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Dental Tribune Middle East & Africa No. 4, 2017

D2 ORTHO TRIBUNE Dental Tribune Middle East & Africa Edition | 4/2017 Archwire Sequence for Insignia®: a Custom Bracket System with a Bright Future By Ormco Abstract Insignia® system is a reverse-engi- neered production of customized brackets, based on the desired final alignment: “begin with the end in sight.” Efficient sequencing is the key to efficient management of a malocclusion with progressive archwire therapy. Each step in ac- tive treatment is directed toward a specific objective, consistent with ensuring patient comfort, maxi- mizing the potential of each step in treatment, and achieving alignment to place the final archwire as soon as possible. There are four phases in Insignia® progressive archwire therapy: (I) stock light round wires, (II) customized rectangular copper- nickel-titanium (CuNiTi) wires, (III) major mechanics as needed, and (IV) finishing. This article recommends archwire sequencing, based on clini- cal experience with the Insignia® bracket system. In addition to tradi- tional progressive archwire therapy, the Insignia® system is well designed for segmental determinate mechan- ics, to decrease PDL compressive stress. Segmental mechanics, with extra-alveolar bone screw anchorage and anterior bite turbos, is designed to enhance outcomes and decrease treatment time by increasing the rate of tooth movement and control- ling root resorption. (Int J Orthod Im- plantol 2017;46:60-69) Fig. 1: Dr. Craig Andreiko (1950-2013) was the inventor of the Insignia® bracket design system based on a futuristic 1992 patent. Key words: Insignia® system, passive self-ligat- ing bracket, archwire sequence, cus- tom bracket, custom torque, low PDL stress, enhanced rate of tooth move- ment, decreased root resorption Introduction Insignia® (Ormco, Glendora, CA), introduced by Dr. Craig Andreiko in 1987 (Fig. 1), involves two compo- nents: (1) customized brackets, place- ment gauges, and archwires, and (2) three-dimensional (3D) real-time virtual treatment planning software. A bracket set is precisely designed for ideal alignment of an entire arch on a full dimension rectangular archwire. The process begins by digitizing the patient’s skeletal and dental anat- omy: scanning PVS impressions or direct dental scanning (Fig. 2a). The teeth are aligned into an ideal posi- tion (Fig. 2b) with a digital 3D po- sitioning algorithm that assists in tooth alignment consistent with the underlying skeletal support (Fig. 2c). According to the desired tooth align- ment (Fig. 2b), the system produces custom brackets (Fig. 2d) and arch- wires (Fig. 2e) by a reverse engineer- ing process. Bracket-positioning jigs are fabricated to assist the clinician in accurately bonding a customized bracket on each tooth (Fig. 2f). The precise placement of each bracket is critical for producing a 3D alignment (Fig. 2d) to accommodate the final rectangular finishing wire (Fig. 2e). The Insignia® system is a reverse- engineered fixed appliance for com- prehensive dentofacial orthopedic treatment; this is a major advance for comprehensive treatment of all malocclusions. The clinician pre- scribes a custom appliance to opti- mize the treatment of each patient by digital simulation of the final desired result. Automated manage- ment, of the demanding technical aspects of routine alignment and lev- eling, allows the practitioner more time to concentrate on treatment planning for advanced mechanics to resolve even severe skeletal maloc- clusions conservatively (no extrac- tions or orthognathic surgery).1 In- signia® was designed to utilize the established preferences of doctors, for creating a custom appliance with a preferred bracket system. Insignia® offers clinical efficiency for control- ling and minimizing variables to achieve optimal results with mini- mal treatment duration.2-5 Bracket torque, archwire configuration, and bonding positions are designed by the Insignia® system, but the arch- wire sequence is selected by the cli- nician. Based on clinical experience, this article recommends an archwire sequence for each stage of Insignia® progressive archwire treatment, utilizing passive self-ligating (PSL) brackets. All products described are obtained from Ormco Corporation, Glendora CA, except where specified. (CuNiTi) wire Phase I: Stock light round wires The objectives for the first phase of treatment are: (1) level and align, (2) initiate arch development as needed, and (3) resolve 90% of the rotations. A stock 0.014-in Damon® copper- nickel-titanium is used as an initial archwire to resolve interdental discrepancies and level the arches. The small dimension of the initial round archwire mini- mizes friction and binding between the wire and the tube-like lumen of the PSL brackets (Fig. 3). With this mechanism the teeth can slide freely along the wire as they are leveled and aligned. To manage severe crowding, narrow arch form and/or compro- mised periodontal support, a stock 0.016-in or 0.018-in Damon® CuNiTi archwire can be used as an alterna- tive second archwire to further align and level the dentition. The purpose of these round CuNiTi wires in the Phase I (initial stage) of treatment is not to completely resolve rotations, but to provide adequate alignment of brackets to atraumatically transition to the sec- ond phase in the sequence (rectan- gular archwires). If a patient feels pain, or the brackets dislodge when closing the slide, progression to the rectangular wire(s) is premature. Phase II: Insignia® Rectangular CuNiTi wires The objectives of the second phase are: (1) start resolving torque and root angulation problems, (2) complete leveling and alignment, (3) finish ro- tation corrections, and (4) continue arch form development, as needed. The recommended Insignia® Cu- NiTi rectangular archwire sequence is 0.014x0.025-in, 0.018x0.025-in, and 0.021x0.025-in. Each archwire must be inserted with minimal ac- tive engagement, or the arch is not ready to progress. Minor spacing in the anterior segments is consoli- dated with elastomeric chains. The latter full sized CuNiTi archwire is used to prepare for insertion of the 0.019x0.025-in stainless steel (SS) wire in the next phase. Phase III: Major mechanics The objectives of the third phase are to close posterior spaces as well as to correct anteroposterior and inter- maxillary relationships. All teeth in the anterior segments of each arch are retracted en masse (altogether). Consistent with a straight wire ap- proach, a stock 0.019x0.025-in SS archwire is used for sliding me- chanics. A relatively rigid SS arch- wire (0.017-in or 0.019x0.025-in) is recommended for maintaining the integrity of the arch during space closure, either by chains of elastics or closing loops; rigidity across eden- tulous segment is particularly im- portant for large extraction spaces. The stock SS archwire is adjusted to fit the patient’s specific arch form before insertion. Moreover, reduc- tion of the SS archwire in the poste- rior segments is recommended to control bracket friction and binding when closing spaces with elastomer- ic chains. In addition, if intermaxillary correc- tion is required, OrthoBoneScrews® (OBSs)(Newton’s A, Hsinchu City, Taiwan) are an ideal source of an- chorage for the Insignia® system. OBSs are typically placed buccal to the molars in each arch to provide skeletal anchorage that does not in- terfere with dental alignment or the path of tooth movement. Each arch can be retracted, intruded or rotated to resolve even severe malocclusions conservatively.6,10 Phase IV: Finishing The objectives of the fourth phase of treatment are to complete torque expression and final detailing to achieve ideal intra-arch and inter- maxillary alignment. An Insignia® 0.021x0.025-in CuNiTi wire is placed to achieve the full expression of the digital set-up. If needed, final finish- ing is achieved with an Insignia® 0.021x0.025-in TMA archwire. It is important to order the final TMA archwire as a backup, because un- controlled anatomical variables can result in minor alignment discrep- ancies, that are easily managed with routine finishing adjustments. Fig. 2: (a) Patient’s oral anatomy is digitized in 3D. (b) Based on the practitioner’s treatment plan, all the teeth are digitally aligned in 3D to an ideal position via an algorithm for auto- mated intermaxillary alignment. (c) Any tooth can be adjusted in 3D as specified by the clinician. (d) According to an ideal tooth position approved by the clinician, the Insignia® system reverse-engineers the production of a custom bracket for each tooth. (e) Straight archwires are constructed as specified by the ideal set-up. (f) Bracket-positioning jigs are fabricated to provide accurate bonding of each bracket. Fig. 3: Small dimension round wires mini- mize frictional binding between the tube- like lumen of the PSL bracket and the con- tinuous archwire. This allows the teeth and brackets to slide freely along the wire during leveling and alignment. Figs. 4 and 5 are sequences of in- traoral photographs documenting the treatment with Insignia® pro- gressive archwire therapy. Discussion The low force to deflection-rate (re- siliency) of an 0.014-in CuNiTi arch- wire results in the application of a relatively low load over an extended range. These are desirable charac- teristics for a more physiologic ap- proach to orthodontic therapy: ap- plying adequate force to stimulate cellular activity in the periodontal ligament (PDL) without occluding its vascularity.7 The 1932 Schwartz7 proposed a 2D histologic concept: if PDL compression in the line of force exceeds capillary pressure (<16kPa),1 necrosis (hyalinization) of the PDL results. More recent experimental studies have demonstrated the im- portance of modeling PDL compres- sive stress in 3D because teeth do not always move along the plane of the force.8 Rodent tooth movement studies analyzed in 3D with finite el- ement analysis show that 8-10kPa is associated with PDL necrosis,9 which is less than the 16kPa required to oc- clude capillaries.1 Recurrent PDL Necrosis: Episodes of PDL hyalinization (necrosis) de- crease the rate of tooth movement and enhance the expression of ex- ternal apical root resorption (EARR). PDL necrosis at the initiation of tooth movement is well known.11-13 Furthermore, histologic data sug- gests that periodic occlusion of the PDL is probably recurrent through- out the entire course of comprehen- sive treatment, with both fixed and removable appliances. Even the re- lapse of unretained teeth can result in PDL necrosis.11,12 Thus, relatively low levels of PDL compressive stress results in necrosis, which is manifest as a lag phase in tooth movement.11-13 Routine archwire changes and reac- tivation of appliances results in re- current loading of teeth which may result in a continuing series of lag phases. Even modest lateral force on the crown of a tooth produces substantial compressive stress in PDL near the apex of the root. This phenomenon in physics is due a long lever-arm between the bracket and the center of rotation (Crot) of the root: ~10mm or more. A relatively light clinical force (≤25cN) at the bracket level generates a large mo- ment (~250cN-mm) around the Crot which is usually ~0.40% down the length of the root.13 The movement of the apex in the opposite direction of the applied force crushes the PDL in a relatively small area (1-3mm2), because of the anatomical irregu- larity of root and bone surfaces.11-13 The relatively large reactive force applied to a small area of the PDL near the apex results in compressive stress of a MPa or more. The crushed PDL produces a lag phase in tooth movement which may last 2 weeks or more.11-13 The usual pattern of en- gaging individual teeth on multiple archwires and periodic reactivation probably generates a continuing series of PDL necrotic episodes (lag phases) that increase treatment time. Thus comprehensive ortho- dontics with progressive archwire therapy requires an extended period of time (2-3 years) because the rate of ÿPage D3

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