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orthodontic | TECHNIQUES

M ost of us are surely familiar with Ortho-dontic braces. They’ve been around for along time, in fact since the late 1800’s.

We’ve either had the experience as a patient orknow someone who has. Simply put, they are com-prised of brackets and/or bands bonded to the teethwith an archwire interconnecting these brackets tomove the teeth in three dimensions. They are veryefficient but in today’s fashion conscious world, forsome, they are just plain ugly, especially for adults.There are alternatives to standard metal labialbonded braces and these include clear ceramic orplastic brackets or a series of invisible aligners suchas Tru-Line™, but these articles will focus on thedevelopment of and some of the laboratory proce-dures of lingual orthodontics.

Lingual orthodontics is exactly as the name sug-gests - orthodontic brackets placed on the lingualsurfaces of the teeth and connected by special arch-wires. The advantages aesthetically are immediatelyevident, but other advantages include the labialenamel is not etched, bonded or scarred duringdebonding. Braces do not have to be removed earlyfor social events and people with highly visible socialjobs can still continue without embarrassment.

The disadvantages of lingual Orthodonticsinclude speech interference and patient adaptationis not always predictable. Tongue irritation iscommon and patients with narrow arches or tonguethrust may not adapt well. The technique is clini-cally more time consuming and patients tend to bemore demanding. Some traditional labialmechanics cannot be used due to the smaller inter-bracket distances and smaller arch radius. Delvinginto the details of most of this is beyond the scopeof the article but suffice to say there are differencesbetween the two modalities.

The lingual bracket had to be specificallydesigned for the lingual surface of the teeth and a

Lab procedures for lingual orthodontics - Part 1

By Terry Whitty

Figure 1. Standard labial-bonded brackets (braces).

Figure 2. Ceramic brackets (braces).

Figure 3. Lingual braces.

“These days, there are many

different types of lingual

brackets on the market

but the positioning ofthese brackets

in relation to the teeth

is really the critical

factor common to all...”

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November/December 2007 eLABORATE 25

orthodontic | TECHNIQUES

method of positioning these brackets hadto be invented as direct bonding of lingualbrackets is virtually impossible, hence anindirect method had to be developed.

These days, there are many differenttypes of lingual brackets on the market butthe positioning of these brackets in rela-tion to the teeth is really the critical factorcommon to all. So the real trick to get lin-gual orthodontics to work in the real worldwas to devise a method so the bracketscould be placed onto the tooth with thecorrect torque and angulation in relationto the tooth already determined. This ismuch easier to do with labial braces but areal challenge for lingual braces.

Lingual braces were invented in the1970’s when a Playboy model wanted toknow if she could have some type of“invisible” orthodontic treament so shecould keep working. The first attemptswere crude but lead to more interest in lin-gual orthodontics. In 1984, the Ormcocompany devised the TARG (TorqueAngulation Reference Guide) device formore precise bracket positioning, espe-cially for the lingual technique. The firstof these machines had a wooden basewhich proved to impede precision.

Over the years, various improvements tothe TARG device were made. Adding thick-ness compensation and height determinationin a digital measuring environment weresome of the advances.

In 1997, a new TARG Professional by DrWeichmann from Germany - the TransferOptimised Positioning System (TOPS) wasreleased, but still used the Torque blades ofthe TARG. He also invented the firstCAD/CAM Incognito system, which usescustomized gold brackets. Various otherinventions were introduced over the yearsbut none with significant merit.

In 2004, a real breakthrough in lingualorthodontics arrived. The Torque Angula-tion Device (TAD) prototype was firstintroduced. This device was unique as it hadthe ability to survey and measure the torqueand angulation of individual teeth in a dif-ferent way than previous devices and withgreat accuracy. With the prepared studymodel in position, the surveyor base is set tohorizontal and then the TAD is adjusted togive the best fit for angulation and torque.The operator thereby receives precise dig-ital measurement data for the mal-occludedteeth in the mouth so that you can make asuitable prescription for treatment.

The laboratory uses it in the oppositeway by pre-setting the angulation andtorque then orientating the survey base tothe best fit, thus giving a reference totransfer the work over and allow correctbracket placement. The invention of theTAD finally provided the orthodontistwith the tools to accurately measureexisting torque and angulation on modelsof mal-occluded teeth. After the prototype TAD was finished, intensivelab work was carried out testing andcross-referencing with the old TARG tofind the differences in Angulation andTorque given. The Torque differenceswere significant, leading the researchersto believe the old TARG had an inaccuracy of + or - 3 degrees! Again theinventors concentrated one ease-of-use

Figure 4. The original TARGwith wooden base.

Figure 5. TARG with DialTest Indicator.

Figure 6. Various bracket placement-measuring devices.

Figure 7. The lingual bracket jig.

Figure 8. Later from Korea came the MiniTARG which was almost impossible touse, lacking in precision and ease of use.

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and speed for the technician. The accu-racy was already there. In 2006, the firstproduction TAD is finished and the worldhad the first digital TARG accurate to 0.1 degrees!

To make bracket placement easy, theBracket Placement Device BPD wasdevised and is used in conjunction withthe TAD. It is reliable, strong, compactand easy to use, as well as being very low

maintenance. Increased accuracy in con-trolled bracket placement allows theoperator to work faster and smarter. Afterthe model is measured with the TAD,these measurements are transferred to theBPD and the brackets are placed onto themodel before a custom tray is fabricated.This process will be fully detailed in part 2of this article.

AcknowledgementThe author wishes to thank Peter Sheffieldfrom Hexa Ceram Dental Laboratory forhis assistance with tis article.

About the authorTerry Whitty is the technical editor ofeLABORATE and also runs a successfulorthodontic laboratory in Sydney’seastern suburbs where he produces inno-vative appliances using the latesttechniques and technologies includinglaser welding. He has also lecturedthroughout Australia and New Zealand ona variety of subjects.

26 eLABORATE November/December 2007

Figure 15. Brackets are accurately placed on the model using the TAD and BPD.

orthodontic | TECHNIQUES

Figure 9. The prototype TAD. Figure 10. Measuring torque and angulation. Figure 11. TAD Device with key elementsexplained.

Figure 14. Bracket Placement Device key- elements explained.

Figure 13. Bracket Placement Device (BPD).Figure 12. Production TAD.

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