Fixed appliances part 2 & 3 Anchorage



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Fixed appliances part 2 & 3


  1. Anchorage

On Christmas day 1642 Galileo died, the English civil war started and Isaac Newton was born. He was useless at school, so they sent him to be a farmer but he was useless at that too so they sent him to Cambridge where he was recognised as the greatest mind that ever lived. If this sounds just like your life story you will know that: -



  1. He revolutionised the picking of apples.

  2. He invented the cat flap.

  3. He put all the little grooves on the outside of 10 pence coins.

  4. His third law of motion states that “Every action has an equal and opposite reaction

This means that when you use an orthodontic appliance to apply a force to a tooth an equal and opposite reactive force springs up to try and spoil things.

The official definition goes something like this: -
Anchorage is provided by those sites, which resist forces of reaction generated by the active components of the appliance.

(Repeat 3 times per day after meals)

The most common orthodontic procedure is to retract either the canines or the labial segment, with anchorage provided by the teeth of the buccal segments. So that if an orthodontist talks of anchorage loss, he means forward movement of the buccal segments. You need to understand this common parlance of orthodontics. We also talk of burning up anchorage this means designing the mechanics to deliberately encourage the buccal segments to come forward. Strictly speaking these terms are not always correct, for example if the appliance were designed to procline the upper incisors then anchorage loss would drive back the buccal segments.

Anchorage support means holding back the buccal segments.
Removable appliances and anchorage.
In the 1950’s when America had Tweed Edgewise, probably the most technically complex orthodontic appliance, we had the Upper Removable Appliance (URA). Actually you can do quite a lot with a URA providing that you select the right case. In particular you can extract upper 4/4, retract upper 3/3 and then retract upper 21/12. Let’s consider how to do this properly: -

  1. Fit the URA before the extraction and only arrange extractions when the patient can demonstrate that they are able to wear the appliance full time including for meals.

  2. Design the appliances correctly using springs, which generate light forces and have a long range of action. Remember to include an anterior bite platform if you need to open the bite and some form of anterior retention.

  3. Try to avoid buccal canine springs if you can, they are quite difficult to wear.

  4. During canine retraction measure the overjet if it increases it is the sign that anchorage is being lost.

  5. Make sure that you trim back the acrylic to allow the teeth to move and deactivate the spring when the canine touches the premolar or it will rotate.

  6. Retract the incisors with a Roberts’s retractor. Make sure that the wire that touches the incisors is ideally shaped or you will not achieve alignment. Also you must trim the acrylic behind the upper incisors hollowing it out under the bite platform so that the gingival margin of the palatal surface of the incisors does not touch the acrylic.


If you try this treatment on a number of cases you will find that in some cases anchorage loss is very very small. This is because the forces of action from these appliances are very small and the sites that resist the forces of reaction include the molar teeth and the whole of the surface of the palate. However you will find other cases where you lose a lot of anchorage. I bet this is not because you have over activated the springs. I hope it would not be because you have foolishly decided to use 0.7 rather than 0.5 springs although this would do it. I bet that the cause is poor wear of the appliance. You see if the patient leaves the appliance out for a day the upper 6/6 will drift forwards a little. When the patient puts the appliance back in it will be a little tight behind the incisors and they will be pushed forwards. Repeat recipe 100 times and the overjet will increase. Strictly speaking this is not anchorage loss but forward drifting of the molars into an extraction space but it comes to the same thing in the end.
The Nance Button

This is a way of getting the anchorage of the palatal vault without using a removable appliance that the little darlings can leave out. Try to persuade your technicians to make a proper one. This has a piece of 0.7 wire from each molar band which goes to the palatal vault and bends about a bit. The two wires are joined by a button of acrylic which is added after the wires have been soldered to bands. The button should be the size of a 2 pence piece or larger and occupy the true vault of the palate. Your technicians will hate this idea. They would like to use a single piece of wire going from one molar to the other. They will bend the wire so that it presses so firmly onto the bands that it will stay in place while it is being soldered without them having to go to the trouble of welding it. But as a result of this when you stick it in the mouth it will not be passive and the molars will expand.

There are a few alternative designs, which use a Nance button that passes behind the upper 7/7 and fits into the EOT tubes. One design enters the tube from the back; it has a little hook so that it can be held in place with a module that goes around the hook on the molar. The other bends gingival to the molar tube and enters the tube from the front.

Can a Nance button loose anchorage?

Yes if the molar tubes are not parallel then you need increase force to retract the teeth because of the increased friction. Two solutions: 1.parallel the molars first. 2. Use the EOT tube to cut down on the friction.


The transpalatal (lingual) arch.

If you stop the molars moving together you make it more difficult for them to move forward and increase anchorage. The idea is that the teeth lie in a narrow channel of cancellous bone and as they move forward the roots will hit the cortical bone unless they can move together.
Ricketts (The Bioprogressive Technique)

The utility arch throws the roots of the molars buccally into the cortical plate the idea is that this will increase their anchorage value. Do you believe it does?
Headgear

This is a big subject consider:-

  1. Orthopaedic change

  2. Force Vectors and type of movement.

  3. Anchorage reinforcement.

  4. raegaeh esrever, sorry I mean reverse headgear.

  5. Safety Headgear

  6. Nudgers and screw plate.

  7. High pull headgear.

  8. High pull headgear with J hooks

  9. Ultra high pull to treat AOB cases

Non Compliance Appliances

Single arch

1 David Lewis uses URA,s

2. I like Gianelley’s appliance because the name reminds me of ice cream.

3. The Jones Jig has a nice sense of alliteration but comes in a lot of tidily pieces.

4. Ormco make a neat “distalizer” like a Jones Jig But in one piece.

5. The pendulum appliance adds a palatal baseplate.

Between the arches

  1. Instead of class II elastics you can use Sentalloy springs, which are little coil springs in a rubber tube. (Combining a coil and a condom sounds a bit contraceptive to me)

  2. Jasper Jumpers.

  3. Eureka Spring.

  4. Herbst appliance

I have done some tutorial notes on non compliance appliances

The Begg Issue

If you cough up your £1.20 and you will find this contains two ideas. One is, that if you have a class 1 incisor relationship and spaces in the premolar region in all four quadrants and try to close the space with elastics; if you use a light force you can tip back the incisors whereas if you do the same with a heavy force the molars will come forward. I don’t believe this. (By the way it is called differential anchorage).

The other is that if you tip the labial segment back and then upright the teeth it takes less anchorage than bodily retracting them. Some people don’t believe this they think that by the time the upper incisors are fully torqued back you will use up the same amount of anchorage. (They also believe in Santa Claus, a flat earth and the tooth fairy)

Implants

  1. On the cheap. You can extract the deciduous canine and re-implant it. Then splint it until it ankyloses and then use it to support anchorage. Or you can make use of any naturally submerged teeth. Remember an ankylosed tooth will also support anchorage in the vertical plane e.g. for bite opening. It can also be used together with inter-maxillary traction to move teeth in the opposing arch. Unfortunately ankylosed teeth can work loose and exfoliate.

  2. Endoseous Implants.

  3. Mini screws

  4. Onplants

Zygomatic Wiring,
Terms you should know

Simple Anchorage

Reinforced Anchorage with headgear.

Reciprocal Anchorage. For example a mid line expansion screw or closing a diastema.

Stationary Anchorage. Does not really exist, the idea is that if you hold lots of teeth together they will give lots of anchorage.

Differential Anchorage. One of Begg,s ideas. If you extract the 4’s and use light forces to close the space the anterior teeth will move back. But if you use a very heavy force the molars will move forward.

Baker Anchorage. Ye very olde term for class II elastics.

Anchorage Preparation This in an interesting idea that was part of the Tweed system. Tweed was an important figure in orthodontics. You may know of the Tweed angle and the Tweed foundation and you should know that tweed was important in the argument to justify extractions as part of orthodontic treatment. He showed cases treated with Angles methods where the treatment relapsed, extracted premolars and retreated to stable results. In the 1960’s and 70’s the Tweed edgewise course was important typodont course. The actual details of Tweeds treatment in a class II case went like this: –

  1. Band the upper 6/6 and apply EOT

  2. Band all the lower teeth. (There were no bonded brackets then)

  3. Place lower archwires with tip back bends and use class III elastics. This tipping back of the lower arch was called anchorage preparation.

  4. Now use lots of class II elastics to pull back the upper teeth.

The idea that tipping back the lower teeth increases their anchorage value lives on in the level anchorage system.
Use Less Force.

If anchorage loss is a reaction in the supporting teeth to the force used to move the teeth then it stands to reason that if you use less force you will get less reactive force. But this is not much good if you get less tooth movement. However you could: -

  1. Waste less overcoming friction by using a low friction bracket such as Dammon of Begg.

  2. Tip the teeth and then upright them as in the Begg and Tip-Edge technique.

  3. Don’t take the wire through the premolar brackets to cut down friction as in the Begg and Tip-edge techniques.

  4. Remove cuspal interferences. Use a bite plane or pre treat with a twin block or put cement on the occlusal surfaces of various teeth.

  5. Don’t start sliding mechanics until the wire has been in place for a while to allow the teeth to align fully.



  1. Devices to increase anchorage ( and some other add ons)

  • Trans Palatal arch also called the TPA. To make select bands a slightly loose fit and take an alginate impression over the top. Carefully remove the bands and place them in the impression. Make sure you put them in the right way up (with the gingival part of the band sticking out of the alginate). Technicians tell me that registrars so often put them in upside down that they always take them out and check. Let’s get our act together. The arch goes straight across the palate but must have either an omega loop in the middle or a u loop each side. You need this little flexibility to get it to seat properly. While waiting for it to be done place some bands on the 6s and cement with runny Poly F cement. This comes off relatively easily, while glass Ionomer tends to stick to the tooth and so it is hard to clean off when you want to fit the TPA. The idea is to fit the TPA before extractions so that it acts as a space maintainer. It can also be used to maintain expansion and to help to give vertical stability while pulling down a canine. The theory behind the use of a TPA to provide anchorage is that as the molars drift forwards they move to a slightly narrow part of the arch and so with a TPA in situ the roots get closer to the buccal cortical plate. This is a nice theory, but it is not evidence based and to be honest it doesn’t make much geometric sense. Measure it out on a precision orthodontics archform and you will see the molar would have to move a long way forward before it has to move 2mm in. And in any case the cortical plate can and does remodel. It is true that if you just extract the 5s and leave the 6s to drift forward they rotate around the palatal root. A TPA would prevent that so it will act as a space maintainer. A problem that you should consider is that a TPA/ Nance/quad-helix may hold the molar tubes at an angle to each other and thus increase the resistance to sliding mechanics. This means that you need to increase the force and this will increase the demands on anchorage. The solution is to use larger diameter tubes (the EOT tubes will do nicely) I have tried to be fair to the TPA but let’s be honest we make Registrars use TPAs for the practice. Young consultants often use TPAs but then they realise they get just as good results without them and save a lot of time and effort.

  • The Nance button adds the anchorage provide by the palatal vault which is good but also can dig into the palate if anchorage is lost which is bad. The previous section tells you how to make one properly.

There are some very useful modifications of Nance buttons. For example they can be extended to support prosthetic teeth. Useful in that patient with a missing central. In these cases put a bracket on the prosthetic tooth and you can use it to intrude or extrude the other incisors. The Nance button with the anterior bite plane is the ultimate weapon for the adult with the very deep bite. Yes it will open the bite. Yes the patient will hate it. Yes it will make the lower incisors frighteningly loose.

  • The lingual arch is like a lower lingual arch. Like a TPA they are effective space maintainers but their logic as anchorage devices is a little unproven. This is especially true in the case of the lingual arch because lower 6s are not very keen on drifting forwards. One very good thing about lingual arches is you can expand the lower arch quite easily so you can use them to correct scissor bites.

  • The quad helix is OK at correcting a crossbite. Maria McNally’s MPhil when she was at Burton (JO 2005 p29-35) compared the quad helix with the simple cheap e-arch (which is just a piece of 1mm wire in the EOT tube) at £75 quid a time the quad was nearly as good as 7 pence worth of wire but you had to take impressions and wait 3 weeks for the lab to make it. The quad also made the tongue sore and prevented the de- rotation of the molars. (to be fair patients preferred the appearance of the quad but this is not surprising since it is palatal. There is a design of the e-arch which runs up in the sulcus and so is invisible. We did not use this for the trial as it can be removed by the patients (effecting the results of the trial) while the design we used was wired into place. To me this seems like a no-brainer, but some people are so frightened at the thought of having to bend a wire that they stick to the quad. To be fair the quad can be used without a fixed appliance e.g. in cleft cases; remember the E-arch can only be used in conjunction with a full fixed.

  • The e-arch. The usual design goes through the EOT tube which is 1.14mm in diameter you have the option of a single “u” shaped piece of wire with molar insets ( to stop it from sliding round) or the invisible type which is set up to run in the sulcus these are usually bent in robust wire 1.1 or 1mm. Because the wire is so robust they only need to be slightly over expanded. If you don’t have any 1mm wire you can use ordinary archwire such as 0.020 special plus but for this you need the E-Arch much more expanded in fact almost straight. What if you don’t have an EOT tube? Well you can use a straight piece of 0.020 with a circle bent at each end going over the base archwire

  • Lip Bumper. Typically 0.9mm wire through a special extra tube buccal to lower 6s. (A Begg tube would do) It goes in front of the lower incisors by 3mm, often supporting an acrylic shield. The idea is that lip pressure is directed from this shield to push the lower molars backwards. In fact the effect is rather small print and most of the change is probably proclination of the lower incisors because the effects of lip pressure has been removed. The lip bumper also appears in the Denholtz appliance. Here hooks are added to the shield for class III traction Upper 6/6 are banded and EOT used; while the EOT is being worn class III traction is worn. The effect is a small distalisation of upper and lower molars. And lip bumpers emerge again in some methods of arch development where RME is used as well as a very expanded lip bumper so upper and lower arches are made a lot wider.

  • This brings us to RME usually bands on upper 6s and 4s and a Hyrax type screw turned 2 times per day for14 to 20 days. In patients over 16 it is usual to do a le Fort 1 osteotomy and divide the palate from above before the RME (this is Surgically assisted RME called SARME, as in “you and who SARME”) RME widens the jaw, opens the bite and makes the patient more class II. So the ideal patient has a mild class III with a slightly increased overbite and a narrow upper arch. The attraction of RME is that it is classic example of orthopaedic change. After all you can take an occlusal X-ray and look at the extra bone. The idea is a bit spoilt by Bill Proffit who says that after the 2 weeks of expansion the tension across the stretched palatal tissues pulls the bone of the maxilla back together the teeth move through the bone as this happens and most of the orthopaedic change is undone.

  • TADs and EOT are in a different section.




  1. Starting with removable appliance

  • Said to test cooperation. Indeed I used to say that, but remember, people are very influenced by peer pressure. You will find some children who will not really try URAs because they want a proper brace like their mates. Also it makes treatment more expensive and slower.

  • Can open the bite with a flat anterior bite plane. A FABP can open the bite even when the lower 6s are missing.

  • Can discourage sucking habits.

  • Can support false teeth e.g. when there is a missing central.

  • All the above are true but nowadays I don’t often start with URAs. It is slow, expensive and unpopular with the patients. Also as the years go by patients seem to wear them less and break them more

  1. Starting with functional appliances

  • The straight wire appliance cannot change molar relationships very easily. Usually you need straight wire plus something else. That might be EOT or TADS or functional appliances. In some cases this is being done in the hopes of producing some orthopaedic change but in most cases you just want to correct the molar relationship.

  • The Twin Block is the most popular functional appliance in the UK

  • The button and bead appliance is the most popular with me and my patients and appears to be much more successful than the twin block

  • The twin block seems to be popular in the UK, but less popular in the rest of Europe

  1. Round tripping

  • It seems to be taken as true that round tripping is a bad thing, but I don’t believe there is any evidence that that is true. If the lower incisors are proclined during treatment and then moved back to the correct position are they less stable? Perhaps, but I know of no supporting evidence or any reasonable theory to say why it should be so. Goonwalle looking at cone beam CTs suggests that if the lower incisors are proclined during treatment the labial bone will thin. But if they are then retracted to the original position the bone will fully return to the original level.

  • Proclining the lower incisors could in theory lead to gingival recession. But if you are using a round wire the teeth will tip forwards and the roots will if anything move lingualy. We are certainly treating cases a lot further forwards than we were 20 years ago and I don’t see a lot of gingival recession.

  • Therapeutic diagnosis. I think this is a good idea. Classic treatment for a class II div ii. Take a lateral skull then align the teeth then take another lateral skull and decide if you need extractions

  1. Sectional arches

  • In the 1960s the mainstay of British orthodontics was URA to retract upper 3/3 second URA to retract upper 21/12.

  • By 1970 we realised that this was not good enough when the anterior teeth were rotated. We graduated to retract upper 3/3 with a URA and then a primitive fixed appliance called a Johnson’s twin wire arch which was molar bands and bands 21/12 and an archwire that was rigid at the side and flexible at the front to align the incisors.

  • By 1976 when the straight wire appliance was being invented British orthodontics had graduated to: (i) a URA to open the bite (ii) a lower plain edgewise in the buccal segments with sectional arches to retract the canines (iii) sectional arches to retract upper canines with a clip over URA with a bite plane (iv) bond the lower incisors and work into a thick archwire (v) throw away the clip over bite plane and bond the upper incisors. THIS WORKED BUT IT WAS SO SLOW. There were no NiTi wires so it was difficult to upright the canine teeth if they were allowed to become retroclined. Official instructions were that at each visit the sectional should be activated by the thickness of a thin dime.

  • So it seems a little surprising that some people are going back to sectional arches.

  • Perhaps I should say that sectional arches are a part of Ricketts or Bio-progressive appliance therapy (we covered this in part one, but you were asleep.)

  1. Auxiliaries

From DJS 2006
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