Fern Leavens (4th year dental student) Summer Research Project (2015) Under the supervision of Dr. Flores-Mir Unpublished

• 172 consecutively treated patients
• T1-T2 = phase one Xbow, T2-T3 = phase two full edgewise
• The mean lower incisor inclination changed from T1 (99.1o) to T2 (102.2o), with a mean difference of 3.1o. The change is statistically significant (p<0.001).
• The mean lower incisor inclination changed from T2 (102.2o) to T3 (103.7o), with a mean difference of 1.5o. The change is
  statistically significant (p=0.01). This may not be clinically significant.
• The mean lower incisor inclination changed from T1 (99.1o) to T3
  (103.7o), with a mean difference of 4.6o. The change is statistically significant (p<0.001).

• Prediction equation is L1IncDiffT3 T1 = -2.2 + 1.3(OB). Or for every extra mm of OB (greater than the ideal overbite of 2mm) there is an increase in lower incisor inclination of 1.3o

• Proclination of lower incisors has been criticized since Angle.
• Calvin Case, who in the extraction debate with Angle in 1911, argued that proclination led to protrusive profiles, gingival recession, and unstable alignment leading to rapid relapse.
• Tweed (1940) argued that the upright lower incisor seen in an ideal Class I skeletal pattern should be the goal in a Class II skeletal pattern for facial balance, stability, and periodontal health.
• In most cases this required the removal of all first bicuspids due to lower crowding and lower mesialization due to Class II elastics.
• Casko (1984) argued that upright lower incisors were not the norm in an untreated Class II skeletal population. He said lower incisor proclination due to treatment copied “natural compensation in an untreated Class II skeletal population”.

Dental and Skeletal Variation Within the Range of Normal
JOHN S. CASKO, WALTER B. SHEPHERD
The Angle Orthodontist: 1984, Vol. 54, No. 1, pp. 5–17.

Untreated Class II and Class III Skeletal Sample with Ideal Occlusion (Naturally Compensated)

All Class II elastics, springs, and functional appliances result in mesialization of the mandibular dentition

Dr. Anthony Mair

Does orthodontic proclination of lower incisors in children and adolescents cause gingival recession?

S Ruf, K Hansen, H Pancherz

“No interrelation was found between the amount of incisor proclination
and the development of gingival recession.”

“This phenomenon may have been due to the fact that an approximately 80% spontaneous reversal of the incisor proclination after Herbst treatment occurs.”

July 1998 • Volume 114 • Number 1

• Proclined mandibular incisors rebounded in Herbst patients 32 years after therapy.
• Incisor irregularity increased, probably because of the physiologic processes occurring throughout life.
• Minor gingival recessions 32 years after treatment seemed unrelated to tooth inclination changes.

• Are we growing mandibles?
• Do fixed functionals work better than removables?
• Are there risks to forcing the condyle to function out of the fossa with Herbst?
• Or do the benefits to the airway outweigh the risks to the joint?
• Are the effects similar to Class II elastics?
• If that is the case, is a Herbst appliance like “taking a tank to the grocery store to buy a quart of milk”?

• Dental and skeletal changes in mild to moderate Class II malocclusions treated by either a Twin-block or Xbow appliance followed by full fixed orthodontic treatment. Sayeh Ehsani ; Brian Nebbe ; David Normando ; Manuel O. Lagravere ; Carlos Flores-Mir (Angle Orthod. 2015;85:997–1002.)
• As for mandibular changes, the corpus length increase was larger in the Twin-block group by 3.9 mm, but an improvement of sagittal position of pogonion was not detected.

• Retrospective comparison of dental and skeletal effects in the treatment of Class II malocclusion between Herbst and Xbow appliances. Natalia Martins Insabralde, Marcio Rodrigues de Almeida, Renata Rodrigues de Almeida-Pedrin, Carlos Flores-Mir, and Jose Fernando Castanha Henriques (Am J Orthod Dentofacial Orthop 2021)
• a larger increase in mandibular length (an additional 3.2 mm) was noted for the Herbst group.

• DeVincenzo wrote the chapter on Class II correction and compliance in Graber and Swain and in 1997 developed the first telescopic spring, the “Eureka Spring”.

The analysis of the effect of treatment with functional appliances vs an untreated control group showed that skeletal changes were statistically significant, but unlikely to be clinically significant.

• Herbst appliances appear to achieve skeletal results by stretching the bilaminar retrodiskal elastic band between the condyle and the glenoid fossa. In contrast, chronic compression of the condyle produces severe condylar resorption that can be prevented to some extent with occlusal coverage by distracting the condyle vertically. The condyle is negatively affected by the return of anterior digastric muscle function and by perimandibular connection tissue pull in retention, seating the condyle posteriorly into the fossa.

Improved clinical use of Twin-block and Herbst as a result of radiating viscoelastic tissue forces on the condyle and fossa in treatment and long-term retention: Growth relativity

John C. Voudouris, Hon DDS, DOrth, MScDa, Mladen M. Kuftinec, DMD (Harv), DStom, ScDb

American Journal of Orthodontics and Dentofacial Orthopedics
Volume 117 Issue 3 Pages 247-266 (March 2000)
DOI: 10.1016/S0889-5406(00)70231-9

November 1998 • Volume 114 • Number 5

Long-term TMJ effects of Herbst treatment: A clinical and MRI study

Sabine Ruf, DDS, Dr med denta
Hans Pancherz, DDS, Odont Drb
Giessen, Germany

Am J Orthod Dentofacial Orthop 1998;114(5):475-83

Fig. 3. Parasagittal MRIs of 4 Herbst patients (cases 3, 6, 9, and 10) exhibiting moderate to severe signs and symptoms of TMD. (See Table I. Tracings are given next to each original image for better orientation. Dotted area represents a fibrotic adaptation of the
bilaminar zone.

Am J Orthod Dentofacial Orthop 1998;114(5):475-83

Signs and symptoms of TMJ disorders in adults after adolescent Herbst therapy: A 6-year and 32-year radiographic and clinical follow-up study Hans Pancherz; Hanna Salé; Krister Bjerklin
Angle Orthod (2015) 85 (5): 735–742.

Conclusions: This longitudinal very-long-term follow-up study after Herbst therapy revealed only minor problems from the TMJ. The TMJ findings 6 years and 32 years after Herbst treatment corresponded to those in the general population. Thus, in the very long term, the Herbst appliance does not appear to be harmful to the TMJ.

RME X 6, posterior bite openers
Xbow 6 months

Day of spring removal
Begin compensatory maxillary expansion with RME

FEA 12 months

3 years post deband

Good For Bite Opening (Especially With a Turbo) May Cause Upper Incisor Extrusion Greater the Class II, Greater the Side Effects Mandibular growth counters downward and backward rotation

May cause temporary posterior openbite Supports upper incisor intrusion

Robbing Peter to Pay Paul

Prevalence and Severity of the Class II Malocclusion

Our hammer is upper incisor retraction, even when the problem is almost always mandibular retrusion.

Treatment plan: extraction of two lower bicuspids and mandibular advancement surgery

Surgery by Dr. Bill McDonald

Superscrew

Informed consent is the legal responsibility of the orthodontist to explain the pros and cons of all possible treatment options and to help the patient and their family determine which option is best for them.

One type of Class II bite problem is when there is a horizontal gap between the upper and lower front teeth, also known as excess overjet. 53% of the population has a Class II bite with an overjet greater than 3mm. 15% of the population has a moderate to severe Class II bite problem with 5mm or more of overjet.

The cause of excess overjet is usually a small or receding lower jaw and chin, but there can also be a protrusion of the upper front teeth.

The Four Tool Boxes Analogy

Dr. Higgins’ office has four different options for treating a Class II bite problem.

1. The Surgery Tool Box
   Braces to straighten the teeth and place the front teeth and lips in an ideal position, followed by surgery to lengthen the lower jaw, is often the best option to correct the bite and balance the appearance of the nose, lips, and chin.
2. The Traditional Treatment Tool Box
   Braces and the extraction of two upper teeth are used to retract or “pull back” the upper front teeth to correct the bite and camouflage the small or receding lower jaw and chin. We call this Class II compensation. This is a good choice if the upper front teeth are crowded or protruding. The downside of this treatment is that it can result in the loss of upper lip fullness.
3. The Crossbow Tool Box
   The Crossbow Class II Corrector shares the correction between the upper and lower teeth. It moves upper teeth back and lower teeth forward. This minimizes the retraction of the upper front teeth and upper lip. This is another type of Class II compensation. It is meant to be used in a growing patient and works best if the patient has a growth spurt. The downside is that it still moves the upper lip back, just not as much as traditional extraction treatment. It also moves the lower lip forward, a plus or a minus. Even if surgery is the best option, most patients still choose the Crossbow Tool Box to avoid surgery and extractions. Sometimes, the Crossbow is not a good option, especially if the patient is finished growing, if the lower front teeth are crowded or protruded, or if the lower lip protruded.
4. The Class II Elastic Tool Box
   Combined with Class II elastics, braces or Aligners are probably the most common treatments today. It is popular because it is the least expensive. It requires the least effort by the orthodontist, but the most effort by the patient. If the patient does not wear the elastics, they end up with straight teeth but with a remaining bite problem or excess overjet.

If the patient wears the elastics well, the result may be similar to the Crossbow, with two exceptions. Class II elastics tend to pull the upper front teeth down, making a gummy smile worse. Two, when used with aligners, Class II elastics may push the lower front teeth out of the bone, exposing the roots. The other problem with aligners is they require much more patient cooperation than braces, and there are many tooth movements that aligners don’t do well or not at all.

This is why the best orthodontists using aligners use them with braces. Braces are still used to do the “heavy lifting.”The general rule is it is best to choose a treatment plan that decreases elastic wear and patient cooperation because poor cooperation can increase the length of treatment. Long treatment time increases the risk of root resorption (root shortening) and decalcification (white spot lesions or cavities).

Dr. Higgins has developed systems that decrease the time in braces to 12 to 18 months, even for extraction treatment. This includes indirect (precision) bonding of brackets (braces). He also uses a low-force technique with a smaller bracket slot and smaller wires than most orthodontists. This is more comfortable for the patients and may result in less root resorption.

The Crossbow appliance is part of Dr. Higgins’ “foundation building” treatment philosophy. It is based on waiting until all teeth have erupted, including second molars, before placing full braces. “Building the foundation” includes establishing a normal upper jaw width with an expander (RME), correcting a Class II bite with a Crossbow appliance, and opening space for upper canine teeth with partial braces (RME X 6).

Dr. Higgins is a clinical assistant professor at the University of British Columbia. More information can be found on the Crossbow website at www.crossboworthodontic.com.

The following is a bicuspid extraction case showing rapid alignment with CAAPP.

I am using the Lotus Plus DS Hybrid self-ligating bracket system, which is active on incisors and passive on canines and bicuspids. I use the MBT prescription in a .018-inch slot. The slot tolerances are tight, and we sometimes find it difficult to close the clips when using .017X.025-inch archwires.

Presently, the archwire progression we are using is .012-inch niti, followed by .014-inch niti (if necessary), followed by .018-inch niti to the second molars, followed by .016X.022-inch niti, and finally, .017X.022-inch heat-treated stainless-steel archwires. Final adjustments are done in .016X.022-inch beta titanium.

When I started with Dr. Michael Wainwright, he used two archwires, a .016-inch Niti followed by .016X.022-inch stainless steel. I was amazed at the simplicity and efficiency compared to the segmented arch technique that we were both taught at Indiana University. I am now using more archwires in the progression, but I am convinced I am using the lightest forces, decreasing root resorption and making it more comfortable for my patients.

The Lotus Interactive Niti clip seats the archwire in the slot’s floor with a force perpendicular to the slot, unlike a “C” Clip.

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 open bite 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 unilateral Class II spring on an FEA can also cause an occlusal cant and an open bite that requires good anterior vertical elastic cooperation to resolve. A unilateral spring on an Xbow does not cause a cant because there are no brackets on the lower incisors. Any unilateral intrusion will relapse.

Class II springs with an FEA cause buccal flaring of upper molars, which may require posterior crossbite elastics to recover from. Class II springs on an 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. Dr. Anthony Mair has warned about the use of Class II elastics with lower aligners, which cause bodily root movement, root prominence, and gingival recession 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 open bite 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 maybe use for rapid bite-opening. The patient only has to cooperate with elastics for a short time so burnout 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.

Longer treatment time with Forsus to the archwire is due to dealing with the spring side effects late in treatment, such as posterior open bite and buccal flaring of the upper molars. The greater the correction, the greater the side effects, and the longer it takes to deal with them.

There is no buccal flaring of the upper molars with Xbow.

Much of the posterior open bite and proclination of the lower incisors rebound before full braces are placed.

Drs. Miller, Tieu, and Flores-Mir’s article titled “Incisor inclination changes produced by two compliance-free Class II correction protocols for the treatment of mild to moderate Class II malocclusions” is in the online version of the Angle Orthodontist.

It is based on Dr. Bob Miller’s clinical study.

He compared 36 Class II patients treated in one phase with Forsus to the archwire in a full edgewise appliance to 38 similar Class II patients treated in two phases with Xbow followed by a full edgewise appliance. The Forsus to the archwire group was finished in an average of 30.2 months (between records). The Xbow group was finished in an average of 24.2 months (between records), which included a 4 to 6 month rest period to allow for relapse. The two-phase Xbow patients were completed 6 months faster on average than the one phase Forsus to the archwire patients (time between records).

The Forsus to the archwire group had full braces for an average of 26.75 months. The Xbow group had full braces for an average of 16.68 months or 10 fewer months. There was no significant difference in the lower incisor to the mandibular plane angle between the two groups. The Xbow patients ended up with lower incisors at an average of 100 degrees to the mandibular plane, which is considered a reasonable compromise for non-extraction Class II compensation.

Editor’s note: Longer treatment time with Forsus to the archwire is due to dealing with the spring side effects late in treatment, such as posterior open bite and buccal flaring of the upper molars. The greater the correction, the greater the side effects, and the longer it takes to deal with them. There is no buccal flaring of the upper molars with Xbow.

Much of the posterior open bite and proclination of the lower incisors rebound before full braces are placed.

The side-effects of Forsus on the archwire are especially problematic when the spring is used unilaterally late in treatment.

The unilateral posterior openbite and anterior canting requires prolonged treatment with good elasitc cooperation to recover.

We do not see the anterior canting when the spring is used unilaterally on a Xbow because there are no lower brackets.

The fact that the first bicuspids are already Class I after Xbow therapy reduces the time in phase two braces and the need for side-effect correction with elastics.

I use the same principles when using the Forsus device with a full edgewise appliance as I do with Xbow.

Use the 22mm 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 the need for rod adjustments. It also keeps the spring distal to the Obicularis Oris muscle, 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 taught us to hook 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. This also negates the need to cinch the distal end of the arch wire.

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 pushrod 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 22 mm or 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. 

Alastic KX-1 module placed with floss threader

Alastic KX-1 module and lingual tuck-in pushrod adjustment on 25mm rod

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 22 mm pushrod.

Spring Sleeve available from Comfort Solutions

1. Treatment with the Xbow appliance in Class II patients resulted in favorable dental and skeletal changes in the direction of a Class II correction. 

2. An increase in the oropharyngeal airway dimensions and volume was observed in the cephalometric and three-dimensional evaluation of the upper airway. 

There were no changes in the nasopharyngeal region and adenoid tissues.