April 29, 2019

Specialist orthodontists treat posterior crossbites more efficiently than general dentists

Interceptive treatment of posterior crossbites is a standard treatment.  But, is this treatment done better by specialist orthodontists or general dental practitioners?

We all have our preferred treatment to correct posterior crossbites. The most common procedures are either a quad helix or removable expansion plate (unless we are going to go for RME).  We also know from previous research that fixed expansion devices are generally more effective that expansion plates.

It is also relevant to consider that either a specialist or a general practitioner can do this treatment.  In some countries, for example, Sweden, this treatment is prescribed by specialists, and general practitioners carry out appliance therapy.  However, we do not know whether this method of delivery is cost-effective.

A team based in Malmo looked at this question. The EJO published this paper.

What did they ask?

“What are the costs of quad helix and expansion plate treatment done by specialists and general practitioners”?

What did they do?

They did a multicentre randomised controlled trial with the following PICO;

Participants: Patients in the mixed dentition who had a unilateral posterior crossbite.

Intervention: Quad Helix treatment by specialists or general practitioners

Control: Removable expansion plate treatment by specialists or general practitioners.

Outcome: The Success rate of crossbite correction and costs of treatment.

They did a sample size based upon a meaningful difference in the cost of treatment. They used pre-prepared randomisation with concealment of allocation using sealed envelopes. The assessor who evaluated the success of therapy was blinded to treatment allocation.

They calculated the total cost of treatment.  This included the cost of appliances, treatment time, loss of income of parents and travelling expenses.

2 specialists and 17 general practitioners did the treatment.  The specialists had 15 years of experience, and the general practitioners had between 1 and 30 years of experience.

What did they find?

110 patients entered the study. They randomly allocated them to the following groups.

  • Quad Helix treatment by a specialist (n=28)
  • Quad Helix by a general dentist (n=27)
  • Expansion plate by a specialist (n=27)
  • Expansion plate by a general dentist (n=28)

They carried out an intention to treat analysis that included all the patients.

I have condensed the data into this table.

GroupSuccess rateRetreatmentsNumber of apptsRemakesCost (€)

The statistical analysis showed that when they looked at overall costs.  The most cost-effective treatment was with the quad helix done by specialist orthodontists. This was due to lower costs,  less failed treatments and fewer remakes.

Their final conclusion was;

“We recommend that treatment of unilateral posterior crossbite in the mixed dentition is best performed by a specialist orthodontist using the quad helix appliance”.

What did I think?

I thought that this was a fascinating, very well done study.  Their methodology was sound, and I could not really detect any issues with this trial.  They wrote an excellent discussion that outlined the essential findings and their implications.

It appears that the differences in the cost-effectiveness of the appliances and operator combinations were due to the overall success rates of the fixed and removable appliances. In addition to the number of remakes of removable appliances that had been lost or broken.

I have thought about why these differences occurred. When we consider the use of removable appliances, I believe that it is clear that there will be more treatment failures, because of the deficiencies of removable appliances when compared to fixed.

Nevertheless, it also appears that the specialist practitioners had the same failure rate as general practitioners when they used removable appliances.  As a result, any differences in cost are due to the GP  removable appliance patients losing or breaking their appliance.  Perhaps, the specialists were better than the GPs in motivating and managing their patients.  But this is only conjecture.

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Have your say!

  1. When we look to the difference in experience between the GP’s and the specialists there is a huge difference!

  2. Thank you Kevin for the excellent review. It is something that specialists have long believed, namely that fixed are more predictable than removable appliances, and that specialists are more efficient than generalists. One could ask how generalists can provide treatment that is financially viable for them that benefits that patient.

    The real questions for expansion could be: whether “interceptive” treatment for a crossbite is even necessary; what the harmful consequences of not treating early are; and whether it is more efficient and cost effective to treat with a single phase of treatment later, as is the case with Class II treatments.

    We know that we cannot “grow” a mandible with an induced slide of a centimetre, but we are concerned that a lateral slide of a millimetre or two will cause asymmetric mandibular growth. If such growth did occur, it would eliminate the slide prior to us seeing the patient, and would certainly eliminate the slide by a recall visit with the amount of growth occurring at that age. This does not occur.

    Perhaps the rationale for treatment is to prevent future TMJ problems, but there does not appear to be significant evidence to support this either.

    If the above is not an indication to treat early, then perhaps it is to benefit from the system in place in that country, or because there is a perception that there is no cost to the patient, although there is a cost to the taxpayers.

    One does not know that a treatment works until one stops doing it. It is easy to see the benefit in our favourite interventions.

  3. The research does not differentiate between ortho-educated GP or just concerned GP confronted with crossbite in their daily office. I’d rather be interested in the combination of three. Otherwise it just looks like a bashing instrument for any GP performing ortho

  4. I think that crossbites in children need to be treated for non-orthodontic reasons. We presented/are presenting data at three medical conferences this year that show an increase in transpalatal bone width in adults appears to be associated with a reduction in AHI (apnea-hypopnea index) by about 60%. The medical criterion for success is 50% in this regard. Since the recent AAO position paper concludes that there is no effective role for specialist orthodontists in the management of OSA, we might need to refer to generalists to collaborate with us for these types of medical conditions.

    GD Singh, SH Kim. Short term changes in upper airway morphology and sleep architecture using biomimetic oral appliance therapy. Chest 155 (4), 1A, 2019.
    GD Singh, HN Kim. Upper oropharyngeal airway changes in Korean adults following biomimetic oral appliance therapy. World Sleep Soc 2019 (accepted).
    GD Singh, Heit T. Changes is sleep parameters following short-term biomimetic oral appliance therapy for obstructive sleep apnea in adults. World Sleep Soc 2019 (accepted).
    Singh GD, Liao F. Long term changes in upper airway volume and sleep architecture using biomimetic oral appliance therapy. Am J Respir Crit Care Med 2019 (accepted).

    • Thanks for this post.I It is very informative and I always enjoy your input !

    • Thank you professor for the explanation and congratulations on your presentations.

      If I understand correctly, all children with crossbites should be treated with expansion to improve their airways without the need to assess or diagnose anything else. This is because the width of the mandible (and hence the maxilla) dictates, or is an indicator of, the respiratory health of an individual?

      Should every child’s respiratory health be improved by expanding the maxilla? Is more expansion better and is there a limit?

      All of this is based on “an increase in transpalatal bone width in ADULTS APPEARS to be associated with a reduction in AHI”. How does this relate to children? Is this childhood expansion stable into adulthood? Or, does this increase that you state, relate to an actual stable increase by expanding the maxilla in adults? I apologise for not having read your papers.

      • Dear Dr Attric:

        If I may rephrase, children with crossbites should be screened for upper airway issues and, following diagnosis, an appropriate treatment plan, including treatment objectives, could be formulated, which might include “palatal expansion”. The position of the mandible, which is an indicator of the risk of SDB in adults, is influenced by midfacial morphology, according to the cranio-caudal gradient of development. However, the cranial base phenotype also needs to be considered.

        Although an increase in transpalatal bone width in adults appears to be associated with a reduction in AHI, this palatal parameter is the one most easily noticed by clinicians – but our data suggests that an increase in nasal airway volume, an increase in midfacial bone volume and an increase in maxillary air sinus volume may be part of the pneumatization process that enables a reduction in AHI in adults. Obviously, more work is required in this regard, but our initial findings look promising.

        Singh GD, McNamara JA Jr. and Lozanoff S. Morphometry of the cranial base in subjects with Class III malocclusion. J. Dent. Res. 76(2): 694-703, 1997.
        Banabilh SM Suzina AH, Dinsuhaimi S, Singh GD. Cranial base and airway morphology in adult Malays with obstructive sleep apnea. Aust Orthod J. 23: 89-95, 2007.
        Singh GD, Heit T, Preble D. Changes in 3D midfacial parameters after biomimetic oral appliance therapy in adults. J Ind Orthod Soc. 48(2), 104-108, 2014.
        Singh GD, Heit T, Preble D, Chandrashekhar R. Changes in 3D nasal cavity volume after biomimetic oral appliance therapy in adults. Cranio 34(1):6-12, 2016.

  5. Hi Kevin, I’m a little confused about some of the data and it’s interpretation – I appreciate we are dealing with low numbers but presumably there is just sufficient power in these to make the claimed differences noted as significant etc.

    If one looks at the Expansion Plate (EP) data, it seems to be countering the ‘cost-effectiveness claims made of GDP vs Specialist – there are more remakes for the GDP yet it comes in still cheaper for the GDP when taking everything into account – how can that be IF the broader assumption of Specialist is cheaper overall stands, then surely it should stand for any/all Ortho. treatment modalities??

    If for some reason it doesn’t stand as a generalisation, then what is it about the Quad-Helix (QH) data that makes it so cost effective – were these the same labs/suppliers used, or were there other variables affecting cost/time beyond the individual’s expertise?

    Also if one is ONLY looking at 2 Specialists vs 13 GDPs, then maybe this is a significant variable as intrinsically, there will be LESS variability between 2 Clinicians than 13 and so, this has a disproportionate effect upon such low-numbers data potentially, surely?

    Why not compare say 6 Specialists with 6 GDPs with say a minimum 5 years Ortho experience in these appliances already, or other sensible equitable participant baselines, rather than so very different/variable/incomparable as a baseline……….?

    Apologies if this is dealt with in the original paper, I haven’t read it, but the results as published in your blog just raised more questions than answers for me and I’m not sure the data supports Specialists are better AND cheaper than GDPs conclusion, because of the above – indeed one could say the opposite if some variables were better controlled and even the existing data suggests GDPs are cheaper than Specialists for the EP option even after any remakes – but again because of the poorly matched participants I would be sceptical about that conclusion too – a classic “more research is needed” conclusion would be safer, surely ??

    Yours observationally,


    • Hi Tony ,having worked in the UK ,many yrs ago ;I frequently question if the UK studies relate to NHS data only.One wonders if fee for service ie.”private “pts. are included in the studies.I would suspect that ,if not ,the data are very skewed in several ways.Thanks.

    • I agree with you, the methodology is not that good… You can check this one : Am J Orthod Dentofacial Orthop. 2004 Nov;126(5):544-8. Comparing orthodontic treatment outcome between orthodontists and general dentists with the ABO index. Abei Y

  6. Dear Prof O’Brien

    Given what is known/published (references upon request) over the past century+ about the positive oral and general health benefits for children, and additionally enhanced quality of life issues, neurological, sleep hygiene and naso-respiratory competence advantages that are associated with early/very early detection, and correction, of posterior cross-bites and other manifestations of maxillary transverse constriction, it seems almost ‘medically indefensible’ to suggest that maybe cost-effectiveness should be a primary consideration as to when, or if ever, to correct this G&D deficiency. Maxillary hypoplasia is aways associated with posterior cross-bites, and is usually first detectable in the primary or early mixed dentition, seldom, if ever, self-correcting, and always persistent and usually worsening beyond. Within the opening paragraphs the authors of this paper give brief attention to the medical seriousness of uncorrected crossbites in childhood, but unfortunately fail to develop this important aspect of the problem over the course of the manuscript. In my Chicago practice of Pediatric Dentistry and in my role as a Sleep Medicine dental consultant for two tertiary care childrens’ hospital Pediatric Sleep Medicine services, these 8-10 year old patients (in the study’s cohorts) who already display well established maxillary hypoplasia, would almost be considered ‘geriatric patients’ relative to when they could/should have been identified and corrected. This may have been as you stated, ‘ …a very well done study…..methodology was sound…’, but do you really think Prof. that these data will lead to optimized oral and general health, improved QOL, etc. for greater numbers of kids than are now being served? I don’t think so sir.

    And FYI- I am not an engineer , but the helices of the quad-helix shown in the paper are oriented vertically rather than horizontally; they should be, according to Ron Bell (R.I.P) et al, oriented parallel to the occlusal plane for maximum efficiency

    • Can I request the references you discuss above…?

    • Generalisations and fixed rules provide a wonderful formula for treatment for the novice, but not for appropriate rational treatment, without a thorough examination and knowledge of the scientific evidence from real peer reviewed journals.

      Beliefs and publications over the last century do not provide evidence that is appropriate in this century. The poorly designed and biased analyses of the Scandinavian studies, over half a century ago, merely mislead. Blood letting was a common treatment for over 2,000 years, until a study was done to assess whether it provided a benefit for the patient.

      I would go as far as suggesting that there is no evidence, of a high enough standard, to conclude the that there are any health benefits resulting from expansion of the maxilla. I would go further and suggest that it is medically indefensible to expand the maxilla or remove lymphoid tissue to change facial growth.

      Evidence is not a four letter word and is something that can be requested in polite company.

  7. This is an interesting study… I have many issues with GP’s and Pediatric Dentists, regarding early intervention with expanders. Expansion should be done, mainly when there is a posterior crossbite, unilateral or bilateral. This is to bring the upper buccal segments to a normal bucco-lingual relationship with the mandibular posterior segment, so transversal growth of the maxilla can progress “normally” without being hindered by the crossbite. But, in real life, we find that GP’s and Pediatric dentists often place expanders to “gain space”, which is exactly the wrong reason to expand. end many place removable expanders which tip the upper molars buccaly, leaving the upper palatal cusp “hanging”. We should only resort to maxillary expansion when there is a transversal discrepancy of the maxilla that has truly been diagnosed against the mandibular bone (our template, since we cannot expand the mandibular bone). When you expand upper molars dentally (not skeletally), we are actually moving the maxillary posterior roots towards the external cortical plate. Long term periodontal issues? Probably.

    • Amen and exactly. I try to educate on this topic every chance I get, but it seems to be a one step forward and 4 steps back battle.
      To add insult to injury, it’s not just that many Drs expand for crowding in absence of a transverse issue, but now many Drs (even some trained Orthod too) also expand to “cure” and “prevent sleep apnea”.
      So, again that is our 4 steps backward process with little progress.
      In all honesty, there are several “airway conscious” orthodontists too who expand for crowding and OSA prevention in the absence of any transverse issues; but I do see your point that none ortho specialists do it more and more severely.

      “Expansion should be done, mainly when there is a posterior crossbite, unilateral or bilateral. ”
      “we find that GP’s and Pediatric dentists often place expanders to “gain space”, which is exactly the wrong reason to expand. end many place removable expanders which tip the upper molars buccaly, leaving the upper palatal cusp “hanging”.”

  8. As a general dentist who has practiced orthodontics for 30 years and completed over 5000 cases
    I think there must be better things to research then this topic in the world of orthodontics
    I find it a waste of time and money

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