Xbow

Xbow^TM shown with Forsus^TM Fatigue Resistant Device with 22 mm pushrods and Gurin Locks (rotated 180 degrees) from 3M Unitek and Spring Caps from Comfort Solutions Inc.

After 3 months of Xbow followed by compensatory maxillary expansion, now will retain expansion and test Class II correction for 5 months before removing appliances.

Xbow Comfort: 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 and Spring Sleeves on hand. Spring Sleeves fit over the spring in cases where the cheek is irritated. 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.

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“Our Orthodontic Study Club flew Dr. Higgins across North America to address our membership and to learn about his appliance and treatment philosophy.

My patients and I couldn’t be more pleased with the results from Dr. Higgins’ Crossbow appliance! It has shortened their length of treatment time as well as deliver a superior final result. Dr. Higgins is a pioneer in the orthodontic field and very well respected amongst his orthodontic peers. Thanks for caring enough to share your ideas with our orthodontic community!”

The following patient was treated by Dr. Hughes with Xbow followed by full braces.

After Xbow. Left spring removed after 6 months. Right spring removed after 7 months.

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"Straight to the Target When Straight is the Target" (STTT) is an orthodontic treatment system that includes Xbow, CAAPP, and the Higgins Indirect Bonding technique. The aim is to use the lightest forces that will move teeth gently but quickly and reduce root resorption as much as possible.

The two main negative side effects that result from orthodontic treatment are root resorption, especially of the upper incisors, and decalcification or "white spot lesions". The third negative side effect is loss of upper lip fullness that results from over retraction of the upper incisors. STTT aims to decrease these negative side effects.

Root resorption is caused by heavy forces which also cause discomfort. The greater the force, the greater the root resorption. CAAPP uses ligated twin brackets on the incisors for early alignment and torque control of the incisors with the lightest archwires, and passive self-ligating brackets on canines and bicuspids to decrease the force needed to move teeth.

Root resorption and decalcification are also caused by long treatment time in full braces. The longer the treatment time the more the root resorption and the greater the risk of decalcification. The STTT system of treatment corrects the bicuspid and molar relationship in Class II malocclusions with Xbow before placing full braces to decrease the time in full braces. The CAAPP system of brackets and archwires aligns teeth and closes spaces as quickly as possible with the lightest, most comfortable forces. The Higgins Indirect Bonding technique allows for precision bracket placement with the most consistent high bond strengths possible. This decreases the need for rebonding loose brackets, repositioning brackets, and archwire adjustments which prolong treatment time in full braces.

Root resorption is also caused by the reduction of overjet with full braces. The greater the overjet reduction, the more the root resorption. The STTT system corrects overjet by passive retraction or transeptal fiber tension with Xbow without a continuous archwire to the upper incisors.

1. Reducing the need to extract upper bicuspids for overjet correction and crowding by efficient distalization of upper bicuspids and molars with Xbow.

2. Preventing the need for bicuspid extractions in Class II malocclusions with deep overbites and short lower facial heights by proclining lower incisors to inclinations which are found in untreated, naturally compensated Class II skeletal patterns with Class I occlusions.

Xbow has been studied at the University of Alberta which has resulted in three published articles in peer reviewed orthodontic journals, and two more research projects underway. The Higgins Indirect Bonding technique has been published in Seminars in Orthodontics. An indirect bonding technique based on the Higgins system was found to be superior to all other techniques tested at the University of Western Ontario (unpublished thesis). It resulted in the highest bond strengths with the least enamel damage.

STTT Class II treatment is a two phase or multiple appliance system with a difference. In most cases we wait until the second molars are beginning to erupt before starting the Xbow. This allows indirect bonding of all the teeth after a brief rest period after Xbow removal. The only situations where we start in the late mixed dentition is if we are concerned about missing out on growth in early maturing females or late erupters, or when the patient is eager to begin for cosmetic reasons.

Xbow allows for rapid over-correction using light, continuous forces without direct retraction of the upper incisors. A period of R and R (Relapse and Rest) halts any root resorption that may have started, allows lower incisors to upright, and tests the stability of the correction for possible replacement of the springs on one or both sides if too much relapse occurs. This minimizes the phase two treatment time and the need for Class II elastics or springs to the archwire, which in turn minimizes root resorption of the upper incisors. Rapid overcorrection and unilateral control allows us to hit the Class I first bicuspid target consistently.

The part of treatment that the orthodontist has control over (other than the treatment plan) is Alignment and Space Closure (ASC). The patient has control over elastic wear to coordinate the arches and finish the occlusion. I looked at 42 consecutively treated patients. 34 were non-extraction and 8 were extraction cases. ASC took an average of 9 months to complete for the non-extraction group and 11 months for the extraction group.

To determine my average treatment time in full braces I looked at my last 145 consecutively debonded patients. The average treatment time from bonding to debonding was 16 months. 78% of patients had an average treatment time of 13.4 months.

Our treatment time has decreased approximately 6 months on average over the years as I became more effiicient and bracket placement became more precise. The short treatment time is also due to the fact that thanks to Xbow we don't put patients in full braces until the buccal occlusion is Class I. The Xbow phase of treatment can add 12 months to overall treatment time if the springs are on for 6 months and you have to expand the maxilla and hold for 5 months.

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Licensed Orthodontic Labs

Great Lakes Orthodontics, LTD. has the exclusive license to fabricate Xbows in the United States.

Integral Dental Lab has been given a license to fabricate Xbows in Canada. The address is #1402-805 West Broadway, Vancouver, British Columbia, V5Z 1K1. Phone (604)872-6656.

Preferred Ortho Dental Laboratory has been given a license to fabricate Xbows in Canada. The address is #207, 14065 Victoria Trail, Edmonton, Alberta, T5Y 2B6. Phone (780)490-6585.

Extreme Dental Lab Inc.

has been given a license to fabricate Xbows in Canada. The address is 87 Thornmount, Unit 27, Toronto, Ontario, M1B 5S5. Phone (416)286-0111 or 1-888-237-5950._______________________________________________________________________________________________________________________________________________________

New method of bending "L" pin. (Thanks to my orthodontic assistant, Sandra Ipsen) We are using "L" pins instead of EZ2 modules. We find it is easier to adjust "L" pins to position the spring ideally. Insert "L" pin with attached spring into headgear tube and let spring and "L" pin fall straight down. Support spring against maxillary teeth with finger and bend "L" pin straight back at 90 degrees to the "axle". Rotate spring so that "axle" points slightly gingivally and end of pin is gingival and against bracket.

We routinely rotate the Gurin Lock 180 degrees after completely tightening it and then rotate it a few degrees clockwise to positon the anterior spring (with cap) about 1 or 2 mm off the gingiva. If the spring or anterior cap still impinges on the lower labial bow or gingiva bend the "L" pin gingivally (see below).

1. straight "L" pin, mesial hookup with spring touching gingiva___2. bending pin gingivally with a fine bird beak plier___3. buccal movement of spring with bent pin and Gurin lock rotated 180 degrees (22 mm pushrod)

We routinely bend an offset (bayonet bend) as far anteriorly as possible on a 22 mm pushrod.

Use a heavy plier such as an Adam's. The first bend is 45 degrees towards the buccal.

The second bend is made with the beak of the plier inserted into the loop of the pushrod. This second bend determines how far buccal the spring is. The more obtuse the angle between the rod and loop is, the more buccal the spring will be. In other words, opening the angle between the rod and loop moves the spring buccally. If the bend is too obtuse the loop will bind on the labial bow and will not slide which reduces the amount of opening before the rod disengages from the spring.

If the pushrod connects too far posteriorly on the labial bow it may be necessary to use a 25 or 29 mm pushrod with a bayonet bend OR a mesial hookup (see below).

Shorty or mesial hookup (22 mm pushrod and "L" pin inserted from the mesial of the headgear tube. This hookup is used if the distal end of the spring impinges posteriorly.)

If a 25 or 29 mm pushrod is required it is necessary to bend a bayonet bend on either side of the stop.

There is a greater chance for interference between the thicker clip and the lower molar solder joint. This may cause the upper molar bracket weld to fail or the band to tear. In this case it is better to expand the maxilla before you place the springs or remove the anti rotation arm. (See photo below.)

EZ2 with anti-rotation arm removed, 22 mm pushrod, and Gurin lock rotated 180 degrees.

The stages of treatment are: 1. Maxillary expansion if a posterior crossbite exists. 2. Maxillary incisor alignment, if necessay. 3. Distalization of the maxillary bicuspids and molars to open space for maxillary canines and achieve Class I first bicuspids, 4. Compensatory maxillary expansion, if necessary, and 5. Phase 2 Alignment, overbite correction, space closure, and arch coordination using a full edgewise appliance.

The Xbow is made up of a maxillary expansion appliance, the Triple "L" Arch^TM, the 3M Unitek Forsus Fatigue Resistant Device with "L" pins, 22 mm Direct Push Rods, and Gurin locks (3M Unitek large size Order #560-400). Don't forget to order a Gurin lock wrench.

Ask for the Dentaurum "Variety" two 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 a narrow maxilla, expand the maxilla first. It makes it easier in a patient with a narrow maxilla to attach the Forsus device 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. 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.

Dr. Bob Miller places compound material over the bands before taking the alginate impression. This method ensures that the band placement in the impression is correct.

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. Don't forget to replace the separators.

Another method is to place separators for a week, remove the separators, take impressions, and replace the separators. Send the models (or impressions) to the lab. The lab will fit bands on the models.

You can use 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.

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 or 2X6 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 Transbond™ Supreme LV Low Viscosity Light Cure Adhesive. 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 Transbond™ Plus Light Cure Band Adhesive 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.

note small amount of Gurin lock movement to acheive first bicuspid movement from half cusp Class II to half cusp Class III

The use of the Forsus device causes rapid over-correction, usually in four to five months. 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 replace the pushrod with a longer one or use a "shorty" hook-up.

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.

Maxillary second molar mini buccal tubes are welded to the first bicuspid bands to shorten the span between the canines and first molars. This is a case where bonding the canines was unavoidable. The patient's parents requested early incisor alignment before the LLL arch and springs were placed. The archwire will be segmented distal to the canines before the springs are placed to avoid actively retracting the incisors.

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Reference⁵: External apical root resorption in Class II malocclusion: A retrospective review of 1- versus 2-phase treatment
Ilana Brin, Camilla Tulloch, Lorne Koroluk, Ceib Philips
AJODO August 2003 • Volume 124 • Number 2
“Significant associations exist between EARR and the magnitude of overjet reduction and the duration of fixed-appliance treatment.
Early growth modification that reduces the severity of overjet in Class II malocclusion might have a role in reducing the likelihood of EARR.”

Solution: Decrease time in full edgewise, especially time that upper incisors are retracted with full edgewise to reduce overjet. Rely on passive (indirect) incisor and canine retraction by transeptal fibers with phase one Xbow.

Editor's note: I still see the most root resorption of upper incisors in Class II cases where four bicuspids have been extracted and overjet is reduced by incisor retraction using a full edgewise appliance, headgear and Cl II elastics or springs. This observation is supported by the literature. ( I am always suprised how much more overjet appears in a deep overbite case when we bond a bite turbo and open the bite.) The theory is that bodily retraction of the upper incisors with a full edgewise appliance and a full size retangular archwire puts the most stress on the root apices. I did not see root resorption with functional appliances until I placed brackets and archwires. Again, the theory is that with functional appliances the upper incisors are retracted by passive or transeptal fibre tension without a lot of tipping, that is the torque on the incisors is pretty well maintained, as long as there is no upper labial bow on the functional appliance.

Even though an advantage of the one phase full edgewise appliance and Class II springs is no first phase appliance with its associated lab costs, the risk of root resorption outweighs this financial benefit.

Problem: Inconsistent results from phase one Class II correction and retreatment of Class II in phase 2.
Lack of stability of early correction related to flat occlusal surfaces of primary molars and Class II growth.
Lack of compliance with removable appliances.
Lack of over-correction with removable appliances.
Lack of unilateral control with functional appliances.
Stainless steel crowns and comfort issues with the Herbst and MARA in order to gain 1 mm of extra mandibular growth which is not clinically significant.

Solution: Wait for first bicuspids to erupt then treat Class II with Xbow, followed by short phase 2.

In an overview article on interarch maxillary molar distalizing appliances, Dr. McNamara 26 states: "The key indicator of success over the long term, as many see it, is holding the Class I relationship once it is achieved. Pancherz is given credit for the revival of the Herbst appliance, nearly 30 years ago, with a cephalometric study of its use in growing boys who were selected in part because they had yet to exhibit maximum pubertal growth. More recently, Pancherz has shifted toward advocating Herbst treatment in the permanent dentition after the pubertal growth peak to ensure stable post-treatment intercuspation and to reduce the length of retention. Avoidance of Class II relapse is known to be a challenge, but studies have demonstrated that good cuspal interdigitation is an excellent predictor of stability."

The end of phase one goal is a Class I first bicuspid relationship achieved by overcorrecting the maxillary first bicuspids from Class II to a half cusp Class III and utilizing the bite-catching effect of the first bicuspids as the distalized teeth rebound mesially and occlusally.

Once the dust clears it looks like there are only two things that help a corrected Class II malocclusion remain Class I (other than indefinite retention with a "passive activator") They are: 1. The fact that the mandible outgrows the maxilla, and, 2. A socked-in buccal occlusion, and more importantly, socked-in first bicuspids. Dr. Herbst had it figured out by 1905.

Fixed or non-compliance Class II correctors such as the Herbst and Xbow have a much lower failure-to-complete rate than removable appliances. In O'Brien's 11 randomized clinical trial invloving 215 patients the Twin-block appliance resulted in a 33.6% failure-to-complete rate. This is such a problem that some clinicians are cementing Twin-block appliances in their patient's mouths. This results in a bulky appliance that makes speaking, eating, and oral hygiene difficult compared to Herbst or Xbow.

It appears that mandibular propulsive appliances offer no significant advantages over other appliances.

In a systematic review 27 titled "Effectiveness of orthodontic treatment with functional appliances on mandibular growth in the short term", Marsico et al concluded: "The analysis of the effect of treatment with functional appliances vs an untreated control group showed that skeletal changes were statistically significant (1.79 mm in annual mandibular growth), but unlikely to be clinically significant."

In an overview article on interarch maxillary molar distalizing appliances, Dr. McNamara 26 states: "After active (Herbst) treatment, however, the rate of mandibular skeletal growth drops below the normal rate. Some investigators have reported that the remaining increase in mandibular length is only an average of 1mm."

Dr. Terry Dischinger is a proponent of the edgewise Herbst appliance and believes that torque control of the incisors with a partial edgewise appliance is important for maximum mandibular growth with the Herbst appliance. Dr. Dischinger 28 published his results from 32 consecutive patients. Sixteen months after overcorrection with the edgewise Herbst appliance and appliance removal: "Net restraint of maxillary growth was 1.3 mm, and net forward movement of the mandible was 1.0 mm." This amount of extra mandibular growth is not clinically significant.

Dr. Carlos Flores-Mir, Head of the Division of Orthodontics and Director of the Orthodontic Graduate Program, University of Alberta , and Director, Cranio-facial & Oral-health Evidence-based Practice Group (COEPG) (http://www.uofaweb.ualberta.ca/ortho/nav02.cfm?nav02=27929&nav01=10601), states: "As shown in a published systematic review 15, the effects produced by the bonded Herbst appliance are significantly dentoalveolar. Some "headgear effect" and changes in mandibular length were reported but they are not likely clinically significant. No good evidence was reported for long term changes.

In systematic reviews of the effects of fixed 16 and removable 17 functional appliances, there were no profile soft tissue changes when normal expected facial growth was factored out.

1. The use of six ordinary bands instead of crowns or reinforced bands. This is possible because of a consistent force from the Forsus device that bands can withstand and the fact that the Forsus device acts as a stress breaker.

2. The Forsus device allows measurable forces of approximately 200 grams or less to be placed on the teeth on one or both sides for as long as it takes to achieve the desired overcorrection. This is handy in asymmetrical Class II cases where the Forsus device is left on one side for a longer time.

3. Forsus devices can be placed in cases with a full cusp Class II molar and little overjet where the canines are blocked out.

4. The Forsus device allows the mandible to function in centric relation with the condyles seated.

The advantages that the Xbow has over maxillary first bicuspid and Nance anchorage to distalize maxillary first molars are:

1. The maxillary first bicuspid is distalized with the Xbow and mesialized with maxillary first bicuspid and Nance anchorage.

2. Space is opened for the maxillary canines with the Xbow and closed with maxillary first bicuspid and Nance anchorage.

3. With maxillary first bicuspid and Nance anchorage once the maxillary molars are distalized, you must "maintain the gain". This requires placing a Nance to the molars, waiting for the first bicuspids to relapse distally, placing full edgewise appliances, opening space for the maxillary canines, and finally, removing the Nance and using anchorage such as headgear, Class II elastics or Forsus devices to retract the maxillary incisors. Why not use the Forsus device on a Xbow in the first place?

Problem: Opening space for crowded upper canines with full edgewise and non-extraction without proclining and round tripping the upper incisors. Waiting for canines to erupt with full edgewise appliances in place often leading to surgical exposure and orthodontic eruption.

Solution: Open space for crowded upper canines with Xbow and allow transeptal fibers to distalize and erupt the canines.

Problem: Waiting to correct Class II with full edgewise and Class II springs.
Leaving Class II correction until late in full edgewise treatment.
Occlusal canting with a unilateral spring in an asymmetric Class II.
Other side effects of Class II springs such as posterior openbite needing correction with vertical elastics late in full edgewise treatment. The more severe the Class II the more severe the side-effects.
Compensatory maxillary expansion by dental movement instead of sutural expansion.
Missing out on the growth spurt and "headgear effect" in early maturing females and late erupters.
Lengthy full edgewise treatment leading to more bracket replacement and patient burnout at a time when they need to be wearing finishing elastics.

Unilateral posterior openbite and occlusal cant after unilateral Class II spring on the archwire. This side effect requires good elastic compliance to resolve. The cant does not always completely level. This side effect occurs late in treatment when you should be fine tuning before deband.

Solution: Xbow to establish Class I bicuspid relationship bilaterally in phase one.
Establish the maxillary width in phase one by sutural expansion, if necessary.
We want the side-effects in phase one so that settling occurs before phase two. We don’t want the side-effects late in phase two.

Over-correction and rebound is important when using Class II springs because the movement is rapid and the teeth are mobile and relapse quickly. Lower incisor proclination is an unstable movement. It makes sense to perform over-correction and allow rebound of lower incisor proclination in phase one instead of late in phase two.

The tipping of the buccal segment occlusal plane with Xbow encourages the bite-catching effect of the first bicuspids.

If the plan includes an RME and lower lingual arch anyway, why not add Class II springs instead of waiting for the permanent dentition, a full edgewise appliance, and rectangular wires?

Crossbow is something to do while your Class II patient is growing and you are waiting for second molars.

Solution: Share the correction between the upper and lower to decrease upper lip retraction with Xbow.

1. 4 upper incisor brackets followed by Xbow, springs for 3 months. 2. Full braces for 1 year

This case shows the importance of non-extraction treatment and not retracting the upper lip in a Class II patient with a convex profile.

In an overview article on interarch maxillary molar distalizing appliances, Dr. McNamara 26 states: "Contemporary edgewise extraction treatment (upper premolars or upper and lower premolars) almost always results in forward displacement of the maxillary molars as the molar relationship is corrected. In contrast, edgewise nonextraction treatment predictably results in an absolute distal displacement (bodily movement and tipping) of the maxillary molars. For a variety of reasons, scientific or not, orthodontic treatment in the past few decades has tended toward nonextraction."

Editor's note: My practice is made up mostly of patients of Northern European and South Asian descent. This means that there are a lot of Class II patients with retognathic mandibles. We generally give the patients and parents two treatment options: 1. mandibular advancement surgery or 2. two phase Class II compensation with Xbow. We are lucky to work with one of the best surgeons anywhere, Dr. Bill McDonald, and that the surgery fees are reasonable, but non-surgical treatment is still the most popular. With retrognathic mandibles and nose prominent profiles we try to retract the upper incisors and upper lip as little as possible. Some proclination of the lower incisors is necessary and we try to take advantage of growth and the heagear effect. With surgery patients the goal is to line up the lips over the chin. With Class II compensation patients we try to keep the lips as close to Rickett's Esthetic Plane as possible.

Overall treatment time for two phase Class II treatment with Xbow is similar to two or four bicuspid "extract and retract" treatment, if you expand the maxilla and retain it for 5 months in every Xbow patient. The main differences are: 1. Xbow treatment does not depend on compliance with headgear and Class II elastics; 2. We do not see the mesial movement of the upper molars and over-retraction of the upper incisors and upper lip that is typical of extraction treatment; 3. There is less root resorption and decalcification because the time in braces is much shorter, usually around one year; and 4. We do not have to deal with the side-effects of using Class II springs late in treatment because full braces are only bonded after the buccal occlusion is Class I.

Reference25: Orthodontic therapy and gingival recession: a systematic review
Joss-Vassalli I, Grebenstein C, Topouzelis N, Sculean A, Katsaros C:
Orthod Craniofac Res 2010;13:127–141
"The amount of recession found in studies with statistically significant differences between proclined and non-proclined incisors is small and the clinical consequence questionable."

With Xbow there is temporary over-proclination of the lower incisors over a short treatment time of approximately two to eight months, after which the lower incisors are allowed to upright, and the tension in the periodontium is reduced. The gingival tissues are monitored closely during this time of rapid tooth movement. Pancherz 12 has shown that proclination of the lower incisors with the Herbst appliance does not cause gingival recession. This has also been the author's experience with Xbow.

It looks like we can get away with some expansion and proclination. Archwire expansion generally results in buccal tipping. This will lead to thinner buccal bone or some boney dehisence but this does not automatically cause gingival recession.

Following is a quote from Dr. Carlos Flores-Mir, Department of Dentistry, University of Alberta, Edmonton, Canada in Evidence-Based Dentistry (2011) 12, 20. doi:10.1038/sj.ebd.6400778:
"Clinicians should not automatically assume that an incisor proclination will generate a correlated gingival retraction."
"While not discussed specifically, presence of gingival retraction before orthodontic movement, poor oral hygiene, gingivitis and/or a thin gingival/bone biotype in addition to proclination of incisors will likely produce some degree of gingival recession."

The Class I Doppelganger Theory by Dr. Anthony Mair
Is it possible that there exists an untreated lookalike with the same Class II skeletal pattern but a Class I dental pattern?
If the answer is yes then it is OK to proceed with Class II compensation with Xbow.

In Dr. Casko's¹ landmark cephalometric study he showed wide ranges of dental and skeletal variation in individuals with untreated ideal occlusions. He showed that when the ANB angle is high (up to 8 degrees), the incisors are normally more upright in the maxilla (down to 93 degrees) and more protrusive in the mandible (up to106 degrees).

Compare those numbers with Dr. Casko's untreated ideal occlusions with an ANB angle of -3 degrees. The lower incisor was compensated back to 83 degrees while the upper incisor was compensated out to 120 degrees. In order to prevent Class III surgery orthodontists will procline upper incisors out to and past 120 degrees without a second thought, which is 18 degrees past the norm. The same orthodontists may criticize a lower incisor proclined to 106 degrees in a Class II patient, which is only 10 degrees past the norm.

Same patient as below, flipped lower to upper. Why should a Class II be treated differently than a Class III?

2. Upper 2X4 and bonded posterior bite blocks to rotate mandible down and back and then procline upper inciosrs.

This is standard treatment for a Class III to avoid jaw surgery. Note improvement in upper lip fullness.

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The longer Class II elastics are used the more tipping of the occlusal plane occurs, the more the upper incisors are extruded, and the more root resorption of the upper incisors occurs. This leads to more upper incisor and gingival display. Where Class II elastics are beneficial is with rapid bite-opening in conjunction with bite turbos on upper incisors. The eruption of lower molars in growing Class II deep bite patients was shown to be very effective by the late great Dr. Fred Schudy and Dr.Tom Creekmore.

Xbow Research

Dr. Bob Miller compared 8 two phase Herbst cases with 7 two phase Xbow cases and 7 single phase Forsus cases.

Herbst (two phase) Xbow (two phase) Forsus on arch wire (single phase)

Avg # of Visits 29 19 26

lAvg Chair Time (min/visit) 32 26 32

Avg Time in Office (min) ______868________________556_____________________818

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Flores-Mir et al 21 from the University of Alberta analyzed the lateral cephalograms of 67 consecutively started Xbow patients and compared them to non-treated controls. The mean treatment time was 4.5 months. The T2 cephs were taken 6.4 months after Forsus removal on average. The following are the results after growth was factored out. SNA was reduced by an average of 1.0 degree and "A" point came back 0.5 mm. The upper incisors came back 1.8 degrees and 0.5 mm. The maxillary first molar was distalized 2.0 mm. The mandibular plane angle opened 1.0 degree. The lower incisors proclined an average of 3.8 degrees and came forward 1.2 mm. The mandibular first molar came forward 0.6 mm. The overjet was reduced an average of 2.4 mm. The ANB angle was reduced an average of 0.8 degrees. No other appliance was used. This compares favorably to Herbst treatment. The conclusion of the study was: "Treatment with the Xbow appliance in Class II patients resulted in favourable dental and skeletal changes in the direction of Class II correction."

Dr. Carlos Flores-Mir has begun a prospective randomized clinical trial comparing Xbow and a delayed treatment group using a dental, skeletal, and facial 3D volumetric analysis.

In another study from the University of Alberta 23 titled "Lower incisor inclination changes during Xbow treatment according to vertical facial type", Flores-Mir et al concluded that "the magnitude of the incisor proclination can be considered not clinically significant but a large individual variation in the incisor response was identified." This study involved 172 consecutively started Xbow patients. The lower incisors ended up proclined an average of 3.6 degrees after 6.4 months of post-Forsus settling. The overjet was reduced an average of 2.6 mm and the overbite was reduced and average of 1.9 mm after 6.4 months of settling, even without any appliance connection to the upper incisors.

In the third published study from the University of Alberta 29 titled "Prediction of lower incisor proclination during Xbow treatment based on initial cephalometric variables", Flores-Mir et al looked at before and after cephs of 249 Xbow patients. "The mean L1-MP at T1 was 95.46 degrees and the mean L1-MP at T2 was 98.51 degrees, resulting in a mean difference of 3.04 degrees."

100 degrees is considered by many clinicians to be the conservative goal for lower incisor inclination in Class II compensation. That is still 6 degrees less than what Dr. Casko found for the upper limit in his sample of untreated, naturally compensated patients with Class II skeletal patterns and Class I occlusions.

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In 1979 the Indiana University orthodontic program focused on the biomechanics of the segmented arch technique or "how to efficiently close extraction sites". Class II correction often involved "extract and retract". Thanks to some younger instructors we were exposed to Ricketts, Roth, and Alexander, and the trend towards two phase Class II treatment, non-extraction, and facial esthetics. We listened to McNamara and his involvement with Frankel.

In 1981 I joined the practice of Dr. Michael Wainwright in Vancouver. He was a pioneer in indirect bonding and used a technique which combined .018 Ricketts and Roth. He used a two phase approach to Class II correction with a combination Hawley bite plane and cervical headgear.

In 1984 I opened the office in North Delta. I continued to use the bite plane and headgear but slowly began using functional appliances, including Frankels and bionators. I put headgear tubes in the appliances so the patients could wear them with a high pull headgear at night. Our study club invited Dr. William Clark to speak to us on Twin Blocks. I designed a Twin Block with Adams clasps on the upper first molars and all first bicuspids, a spring retainer type labial bow on the lower incisors, and headgear tubes. It was a big improvement over the bionator but compliance was still a big issue. It was difficult to achieve over-correction and unilateral control was impossible. It could open up some space for crowded upper canines but only if there was significant overjet to begin with.

In the 1990's I began using the Herbst appliance when Ormco introduced the four crown Cantilever Bite Jumper. This was my first experience with automatic Class II correction and the ability to over-correct and sock in the first bicuspids. Removing the crowns was a pain and some small patients could not tolerate the bulky appliance. The lack of unilateral control led me to look at Ormco's Bite Fixer spring. Two problems came to light very quickly. The first was breakage. The second was the side effects of using the spring unilaterally which were the posterior openbite and anterior canting. This happened late in treatment and required good elastic compliance to recover from.

In order to decrease spring breakage I used a lower lip bumper to allow greater opening. It worked so well, especially in asymmetric Class II's that I experimented with a "spring-loaded Herbst" which became the Xbow.