Lingual Appliance System: A Literature Review of its Evolution and Development

Headnote

Abstract

The true lingual appliance system developed in the 1970's in 2 countries. Kinj a Fujita in Japan designed a lingual appliance sy- stem and simultaneously Craven Kurz in United States developed his lingual system. The Kurz lingual bracket evolved from 131 to 7th generation from 1976-1990. After the first enthusiastic phase of development of the technique, a kind of depression fol- lowed, due to problems which arose during early clinical trials. Most orthodontists considered the lingual method different only in so far as the position of the attachments was concerned, and did not take into account the different skill and mental approach of the system itself. During the last few years the work of many specialists renewed the interest of the lingual appliance system. By 2001, the number of patients treated with lingual systems in Japan and in Europe was more than twice that of the US. In 1999 use of self-ligating brackets in lingual orthodontics was first presented by Neumann and Holtgräve to improve the performance of the lingual appliance and to increase the efficiency of lingual orthodontic treatment. The purpose of this article is to review the evolution and present status of lingual appliance system

Keywords: Lingual appliance; lingual orthodontics; evolution.

Introduction

Many of us have bonded lingual attachments, buttons, cle- ats, and retainers. Since plastic and other labially bonded brackets have not provided the esthetics we strive for, ma- ny orthodontists at least considered bonding brackets on the lingual, and a few were bold enough to attempt lingual orthodontics. Thomas Edison and many others must have had the concept of a light source without a flame, but it took several advances in electromagnetic technology and the development of tungsten filaments before the electric light bulb became a reality. Likewise, refinements in bonding technology and the development of more resilient orthodo- ntic alloys and wires were necessary before lingual orthod- ontics became practical.1

Nothing stays the same in life, given time; everything cha- nges, so it is with orthodontics. Who would have thought that when Kinj a Fujita placed orthodontic brackets on the lingual surfaces of his patient's teeth, not for esthetic reas- ons, but to avoid trauma to the lips and cheeks from the ph- ysical contact encountered during martial arts activities, this would spawn the discipline of lingual orthodontics. In the early days of its development, the lingual technique we- nt through some difficult times. However, since then it has evolved into a sophisticated technique capable of treating most malocclusions to a standard comparable with that cu- rrently achieved with labial techniques.2

One of the most important challenges in orthodontics is to attain excellence in treatment with comfortable and esthe- tic appliances. From the esthetic perspective, lingual ortho- dontics provides the best option for comprehensive treatm- ent ofmost malocclusions while maintaining full 3-dimen- sional control of the dentition.3

Evolution and Development

In 1726, Pierre Fauchard suggested the possibility of using appliances on the lingual surfaces ofteeth.4 In 1841, P.J. Le foulon designed the first lingual arch for expansion and alignment of the teeth. In 1889, John Farrar, developed the "lingual removable arch". In 1918, Dr. John Mershon intro- duced the removable lingual arch as an appliance for the treatment of malocclusion of the teeth". In mid-1950's lingual appliances were used in combination with active labial appliances such as Dr. William Wilson's labio-loop- lingual appliance (3D modular enhanced orthodontics). Rickets' quad helix and Goshgarian's transpalatal bar.5

The true lingual appliance system developed simultaneou- sly in the 1970's in two countries. The lingual appliance was not the consequence of an esthetic demand, but it was started in Japan by Kinj a Fujita to satisfy the orthodontic needs of patients who practiced martial arts, to protect the lips and cheeks from the possible impact against brackets. Fujita was the first to develop the lingual multibracket tec- hnique using the mushroom shaped arch wire. He publish- ed the Fujita method in 1978, treating Class I and Class II cases with extraction of 4 bicuspids. The Fujita bracket had 3 slots occlusal, horizontal, and vertical (US patent No. 4, 209,906; July 1,1980).68

In early 1970's Dr Craven Kurz, an orthodontist, found his private orthodontic practice to be increasingly dominated by adult patients. As many ofhis patients were public figur- es, esthetics became a major concern. Craven Kurz and Jim Mulick in 1975 started using plastic brackets bonded to the lingual tooth surfaces. Apparently an employee ofthe Bun- ny Playboy Club with crowded teeth came to Craven Kur- z's office asking him for non visible orthodontic treatment, further stimulating his interest in the subject. Using plastic brackets, it was easy to shape them for a better fit to the li- ngual surfaces; however, there were many problems, espe- cially with regard to bonding failures and patient comfort (US patent No. 4,337,037; June 29,1982). In 1979, Craven Kurz, Craig Andreiko, and Frank Miller developed a proto- type lingual Edgewise bracket. In 1980 to test and continue their research in this field, Ormco founded Lingual Task Force comprising Craven Kurz, CA Jack Gorman, Bob Smith, Wick Alexander and Mood Alexander, James Hilg- ers and Bob Scholz. The principle characteristics of this br- acket were a bite plane, a base pad adapted to the anatomic characteristics of the lingual surfaces of the teeth, and a pre angulated slot according to the conversion of the torque used on the labial surface.'10

The Kurz lingual bracket developed and evolved from 1stto 7th Generation (1976-1990).11 First generation (1976): Flat maxillary occlusal bite plane from canine to canine, Lower incisor and premolar bracket had low profile and half rou- nd, no hooks on any brackets and the bracket was large. The advantages of the bite plane included: opening the bite ant- eriorly with possible repositioning bar. Second generation (1980): Hooks were added to canine brackets. Third gene- ration (1981): Hooks added to all anteriors and premolar brackets. The first molar had a bracket with internal hook. Fourth generation (1982-84): Additionoflowprofile ant- erior inclined plane. Hooks were optional. Fifth generati- on (1985-86): Anterior inclined plane became pronounced. Increase in labial torque in maxillary anterior region. Attac- hment for trans palatal arch provided. Sixth generation (1987-90): Inclined plane became squarer in shape. Hooks on anterior and premolars were elongated. Hooks incorpor- ated on all brackets. Seventh generation (1990): Maxilla- ry anterior inclined plane is now heart shaped with short hooks. The lower anterior brackets have larger inclined pl- ane with short hooks. The premolar brackets were widened mesiodistally and hooks were shortened, the increased wi- dth of Premolar bracket allows better angulation and rota- tion control.

After the first enthusiastic phase of development of the tec- hnique a kind of depression followed, partly due to proble- ms which arose during early clinical trials and partly due to erroneous use: most orthodontists considered the lingual method different only in so far as the position of the attach- ments was concerned, and did not take into account the di- fferent manual and mental approach of the system itself. These difficulties discouraged many orthodontists and help spread the opinion that the results obtained by this techniq- ue could not stand up to those obtained by using Labial method.

Theproblems ofthe lingual technique are:12

1. The discomfort to the patients regarding speech disturb- ances and tongue irritation, due to the thickness of the brackets;

2. The difficulties in accurate bracket positioning, due to the anatomical variations ofthe lingual surface;

3. The mechanical difficulties: the short arch perimeter, small inter bracket distance, and the position of the bra- ckets palatal to the center of resistance, resulting in dif- ficulties in achieving full control ofrotations and torque.

Despite disadvantages, lingual orthodontics did not compl- etely disappear from orthodontic practice; in fact, there was a renewed interest. Sporadic literature reports appear- ed throughout the late 1980's and early 1990's.' '

Previous publications can be classified into 4 categories. The first category was centered on introductions to new ap- pliances by Fujita and the Ormco Task Force presented the use of the lingual brackets patented by Kurz. The second category focused mainly on the problems encountered by the clinician: bracket bonding, impediment of speech, liga- tion techniques and practice management. The third categ- ory focused on the fact pointed out by Artun that relatively few reports of finished cases had been published. The sca- rcity of objective studies served to reinforce the hesitancy of many orthodontists to invest time and effort in the tech- nique. The fourth category presented anecdotal evidence gathered from interviews and commentaries and letters, th- eir topics ranging from speech impairment due to the brac- kets and the actual viability ofthe technique.13

During the last few years, the work of specialists has led to the codification of the main steps of the lingual technique. The lingual treatment developed outside ofthe US, especi- ally in Europe and Asia, with a steady increase in the numb- er of orthodontists and patients. Scuzzo and Takemoto rep- orted that by 2001, the number of patients treated with lin- gual systems in Japan and in Europe was more than twice that ofthe US.14

In 1982, Paige Introduced ? Lingual Light-Wire Techni- que", who used Begg light wire brackets (Unipoint combi- nation bracket Unitek) on the lingual surfaces.15 He chose to use a Begg bracket because it satisfies the design criteria nicely and is presently available from many manufacturers. It is as narrow as possible and has a vertical slot for use of auxiliaries. Lingual tooth contours on the maxillary and mandibular teeth are much less of a factor because torque control can be achieved by properly shaped torquing auxi- liaries, much like conventional Begg mechanotherapy. Li- gation can be achieved with steel ligatures, elastic modul- es, or pins. The slot can be oriented in an occlusal-incisal direction to ease archwire placement and removal. Placem- ent of the bracket is sensitive only to the incisal-gingival placement because angulation and inclination can be achie- ved with the use of auxiliaries. Therefore, while indirect bonding may be employed, it is not required. Kelly VM also used Unitek labial brackets (3M Unitek) on the lingual surfaces.16

Scott Huge developed the customized lingual appliance set up services (CLASS) technique.17 The technique offers a method of lingual bracket placement that takes into accou- nt the anatomical discrepancies in the lingual surfaces of the tooth. The CLASS system procedure begins with dupli- cation of the malocclusion model to produce diagnostic set up where teeth have been cut and correctly repositioned and aligned. On this model brackets are accurately positio- ned, a flat metal piece helps positioning ofthe anterior bra- ckets. A separate posterior device is used to position the po- sterior brackets. A strip of acrylic covers the incisai edges ofthe tooth and overlaps onto the top ofthe bracket making them one unit. This unit is then separated from setup and transferred to malocclusion model. At this point single tra- nsfer trays are fabricated so the brackets can be delivered clinically via the indirect bonding method. Advantage of this technique is that the final occlusion on the articulated set up model can be visualized. Disadvantages of this tec- hnique are, many steps required before delivering the final product, many small error may occur during the procedure, resulting in a less than ideal bracket setup and several com- pensatory bends on archwire become necessary during tre- atment.

In 1984, Ormco Company developed an apparatus. Torque Angulation Reference Guide (TARG) for lingual bracket bonding.18 It has 'Mitutoyo' Digital Indicator and Caliper with clear LCD displays. Fine adjustments using the up and down fine adjustment screw with a precision linear slide allowing bracket-positioning up or down by increments of 0.01mm. There is no chance of further movement while fixing the bracket in place.

The TARG machine has several blades, making it possible to prescribe the torque and angulation for each individual tooth. It allows the accurate placement of the brackets at a precise distance from the incisai and occlusal surfaces of the tooth. This creates a virtual setup and the brackets can be bonded on the malocclusion model, with each bracket having a specific resin- modified base. Main disadvantage of technique is that, it does not take into consideration the different thickness of the teeth, many 2nd order bends must be made during treatment.

In 1986, Didier Fillion developed Bonding with Equal Sp- ecific Thickness (BEST) technique for bonding lingual br- ackets. This technique has been developed by taking into account the disadvantages and pitfalls of the TARG. A dev- ice to measure the distance in the horizontal plane from the labial surface of the tooth to the slot of the lingual bracket. He added a precise measuring device to the original TARG machine to allow compensation for the different thickness between the teeth and called it as electronic TARG. Positi- oning the bracket so as to allow for compensation for diff- erent labiolingual thickness of the teeth facilitated the use of straight wire principle for both anterior and posterior te- eth, thus reducing the need for 2nd and 3rd order bends during treatment. The advantages of this technique are that the br- ackets are directly bonded on the malocclusion model, no set-up is required during the bracket positioning, the tip, to- rque, height, and thickness is determined. A special comp- uter software package was developed to trace the ideal arch wire for individual patient called as DALI (Design de l'arch linguale information).18 20

In 1989, Creekmore developed a lingual mechanical appli- ance (Conceal; 3M Unitek). Conceal brackets are designed around the Unitwin bracket "centered slot" concept. He bu- ilt "The Slot Machine" for bracket-placement on lingual surfaces. The slot machine defines the orientation of the slot of the bracket by the labial surface. After adjustment of torque, tip, rotation, height, and faciolingual thickness, the adhesive will fill the space between bracket and tooth. He also designed arch wire templates and clinical instrumen- . 21 ts.

In 1999, Silvia Geron developed the Lingual Bracket Jig for direct and indirect bonding in lingual orthodontics. The Jig consists of labial arm and a lingual arm. The labial arm holding the labial bracket slot transfers the straight wire appliance (Andrew's) labial bracket prescription to the lin- gual surface. Brackets can be placed directly on lingual su- rfaces of the teeth.22

In 2000, Kim and Bae developed new indirect bonding me- thod called convertible resin core system (CRC Ready- Made Core Trays), the Model Checker, and a bracket posit- ioner, which together form the Korean Indirect Bonding Setup System (KIS System).23

In2001, Scuzzo andTakemoto developed a lingual straight wire bracket (Ormco/A Company) with labial and buccal slot opening, the STb, this bracket represents a significant advance, because its design facilitates the use of light for- ces with reduced friction and its small size enhances patie- nt comfort.24

In 2002, Dirk Wiechmann developed a customized Incog- nito bracket (Lingual Care) with occlusal slot opening (0.018x0.025 inch). Transfer Optimized Positioning Syst- em (TOP) is used for positioning/indirect bonding of the brackets on the lingual surfaces of the teeth. The prescrip- tion for tip and torque is customized according to the ortho- dontist's treatment plan.2526 Hee-Moon Kyung developed the Individual Indirect Bonding Technique and the Mushr- oom Bracket Positioner. He also founded the Korean Lin- gual Orthodontics Association (KLOA).27

In 2004, Echarri and Kim developed double transfer trays for indirect bonding. The technique consists of adapting the single-tooth trays to each bracket after the bracket pos- itioning on the cast, according to the method of the Korean Society of Lingual Orthodontics: CRC ready-made core system. The trays are then joined together by means of a complete arch silicon transfer tray.28,2' In 2005, the Dentau- rum Company developed lingual bracket called Magic lin- gual system with occlusal slot opening (0.020x0.020 inch). In 2008, Hiro et al., developed the technique of creating individual indirect bonding trays for each bracket: the Hiro system. It's a laboratory technique that does not require sp- ecial equipment. The technique relies on the preparation of set-up model. The brackets are positioned on the setup mo- del with the help of a full sized rigid 0.018x0.025" stainless steel wire. Transfer trays are prepared for individual tooth. The advantages of this technique are, the technique is sim- ple and low cost, the transfer trays for each bracket are ma- de individually and transferred directly from the setup mo- del to the mouth. Extractions, elastic separation, expansion and/or distalization can be carried out between impressions and bonding. Individual hard tray is very small and rigid, making bonding very accurate. The disadvantage of this te- chnique is that the initial bonding appointment is longer as individual tooth is bonded separately.30In 2011, Gilbert de- veloped an in-office wire-bending robot for lingual ortho- dontics.31

Evolution of Lingual Self-ligating brackets

In 1999, use of self-ligating brackets in lingual orthodo ntics was first presented by Neumann and Holtgräve who suggested the use of SPEED (Strite Industries Ltd.) self- ligating labial brackets for application in the lingual techn- 32ique.

Philippe 2D self-ligating lingual bracket (Forestadent Ber- nhard Foerst er, Germany) provides 2-dimensional control. 33 Four types of Philippe brackets are available: a standard medium twin (regularly used for the lingual tech-nique), a narrow single wing bracket for lower incisors, a large twin, and a three-wing bracket for attachment of inter maxillary elastics. The Forestadent 3D Torque-Lingual self-ligating brackets have the similar design as the Philippe 2D self- ligating brackets, but have a vertical slot for fast and easy archwire insertion.

The Hatto Loidl developed Adenta Evolution lingual brae ket (Adenta, Germany) is designed as a one piece bracket with a clip that opens at the incisai edge and allows inser- tion of the arch wire from the occlusal direction. Bracket positioning ofthe Adenta evolution brackets is done indire- ctly using a laboratory HIRO system modified with a spe- cial "Smart Jig".30 The Smart Jig combined with individual transfer caps comprises a mini transfer tray for indirect bo- nding and simplifies the lingual technique system.

In June 2006 two ofthe latest developments in self-ligating lingual brackets were presented at the ESLO (European Society of Lingual Orthodontics) congress in Venice. In- Ovation-L (GAC International, Bohemia, NY) self-ligati- ng bracket, these lingual brackets are twin, horizontal slot brackets, with an interactive clip with very easy effortless opening. Phantom (Gestenco International Gothenburg, Sweden) is a poly ceramic self-ligating bracket. These bra- ckets are bonded directly in the mouth.12

Conclusion

Lingual orthodontics acceptance by both the profession and the patient population continues to grow internationa- lly. The future of lingual orthodontics is dependent on adv- ances in technology related to appliance design and labora- tory procedures. Lingual appliance treatment is suitable for most orthodontic patients and is the best choice for adult patients who reject the conventional visible appliances for social or professional reasons.

References

References

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