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20 quick facts about the treatment of Class II malocclusion

I am a subscriber to Dr Kevin O’Brien‘s blog. He is a professor at the University of Manchester, UK. He has been a clinical orthodontist and a researcher for about 30 years. He directed several research projects on the result of orthodontic treatments by using the method of randomized clinical trials, including the treatment of Class II malocclusion and more particularly on the effects of the Twin Block removable functional appliance.

My attention was brought to one of his blogs on facts about the treatment of Class II malocclusion. I reproduce below its contents with my personal annotations.

20 quick facts

1. Treatment should be considered if the overjet is greater than 6 mm. This is also the IOTN (index of treatment need) criteria.

2. There is an increased risk of trauma to the upper incisors particularly if the lips are incompetent (when the teeth are prominent and the lower lip rests under the upper teeth). 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 (2-3 mm) Class II!

4. Early treatment (phase 1) as part of a two-phase treatment to correct Class II malocclusion is rarely indicated as it is not effective and incurs greater cost than one course of treatment with fixed appliances provided when the child is in adolescence.

5. Early treatment costs more money (in reference to a two-phase treatment to correct Class II malocclusion).

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. In other words, the effect does not last since another treatment is required in adolescence. In other words, the effect does not last since another treatment is required in 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 removables.

13. The Twin Block is the most popular removable 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 1.6 mm.

16. When a fixed functional breaks it is more hassle to repair than a Twin Block. Personal comment: With the new fixed functional appliances, breakages are not as problematic. Indeed, even if it is true that a fixed appliance that breaks is more hassle to repair than a Twin Block that breaks, this problem is largely compensated by the fact that a fixed functional appliance is smaller and easier to adapt to than a Twin Block.

17. We should trial removable functional appliance treatment against fixed appliance treatment.

18. The major aetiological feature of Class II malocclusion is a retrusive mandible (retrognathia).

19. The major aetiology is genetic (hereditary) with a small environmental component (allergy, respiratory function, atypical swallowing, chronic mouth breathing or nonnutritive sucking behavior).

20. No orthodontist or dentist can grow a mandible!

Questions et commentaires

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  1. MARTIN AMTMAN says:

    My Dentist diagnosed TMJ (moderate to severe) he recommended invisionlign braces which caused pain headaches and other adverse reactions I also have a type 2 open bite malocclusion

    1. It is difficult to make a recommendation from the description you did. TMJ: what type of temporomandibular disorder?
      Type 2 open bite: do you mean class II openbite?
      Invisalign braces which cause pain headache: Are you receiveng a treatment with invisalign to close an open bite?

      In my opinion, if you have a class II open bite malocclusion and that you have TMJ pain, i would not recommend Invisalign and you need a comprehensive multidisciplinary orthodontic treatment plan.

  2. Dr. Bhawani s POUDEL says:

    Comment*how to correct class 3 case .a 13 years male patient

    1. Chances are that I would wait until he is 17 and plan a surgical orthodontic treatment.

  3. Aileen Blok says:

    If possible, I would really appreciate your advice.
    We moved country (UK to NL) and my 11year old daughter was suddenly told she needed (and rather urgently) orthodontic treatment and was prescribed a twin block.
    We never got specific measurements from the Dutch orthodontist (just that she had an overjet and lower jaw with potential for overcrowding) but he did suggest that one of the aims was to grow her lower jaw.
    She has been wearing it about 2 weeks, but when we were back in the UK recently I sought a 2nd opinion.
    Seems her IOTN score is 2 i.e. overjet about 3.5mm but competent lips, with some contact point misalignment 2mm.
    The UK orthodontist implied the treatment was for cosmetic reasons (something we were never worried about) rather than medical.
    We have an appointment with the NL orthodontist shortly where we will discuss these things, but we are considering stopping her treatment.
    Will there be any problems, if we do i.e. her incisor position and bite has already changed, would we expect that to change back to “normal” if she stops treatment and if so how long might it take?
    We are concerned that we’ve already started on the treatment with the twin blocks, that she’ll need to complete the full treatment (twin blocks and fixed appliance) when we may wish to stop.
    I appreciate that you may not have time or be able to respond to my query.
    Thanks for any help you can advise.

    1. Index of Treatment Need

      An ITON of 2 describe a fairly mild malocclusion as you can see in the description in the left picture. It does not mean that an orthodontic treatment may not be necessary later if she want to have straight teeth.

      It is a well accepted fact, that functional aplliances such as twin block, bionator or frankell do not grow mandible although they can correct class II malocclusion. This was demonstrated in the late 90’s (1997-99 to be precise). It was 20 years ago…

      Your daughter may be slightly too young, particularly if she is still in mixed dentition. I stop using removable functional appliance in early mixed dentition some 20 years ago. Nowadays, I use fixed functional appliance with braces in very late mixed dentition or early permanent dentition.

      You can stop the treatment and it the correction will relapse. You can resume a comprehensive orthodontic treatment later with no problem.

      An ITON of 2, an overjet of 3,5 mm and an  overbite of 3,5 mm is a piece of cake to treat. I mean “easy” to treat with braces only.

      Best regards



  4. Tanya says:

    12 year old girl with Class II Div I malocclusion and 12mm overjet – orthodontist recommends braces with extractions of the two maxillary premolars as well as release of tongue tie and top lip frenum. Would it be possible to treat without extracton, do you think? Should she also use a functional appliance?

    1. Extraction of 2 maxillary premolar can be a viable treatment option.
      Non extraction approach with fixed functional appliance can be an option too.
      I can’t say what I would do without a consultation and xrays.

  5. K says:

    It has been “recommended” my daughter age 13 get braces. She has class 2 mallocclusion, overbite closed OB=7mm, overjet moderate =6mm, no crossbite
    I am trying to determine if this recommendation is a more cosmetic or truly medically necessary. The dental receptionist believes braces are medically necessary for the overbite. Thoughts?

    1. OB of 7 mm is deep overbite. Overjet of 6 mm is large. Chances are that an orthodontics treatment is truly necessary and will be beneficial for eshtetics at the same time.

  6. Amr says:

    Dear, I have a convex profile.Age 34, My SNA is 82, SNB 76, ANB 6.4,Nm-Li-PGA 160, lower incisors NBA PNP 10.9. Over jet is 0, proper occlusion. Could you please tell me What would be the treatment of choice to correct the convex profile?

    1. I don’t treat numbers. I need to look at the patient, the ceph, and the intraoral examination.
      It is imposible to make any recommendation with so few information.

  7. Andrea says:

    Dear Dr Sylvain

    I am in Australia but would really appreciate if you have any thoughts on this situation.

    I have a type 2 malocclusion. I do not know the measurements however my upper front teeth sit down over my crowded lower front teeth as far as the gum line of the lower teeth. I seem to have one of those more pointy chin for it – not broad at least. It is quite a tight bite and I have ended up with stress breaks of one of the lower front teeth from it by the time I was 25. I also have quite fangy upper incisors that just keep pushing forward with age. Add to that a nasty case of TMJ. It’s not nice.

    The issue I have is that my 3.5yr old daughter is shaping up to have the exact same jaw and teeth alignment. It appears exacerbated a little by constantly putting comforters in her mouth (apparently I was the same) – she wont sleep without it in there. I worry that she will have the same issues of TMJ pain, pressure on her front teeth, clenching, a gummy smile etc.

    Is it worthwhile to have early intervention to help the jaw grow before braces in adolescence? I understand from what you wrote that it may be helpful for the upper incisors though beyond that, the intervention is not helpful?? Would it help to expand the jaw and keep it expanded even if further teeth alignment was required in adolescence?

    Just trying not to leave things too late. I live in a rural area so many things just get ignored if they are not life threatening. I don’t want that for my daughter. I don’t want her facing a life of jaw pain and self esteem issues around the way her smile looks.

    Very much appreciated if you might be able to provide some insight into the best process/timing to make sure my little one doesn’t end up like me.

    Kindest Regards


    1. You should wait until she is 6-7 year and then get a consultation with an orthodontist. 3.5 years is too early for sure.

  8. Jimmy jamm says:

    My 12 year old son has a class 2 malocclusion. I do not know the measurement of his overbite. The orthodontist gave us 2 options. A Mara appliance 10-12 months followed by upper and lower braces for 18 months. Or invisalign for 30 months. Any thoughts on the 2 treatment options we were given? It is very hard to find solid reviews on the Web that weren’t paid for by the company. Thank you in advance

    1. I do not beleive that Invisalign will be effective to correct class II malocclusion with effectiveness although it may achieve some change.
      I would prefer braces and fixed functional device like Forsus or mara.

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