. 8 Molar intrusion supported by miniscrew anchorage and elastics. A. Adult patient with missing lower right first molar and overerupted upper second premolar, initially treated with chain elastic from miniscrew to bonded button on premolar. B. During later Invisalign phase, intramaxillary triangle elastics worn from mini-screw to bonded buttons on aligners, ensuring proper tray seating and consistent leveling of oc-clusal plane. C. Resulting slight overcorrection provided sufficient clearance for implant in 14 weeks of treatment.

A

B

C

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Creative Adjuncts for Clear Aligners

Fig. 9 Deep-bite treatment with anterior intrusion. A. Adult male patient with mutilated dentition and deep overbite associated with significant anterior wear before treatment. B. Miniscrews inserted between roots of upper lateral incisors and canines for anchorage of intrusion elastics (continued on next page).

A

B


Bowman, Celenza, Sparaga, Papadopoulos, Ojima, and Lin

§Registered trademark of Dentsply Raintree Essix Glenroe, Sarasota, FL; www.essix.com.

Fig. 9 (cont.) C. Elastic hook formed by placing circular extrusion in facial aligner surface with Hilliard Thermoplier Hook-Forming Pliers,§ then notching half of plastic extrusion with cutting tool. D. Improve-ment in overbite after 22 months of treatment and 35 pairs of aligners.

C

D

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1. To open sufficient space adjacent to the af-fected tooth, program a visible opening of .25-.5mm into the aligner treatment and/or use inter-proximal reduction.2. Design appropriate bonded attachments to elic-it rotational and/or extrusive forces.9,42,43

3. Program overcorrection into the aligners to ac-count for the flexibility of the plastic.4. Use detailing pliers such as Clear Collection’s The Vertical*** and The Horizontal*** to accen-tuate rotational or extrusive couples.5. Supplement treatment with bonded buttons and elastics or even fixed appliances before or after aligner therapy.6. Due to the inherent risk of rotational or vertical relapse, discuss the need for supracrestal fiberot-omy (Edwards procedure44) and long-term fixed retention as part of informed consent.

The failure of upper lateral incisors to track properly, commonly seen with Class II, division 2 malocclusions, is especially disconcerting. In some instances, the central incisors would benefit from intrusion while the lateral incisors require extru-sion and rotation. Combining selective intrusion, extrusion, root torque, and rotation of anterior teeth requires more than just casual approval of a tech-nician’s programmed treatment plan.

Failure to address the arch-length discrep-ancy before initiating any movement of the lateral incisors is likely to result in disappointment. If extrusion is attempted with insufficient adjacent space, iatrogenic intrusion may occur as the tooth is inadvertently “squeezed” apically. Space open-ing also increases the tooth-surface area for the plastic to contact—an important consideration with a small, blade-shaped lateral incisor. The ad-dition of bonded attachments on the lingual or facial surfaces or both should be considered to increase the contact surface area and produce ex-trusive and/or rotational forces. If tracking is still lagging behind, other adjuncts can be considered.

Aligner Chewies§ are one of the earliest methods developed to overcome poor tracking or “aligner lag” (Fig. 10).45 Like sequential aligners themselves, these simple devices were based on the concept of the tooth positioner.46 With the trays

in place, the patient bites down repeatedly on the soft Chewies, each the size of a cotton roll, for several minutes a day to help seat the aligners, especially as each new pair is started. Chewies are also prescribed when an air gap develops at the incisal edges. In that case, the Chewie should be positioned directly over the affected region to fo-cus the chewing forces, with the patient holding the device solidly between the teeth for 10-15 sec-onds, releasing, and repeating for about five min-utes twice a day.

Fig. 10 Chewies§ tray seater positioned at “air gap” between incisal edge and aligner.

***Clear Collection, Hu-Friedy Manufacturing Co., Chicago, IL; www.hu-friedy.com.§Trademark of Dentsply Raintree Essix Glenroe, Sarasota, FL; www.essix.com.



Open-Bite Treatment

Passive posterior intrusion is a common issue in clear-aligner treatment. Posterior plastic can be removed to permit spontaneous settling or eruption of the posterior teeth into occlusion, and forced eruption can also be applied with intermaxillary elastics (Fig. 13).

Clever methods for using clear aligners to improve the closure of anterior open bites by intru-sion of posterior teeth have been proposed by Boyd39 and Dayan.48 The underlying concept is to harness the aligners’ propensity to produce an iatrogenic posterior open bite simply as a result of holding plastic between the teeth for extended pe-riods of time.1,2,49,50 One such strategy involves sequential intrusion of specific posterior teeth while maintaining or extruding the anterior teeth, thus creating a deeper curve of Spee.48 Using Chewies to exert intrusive forces on targeted pos-

Even with the best planning for clear-aligner biomechanics, aligner lag or tracking error of spe-cific teeth can still occur, often as a result of less-than-ideal patient compliance with aligner wear. The application of adjunct elastics may assist with the extrusion of selected teeth into the aligner trays. “Bootstrap” elastics are attached to bonded buttons on the facial, lingual, or both surfaces of the lagging tooth at the gingival margin.47 An orthodontic elastic is stretched across the incisal surface of the seated aligner to the button, thus extruding or pulling the tooth into the tray. The gingival margin of the aligner plastic must be cut to avoid the buttons, so that the tray can seat com-pletely. Alternatively, to avoid the need for a button on the facial side of the tooth, elastic hooks can be cut into the aligner tray (Fig. 11). Bootstrap elastics may prevent or at least delay the need to interrupt a series of aligners for the fabrication of refinement trays (Fig. 12).

Fig. 11 “Bootstrap” elastics used to extrude lagging teeth for proper tray seating. A. Elastics stretched from buttons bonded near gingival margin on lingual surfaces of affected teeth to hooks created in facial aligner surface by notching with Tear Drop*** plier. B. Elastics in place in patient with lagging upper lateral incisors (colored elastics worn in occlusal view for demonstration purposes).

A

B

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Fig. 12 Maxillary retraction and anterior torque control supported by elastics. A. 12-year-old female patient before treatment with Invisalign TEEN* and Class II elastics. B. After 20 months, due to progressively wors-ening upper left lateral incisor tracking, bonded button and bootstrap elastic added to extrude lateral inci-sor into aligner tray. C. Patient after completion of treatment, six months later, showing improved smile line.

B

A

C



Fig. 13 Forced posterior eruption supported by elastics. A. Young adult patient with anterior open bite and reverse smile line before treatment with clear aligners. B. Development of posterior open bite during align-er treatment. C. Buttons added for attachment of posterior rectangular intermaxillary elastics to assist refinement aligners in seating occlusion. D. Patient after 24 months of treatment; addressing curve of Wil-son could have improved these results.

*Registered trademark of Align Technology, Inc., Santa Clara, CA; www.aligntech.com.

Fig. 14 Extrusion supported by elastics. A. Adult patient with poor tracking of aligner trays in anterior re-gion. B. Buttons bonded to lingual surface of upper left lateral incisor and facial surface of lower left ca-nine for attachment of intermaxillary elastics during refinement stage. C. Patient after 10 months of treat-ment.

C

D

A

B

A B C

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Fig. 15 Posterior intrusion supported by miniscrew anchorage and elastics. A. Adult female patient with frank anterior open bite treated using Dayan open-bite protocol48 combined with six miniscrew implants (two each on buccal and palatal sides of posterior maxillary alveolus, two in buccal alveolus of posterior mandible). “Sling” elastics worn from palatal to buccal maxillary miniscrews, across occlusal surfaces of aligners, to support intrusion. In lower arch, teardrop notches placed at lingual gingival margin of aligners mesial and distal to first molars; elastics worn from lingual notches to buccal miniscrews, across occlusal surfaces of aligners, to support mandibular vertical control. B. Maxillary left palatal miniscrew relocated mesially; metal and esthetic attachments bonded in upper and lower arches for intermaxillary elastics (continued on next page).

B

A



terior teeth can improve the predictability of this method.

The addition of miniscrew anchorage to sup-port biomechanics involving elastic forces for the extrusion of anterior or posterior teeth is another logical extension of their application to clear-align-er treatment (Fig. 14). An alternative type of boot-strap mechanism employs miniscrews to improve the reliability of posterior intrusion and poten-

tially produce spontaneous mandibular autorota-tion (Fig. 15).47

Although there is seldom a need to extrude anterior teeth during the correction of anterior open bites,51 the combination of clear aligners with miniscrew anchorage for such treatment has been described by Lin and colleagues.36,52

(TO BE CONTINUED)

Fig. 15 (cont.) C. Rectangular intermaxillary elastics worn after sequential posterior intrusion to assist in seating occlusion. D. After 26 months of treatment, patient in refinement stage.

D

C

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1. Boyd, R.L.; Miller, R.J.; and Vlaskalic, V.: The Invisalign sys-tem in adult orthodontics: Mild crowding and space closure cases, J. Clin. Orthod. 34:203-212, 2000.

2. Vlaskalic, V. and Boyd, R.: Orthodontic treatment of a mildly crowded malocclusion using Invisalign system, Austral. Orthod. J. 17:41-46, 2002.

9. Boyd, R.L.: Complex orthodontic treatment using a new proto-col for the Invisalign appliance, J. Clin Orthod. 42:525-547, 2007.

22. Bowman, S.J.: Thinking outside the box with miniscrews, in Microimplants as Temporary Anchorage in Orthodontics, ed. J.A. McNamara Jr. and K.A. Ribbens, Craniofacial Growth Series, University of Michigan, Ann Arbor, 45:327-390, 2008.

31. Chisari, J.R.; McGorray, S.P.; Nair, M.; and Wheeler, T.T.: Variables affecting orthodontic tooth movement with clear aligners, Am. J. Orthod. 145(4 suppl):S82-91, 2014.

32. Kravitz, N.D.; Kusnoto, B.; Begole, E.; Obrez, A.; and Agran, B.: How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign, Am. J. Orthod. 135:27-35, 2009.

33. Turatti, G.; Womack, R.; and Bracco, P.: Incisor intrusion with Invisalign treatment of an adult periodontal patient, J. Clin. Orthod. 40:171-174, 2006.

34. Krieger, E.; Seiferth, J.; Marinello, I.; Jung, B.A.; Wriedt, S.; Jacobs, C.; and Wehrbein, H.: Invisalign treatment in the ante-rior region: Were the predicted tooth movements achieved? J. Orofac. Orthop. 73:365-376, 2012.

35. Lin, J.C.Y.; Liou, E.J.W.; and Yeh, C.L.: Intrusion of over-erupted maxillary molars with miniscrew anchorage, J. Clin. Orthod. 40:378-383, 2006.

36. Lin, J.C.Y.; Yeh, C.L.; Liou, E.J.W.; and Bowman, S.J.: Treatment of skeletal-origin gummy smiles with miniscrew anchorage, J. Clin. Orthod. 42:285-296, 2008.

37. Lin, J.C.Y.; Liou, E.J.W.; and Bowman, S.J.: Simultaneous re-duction in vertical dimension and gummy smile using mini-screw anchorage, J. Clin. Orthod. 44:157-170, 2010.

38. Giancotti, A.; Germano, F.; Muzzi, F.; and Greco, M.: A mini-screw-supported intrusion auxiliary for open-bite treatment

with Invisalign, J. Clin. Orthod. 48:348-358, 2014.39. Boyd, R.: How successful is Invisalign for treatment of ante-

rior open bite and deep overbite? lecture, AAO annual session, Philadelphia, May 5, 2013.

40. Nicozisis, J.L.: Tripping the plastic fantastic, Orthod. Prod., Nov. 2013, pp. 28-34.

41. Humber, P.: Rotating canines using the Invisalign system, Aesth. Dent. Today 7:30-34, 2013.

42. Kuo, E. and Duong, T.: Invisalign attachments: Materials, in The Invisalign System, ed. O.C. Tuncay, Quintessence, London, 2007, pp. 91-98.

43. Boyd, R.L. and Vlaskalic, V.: Three-dimensional diagnosis and orthodontic treatment of complex malocclusion with the Invisalign appliance, Semin. Orthod. 7:274-293, 2001.

44. Edwards, J.G.: A surgical procedure to eliminate rotational relapse, Am. J. Orthod. 57:35-46, 1970.

45. Tuncay, O.: The iatrogenic crowding caused by aligner length/arch length discrepancy, Clinical Reports & Techniques (Align Technology), Fall 2005, pp. 3-5.

46. Kesling, H.D.: The philosophy of tooth positioning appliance, Am. J. Orthod. 31:297-304, 1945.

47. Giancotti, A. and Ronchin, M.: Pre-restorative treatment with the Invisalign system, J. Clin. Orthod. 40:679-682, 2006.

48. Dayan, W.: Techniques for posterior intrusion in the correc-tion of anterior open bite with Invisalign, Align Technology white paper, 2010.

49. Womack, W.R.; Ahn, J.H.; Ammari, Z.; and Castillo, A.: A new approach to correction of crowding, Am. J. Orthod. 122:310-316, 2002.

50. Schupp, W.; Haubrich, J.; and Neumann, I.: Treatment of ante-rior open bite with the Invisalign system, J. Clin. Orthod. 44:501-507, 2010.

51. Guarneri, M.P.; Oliverio, T.; Silvestre, I.; Lombardo, L.; and Siciliani, G.: Open bite treatment using clear aligners, Angle Orthod. 83:913-919, 2013.

52. Lin, J.C.Y.; Tsai, S.J.; Liou, E.J.W.; and Bowman, S.J.: Treatment of challenging malocclusions with Invisalign and miniscrew anchorage, J. Clin. Orthod. 48:23-36, 2014.

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