CLINICAL TIPS & TECHNIQUES

Class II Correction with MARA Followed by Invisalign® Dr. James E. Eckhart

The MARA helps correct Class II malocclusions by holding the

mandible forward in a Class I position for an extended period

while dental and skeletal changes occur. The proportions dental

versus skeletal depend mostly on how much the mandible

grows during the

treatment interval,

and in the presence of

mandibular growth the

MARA offers the hope

for horizontal chin

enhancement.

Patient Selection & Rationale

In peri-pubertal teens, there is a mandibular growth spurt

(7-9 mm cumulative over 30-months), with boys peaking at age

14 years 4 months on average and girls peaking at age 11 years

6 months on average. There is considerable variation in individuals’

peak mandibular growth rates ages, magnitudes and durations,

but these average ages can nevertheless be a valuable tool.

Experience has shown that MARA results are more stable if the

MARA is left in place for approximately 12 months. If we knew

for certain when an individual’s peak mandibular growth would

occur, ideally we would like to have the MARA in place for the

6 months preceding and the 6 months following that peak, in

order to experience the greatest mandibular growth during the

year-long MARA treatment. However, in the absence of reliable

predictors of mandibular growth rate peak age for any individual,

when I wish to use mandibular growth for correcting a large

class II malocclusion and intend to improve the chin prominence

as well, I find it useful to use the MARA alone for about a year,

starting during a period within 15 months preceding the average

peri-pubertal growth peak, followed by Invisalign to finish

aligning the teeth. Thus, I like to start the MARA for peri-pubertal

teens as follows:

• Boys between ages 13 years 0 months and 14 years 4 months

• Girls between ages 10 years 3 months and 11 years 6 months

At this young age, many girls will still be in mixed dentition

during the MARA portion of their orthodontic treatment.

The relative proportion between horizontal and vertical chin

change to be achieved by treatment is partly determined

by the incisor overbite existing before the MARA is begun

and partly determined by the movement of the upper incisor

during MARA treatment. In case selection, I prefer a case that

is not an exceedingly deepbite, if I wish to get more horizontal

expression of the chin when the mandible is advanced with the

MARA. An incisor openbite case will experience more horizontal

chin movement regardless of the direction of condylar growth.

An incisor deepbite case will experience more vertical chin

movement, regardless of the direction of condylar growth. If

the upper incisor is moved downward and backward during

treatment, the patient will experience the most vertical chin

movement regardless of the direction of condylar growth.

Mandibular Anterior Repositioning Appliance (MARA) is a Class II corrective device which postures the mandible forward using bands or stainless steel crowns anchored to the first molars, with attached cam arms to guide the mandible forward

•Takeadvantageofperi-pubertalmandibulargrowthtocorrectalargeClassIImalocclusionandimprovethechin prominence with the MARA

•FollowMARAtreatmentwithInvisaligntoalignupperandlowerarches

— Class II Growing According to Bjork

— Assume Molars Do Not Erupt

• New Chin Position with No Incisal Guidance

• New Chin Position with Non-Moving Incisal Guidance

• New Chin Position with Incisors Moving Down and Backward

I have found it impractical to combine Invisalign with the MARA

during the year of MARA treatment, because the MARA employs

a lower lingual arch to stabilize the lower molars, and the lingual

arch rests on the lingual of the lower anteriors, which prevents

aligners from seating. (If the lingual arch is built away from the

lower anteriors, the lower molars intrude at the mesial due to the

pressure from the upper MARA, and this tipping is a challenge

to recover from using only Invisalign, see diagram below.)

Therefore, I treat the case with MARA alone until it is Class I,

and then align the case with Invisalign. The MARA is somewhat

unique among fixed Class II correctors in that it does not rely on

braces for attachment or stabilization, yet elicits a high percent

of mandibular skeletal response in peri-pubertal teens.

Mandibular lingual arch used with MARA. Mandibular molar tips mesially when lingual arch is not in contact

with lower anteriors.

Case and Technique

A 13 year old male presented asking for his overbite to be

corrected. He had a severe Class II Div 1 with a deepbite and

rotations. He had a horizontally prominent chin, so vertical

increase in face height would be acceptable. We recommended

a year of MARA followed by a year of Invisalign.

The MARA was made with stainless steel crowns and cemented

with glass ionomer cement. The initial advancement was 4 mm.

The patient was seen at 3 month intervals for 15 months, with

additional advancements made until he was Class I. Minor

spacing and intrusion occurred in the lower incisors due to

pressure from the lower lingual arch, and spacing occurred in

the upper posterior as the buccal teeth distalized. The initial

posterior openbite, created by advancing the mandible, drifted

closed as the posterior teeth erupted. The upper incisors

uprighted as well. The upper molars tipped distally and rotated

mesial-to-buccal, because no transpalatal arch was used, and

because no occlusal rests were placed on the upper second

molars. The MARA was removed after 15 months and the teeth

were allowed to settle (there was a slight posterior openbite

where the MARA had been).

After 3 months of settling, PVS impressions were taken for

Invisalign. In ClinCheck, the posterior openbite was closed

virtually, spaces were closed, and lower incisor rotations were

corrected. At the Invisalign delivery appointment, IPR was

performed on the lower incisors using a single-sided flexible

rotary diamond disc. The patient was seen each 12 weeks, and

the case tracked well. There were 18 each of upper and lower

aligners. The attachments were removed after 12 months and

Hawley-style retainers were provided. By today’s standard we

would have done a refinement to get more upper incisor lingual

root torque and to overcorrect the lower incisor rotations.

This treatment successfully corrected a deepbite Class II into a

normal-bite Class I with a nice looking face.

CLINICAL TIPS & TECHNIQUES

INITIAL

END OF MARA

FINAL (After 12 Months of Invisalign treatment)

Superimpositions of Pre- and Post- Treatment Cephalometric Tracings

MARA treatment alone

Invisalign treatment alone

MARA and Invisalign treatment combined

Black = Before Treatment

Red = After MARA

Green = After Invisalign

AlignTechnology,Inc.2560OrchardPkwySan Jose, CA 95131

WWW.INVISALIGN.COM

CLINICAL TIPS & TECHNIQUES

©2013AlignTechnology,Inc.Allrightsreserved.InvisalignandClinCheck,amongothers,areregisteredtrademarksofAlignTechnology,Inc.M20228 Rev B June 2013

Disclosure:Dr.JamesEckhartwasprovidedanhonorariumfromAlignforhispresentation.Thestatements,viewsandopinionsexpressedinthispresentationarethoseoftheauthor,anddonotnecessarilyreflecttheviewsandopinionsofAlignTechnology,Inc.

DR. JAMES E. ECKHART

Dr. Eckhart attended dental school at the University of Southern

California where he was class president and valedictorian and

graduated in 1970. After practicing general dentistry for 2 years,

he attended the orthodontic program at University of California

at San Francisco and obtained his certificate in orthodontics in

1974. He has practiced orthodontics in Manhattan Beach and

Torrance, California since 1975.

After using the Herbst appliance for some years, Dr. Eckhart

started developing the MARA, and obtained a patent for it in

l996. He worked closely with the engineers and technical staff at

Ormco and Allesee Orthodontic Appliances to bring the MARA

to market, and has lectured on it extensively ever since.

Dr. Eckhart became certified in Invisalign in 2000, and in present

time his practice is more than 50% Invisalign. He is an Invisalign

Super Elite Provider.