Clinical Use of the Xbow Appliance

The Xbow  is made up of a maxillary expansion appliance, the Triple "L" Arch^TM, the 3M Unitek Forsus  Fatigue Resistant Device EZ Module (Left Side Order #885-138, Right Side Order #885-139, Direct Push Rod 25 mm Right Side Order #885-112, Left Side Order #885-111), and  Gurin locks (3M Unitek large size Order #560-400).  Don't forget to order a Gurin lock wrench. 

Ask for the  Dentaurum "Variety" one leg expansion screw.  There is less chance of palatal impingement with distal tipping and intrusion of the first molars than with a two leg screw design.  If the patient has a posterior crossbite or crowding because of a narrow maxilla, expand the maxilla first.  It also makes it easier in some cases to attach the Forsus devices if you expand the maxilla first.  If more than 12 mm of expansion is necessary use a SuperScrew.  Band the upper 6’s and  the upper 4’s to prevent the upper 6’s from tipping too much.  Control of the upper first bicuspids is important if the goal is overcorrection and the bite-catching effect of the first bicuspids. If the treatment plan involves serial extraction of all four first bicuspids, band the upper e’s or 5’s, and 6’s.

Fit the bands and take an alginate impression.  Place the bands in the impression and secure with sticky wax.  Pour the impression and check the band position before sending the case to the lab. 

The next most accurate method is to fit the bands but remove them before taking the impression.  Pour the model and send with the bands separately.   The lab will place your bands on the model.   Use this method with VPS impression material if you want the lab to pour the model.  Don't try to take an impression of the bands on the teeth with VPS.  It's difficult enough trying to get those impressions out of the mouth WITHOUT bands.  Don't forget to replace the separators.

Use occlusal headgear tubes on the upper 6’s to attach the Forsus device springs. 

Once space is gained from the expansion, use upper 2x4 mechanics, if necessary. After alignment, segment the archwire to maintain the incisors. This allows over-correction of the Class II buccal segments without over-retraction of the upper incisors.

If the upper incisors are well aligned and the maxilla doesn't need expanding initially, cement the maxillary expander and the Triple "L" Arch at the same time and place the springs immediately or one week later.  If you need to expand the maxilla first, wait to cement the Triple "L" Arch until you are ready to attach the springs. 

Microetch the bands and occlusal rests just before cementation.  We use the Unitek^TM Multi-Cure Glass Ionomer  Band Cement from 3M Unitek. This powder-liquid cement has a long working time and on demand light cure.  We rarely have a loose band. Bond the occlusal rests with  Filtek^TM  Supreme Plus Flowable Restorative from 3M ESPE. If the upper second molars have erupted bond an occlusal rest to prevent the first molars from intruding too much.   Occlusal rests for the maxillary second molars can be placed even if they are just erupting and still mostly covered with soft tissue.  The rest can be placed at the level of the soft tissue so that when the second molar erupts further the rest will contact the occlusal surface.  It is not necessary to bond the rest in this case.

If there is an interference between an upper tooth and the lower labial bow or Gurin Lock, bond Filtek^TM Supreme Plus Flowable Restorative to the occlusal surface of the lower first molars to open the bite. 

If the labial bow is too close to the gingiva of the lower incisors use a three prong plier posteriorly to raise it.  If the buccal section of the labial bow is too close to the teeth and the pushrod is hung up then use the three prong from the occlusal on the spot with the least clearance to bow out the wire.

 To open the pushrod loop enough to place it on the labial bow simply push a bird beak far enough into the loop and squeeze the tips together through the opening.  To remove the rod from the labial bow take the end with your fingers and flip it anteriorly so that the labial bow passes through the loop opening.

See the patient every six weeks and overcorrect the maxillary first bicuspid to a half  cusp Class III.

Half cusp overcorrection of first bicuspids after 4 months Xbow

"Bite-catching" by first bicuspids after rebound (7 months post Forsus)

The use of the Forsus device causes rapid over-correction, usually in four to five months for a full cusp Class II.  Fully compress the springs by distalizing the Gurin locks with the Gurin lock wrench.    If you don't keep the spring compressed it will flop around, wing out buccally causing sores, and increase the chances of the patient biting on it and causing distortion.  A properly compressed spring will also stay active longer as the patient opens.  A fully compressed Forsus device has 200 grams of force and looses 20 grams for every 1 mm of deactivation.  If you run out of length on the labial bow to reactivate the spring then you can either place crimpable stops on the pushrod or replace the pushrod with a longer one.

Once overcorrection has been achieved remove the springs and Gurin locks and start maxillary expansion, if necessary. Test the stability of the Class II correction for a couple of months and replace the springs on one or both sides, if necessary.  The goal is a socked-in Class I first bicuspid so the best time to start is after the first bicuspids erupt. If the lower e's have not exfoliated cut the labial bow and occlusal rests off with a high speed. 

We overcorrect maxillary expansion depending on the amount of constriction.  If there is a complete bilateral crossbite we overcorrect the upper molars into a buccal crossbite.  If the crossbite is unilateral we overcorrect the non-crossbite side into a buccal crossbite.  If there is a crossbite tendency as a result of Class II correction we overcorrect the molars until the lingual cusp tip of the upper molar contacts the buccal cusp tip of the lower molar on one side.  We leave the RME in place to retain the expansion for an additional five months.  This gives us the opportunity to check for Class II relapse two months after completing expansion and replacing the Forsus device on one or both sides.  

Xbow Comfort

To address the issue of comfort, I went to Sandra Ipsen of Comfort Solutions.    Orthodontists are contacting Comfort Solutions after their patients experience sores.  I recommend that you start with anterior and posterior spring caps and have Spi-Wrap on hand.  Spi-Wrap is spiral cut tubing that works well for sores from the lower labial bow as well as transpalatal arches.  Comfort Solutions offers these items together in a Xbow kit (Order #4201).  Great Lakes Orthodontics will supply the end caps if you check the option on the lab prescription.  For buccal mucosa sores place two anterior caps, one on the spring and one on the pushrod.  Another option is to change the pushrod from 25 mm to 29 mm and use back to back 4 mm Herbst screw caps from Comfort Solutions.  This moves the impinging corner of the pushrod anteriorly away from the sore.

Double anterior caps on 25 mm pushrod for buccal mucosa sore (most commonly used with a straight pushrod to keep the caps away from the gingiva)

Back to back 4 mm Herbst screw caps on 29 mm push rod

If you run out of room to reactivate the Forsus device or if the distal end of the spring is impinging then switch to a mesial hook-up using the same 25 mm pushrod and an "L" pin instead of the EZ Module.

Mesial headgear tube pin insertion (note rotated Gurin lock for comfort)

For small mouths we use the "Shorty Hook-Up".  Use the XXL Pushrod (38 mm) which comes without a stop and cut it to fit.  This is done by completely compressing the spring with the 38 mm pushrod (out of the mouth) and cutting the pushrod at the distal end of the spring.   Use an "L" pin instead of an EZ Module and insert the pin in the headgear tube from the mesial.

Shorty Hook-Up

Pushrod Adjustments

EZ Module has decreased the need for pushrod adjustments to keep the loop from interfering with the cheek or gingiva.  In many cases no adjustment is needed.  The first and most common adjustment is the lingual tuck-in bend to prevent the "elbows out" cheek impingement by the pushrod (see below).  The second adjustment, if necessary, is the step-out or bayonet bend.  The bayonet bend is used most often in patients with small mandibular arches where the pushrod hooks up further anteriorly around the curve of the arch and the spring needs to be stepped out to avoid interference with the gingiva.  As the Forsus device is reactivated with distalization of the maxillary buccal segment the pushrod sometimes needs to be readjusted to prevent gingival impingement by the rod.  The adjustment bend in the rod needs to be more pronounced the more mesial the rod is due to the curvature in the arch.

In most cases we use the short 25 mm pushrod to keep the Gurin lock distal to the Obicularis Oris muscle, preventing sores. 

If the patient develops a sore adjacent to the anterior end of the pushrod try the following:  1. Distalize the Gurin Lock to compress the spring fully.  This may move the lock and Forsus device distally enough to reduce the soft tissue impingement.  If not this is still the best position to observe the relationship of the Forsus device to the soft tissue.  2. If the pushrod is impinging on the gingiva, move the Gurin lock mesially,  remove the rod from the spring but leave it on the labial bow.  Use a three prong plier to remove some or all of the adjustment bend.  The lingual tuck-in bend determines the position of the loop relative to the soft tissue.  Bend the distal end of the rod buccally to rotate the loop away from the gingiva.  Bending the distal end of the rod lingually will rotate the loop towards the gingiva.  3. Rotate the Gurin locks 90 degrees to present a round surface to the cheek. 4. Use Comfort Caps as above.

Lingual Tuck-In Bend.  With a 25 mm pushrod the bend is distal to the stop.  On the 29 mm pushrod the bend is mesial to the stop. 

25 mm Straight Rod, Lingual Tuck-In Bend (distal to stop), Bayonet Bend

     Straight Rod              Lingual Tuck-In Bend              Bayonet Bend

Video courtesy of Dr. Bob Miller.

A problem that we are seeing with the new EZ Module is interference with lower molar brackets or gingiva.  In these cases we remove the anti-rotation arm on the EZ module to allow it to roll out.

With and without anti-rotation arm

Forsus and Full Edgewise     

In most moderate to severe non-extraction or borderline extraction Class II cases I use a two phase approach with the Xbow.  With the borderline extraction cases if the case becomes too protrusive in phase two we then extract.  In an extraction case we begin with headgear and start Class II elastics as soon as rectangular stainless steel arch wires are placed and space closure is begun.  In deep bite cases we add a bite turbo as soon as there is incisor contact.  Once the lower spaces are closed we decide whether to finish with headgear and elastics or place Forsus.  The reason I use headgear and elastics is twofold.  First, I don't like to wait to begin Class II mechanics until I have placed rectangular stainless steel arch wires and closed the lower spaces.  You may be missing out on growth, especially in late eruption or early maturing females.  Second, in a deep bite case you want the posterior eruption that elastics give.  Forsus is vertically neutral.

I use the same principles when using the Forsus device with a full edgewise appliance as I do with Xbow.  Use the 25 mm Direct Pushrod distal to the lower first bicuspid instead of the canine, if possible.  This keeps the Forsus device more compact and  moves it distal to the anterior curvature of the arch,  preventing sores.  The only difference is you cannot fully compress the spring with an edgewise appliance if you use a bracket as the anterior stop.  If you do be prepared to rebond the bracket.  Don't forget to steel tie the first bicuspids.  Reactivate the springs with crimpable stops on the rods or use longer rods.

Dr. Bob Miller hooks up the pushrod using an Alastic KX module to activate the spring but at the same time remove the force from the canine or first bicuspid bracket. (see below).   Place the springs and pushrods as you would normally but don't close the loop yet.  Make the pushrod adjustments leaving 1mm of play in the spring, remove the pushrod, pre-stretch a KX-1 module, place the KX module on the pushrod,  place the pushrod on the archwire, close the loop, hook the KX module to the first molar hook using floss and a floss threader over the second bicuspid bracket and down between the second bicuspid and first molar, then place the pushrod in the spring.  This completely activates the spring without debonding the canine or first bicuspid bracket.  If we place the 25 mm pushrod distal to the first bicuspid we use a KX-1 module.  We also use a KX-1 module distal to the canine in a bicuspid extraction case or a severe Class II.  A 38 mm pushrod (no stop) cut down to the length of a compressed spring is used if a 25 mm pushrod is too long (see below).

Alastic KX-1 module placed with floss threader

Alastic KX-1 module and lingual tuck-in pushrod adjustment

Alastic KX-1 module hook-up distal to canine (severe Class II, patient decided against mandibular advancement surgery after preparation)

Alastic KX-1 Module hook-up distal to first bicuspid

Alastic KX-1 Module hook-up distal to canine (bicuspid extraction) with a 38 mm pushrod (no stop) cut to fit (25 mm pushrod was too long)

Modified Mouth Guard with Slots for Forsus  Device

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Xbow Cases

5 months Xbow (8 months after Forsus removal) 

post phase one, Edgewise appliances have not been used

Superimposition below

Impacted canine, retained primary canine              1. Extract primary canine, 2. Xbow (3 months Forsus Device right,

                                                                            6 months Forsus Device left), 3. RME

                                                                            post phase one, Edgewise appliances have not been used

1.  2X4                                              7 months post Forsus, post phase one

2.  Xbow (4 months Forsus Device)   Full edgewise appliances have not been used

1. Xbow (4 months Forsus device)     6 months post Forsus

2. RME                                              post phase one

                                                          Edgewise appliances have not been used

1. Xbow (4.5 months Forsus)     9 months post Forsus, post phase one

2. RME                                      Edgewise appliances have not been used

3. Replace Forsus (1.5 months)  Cephs below

Initial ceph                                                             2 months post Forsus, lingual arch in place

Xbow and Upper 2X4                 Post Xbow (Full edgewise appliances have not been used)

Xbow 4 months                            Post Xbow                                  1 year Full Edgewise Appliances (treated by Dr. Lesley Williams)

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Indirect Bonding

The March, 2007 issue of "Seminars in Orthodontics" features indirect bonding and includes an article written by this author⁶ .

I have been informing other indirect bonders of a new tray system that I have been using and thought it would be easier to just summarize the technique on this website.  As many of you know I have been involved with indirect bonding since 1981 when my mentor Dr. Michael Wainwright of Vancouver, B.C. taught me the technique which he pioneered. 

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Combination

Active

Anteriors

Passive

Posteriors

The CAAPP Gun (Incisor Alignment Spring Theory)

Think of engaging a light round niti arch wire into crowded incisors as activating a spring.  In order for the arch wire to work out and the incisors to align efficiently the arch wire must be able to feed through the canine and bicuspid passive self-ligating brackets and molar tubes with as little friction or resistance to sliding as possible.  In order to get maximum activation with the lightest force arch wires they must be ligated to the base of the slots in the incisor brackets.  This is analogous to cocking the trigger of a gun.  If passive self-ligating brackets are used on the incisors and the arch wire is not ligated to the base of the slots the spring is not completely activated due to the play between the initial light round arch wire and the slot.  In that case  the trigger is "half-cocked".  There is ten degrees of play between an .014 arch wire and an .0275 inch slot.  Two .014 arch wires can piggy back in an .0275 inch slot. 

Most of the initial first order movement of crowded incisors is in the labial direction, either tipping of the crowns or derotation.  If the arch wire is not ligated to the base of the incisor bracket slots there is a loss of the labial activation force.   This is analogous to squeezing a tube of toothpaste with two extra holes.  Some of the toothpaste squeezes out the nozzle but some also squeezes out the other two holes.  The force is dissipated in three directions instead of one. If passive self-ligating brackets are used on the incisors without ligatures then a dimpled arch wire or crimpable stops are necessary to prevent the arch wire from being squeezed sideways. This introduces another force system on the bracket that the dimple or stop contacts.  This can result in an anterior space opening which requires the placement of power chain to close.

CAAPP is a system of brackets with the following goals.

      1.  Creating a “Long Buccal Tube” for low friction arch wire feeding with passive self-ligating brackets on the canines and bicuspids, and tubes on the molars.

      2.  Getting the most movement of the incisors with the least force with traditional twin brackets and a light round niti arch wire ligated to the base of the slot ("All or None Ligation", "Targeting Incisor Activation")

      3.  Patient comfort.

      4.  Respecting patient's request for colored ligatures on their incisors.

The SmartClip bracket from 3M Unitek was chosen as the best bracket for the canines and bicuspids for the following reasons. 

1. It is a  true twin with the ability to ligate the arch wire to the base of the slot when necessary for optimum first order control (Active on Demand), when the force is too high for the clip to hold, or when we want to “turn on” friction to retard movement of a particular tooth or group of teeth for increased anchorage.
2. It is a passive bracket which allows easier sliding for canine retraction, posterior space closure, and incisor advancement in non-extraction cases.   
3. It is designed to have the optimum width for each tooth to maximize the inter clip distance which reduces binding friction with sliding mechanics.  Inter bracket distance is not nearly as important with niti arch wires.
4. There are no moving parts to break or bind compared to brackets with active clips or sliders.
5. Each bracket has two narrow clips which allow the engagement of one clip with the initial arch wire.  This reduces the force compared to using a bracket with a slider which is much wider. 
6. APC (Adhesive Pre Coated)

Traditional twin brackets (Standard Victory Series, 3M Unitek) are used on the incisors for the following reasons.

1. They allow the initial .012 to .014 niti arch wire to be ligated to the base of the slot for the most movement with the lightest force ie. 50 to 75 grams.  Passive brackets were not chosen for the incisors because of the first order slop with a light round wire.  There is almost 10 degrees of rotational slop with an .014 niti arch wire.  Miles ⁸ did a split mouth comparison of passive vs twin brackets and found no advantage to the passive brackets for incisor alignment.  They did find more discomfort with the passive incisor brackets due to the larger arch wire necessary to fill the slot and align the incisors.  An .014 niti deflected 2 mm over a 12 mm span delivers a force of 76 grams.  An .018 niti delivers 167 grams or twice the force of the .014.  An .014X.025 niti delivers 328 grams in the horizontal direction.  That is over four times the force of the .014 niti.  (The amount of root resorption is proportional to the force⁹.)
2. Patients want colored elastic ligatures or chain on the incisors.  We could use SmartClip brackets on the incisors but it would require engaging the clips and placing the ligatures which is double ligation. This defeats the purpose of self-ligation.
3. They allow the use of lighter rectangular arch wires to place detailing bends on incisors (.016X.022 beta tiranium in an .018 slot). Ligatures allow the arch wire to be pulled to the base of the slot on incisors for maximum activation and alignment of interproximal contacts.  This is not as important on canines and bicuspids so some first order slop is tolerated and may even be desirable for settling.  Canines and bicuspids are not as sensitive to clip engagement and disengagement forces as incisors so it is not necessary to use rounded rectangular or hybrid arch wires.
4. With ligatures on the incisors we do not need dimpled or stopped arch wires as the wire does not tend to creep around the arch.

CAAPP Tips

1. We use heat treated (gold tone) rectangular stainless steel arch wires for arch coordination and space closure.  These stiffer arch wires are less prone to distortion which improves low friction sliding, as well as maintaining arch form.
2. We use the MBT prescription except for the lower second molar where we substitute a minus 20 degree bracket for the minus 10 degree bracket which tended to upright the second molar into a crossbite tendency.
3. We place elastic chain under the arch wire for canine retraction.  For space closure we place three pieces of chain, under the wire from the lateral incisors back, and over the wire from lateral incisor to lateral incisor.  Once the space is closed we place the chain over the arch wire from molar to molar or lace a steel ligature under the arch wire to keep the space closed. Once teeth are aligned and space is closed, passive self-ligation serves no further purpose to help finish the case.
4. We don't pick up the second molars until we place .018 niti or .014X.025 niti (in an .018 slot).
5. We place bite turbos to open the bite after the overjet has been reduced to the point of interference between the upper incisors and the lower incisor brackets.  We then begin Class II elastics if we have not already started them, unless there is enough upper space to resolve the overjet without additional anchorage.
6. After an .014 niti the ideal second arch wire is an .018 niti (in an .018 slot), followed by an .014X.025 niti, and then an .016X.022 or .016X.025 SS.  We generally finish in an .016X.022 beta titanium.

.

Comments on what passive is and isn't. 

1.  Passive allows easier sliding for canine retraction, posterior space closure, and incisor advancement in non-extraction cases. 

2.  There is less resistance to movement (ski wax or parking brake analogy) with fewer interruptions of movement.

3.  We are still using the same basic forces to move teeth, i.e. the same arch wires but broader arch forms, the same elastic chain, the same springs, the same elastics.  Brackets don't move teeth.  Forces move teeth.  The only force that has changed with passive is the braking force from ligatures which is estimated to be approximately 50 grams. We can move teeth with 50 grams less force with passive self-ligating brackets.  We can also move teeth with an .012 niti arch wire which delivers about 50 grams of force.  If the .012 niti arch wire was used with ligatures on the canines and bicuspids there would not be enough force to overcome the braking force from the ligatures and very little tooth movement would occur.

4.  The big change was nickel titanium arch wires.  Passive just allows more efficient use of nickel titanium.  Broader arch forms in nickel titanium have allowed us to treat more borderline extraction cases non-extraction.  This allows us to assess whether or not the case is too protrusive before we make the extraction decision.  If we decide to extract late in treatment we can close the spaces faster than we have been able to in the past.

5.  We still need to extract in some cases.  Head gear is still useful.  An arch wire cannot exert the same direction of force as an RME for sutural expansion. Dr. Ricketts reminded us that the majority of patients can be treated non-extraction decades ago.  He taught us that constricted mandibular arches could be expanded to match a suturally expanded maxillary arch.  But don't throw away that retainer.

Over and Under Elastic Chain 

7 months alignment with .014 and .018 niti (day of .014X.025 niti placement, .018 CAPP)

References

1.  Casko J, Shepherd W.  Dental and Skeletal Variation Within the Range of Normal.  Angle Orthod 1984; 54: 5-17.

2.  Sameshima GT, Sinclair PM. Predicting and preventing root resorption: part II. Treatment factors. Am J Orthod Dentofacial Orthop 2001;119:511-5.

5.  Brin I. Tulloch C. Koroluk L. Philips C. External apical root resorption in Class II malocclusion: A retrospective review of 1- versus 2-phase treatment. Am J Orthod Dentofacial Orthop 2003; 124:151-6.

6.  Higgins D. Indirect Bonding with Light-Cured Adhesive and a Hybrid Transfer Tray. Semin Orthod 2007;13:64-68.

3.  Sondhi, Anoop:  Efficient and Effective Indirect Bonding.  Am J Orthod Dentofacial Orthop 1999;115:352-9.

4.  Kalange J: Ideal appliance placement with APC brackets and indirect bonding. J Clin Orthod 33:516-526, 1999

8.  Miles P, Weyant R,  Rustveld L. A clinical trial of Damon 2 vs conventional twin brackets during initial alignment.  Angle Orthod 2006; 76: 480-485.

9.  Harris D, Jones A, Darendeliler A.  Volumetric analysis of root resorption craters after application of controlled intrusive light and heavy orthodontic forces:  A microcomputed tomography scan study.  Am J Orthod Dentofacial Orthop 2006; 130: 639-647.

Credit to Sandra Ipsen of Comfort Solutions for Forsus Fatigue Resistant Device adjustment and photography, Wendy Schock for photography,

and Libby Pearson of Delta Orthodontic Technical Services for artistic wirebending

Herbst is a trademark of Dentaurum, Inc.

APC, Filtek, Forsus, SmartClip, Transbond, and Unitek are trademarks of 3M Company.

Crossbow, Xbow,  Triple "L" Arch and "Straight to the Target when Straight is the Target" are trademarks of Dr. Duncan W. Higgins.