hiro - hiro system

Indirect bonding technique in lingual orthodontics: the HIRO system

Toshiaki Hiro*, Fernando de la Iglesia**, Puigdollers Andreu***

*DDS, PhD, EBO.**DDS, PhD, Professor Orthodontics of the University International Of Catalunya.***DDS, PhD, Chairman of Orthodontics of the University International Of Catalunya.

Correspondence to:Fernando de la IglesiaC/ Emancipación 20 1º1ºBarcelona 08022SPAIN

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1 Indirect bonding technique in lingual orthodontics: the HIRO system

PROGRESS in ORTHODONTICS 2008; 9(2):34-45

The indirect bonding technique is pivotal for success in lingual or-thodontics. There are different laboratory techniques available for in-direct positioning and bonding of lingual brackets. The HIRO systemis one of the most used and easy to perform. In this article the HIROlaboratory and bonding technique and the different innovations andimprovements made to the previously described technique are pre-sented.

Hiro T, De la Iglesia F, Puigdollers A. Indirect bonding technique inlingual orthodontics: the HIRO system. Prog Orthod 2008;9(2):34-55.

Introduction

In the early 70`s, lingual ortho-dontics made a sensational debut,and the number of initiated casesincreased exponentially. A fewyears later, the number of lingual or-thodontic cases decreasedgreatly1. The reason was veryclear; most doctors could not achie-ve satisfactory results with lingual or-thodontics. Since then, there are afew who practice lingual ortho-dontics and there are limited num-bers of finished treatments. As timepassed and problem solving asso-ciated with lingual orthodontics we-re improved, lingual orthodonticsexpanded around the World, spe-cifically in European and Asiatic

PIO08_34-45_Delaiglesia 3-11-2008 16:24 Pagina 34

countries. Today, lingual orthodon-tics is no longer a technique for li-mited numbers of orthodontists2.One of the most dramatic changescan be found in the evolution of thebonding procedures. Current bon-ding procedure is totally different fromthat of ten years ago. In the 90´s or-thodontists favoured the use of the si-licone tray indirect bonding system.However, this technique didn’t satisfymany orthodontists because of it’slack of accuracy in indirect bonding.Other techniques began to developand were based in an ideal arch toperform indirect bonding3. Dr. Hirodeveloped at the beginning of 1990a laboratory system and indirect bon-ding technique that was publishedin 1998 4. The author described thistechnique as the Resin Core IndirectBonding System (RCIBS). This techni-

que had a great impact in the lingualorthodontic world and was called theHIRO System. Every single laboratory and indirectbonding technique must match thefollowing objectives: easy to make,provide accurate bonding, freefrom bonding failure, rebondable

and low cost. In this article we willexplain the HIRO laboratory andbonding technique and explain thedifferent innovations and improve-ments made to the previously de-scribed technique4.The laboratory and indirect bon-ding HIRO technique.

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Indirect bonding technique in lingual orthodontics: the HIRO system 2


La tecnica di bonding indiretto è un elemento fondamentale per la ri-uscita di un trattamento ortodontico linguale. Esistono attualmente di-verse tecniche di laboratorio per il posizionamento e il bonding in-diretto dei bracket linguali. Il sistema HIRO rappresenta una delle so-luzioni di utilizzo più frequente ed agevole. Il presente articolo illustrala tecnica HIRO e i numerosi miglioramenti ed innovazioni apporta-ti alla versione precedentemente descritta.

Key words: Lingual orthodontics, Lingual Indirect Bonding technique,HIRO system.

Fig. 1 Hard plaster models.

1. Impressions of the patient’smouth (Fig. 1)

The impressions of the patient’smouth can be taken with silicone,polyether or alginate if you canuse a vacuum mixer. The modelsshould be poured with hard plaster.2. Setup (Fig. 2)Next fabricate the setup with athree point articulator. 3. Prepare the ideal archwire

(Figs 3-4)Once the setup has been finishedwith wax, begin to bend an idealarchwire using the same width asthe slot of the brackets that are goingto be used (example: with a slot .018bracket, we will use a .018 x .025ss archwire). The bended archwiremust follow the lingual arch form andmust be as symmetrical as possible.


If a step-down is made in the idealarchwire, this bend must be repro-duced in the final archwires at theend of the treatment. 4. Position the surgical hooks

(Figs 5-6)Once the ideal arch has been do-ne and the brackets are correctlypositioned in the centre of the teeth,remove the arch wire from the setupand crimp three surgical hooks on

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Before doing the premolar bend, it isadvisable to position the six anteriorbrackets initially. This will make thebrackets have the smallest possiblegap between the mesh pad and thetooth’s lingual surface. Sometimes,the bracket form does not adapt tothe dental anatomy, so we will haveto make adjustments to the mesh pad

by grinding or bending it. The brac-kets must be positioned in the gingi-val or inferior third of the tooth. Thispositioning will help the patient’sspeech and occlusion by not creatingany interferences. If we observe thatthe premolars have a very short cli-nical crown, a vertical step-down canbe made on the archwire to com-pensate; another option is to build upthe lingual cusp with composite resin.


La technique indirecte de bonding est prioritaire pour le succès dansl’orthodontie linguale. Il y a différentes techniques de laboratoire dis-ponibles pour le positionnement et le collage indirects des brackets lin-guales. Le système de HIRO est une de plus employée et facile à exé-cuter. En cet article la technique de laboratoire et de collage de HI-RO et les différentes innovations et améliorations apportées à la tech-nique précédemment décrite sont présentées.

Traduit par Maria Giacinta Paolone

Fig. 2a,b Models setup.

Fig. 3 Bending the wire.

Fig. 4 Ideal archwire.



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the wire. This will help position thearchwire in the setup. The hookswill be positioned between the twocentral incisors and between the

first and second molars in both si-des. Afterwards the surgical hooksare bent lingually.5. Position the dowel pins (Figs 7-9)Next, heat three dowel pins andstick them in the wax base just un-der the surgical crimped hooks. 6. Fabricate the acrylic resin

hoods (Figs 10-11)Once the dowel pins are fixed inthe wax the next step is to fabrica-te the acrylic resin hoods powder-liquid that will help position thearchwire exactly when rebonding.Use gutta-percha at two points ofthe arch to keep the wire for a


La cementación indirecta es una técnica fundamental para el éxito enel tratamiento ortodontico lingual. Existen diferentes técnicas de la-boratorio disponibles para el posicionamiento indirecto y la cemen-tación con brackets de la técnica lingual. El sistema HIRO es uno delos más utilizados y fáciles de aplicar . En este artículo, se presentanlas diferentes innovaciones de cementación propuestas por el labo-ratorio HIRO con respecto a las técnicas descrita anteriormente.

Traducido por Santiago Isaza Penco

Fig. 7 Heat the dosel pins.

Fig. 5a,b Crimped surgical hooks. Fig. 6 Bend the surgical hooks lingually.

Fig. 9 Dosel pins positioned.

Fig. 8a,b Stick the dosel pins under the surgical hooks.



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short time in its position until theacrylic resin hoods have been fi-nished (observe the detail of thegutta-percha on top of the arch atthe canine). When making theacrylic resin hoods the resin mustcover the crimped surgical hookstotally and the dowel pins partially.Now the ideal archwire can bepositioned exactly in the model atany time thanks to the acrylic resinhoods and the dowel pins.7. Prepare the models (Figs 12-13)Subsequently, block out the molar

small grooves with wax to preventthem from being retentive when therigid cores are being constructed.Next soap the casts for 3 to 4 hoursand polish them afterwards. Soa-ping the models is done instead ofapplying separator. Since the sepa-rating layer of soaping is quite thinthe brackets can be bonded muchmore precisely comparing it withapplying separator to the model. 8. Transfer the information from the

setup to the bracket (Fig. 14)The next step is to transfer all the in-

formation of the setup to the brac-kets. First we will apply light curecomposite resin (Transbond®3M)on the bracket bases. Position thearchwire in the setup with the helpof the acrylic resin hoods. Then cu-re all the light cure composite resinof the bracket bases. Now all theinformation of the setup has beentransferred to the brackets.9. Construction of the resin cores

(Figs 15, 16 and 17)This is the time to begin the con-struction of the transfer resin cores.


Fig. 10a,b Fabricate the acrylic resin hoods.

Fig. 11a,b Acrylic resin hoods fabricated.

Fig. 12 Block out the molar small groo-ves with wax.

Fig. 13a,b Soap the casts and polish them afterwards.



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First cover all the brackets with pro-visional dental resin (Fermit® Viva-dent) paying special attention in notcovering the ideal archwire and co-

vering 1-2 mm of the teeth beyondthe bracket’s base. This material ad-heres to the brackets and its elasticitymakes the removal of the resin cores

easy. Do the same for all the brac-kets and cure the provisional dentalresin (Fermit® Vivadent).The next step is to mark with a pen-cil the lingual functional cusps of mo-lars and premolars. This will help asa reference guide for re-checking theheight of the brackets. The bracketsmust never be positioned higher thanthe functional cusps. Another reasonfor marking the cusps with a pencil isto leave a small hole in the resin co-re. This will permit the excess of ad-hesive to come out. Afterwards use apowder-liquid acrylic resin to con-struct the resin cores and before theacrylic has harden put an elastome-ric ring that will help afterwards trans-fer the individual resin cores from themodel casts to the patients mouth.10. Polish the resin cores

(Figs 18-20)Once all the resin cores have beencompleted, they are numbered ac-cording to the tooth and separatedfrom the setup. Excess resin is groundoff and a heated instrument used tocut the elastomeric ligatures. This al-lows for separation of the resin corefrom the ideal archwire. At this time,all the transfer resin cores are doneand the bonding can begin. 11.- Picture of the transfer resin co-

res (Fig. 21)


Fig. 14a,b Apply light cure composite resin on the brackets bases and positionthe ideal archwire.

Fig. 15 Cover all the brackets withprovisional dental resin ( Fermit®).

Fig. 16a,b Use a liquid-powder acylic resin to construct the resin cores.

Fig. 17a,b Elastic ring positioning.

Fig. 18a,b Transfer resin cores finished.



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Bracket bonding

The bonding technique is simple buthas some peculiarities. First, the teethmust be etched with orthophosphoricacid. (Fig. 22). After 15 seconds rin-se with water and dry. Apply a thin co-at of bond to the etched surface (Fig.23) and afterwards apply a very smallamount of bond and light-curing com-posite to the bonding surface of thebracket. (Transbond®) (Fig. 24). Ca-refully pick the transfer resin core by theelastomeric ring (Fig. 25) and seatthe resin core on the correspondingtooth. Using a light-curing lamp, curefor at least 20 seconds (Fig. 26). Sub-sequently with a pointed instrument se-parate the acylic resin from the trans-fer core (Fig. 27). Then take off the pro-visional dental resin (Fermit®) from thebracket. Now the bracket is rea.

Bracket rebonding

Any indirect bonding technique inlingual orthodontics must be easyand quick to perform when rebon-ding brackets. With the HIRO system,rebonding of brackets is easy andcan be done in the office in a shortperiod time. The transfer resin coresused at the beginning of treatmentcannot be used again for rebonding.Firstly, the new bracket is positionedon the ideal wire of the setup with anelastomeric ring. Afterwards seat theideal wire in the setup using the acry-lic resin hoods (Fig. 28). Next, buildup the transfer resin core as shownin figures 14-17. First apply light-cu-ring composite (Transbond®) in thebonding surface of the bracket, co-ver partly the bracket with provisionaldental resin (Fermit®) and subse-


Fig. 19a,b Grind off the excess resins and cut the elastic ligatures.

Fig. 20a,b Transfer resin cores ready to be bonded.

Fig. 21 Transfer resin cores.

Fig. 22 Etch the lingual surface with or-thophosphoric acid.

Fig. 23 Apply athin coat of bondto the etched sur-face.



She had no history of physical traumato the head or neck. The patient hada convex profile with a symmetric fa-ce and lip competence at rest. In-traorally, she had a bilateral Class Imolar and canine relationship. Shehad a correct overjet and 2 mm ofoverbite. The maxillary arch was U-shaped with mild crowding. The man-dibular arch also was U-shaped andhad mild crowding. The cephalome-tric analysis showed a skeletal ClassII anteroposterior discrepancy with anANB angle of 6,2º and a normofa-cial pattern, as shown by an SN-GoGn of 38°. The lower incisors we-re excessively protruded as shown byan IMPA of 101,7º. (Fig. 30). The treatment plan was not to pro-trude the upper and lower incisorsand solve the upper and lower crow-ding. The decision taken was to ex-tract the first upper and lower pre-molars. Figures 31- 34 shows thepatient`s evolution. Orthodontic treat-ment lasted 20 months. An accep-table occlusion was obtained. Figu-re 35 shows the three year follow-up.The superimposed cephalometric tra-cings (Fig. 36) show a correct incisorinclination at the end of treatment.

Discusion

There are many different indirect

Clinical case

A 26-year-old woman was referredfor orthodontic consultation. Her chiefcomplaint was her crowded teeth.

quently add liquid-powder acylic re-sin to build up the resin cores . It ta-kes just 3 minutes to build up thetransfer resin core (Fig. 29).

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Fig. 24a,b Apply a very small amount of bond and lightcuring composite.

Fig. 26 Seat the resin core and cure. Fig. 27 Separate the acylic resin fromthe transfer core.

Fig. 25 Pick the transfer resin core.

Fig. 28a,b Rebonding of brackets. Seat the ideal wire using the acrylic resin hoods.

Fig. 29a,b Transfer resin core finished.




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bonding techniques in lingual or-thodontics. The HIRO system hassome advantages which are1:• No electronic equipment is nee-

ded for bracket positioning orrebonding, and consequentlythere is no commercial relations-hip to any company.

• There is no need to transfer brac-kets from the setup model to theoriginal cast (malocclusion mo-del) as in the CLASS system.

• Extractions, elastic separations,

expansion and/or distalizationcan be carried out between im-pressions and bonding.

• The individual hard tray is verysmall and rigid, making bondingmore accurate. This eliminates de-formations and poor adhesion dueto excess flexibility. In other indirectbonding techniques the transfer isdone with silicone trays, and thebonding is less accurate becausethe position of the bracket will varydepending on the amount of pres-

Fig. 30a

Fig. 30a-c Pretreatment records.

Fig. 30b




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sure applied to the tray. This excessof flexibility of the silicon trays iscorrected by some clinicians withdifferent thermoplastic materialsthat make the trays harder.

• The resin core has no relationwith tooth alignment, so brac-ket/tooth fit against it is not af-fected by tooth movement.

• Limited composite overflow ma-kes hygiene easier, is more com-

fortable for the patient and alsoreduces chairtime.

• In cases of severe crowding, se-quential bonding is easier to ma-nage than in other lingual indi-rect bonding procedures.

• Rebonding is quick, easy and eco-nomic to perform with the setupmodel and the ideal archwire.

• Is an easy, economic and accu-rate system.

• It takes approximately ten to fif-teen minutes to bond a comple-te arch, more or less the same ti-me that with other techniquessuch as the silicone trays.

Conclusions

The HIRO indirect bonding techni-que is easy, economic and accura-

Fig. 31 Records at two months of treat-ment. Upper and lower 0.12 Ni-Tiarchwires.

Fig. 32 Records at 10 months of treat-ment. Upper .014 ss archwire and lo-wer .016 x .022 TMA archwire.



Fig. 34a


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Fig. 33 Extraction spaces closed at20 months of treatment. Upper .017 x.025 TMA and lower .016 x .022TMA archwires.

Fig. 34b




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te and makes the orthodontist havereliable results in any orthodontictreatment.

Fig. 35 Three years postreatment re-cords.

Fig. 34a-c Postreatment records.

Fig. 36 Superimposed cephalometric tracings.

References

1. Scuzzo G, Takemoto K. Invisible Or-thodontics. Current concepts and so-lutions in lingual orthodontics. Ger-many, Quintessence, 2003.

2. Buso-Frost L, Fillion D. An overallview of the different laboratory pro-cedures used in conjunction with lin-gual orthodontics. Semin Orthod2006; 12: 203-10.

3. Macchi A, Nidoli G, Lazzati M. Di-rect or indirect application of theLingual Brackets. Mondo Ortod1984; vol. 3: 73-82.

4. Hiro T. Resin Core Indirect BondingSystem: Improvement of Lingual Or-thodontics. J. Japan Orthod. Society1998; 57 (2): 83-91.



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