November 23, 2020

15 quick “facts” about the treatment of Class I malocclusion.

I previously put together a simple list summarising my views on Class II problems. I drafted a similar set of rules about Class I, and this sparked a little discussion between Padhraig and me. We have decided to summarise our amicable disagreements below as we hoped that you might find these interesting and amusing.

You will see that I drafted the initial point, and Padhraig suggested several changes. I listened to him occasionally! Ultimately, we feel that this ‘agreed’ summary reflect the current state of the evidence.  My first comment on Class I treatment is in black. Padhraig’s responses are in red, and my replies are in blue. Our agreed statement is at the end of each section.


Point 1

“We should consider treatment if there are impactions or at least one contact point displacement of 4mm. This is also the IOTN criteria“.


Hmmm .. I’m not sure I believe this on the basis of either aesthetic or dental health grounds. Milder problems can still be unaesthetic, and the dental health implications of more marked displacements are often minimal. Equally, we know patients dislike other types of malalignment, e.g. vertical discrepancy between incisal edges.

I think this is more nuanced, and the impact of malalignment varies between individuals. The IOTN was developed many years ago. It has served a purpose in terms of rationing treatment. However, I do think that treating milder crowding is very reasonable. Clearly, we need to ensure that our retention protocols are thought through, made clear and hopefully understood at the outset in these cases.


I based my recommendations on Dental Health indications for treatment and the use of IOTN. However, I agree that IOTN was developed many years ago. I also think that it is outdated for the societal norms of dental aesthetics.  So, I agree with your change.

So let’s amend to:

‘We should consider treatment if there are impactions, significant contact point displacements or other alignment issues’

Point 2.

Severe visible crowding may influence our patients’ self-esteem. This may be obvious, but some people state that orthodontics is simply cosmetic treatment.


I agree. We also know that spacing and missing teeth can have significant effects. The link between aesthetics and these ‘downstream impacts’ is often unclear. We may, therefore produce dramatic changes in certain patients. We just find it hard to identify these people.


I agree with myself too!


Let’s change to:

‘Visible features of malocclusion may influence our patients’ self-esteem. This may be obvious, but some people state that orthodontics is simply cosmetic.’

Point 3.

“No one ever had any problems from mild lower incisor crowding”.


I tend to agree. One could argue that, over many decades, movement of lower teeth can ultimately lead to movement of the upper teeth (overeruption, localised and uneven wear etc.). The latter again is of limited consequence. However, some of these patients may be recommended complex and invasive prosthodontic solutions to what began as a minor orthodontic issue.

Point 4

“Early treatment for crowding is rarely indicated, unless there is a crossbite”.


I agree. In fact, I would suggest that a crossbite is only problematic in the presence of associated displacement.


Yes, I agree with crossbite being an indication for early treatment. But we won’t open up the expansion/RME/MSE debate here.

Let’s go with:

‘Early treatment for crowding is rarely indicated, unless there is a crossbite with associated displacement’

Point 5.

“Crowding does not cause periodontal disease or caries”.


I agree. Crowding can make certain surfaces less accessible. This does not mean that caries or periodontal disease will occur.

Point 6

“If there is lower incisor irregularity we should consider loss of the primary canines. But this may simply transfer the crowding posteriorly”.


I agree. Interceptive removal of primary canines may (in some cases) lead to a temporary improvement in the alignment. If anything, it may make space conditions marginally worse. It may also involve a rather unpleasant intervention for child, parent and dentist.


Yes. We do need to remember that the first experience of many patients could be the removal of primary canines. This could be traumatic to them, and we should consider it carefully.


Point 7

“Non-extraction treatment is easy and we are not orthodontic heroes for treating non-extraction”.


I agree. Generally, it is super easy, and there is no amount of irregularity that we can’t deal with. The bigger question is, of course, whether it is the correct solution from dental health, aesthetic or stability viewpoint. I hate to sound old-fashioned but clear intra-, and inter-arch objectives and a thorough space analysis are a pre-requisite in informing this. I think we should acknowledge that non-extraction treatment is not always easy, particularly if (rightly or wrongly) we are distalizing in both arches in a Class I case.


Yes, I agree again. I suppose that I mentioned this because it appears to me that there are orthodontists who treat every case non-extraction using a “cookbook” approach. This is clearly incorrect.


How about?

“Non-extraction treatment is often particularly easy and we are not orthodontic heroes for treating non-extraction”?



Point 8

“If treatment results in flaring of the lower incisors out of the alveolar bone, you are not an orthodontic non-extraction hero”.


It’s hard to argue with this one!




Point 9

“In moderate to severe crowding, we are likely to need to extract teeth as part of treatment. No appliance will grow the bone to accommodate the teeth”.


I agree but prefer to use the phrase significant space requirement.  To me, this is more holistic as it accounts for other space requirements (levelling Curve of Spee, torque expression etc.). Again, this is me being old-fashioned and pedantic.

I completely agree that we (or indeed our appliances) are incapable of growing bone. My new patients sometimes doubt me when I say this as other clinicians that they have seen occasionally claim to possess this higher power.


My thoughts reflected my training which was not so deeply based on space requirements (Did you train at the London, of space analysis fame?). Or perhaps this is just me being a little too traditional and old fashioned when we did not measure everything?  But in general, we agree.


I did train in London, Kevin. And I wouldn’t change it for the world!

We could go with

‘In the presence of a significant space requirement, we are likely to need to extract teeth as part of treatment. No appliance will grow the bone to accommodate the teeth.’


Point 10

“No orthodontic appliance is any faster than another”.


I couldn’t agree more. Time and again we seem to be lured into the notion that a bracket, wand, potion or surgical insult will make us more efficient. The jury is out on essentially all of these. The answer to efficiency and predictability lies closer to home.


Yes, it is clear from research that the operator and the patients are clear factors that influence the efficiency of treatment.

I would suggest that we amend as follows:

‘No orthodontic appliance is any faster than another. The operator and to an extent the patient are the main determinants of both efficiency and outcome’


Point 11

“Vibration, pills, potions, mild to severe trauma to the bone and magic sound waves are not going to speed up treatment”.


That certainly seems to be the case at this stage.


All research is currently pointing to a lack of evidence on things that speed up tooth movement. Perhaps, this will change with further research. However, I would be surprised if this is the case.


Point 12

“Operator skill is likely to be the greatest predictor of treatment success”.


Without question. Although optimal patient compliance can also be crucial in this respect.


Yes, see above


Point 13

“Aligners will align teeth nicely.  But they are not better than fixed appliances”.


There is no question that aligner therapy is advancing. My view, however, is that they continue to lack predictability in terms of certain fundamentals which we can correct so easily with fixed appliances, e.g. derotating premolar or canine teeth. Nevertheless, they are improving in many respects. My anecdotal view is that they are more effective than fixed appliances in few (if any) respects but, by combining the use of aligners and fixed appliances, we can significantly improve the predictability of aligner therapy.


I will be guided by you. My caseload in the last 10 years of my clinical practice was children with severe medical problems. So, I did not have any experience with aligners.  I have mentioned this in my blog, and I do wonder if I am a bit too cynical about this treatment?

How about:

‘Aligners will align teeth nicely.  But they do not at this point align teeth more predictably than fixed appliances’?


Yes, I think that is a fair summation.

Point 14

“No form of retention is more effective than another”.


I am slightly biased on this one (by research). My feeling is that fixed and removable approaches are both effective in the short-term. However, there is evidence that compliance does wane with removable retainers over time. As such, maturational changes are more likely to present in these cases.


Yes, the long-term changes are important. But we also need to acknowledge that very few patients are going to wear their retainers in the long-term.  This was what I really meant in my statement. So I agree with your change.

We can therefore change to:

‘No form of retention is more effective than another in the short-term’?


Point 15

“Bonded retainers are hassle to patients and operators. Vacuum formed appear to work well”.


As per the previous comment, I am a great advocate of fixed retention. Clearly, bonded retainers may place a greater onus on us as practitioners, but that is a challenge that I feel we need to meet.


When I was much younger, I used to think that fixed retainers were great.  The problem is that as you get older, you become aware that your clinics are filling up with review fixed retainer patients. You also see the problems when they distort etc.  However, we do not really know how effective vacuum-formed retainers are in the long-term. Unfortunately, this will always be the unanswered question in orthodontics. So I agree with your suggestions.


Could we consider revising this one as follows?:

“Bonded retainers are hassle to patients and operators. Vacuum-formed retainers appear to work well in the short-term, although long-term compliance with their use may be problematic”.


That sounds good to me, Kevin.

Final comments.

I thought that it was interesting to do a blog post like this, and it was great to see that most of the time, you agreed with me!  Let’s do this again with my old Class II post?


Thanks, Kevin. I am more than happy to repeat this. Yes, we agreed on most things, in the end!


Related Posts

Have your say!

  1. Point 3 is just wrong
    the envelope of function becomes restricted as mesial drift causes lowers to move forward and crowd, resulting in upper and lower incisal wear due to crowding and patient sipping more class III with time. This is a well known restorative problem that results in incisal wear

    maybe you need Point 16 ‘ The need to look side of orthodontics for answers’ 🙂

  2. Great overview
    There is abundant evidence showing expansion is a high risk factor for both future gingival recession and also long term instability post treatment
    The surgical procedure of Surgically Facilitated Orthodontic Treatment (SFOT) predictably minimizes this potential Risk often Iatrogenically induced.
    The fundamental etiology of crowdinq is “fitting bigger teeth into smaller jaws with a significant discrepancy of alveolar bone usually on the pressure side.
    We CAN GrOW bone but not through mechanical devices instead biologically proven surgical augmentation procedures when the orthodontist works closely with the periodontist
    Would be keen to discuss this further
    Colin Richman DMD
    Practice limited to Periodontics and SFOT

  3. Q1. In children, do you expect to see missing interdental papilla and black triangles after unravelling crowding? A1. NO.
    Q2. In adults, do you expect to see missing interdental papilla and black triangles after unravelling crowding? A2. YES
    Q3. Does becoming adult cause lost interdental papillae? A3. NO.

    In relation to point 3, then, Crowding harms dental health.

  4. Excellent summation and thanks for a well balanced summary.
    As far as retention is concerned,whatever type is used ie .bonded ,vacuum formed etc.I think it is vital stress that this is for life!!Ongoing fees will be billed to cover this.This ,in my view,should be fully explained at the completion of tmnt.and ,I highly recommend having pt /parent /guardian sign a “contract”at the completion of active ratify this.
    In the world of fee for service it is not reasonable ,or advisable ,to be expected to cover retainer “servicing “for life.
    Tyres and eyeglasses need upgrading periodically.
    Nothing is “free”or warranted for life !

  5. That was entertaining and educational. Looking forward for the Class II exchange.
    Point 13: I think aligners, as well as braces, align teeth well. That is not an issue.
    I also think that aligners are more predictable for some movements and braces are for others. But it’s all related to point 12. The level of experience we have with what we are using. The same way I agree that there is no magic to make teeth move faster, but as Daniel Gilbert pointed in his book “Stumbling on happiness”: Our brain accepts what the eyes see and our eyes look for whatever our brain wants”. Once we start believing in something, whatever it is, it becomes hard not to be convinced it really works.
    Question: In a case where we would agree that it could be treated as well with clear aligners or braces, my impression is that it could be treated faster with aligners. Not because aligners move teeth faster, but because I see less unwanted secondary effects with them or less collateral damages. But then… maybe it’s just me not being talented enough with fixed appliances 😉

  6. And one of the most important things is that it must be considered that there are classes I that are actually classes II and therefore the treatment plan, the treatment itself and the prognosis can change drastically.

  7. Vacuum formed retainers covering the occlusal inhibit settling and they do not last long. Also serial extraction or guided eruption as Jack Dale use to call it is an excellent early approach for severe crowding. Our surgeon removes the primary canines and 1st primary molars along with the 1st premolars at the same time under sedation. This significantly reduces the treatment time and the incidence of impacted teeth and ectopic eruption.

  8. I agree with Ross on Point #3

    For Point #10, in view of Dr Richman’s comments, we need to define “growth”.

    I kinda agree with Dr Moises Martinez Leyva – since Class twos can be Class ones also! 🙂

  9. I am afraid I disagree with point 2. People with low self-esteem will be more bothered about the arrangement of their teeth than people with normal or high self-esteem. ‘Normalising’ the appearance of their teeth will help people with low self-esteem become less concerned about interacting with others and their community (emotional and social well-being), which I think is worthwhile, but it will not improve their self-esteem. There is evidence that quite intensive and prolonged psychological interventions can improve psychological well-being (Bolier et al 2013, but not orthodontic treatment.
    Please see this article for a more extensive discussion – Benson et al 2015

  10. Interessante exposição de opiniões.

  11. Some interesting concepts but the wording makes the list problematic.

    For example: #3 “No one ever had any problems from mild lower incisor crowding”.
    But in reality, my patients DO have a problem with lower incisor crowding. They show up every day with that specific problem. That problem might only be social distress, but it is a problem for them.
    So that statement, as it stands, is objectively false. Lots of people have “problems” from lower incisor crowding.

    Or statement #4: ‘Early treatment for crowding is rarely indicated”
    Do you feel the same about the statement “treatment for crowding is rarely indicated”? Probably not, so why does the timing matter? Early, late, whatever.
    Many of the other statements have similar problems.
    I think I know what you meant to say in many of these statements, but I don’t think you say what you meant. So, an interesting list but not as valuable as it could be.

  12. I disagree some points but it all depends on your training and experience as to what is or isn’t possible or appropriate. We are all on a journey to seek the truth and it continues to change as you practice. Good discussion.

  13. I’m happy to see the end of IOTN as an indicator for treatment, it does not relate to dental health need. It does not do what it says on the tin.
    In the UK we are looking (desperatley) for reasons to justify what we do to commissioners of orthodontic services. There is no argument that patients want cosmetically improved teeth, the argument is who should pay for it.
    Finally, there are lots of things we can offer patients to improve their view of themselves, but we do not fund them. In the UK there is a desperate shortage of funding for children’s mental health services, the £300, 000, 000 we spend each year on orthodontic treatment could be better used if improving health is the aim.
    We need someone to look at the long term dental and general healthcare outcomes following orthodontic treatment. My feeling is that a lot of what we achieve is lost when people stop wearing their retainers.

Leave a Reply

Your email address will not be published. Required fields are marked *