The Class II Compensation Compromise: Preserving the Upper Lip

Lower incisor proclination is not ideal, but neither is orthodontic compensation when the ideal treatment

is jaw surgery. Sometimes we get lucky and the patient and parents agree to ideal treatment. Sometimes

we compromise.

Every functional appliance I used in the 80's and 90's, including Frankels, bionators, twin blocks,

and Herbst, proclined lower incisors. I noticed it more with Herbst simply because compliance

was not an issue. This is also why lower incisor proclination is noticeable with Xbow.

Over-correction and the "bite-catching effect" are important for both Herbst and Xbow.

That means temporary over-proclination, followed by partial uprighting of the lower incisors.

The important point is that gingival recession does not occur, as long as there is adequate

attached gingiva, or a graft placed before treatment starts.

 

 

 

 

My favorite quote is by Abraham Maslow: " If the only tool you have is a hammer, you tend to see

every problem as a nail." As an orthodontic student in 1979 we were taught that our tool for a

Class II malocclusion was orthodontic retraction and every problem was a protrusion.

Our toolbox had headgear and upper bicuspid extraction in it. In an emergency we could pull

the red handle and use Class II elastics, but only if the lower incisors were retroclined or if we

also extracted lower bicuspids. We looked at the models and the hard tissue

ceph measurements. For years I have been looking at the face as the most important determinant

of which treatment I should recommend. For Class II patients this often means I will recommend

jaw surgery as the best treatment. If the patient declines surgery I tell them treatment will involve

dental compensation for their underlying jaw problem and that a compromise will involve a certain

amount of upper incisor and upper lip retraction. To minimize the retraction, Xbow shares the

correction with the lower arch. This means lower incisor proclination and pemanent retention.

Xbow proclines lower incisors 3 degrees on average after a short period of over-proclination

and rebound uprighting. In an unpublished study at the U of Alberta on 172 consecutively

treated Xbow patients, the average lower incisor started at 99 degrees and ended up at 102.

The literature is very clear. Lower incisor proclination does not cause gingival recession in healthy

periodontium.

The literature is also very clear that all inter-arch Class II appliances procline the lower incisors a

similar amount, even functional appliances. The non-edgewise Herbst appliance is capable of

temporary over-proclination of the lower incisors similar to Xbow. This same over-correction

is why the results are stable, and why phase two is shorter.

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Xbow two phase non-extraction treatment to preserve the upper lip

Initial (I was the second opinion. Initial opinion was the extraction of four bicuspids and braces.Instead, I treated non-extraction with Xbow two phase treatment)

1. Xbow___ 2. RME___ 3. FEA

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The Xbow system for Class II compensation is based on building the maxillary foundation for

ideal treatment as if we were proceeding with jaw surgery. After maxillary expansion and upper anterior alignment, instead of

proceeding with full braces and jaw surgery we use the Xbow appliance to share the correction between both arches to minimize

retracting the upper incisors and upper lip, compared to headgear or upper extractions.

Initial, Class II elastics should be minimized due to the gingival display

1. RME X 6 to intrude incisors 2. Xbow (springs for 2 months, intrusive springs support incisor intrusion)

14 months full braces

Upper lip preservation with a convex profile and obtuse naso-labial angle, non-extraction in a crowded Class II deep overbite patient

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Initial

1. Xbow 2 months left spring, 3 months right spring 2. Compensatory maxillary expansion 3. Full braces

Sharing the correction between the upper and lower arches preserves upper lip fullness in patients with retrognathic mandibles

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Surgical correction to preserve the upper lip

 

Initial ____________________________15 months total treatment time including

lower bicuspid extraction site space closure and lower jaw surgery by Dr. Bill McDonald

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Initial

After lower bicuspid extraction site space closure and lower jaw surgery by Dr. Bill McDonald. The upper

second molars are unopposed and can be removed if they ever cause a problem which is very rare.

There are only two upper molars in occlusion and the molar relationship is Class III. In these cases we look

for a Class I bicuspid relationship. When a patient chooses surgery we concentrate on ideal facial esthetics.

The upper incisors are slightly proclined which prevents the upper lip from hanging straight down.

This creates complementary curves between the nose and upper lip, and the lower lip and chin.

Upper lip projection should be slightly ahead of the lower lip. Lower lip projection should line up with chin.

The nose blends in beautifully with the face.

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Rationale for the Xbow

History

1979-1981: I was an orthodontic resident at Indiana University. Class II's were treated by bicuspid extraction

and headgear. Class II elastics were discouraged. We heard Drs. Rocke and Kesling speak on

treating non-extraction with Class II elastics. They showed ceph tracings similar to what other orthodontists

were achieving with functional appliances such as activators, bionators, and Frankel appliances. It was a

combination of skelatal and dental effects including lower incisor proclination.

1981: Dr. Behrents published the ground breaking article in the Journal of Periodontology that was the

first to bebunk myths that I had been taught.

1981-1984: I was an associate with my mentor, Dr. Michael Wainwright. He taught me indirect bonding,

two phase treatment, and combined orthodontic/orthognathic surgical treatment.

1984: I opened my office in North Delta. I began using functional appliances. I took a ceph at the final records.

I was proclining lower incisors with the functional appliances, but I was not

seeing gingival recession. This became a subject that would interest me for my entire career.

Dr. Casko published his findings that questioned Tweed's 95 degree IMPA in untreated Class II skeletal patterns with

Class I occlusions. More myth debunking.

 

1990: My study club invited Dr. William Clark to speak to us about twin blocks. I began using them.

1991: Dr. DeVincenzo publishes his research which is the first of many to question the ability of functional appliances

to increase mandibular length in the long term. Dr. Lysle Johnston coined the term "mortgaging mandibular growth".

More myth debunking.

 

1995: I began using the four crown Herbst appliance which got me interested in non-compliance appliances.

My main conern was with over-correction I was seeing noticeable lower incisor proclination

that I had not noticed with removable functional appliances. I tried placing -5 to -10 degree lower incisor brackets but

instead of proclining the lower incisors I noticed that the bodily mesialization of the incisors resulted in a "washboard

effect". I preferred tipping the lower incisors temporarily and then allowing them to upright before phase two.

The important thing was I did not see the gingival recession that I had been taught would happen.

Dr. Alan Lowe developed the Klearway appliance for snoring and sleep apnea. Long term wear has resulted

in severe proclination of lower incisors without significant recession.

1997: Dr. Pancherz published his summary of the effects of the Herbst appliance. There was no long term increase in

mandibular length. He did not recommend it in non-growing patients, possibly due to the risk of condylar resorption.

The take away message was that mixed dentition treatment was not recommended because "a stable cuspal interdigitation

after therapy is difficult to achieve and relapses are prone to occur." Pancherz had proven what Dr. Herbst called

"the bite catching effect".

Thanks to Dr. Herb Hughes for the above slide showing over-correction with Xbow

and the bite catching effect of the steep cuspal inclines of the first bicuspids.

1998: Dr. Jay Bowman published an article in the JCO using Jasper Jumpers attached to a lower lip bumper instead

of a bypass. I was convinced that most Class II's required maxillary expansion. I was also using lower lingual arches

to preserve the "e" space. I added a lip bumper and Ormco's Bite Fixer springs. This led to the Xbow appliance.

Dr. Pancherz publishes his findings that lower incisor proclination does not cause gingival recession.

2000: Dr. Gianelly gives us a target to shoot for.

2001: Granted a US patent and registered trademarks for the Xbow

2002: I lectured on the Xbow appliance with Dr. Pancherz at the GLAO/MASO meeting. We discussed lower incisor

proclination and agreed that temporary over-proclination followed by uprighting did not cause gingival recession and

in fact over-correction followed by the bite catching effect and cuspal interdigitation was necessary for long term stability.

2009: First Xbow research paper published in the AJODO after working with Dr. Carlos Flores-Mir at the U of Alberta.

We showed the lower incisor proclined a similar amount to the Herbst appliance. A total of seven papers on Xbow

would be published as a result of Dr. Flores-Mir's effort.

2013: Drs. Bob Miller and Carlos Flores-Mir publish the definitive research paper on the efficiency of two phase Xbow

treatment compared to one phase Forsus to the archwire treatment.

2015: The data from 172 consecutively treated Xbow patients was studied at the

U of Alberta. An interesting finding was that the average initial lower incisor inclination

was 99 degrees. This agrees with Dr. Casko's belief that Class II skeletal cases are

naturally compensated.

2016: I was asked to speak at the AAO Scientific Session. My conclusion was that the results are similar for all inter-arch

Class II appliances. The differences are probably not clinically significant. We should be focusing on preserving the upper

lip and treatment efficiency, including decreasing the treatment time in full edgewise appliances.

2017: Dr. Gianelly's 76% non-extraction target looks right on.

 

More myth busting

 

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Preference vs evidence based treatment decisions

 

As much as we want to make evidence based decisions, orthodontist and patient preference plays a major role

in the decisions we make. In the 1980's my Class II patients fell into four groups.

1. Orthodontic decompensation and jaw surgery. 2. Two phase non-extraction beginning with a functional appliance

(which evolved into Herbst followed by Xbow). 3. One phase four bicuspid extraction and headgear

(I still have a few of these). and 4. One phase upper bicuspid extraction (I still have a few of these, as well).

One thing became clear. If I extracted four bicuspids in a deep overbite case, I ended up chasing the lower incisors

in what I call the "never ending overjet". It was in these cases where I saw the most lip retraction, or profile flattening.

I began treating more and more of these cases non-extraction and in two phases. By this time I was expanding the

maxilla in just about every two phase Xbow case and I used a lot of RME X 6's to align and open space for upper canines.

My treatment time for phase two decreased to about a year. I sent all my Xbow patient cephs to the U of A for analysis.

I wanted to be evidence based but really it came down to my preference.


No matter which interarch Class II appliance I used, I proclined lower incisors.  Whether it was Xbow or Herbst or

Twin Block or Class II elastics or Forsus, it didn't  matter. Expand buccally? Interproximal reduction? 

Fill the slot and tie back? Minus six degree lower incisor brackets? They still proclined.

 
I didn’t worry about proclining lower incisors with functional appliances until I began using Herbst.

(So this is what happens with full time wear.) Even then, I didn’t see any gingival recession which agrees with the

article by Hans Pancherz and a systematic review on proclination.  I am more comfortable with  lower

incisor tipping followed by partial uprighting with Xbow and non-edgewise Herbst,  than I am with bodily

mesialization with a rectangular archwire and minus six degree lower incisor brackets, which I find results

in root prominence. Again, it's a preference. There isn't good evidence, one way or another.

Dr. Anthony Mair is the best orthodontist I know. He explains it this way: "It is better to tip

the crown and leave the root in bone than to bodily move the root out of bone."

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A 95 degree IMPA is a good target if the skeletal pattern is Class I, and the mandibular plane angle is normal.

The problem is saying that you cannot procline lower incisors unless they start at less than 95 degrees and will

end up at 95 degrees. If you follow this rule you will be extracting four bicuspids in many crowded

cases and over-retracting incisors in some of them. Over-retraction of the uper incisors is a major side effect

of traditional Class II compensation where four bicuspid extraction, cervical headgear, and Class II elastics

are used and the goal is a 95 degree IMPA. It was first studied by Drs. Stoner and Lindquist and published

in 1956 in the Angle Orthodontist. The title was "Consecutive Cases Treated by Dr. Charles Tweed" and it

looked at the claim that Tweed mechanics resulted in improved facial esthetics.The conclusion was that most

of the overjet correction was by upper incisor retraction and that many incisors were over-retracted.

I met Dr. Lindquist while I attended Indiana University. He was the first orthodontist that I heard warn of

over-extracting. He said that serial extracting was a "self fulfilling prophecy" in that extracting primary canines

increased the odds that first bicuspids would need to be extracted. He advised to only extract lower primary

canines if the lateral incisors were impacted. He respected Dr. Tweed but said some Tweed followers were

extracting if there was any lower anterior crowding or if any Class II elastics would be used. Dr. Lindquist

argued that lower incisors could be proclined without causing gingival recession but the movement would

be unstable and require permanent retention. He said to look at the face and only extract if after alignment and

interproximal reduction there was a protrusion or an anterior openbite.

Dr. Casko believed that incisor inclination was linked to the skeletal pattern and showed that it was normal for

the lower incisor to have an IMPA higher than 95 degrees in an untreated skeletal Class II with a Class I occlusion.

He argued that this should be the goal for Class II compensation.

 

It is normal for lower incisors to be proclined in a Class II skeletal pattern.

Casko showed that it happens in untreated Class II skeletal cases with Class I occlusions.

Naturally occurring Class II skeletal with Class I dental with a non-protrusive upper incisor

Yes there is a cyst associated with the third molar which has been removed.

Naturally occurring Class II skeletal with Class I dental with protrusive upper incisor

 

In 1980 Dr. Ricketts was making an impact on our profession when he introduced the soft tissue analysis

and the "Esthetic Plane". He said that over-extracting could be detrimental to the face. He suggested that

lower crowding in a deep bite was related to the lower arch being contained by a constricted upper arch.

The lower incisor tends to be more proclined in low mandibular plane angle cases with normal overbite and more

upright in high mandibular plane angle cases with normal overbite. Four bicuspid extraction should be done more

in high angle cases with a shallow overbite. Low angle cases with deep overbite should be treated non-extraction.

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The myth that I was taught to believe was that lower incisor proclination would result in gingival recession.

If an orthodontist treats lower crowding non-extraction, or if they use Class II elastics, Class II springs,

or functional appliances, they are advancing lower incisors. If the occlusion looks good, and the face looks good,

and the lower anterior gingiva looks good, then the lower incisors are where they should be aesthetically.

This may not be the most stable position. The most stable position was that of the orignial malocclusion,

and even that will change over time.

Dr. Tom Graber told me that it is perfectly fine to begin borderline extraction cases non-extraction.

He said if that produced an overly protrusive profile or an anterior openbite, I could then extract four bicuspids.

My non-extraction rate is about 80%. I tend to treat Class II deep overbite cases non-extraction.

 

 

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Below are pretreatment cephs with Class I skeletal patterns with good lip fullness, but different soft tissue

convexity angles and midface development.

Patient #1 pretreatment ceph________________Patient #2 pretreatment ceph

Patient #1: Class I skeletal, upper and lower incisors are naturally more proclined than established "norms"

Lips are slightly protrusive and balanced perfectly to Rickett's E plane due to short nasal projection

Is a slight protrusion the new ideal?

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Patient #2: Class I skeletal, high soft tissue convexity angle due to strong nasal growth , upper lip retrusive to Rickett's E plane

The goal should be to maintain the upper incisor position. If this is not possible it is better to end up with a slight protrusion

and long term retention instead of a retrusion based on wishful thinking of better stability. We cannot predict how much more

nasal growth will occur, only that it will.

 

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More History

Dr. Angle's Class II "bite-jumping" appliance, photo courtesy of Dr. Lysle Johnston. This would have

resulted in lower incisor proclination. If this caused gingival recession Dr. Angle would have reported it.

Dr. Angle's students, Begg and Tweed stopped doing what they had been taught and followed

the teachings of Calvin Case. Dr. Tweed was able to control the torque of the upper incisors as he

retracted them to reduce the overjet in Class II's. He was also able to level the Curve of Spee with

full size rectangular arch wires and Class II elasitcs to erupt the lower posterior teeth. When you

just looked at the models Tweed was able to make a Class II case look like an ideal Class I

skeletal-dental, complete with upright incisors. In 1930 Dr. Broadbent invented the cephalometer

which allowed Tweed to measure the inclination of the incisors and compare his results to untreated

Class I dental-skeletal patients. This led to the Tweed Triangle and the goal of treating to an

upright lower incisor. Tweed was known for saying "Put your plaster on the table", but it was

the cephalometric measurements that gave scientific support to the upright lower incisor.

It wasn't until 1956 that Tweeds results were studied closely by Drs. Stoner and Lindquist

at Indiana University. Their study "Consecutive Cases Treated by Dr. Charles Tweed"

was published in the Angle Orthodontist. The main finding was that overjet reduction was almost

all by upper incisor retraction. There was no mandibular advancement surgery so there was no

way to change a Class II skeletal to a Class I, unless you believed Herbst who published his work

"Orthognathia" in the AJO in 1930, or you believed that by reducing the SNA angle you changed

a Class II skeletal to a Class I. There was no gingival grafting so over-expansion did cause some

gingival recession if there was no attached gingiva.

When I was an orthodontic resident in 1979 we were taught to treat to an

upright lower incisor. The only expansion allowed was sutural expansion with an RME. Any other

expansion would lead to gingival recession. These "shared beliefs" are still taught today.

 

Fast forward to 2019.

These are some heavy hitters in our profession. Dr. Buschang's research has shown there is little

evidence to prove that lower incisor proclination causes gingival recession. Dr. Behrents told us in

1981 that some recession was normal and that severe recession could be prevented as long

as there was attached gingiva present or a graft placed before ortho.

Dr. Lindauer asked me to speak on Crossbow at the AAO in 2016. Dr. Bob Miller will be speaking

on Crossbow at the next AAO meeting. There are conscientious orthodontists that will attend that

lecture looking for answers to questions that they have and their patients have. Questions like:

"Doctor, can you treat my child without surgery or without extractions?" "If we have to accept a

compromise, what is the most efficient method of treatment that will decrease the time in braces?"

"Can we decrease the amount of upper lip retraction compared to upper extractions and headgear?"

"Can we prevent the gummy smile caused by Class II elastics?"

 

More Compromises

This is a common conversation I have with orthodontists that criticize Crossbow. It starts by an

orthodontist saying he uses headgear to prevent lower incisor proclination. I ask what if the patient

doesn't wear the headgear? The orthodontist will reply that they will add Class II elastics. I add

that will procline lower incisors. They reply that they use a full size wire and -6 degree lower incisor

brackets to prevent the lower arch from coming forward. (Myth) I ask what if the patient doesn't

wear the elastics. They reply that is when they place Forsus Springs. I add that will push the lower

arch forward. They reply not if they use a full size wire and -6 degree lower incisor brackets. (Myth)

I ask what if they see side effects like posterior openbite, upper molar flaring, or occlusal plane canting.

They reply they add vertical elastics. I thought they wouldn't wear elastics. They reply the result will be

a compromise:)

Lower incisor proclination is not ideal, but neither is orthodontic compensation when the ideal treatment

is jaw surgery. Sometimes we get lucky and the patient and parents agree to ideal treatment. Sometimes

we compromise.

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The greater the Class II, the greater the side effects from Class II elastics and Class II springs.

Class II elastics cause tooth eruption which does not tend to relapse.  Class II springs cause tooth

intrusion and posterior openbite which does tend to relapse. Over-eruption of upper incisors

(and upper canines with phase one Class II elastics) can lead to a gummy smile.

A unilateral Class II elastic on a full edgewise appliance (FEA) is no problem. 

A unilateral phase one Class II elastic is likely to cause an occlusal cant that might be unrecoverable. 

A unlateral Class II spring on a FEA can also cause an occlusal cant and an openbite that requires

good anterior vertical elastic cooperation to resolve.  A unilateral spring on a Xbow does not cause

a cant because there are no brackets on the lower incisors.  Any unilateral intrusion will relapse.

Class II springs with a FEA cause buccal flaring of upper molars which may require posterior crossbite

elastics to recover from. Class II springs on a Xbow do not cause the same flaring because of cross arch

stabilization  by the RME.

Both Class II elastics and Class II springs cause proclination of the lower incisors. 

Xbow causes a temporary over-proclination of the lower incisors followed by partial but incomplete uprighting. 

This is necessary in order to over-correct the Class II buccal relationship and to achieve the "bite-catching effect"

and a socked in Class I bicuspid relationship BILATERALLY!

The fact that the Xbow is a phase one appliance allows the clinician to achieve RAPID over-correction of the

sagittal and transverse problems soon after the eruption of the first bicuspids to take advantage of the

"bite-catching effect" of the steep cusps of the first bicuspids.  The side effects such as posterior openbite

and over-proclination of the lower incisors tend to relapse before phase two full edgewise. 

The clinician has a better idea of where the incisors will end up after phase two and can modify the treatment

plan at the beginning of phase two. 

If there is still a deep overbite to treat in phase two then a combination of a bite-turbo and Class II elastics

may be use for rapid bite-opening.  The patient only has to cooperate with elastics for a short time so burn out

is not as big a problem compared to depending on Class II elastic use in phase one and phase two to correct

the entire malocclusion. There is also less chance of over-erupting the upper incisors with short term use of the

Class II elastics.