The Class II Compensation Compromise: Preserving the Upper Lip

This is from a Crossbow lecture that I give to orthodontic residents.

 

If the best option for a Class II patient is mandibular advancement surgery, but they decline, then treatment

will be some sort of orthodontic compensation.  By definition, dental compensation for a jaw problem will

be a compromise.  The choices are either upper incisor retraction only, or sharing the correction between

the upper and lower.  That is really all we are doing with functional appliances, other than a small skeletal effect.


The Catch 22 is that both choices have drawbacks.  Too much upper incisor retraction will result in noticeable

upper lip retraction.  If we’re not retracting the upper incisor and lip we are proclining the lower incisor and

increasing lower lip protrusion.  If we extract four bicuspids to keep the lower incisors upright, in an

attempt to improve stability, then we retract the upper incisors and upper lip even more. 

The fact that we can't predict individual facial growth complicates matters more. Esthetics should trump

the endless pursuit of stability without retainers.

 

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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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Initial

1. RME X 4 2. Xbow with springs for 7 months 3. Full braces for 14 months

Opening the bite and proclining upper and lower incisors enhanced the lips.

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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. 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.

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

I was proclining lower incisors, especially in non-extraction cases and where I used Class II elastics, 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.

 

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".

 

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.

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.

 

 

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Preference vs evidence based treatment decisions

 

The lower lip flattens 3.5 mm on average with growth and if first bicuspids are extracted it flattens another 2 mm

on average for a total of 5.5 mm. Another way of saying this is that a slight protrusion appears more youthful.

I prefer a slight protrusion to a flattened profile in most cases. As far as stability goes, practically all orthodontic

movement is unstable and requires long term (life long) retention. Proclined lower incisors will relapse if not

retained. I retain every full treatment case, anyways.

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).

For a very short time I tried one phase headgear, followed by Forsus to the archwire (if they didn't wear the headgear,

which happened too often). I have always waited for second molars to erupt before indirect bonding,

so with these cases I was leaving the Class II correction to later in treatment compared to two phase.

I missed out on the growth spurt in early maturing girls. The advantage to a headgear practice is that there are

no emergencies, but it is a very confrontational type of practice, where I was always discussing cooperation

(or lack of it) with patients and parents. My Eureka moment was when I began using Herbst appliances and saw

what full time wear looked like. I preferred two phase where I corrected the Class II buccal segments early on,

and opened space for the erupting upper canines. It wasn't evidence based. It just made sense to me to connect

the Class II springs to the RME when I was expanding the maxilla on so many of my Class II patients.

Many of them had a lower lingual arch already to preserve the "e" space, so all I needed to add was a lower labial bow,

occlusal rests on the lower first bicuspids, and headgear tubes. It gave me something to do while I was waiting for

second molars to erupt and the patient was growing. Welding tubes to the upper first bicuspid bands made early incisor

alignment and canine management more comfortable and efficient, compared to connecting the archwire to the first molars.

 

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. Non-extraction without headgear turned out

to be my patient's preference, as well.


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.

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

 

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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Xbow is critisized for proclining lower incisors.

The Xbow Appliance has been used around the world in thousands of patients.

If there was a problem with lower incisor gingival recession, I would know about it.

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 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 have learned a lot about the aging face since 1979.

There were 2.6 million paitients injected with dermal fillers in 2016 in the U.S.

Many of those patients look like they have been in a fight, even the movie stars.

Some of those patients sought treatment for a retracted upper lip which was a result of orthodontic

treatment as a teen.

When I was an orthodontic student, 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. If temporary over-proclination bothers

you, then stick to Twin Blocks and Class II elastics.