Functional appliances

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Functional appliances
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Background

• Functional appliances are conceptually based on
  Moss functional matrix theory
• Functional matrix theory proposes that functional
  matrices, tissues like muscles and glands
  influence skeletal units such as jaw bones and
  ultimately control their growth

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Form follows function
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Functional appliance types

• Orthodontic functional appliances may be active
  or passive
• Active appliances reposition the mandible so that
  the condyle is forced out of the glenoid fossa
  and this in turn is thought to stimulate the
  posterior/superior growth of the condyle
• Passive appliances act by repositioning the
  musculature associated with the mandible so that
  the jaw bone itself responds by growing to the
  new equilibrium position

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Passive functional appliances

• Frankel

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Active functional appliances

• Fixed active functional appliances
• Herbst

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Active functional appliances

• Removable active functional appliances
• Bionator

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Active functional appliances

• Removable active functional appliances
• Woodside activator

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Active functional appliances

• Removable active functional appliances
• Twin-block appliance

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Duration and timing of wear

• Functional appliance treatment should be started
  before the pubertal growth spurt
• This is the time when the mandible may exhibit
  increased growth which may be influenced
• Functional appliances should be worn for at least
  10-12 hours a day
• These appliances should be worn at nighttime as
  this is when growth takes place

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Evidence of clinical effectiveness

• A Cochrane review, published in 2008, studied
  orthodontic treatment for prominent upper teeth
  in children
• The study concentrated on primary outcomes
  including the prominence of upper front teeth and
  the relationship between upper and lower jaws
• The secondary outcomes compared included
  self-esteem, injury to teeth, joint problems,
  patient satisfaction and the number of
  appointments during active treatment

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Evidence of clinical effectiveness

• It has been shown that when front teeth stick out
  by more than 3mm, they are twice as likely to be
  injured
• The Cochrane review included eight clinical
  trials, based on data from 592 patients with
  Class II Division 1
• Three trials, evaluating 432 patients, compared
  early treatment (before the age of 10) with a
  functional appliance compared to no treatment
• It was found that functional appliance treatment
  resulted in significant decreases in overjet and
  the ANB angle

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Evidence of clinical effectiveness

• When the same patients received the second phase
  of treatment (full fixed treatment) and when they
  were compared to patients who only received one
  phase of treatment in adolescence, it was found
  that there were no significant differences
• Other reviews have also found that although the
  overall effect of early treatment was not
  significant, the patients did have a milder
  malocclusion at the start of full fixed treatment

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Evidence of clinical effectiveness

• A systematic review by Cozza et.al. included 18
  retrospective longitudinal controlled clinical
  trials
• It was found that functional appliances did
  result in a significant elongation of mandibular
  length (gt2mm)
• It was concluded that the effect of growth
  modification is the greatest during the pubertal
  growth peak

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What does this mean?

• According to the evidence one should not use
  functional appliances as they are not necessarily
  more efficient than one phase treatment
• Should we rely only on evidence in guiding our
  clinical decisions?
• I would argue that although sound scientific
  evidence is the most important aspect of clinical
  practice, it is not the only factor to consider

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What does all this mean?

• Indeed, care for our patients extends beyond all
  the evidence available
• True care also includes
• Honesty
• Empathy
• Being genuine
• Patient centered approach

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Refernces

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  Karen_in_Shan_state_of_Burma-Burma.jpg
• http//farm1.static.flickr.com/47/154578698_6011a4
  85ce.jpg
• http//www.sleepingtiger.org/blog/wp-content/uploa
  ds/2007/08/maxyawns.jpg
• http//imagecache2.allposters.com/images/146/PP019
  5.jpg
• http//www.nimrodental.co.uk/appliances/media/func
  tional5.jpg
• http//coloradospringsortho.com/Web20site/About2
  0braces_files/herbst_appliance.jpg
• http//www.weisskircher.de/bilder/bionator.jpg
• http//www.tanos.co.uk/braces/bkb/images/activator
  woodside.jpg
• http//www.orthodentlab.com/products/images/photos
  /TwinBlock1.jpg

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References

• Harrison JE, OBrien KD, Worthington HV.
  Orthodontic treatment for prominent upper front
  teeth in children (review). The Cochrane
  Collaboration. John Wiley Sons, 2008.
• Nguyen QV, Bezemer PD, Habets L, Prahl-Andersen
  B. A systematic review of the relationship
  between overjet size and traumatic dental
  injuries. European Journal of Orthodontics
  199921(5)503-515.
• Pavlow SS, McGorray SP, Taylor MG, Dolce C, King
  GJ, Wheeler TT. Effect of early treatment on
  stability of occlusion in patients with Class II
  malocclusion. American Journal of Orthodontics
  and Dentofacial Orthopedics 2008133235-244.
• Dolce C, McGorray SP, Brazeau L, King GJ, Wheeler
  TT. American Journal of Orthodontics and
  Dentofacial Orthopedics 2007132481-489.
• Cozza P, Baccetti T, Franchi L, De Toffol L,
  McNamara JA. Mandibular changes produced by
  functional appliances in Class II malocclusion a
  systematic review. American Journal of
  Orthodontics and Dentofacial Orthopedics
  2006129599.e1-599.e12.