September 17, 2013

Class II malocclusion 20 facts about treatment

Treatment of Class II malocclusion: 20 quick facts

This is going to be a list on the treatment of Class II malocclusion.  I have been prompted to write this as our update of the Cochrane review on the orthodontic treatment of prominent upper front teeth ( is about to be published.  As a result, I thought that I should post a list of what I feel is current evidence based practice


  1. Treatment should be considered if the overjet is greater than 6mm. This is also the IOTN criteria
  2. There is an increased risk of trauma to the upper incisors particularly if the lips are incompetent.  However, most trauma has occurred before orthodontic treatment can be started.
  3. No one ever had any problems because their molars are half a unit Class II!
  4. Early treatment  as part of a two-phase treatment is rarely indicated as it is not effective and incurs greater cost than one course of treatment provided when the child is in adolescence.
  5. Early treatment costs more money
  6. When children have  early treatment there is a 40% less chance of trauma to their upper incisors.
  7. Early treatment does increase the attractiveness of the facial profile and increase self-esteem. But…this effect ‘washes out’ by adolescence.
  8. Functional appliances are very effective at correcting Class II incisal relationships
  9. Functional appliances do not change the skeletal pattern to a meaningful degree.
  10. In adolescent treatment there is nothing wrong with extracting upper first premolars and reducing the overjet. This treatment is practiced all over the world in countries where functional appliances are not so extensively used.
  11. There are no differences in the treatment result of fixed and removable functional appliances
  12. There is greater patient co-operation with fixed functionals than removable
  13. The Twin Block is the most popular functional appliance in the UK.
  14. There is no point in putting on or leaving off the labial bow on a Twin Block.
  15. If headgear is used to “drive Class II molars distally” the average length of the “drive” is 1.6mm
  16. When a fixed functional breaks it is more hassle to repair than a Twin Block.
  17. We should trial functional appliance treatment against fixed appliance treatment
  18. The major aetiological feature  of Class II malocclusion is a retrusive mandible
  19. The major aetiology is genetic with a small environmental component
  20. No orthodontist or dentist can grow a mandible!

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Have your say!

  1. What are your thoughts on Orhtotropics?

  2. Dear Prof O’Brien Thank you for sharing your valuable knowledge. Based on the fact that functional appliances may result in small skeletal changes that are not clinically significant, will you still consider them to provide growth modification? If not and if we mainly rely on their dentoalveolar effects then can we treat Class II cases with Class II elastics only especially that a recent systematic review by Janson et al. 2013 found that CL II elastics to be as effective as fixed functional appliances in terms of the dentoalveolar changes. I prefer to use functional appliances on growing patients with a skeletal discrepancy but with the amount of the available evidence I still wonder why do we really use them, why they’re different from using fixed appliances? Your opinion is highly appreciated.

    • Hi Rana, thanks. It appears that current knowledge and research suggests that we can get some minimal changes in skeletal pattern from the use of functional appliances, but most of the movement is dento alveolar. This is, of course, due to the Class II forces. As you pointed out these are similar to the forces that are achieved with Class II elastics. It is also interesting and very relevant that in the USA Class II correction is often achieved by bonding up both arches and then using Class II elastics. It is, therefore, likely that this has the same effect as functional appliances. Both appliances probably get the same result, it is just that we prefer to use functional appliances in the UK. I hope that this has answered your question?

      Best wishes: Kevin

      • That’s extremely helpful. Thank you very much Prof.

      • I would use functional appliance for >4mm overjet and Class II elastics for 3months) often results in clockwise rotation of the mandible thereby negating the effect of Class II correction in the horizontal dimension. Functional appliances tend to keep the mandibular plan angle.

      • I would use functional appliance for >4mm overjet and Class II elastics for 3months) often results in clockwise rotation of the mandible thereby negating the effect of Class II correction in the horizontal dimension. With functional appliances such as herbst, mandibular plane seems unaffected, if not reduced.

    • They would probably be just as effective if the patients wore them. Maybe not a problem in the UK but definitely one here in the States.

  3. Dear Prof O’Brien Thank you for these informations, Iwould like to ask you about the best time or age to start the treatment of Class II malocclusion especially in children with bad oral habits like thumb sucking

  4. Dear Prof O’Brien Thank you for these valuable informations . what is the best time to start treatment of Class II malocclusion in children with bad oral habits such as thumb sucking?

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