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 • Take advantage of peri-pubertal mandibular growth to correct a large Class II malocclusion and improve the chin prominence with the MARA • Follow MARA treatment with Invisalign to align upper and lower arches
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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