November 20, 2022

Do we need to correct posterior crossbite early?

You see a young patient with a posterior crossbite with a centric shift in the deciduous dentition. Do you treat them immediately or wait until the transitional dentition? Unfortunately, there is little evidence to help you make this decision. However, this new study provides us with great information.

A posterior crossbite is a common form of malocclusion. The prevalence of posterior crossbites in the permanent dentition is approximately 9%, and it is about 12% in the mixed. Most of these crossbites are unilateral with a functional component. Therefore, treatment is indicated to improve function and asymmetry.

When we see a patient with a crossbite in the primary dentition, it is tempting to start treatment early to avoid growth consequences, etc. However, we also know that there may be a chance that these crossbites will spontaneously correct. This was looked at in this interesting new study.

A team from Geneva, Switzerland, did this study. The EJO published the paper.

Spontaneous correction and new development of posterior crossbite from the deciduous to the mixed dentition

Meryam Khda et al. EJO advanced access. DOI

What did they ask?

They did the study to find out;

“The prevalence of spontaneous correction of posterior crossbites from the deciduous to the permanent dentition, in an orthodontically untreated sample of primary school pupils.”

And to

“Determine the development of new posterior crossbites during this period”.

What did they do?

The team analysed data collected as part of a school screening study carried out in two schools in Geneva. A study team examined children between 2001 and 2019. They selected the following group of children.

  • Children who were screened for the first time in the deciduous dentition.
  • They also had to have a minimum of two screenings carried out.

 They identified the children diagnosed with a crossbite in the deciduous dentition on at least the second primary molars on one side. The authors then reviewed data from subsequent follow-up screenings to identify if the crossbite persisted in the mixed dentition on the permanent molars.

Similarly, they followed the children who did not have a crossbite to see if one developed at follow-up.

They collected the data from study forms that were completed during the examination. However, it was not clear how they defined the crossbites. I will return to this later.

What did they find?

The authors presented the data very simply, which was great!

They identified a sample of 693 children who satisfied the selection criteria. 70 (10%) of these children had a posterior crossbite. However, only 16 had a posterior crossbite when their first molars erupted. Notably, the crossbite disappeared in 54 (77%) of the mixed dentition.

When they looked at the 623 children who did not have a crossbite on the first examination. They found that 26 (4%) developed a crossbite later.

Their overall conclusions were

“1 in 10 children have a crossbite in the deciduous dentition. However, this self corrects in 77% of the children”.

“When we see a patient with a crossbite in the deciduous dentition, it may be wise to wait for the eruption of the first permanent molars before attempting treatment”.

What did I think?

This is a simple, nicely carried out and well-written study. But, importantly, it provides valuable data about a common clinical problem. The most compelling finding is that we should allow malocclusion to self-resolve instead of piling in and carrying our unnecessary treatment in the deciduous dentition. In other words, normal facial growth maybe the best interceptive treatment.

On the other hand, we could treat every patient and claim very high success rates for a problem that will solve itself!

These findings are also relevant to the clinicians who post up records of patients they treated early, or have done treatment with oral exercises and/or Myofunctional appliances. We must remember that doing nothing results in a 77% success rate. As a result, their treatment will work 77% of the time!

The study had many good points. Notably, the team used readily available data and a simple research method.

However, as with all studies of this nature, there are some problems that we should consider. For example, I was unclear on how the crossbites were identified, and there could have been some inconsistencies between the two examinations. Nevertheless, they pointed out that the senior author supervised the data collection.

I was also a little concerned that the authors did not provide much information on the nature of the source population. As a result, we do not know how generalisable the findings are likely to be.

Final thoughts

Importantly,  the findings are similar to other studies and emphasise that for some conditions, it is best to wait for normal development before we provide treatment that may not be necessary.


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Have your say!

  1. It is so useful and refreshing to be informed of research with such a good sample and such clinically relevant results.
    However, there are three interesting remarks to be taken into account:
    1. CROSSBITE what KIND of Crossbite? Are unilateral cross bites the same as bilateral, single tooth the same as multiple tooth, symmetrically constricted palates & arches the same as asymmetrically skewed ones? Can we put them all in one bag and WAIT for self correction??
    2. LIMITATIONS. Very WISELY the authors stated the following limitation:
    “The absence of data on para-functions and oral habits “. Obviously, when a parafunctional habit is discontinued by the patient himself or mouth breathing is improved, then NATURE (the wisest of us all) self-corrects and restores harmony and transversal dimensions.
    3. TIMING and monitoring the evolvement of the dentition. A clinical pearl that, probably most orthodontists follow, is stated in the Conclusions:
    “It may thus be reasonable in cases with posterior crossbite in the deciduous dentition to wait for the first permanent molars to erupt before initiating treatment.” But of course, this has also been written in classical textbooks:
    “ As a general rule, little if any orthodontic treatment is indicated for preschool children” W.R. Proffit, Contemporary Orthodontics
    Finally, I can but AGREE with you that :
    “We could treat every patient and claim very high success rates for a problem that will solve itself!”
    The patient’s ACTUAL benefit is THE top priority and indeed more often than not in Orthodontics, as in life:
    “Good things come to those who wait, They come, but often come too late.”
    Vicky Tarantili
    Orthodontist, MSc
    Athens, Greece

  2. It is good to see an interesting study on the subject.Unilateral Posterior Cross-bites in developing dentition, is definitely an issue of concern. Firstly it is almost always associated with deviated(sidewise) path of closure of mandible, a definitive functional anomaly, with far reaching implications on adaptive growth and TMJ. Secondly, Transverse discrepancy needs to be addressed early, as it is the dimension of the face and jaws that completes its growth earliest. Another reason is that the long-standing unilateral posterior cross bites will reverse the attrition pattern(bucco-lingual plane) of the affected posterior teeth.I agree with the conclusion to wait till eruption of first molars, but if it persists, there is no reason to wait to loose the most precious and critical time, to restore the faulty form and function.
    A innovative new device was suggested, named “Transinclined Plane Appliance” to address the form and Function simultaneously, by ‘De-programing and expanding'(AAO-Hawai-2012) by this author. Details of design may be sought by e-mail:[email protected]

  3. Nice study. Some comments that I’m not sure about. Are MOST cross bites associated with a functional shift? Does this then lead to asymmetric jaw growth? I’m not sure that there is evidence for either of these.
    There are certainly many asymmetric jaws out there just as there are many class 2 and class 3 jaws. These are difficult to alter. Maybe I don’t see the functional shift ones very often since I’m waiting until later and 77% (of all cross bites) self correct leaving mainly the skeletal ones. Basically there is a lot to be said for leaving those kids alone until the face and dentition is fully developed. We do this with class 3s maybe we should do it for all cases (other than impacted teeth), class 2s as well as asymmetries.

    • Andy,
      I believe Hugo DeClerk and his work with bollard plates (bone anchored maxillary protraction) has shown that leaving Class 3’s alone “until the face and dentition is fully developed” would be missing an opportunity to make significant skeletal correction. There are windows of time when significant skeletal correction can be made in the AP as well as in the transverse dimension. Like with Bollard plates, I find that earlier correction of narrow maxilla’s yields a better skeletal correction and less dental tipping and/or alveolar bone bending.

  4. Dear Prof.

    Beside the presence of a posterior ‘dental’ cross-bite which might auto-correct, which are other metrics that might be utilized by orthodontists (who provide services for pre-school age children) for identifying possible maxillary ‘skeletal’ transverse deficiency (at the alveolar and/or apical base) in young kids who might present in the full primary dentition with crowded U/L incisors, deep/narrow palatal vaults and a v-shaped maxillary arch; and, like posterior dental cross-bites, does anyone think that some, or all, of these additional/aforementioned malocclusion traits could also auto-correct?

    Thanks for considering my questions.

    Kevin Boyd

  5. Unfortunately I do not have access to the complete article, just the abstract.
    Based on the abstract I would respectfully disagree with your assessment that this was a well designed study.
    They do not define x-bite: is this full, cusp tip to cusp tip, etc.
    They do not break out in the abstract if this is a single tooth x-bite, 2 teeth or unilateral or bilateral x-bites.
    They mention that they had no data on para-function which could have a major effect on this issue. Were any of these “autocorrected” bites in patients that had any myofuntional training between evaluations?
    Just because the x-bite is “fixed” does not mean that the child has avoided craniofacial dystrophy.
    I find that most articles in orthodontics seem to originate from a mechanical rather then biologic perspective in assessing outcomes which I feel does our patients a disservice.
    I look forward to having full access to this article so I can more fully evaluate their work and perhaps change my initial impression.
    Stephen Coates, DDS, FAGD

  6. This is a nice, clean (if you will) study. The issue, as I see it, is that “crossbite” is not always a reliable indicator of a transverse skeletal discrepancy. (Just as overjet is not a reliable indicator of class 2 or class 3 skeletal discrepancy.) The results actually bear this out as I don’t think skeletal discrepancies either “appear” or “disappear” due to the eruption of the first molars. It is good information none the less in that one needs not worry about the growth effects of the functional shift in a majority of cases of deciduous dentition crossbite.

  7. Has anyone in orthodontics done a well-designed study to determine the extent to which training children to chew correctly can self-resolve various cross bites and other malocclusions? As parents of 3 children, we observe how 2 of our children chew carefully, and 1 is always chewing sloppily while talking and always chewing only on the right side where he uses the same hand to put food in his mouth? He’s also generally less coordinated. He’s the one with poorly aligned adult teeth that are coming in.

    Would you please post some training articles to show the correct way for children to chew? Let’s not assume that all children are naturally chewing correctly. Shouldn’t orthodontics consider that some children may be chewing in a harmful way, throwing teeth out of alignment, and that all parents should know how to train them correctly?

    Or, to look at it from another angle: dentists already know that some people bite too hard, too fast, cracking teeth on harder foods, and that some people are more tactile, never cracking teeth while chewing. A little training at a young age could go a long way towards self-correction ? Maybe the self-resolving children are more perceptive while chewing with more coordination, causing the self-correction. Coordination is something that can be practiced with correct training. Why leave this to chance? This Swiss study should be extended to find out why? Thank you kindly for your review of the study.

  8. I have always waited for the first molars to erupt before considering correcting a posterior x bite. Efficiency, and the ability to correct upper incisors at the same time are the my primary reasons, but its nice to have data that most get better without tx. My clinical observations are in line with this study. Thank you for posting!

  9. Dear Ernest

    Tx efficiency of course should always be factored into a therapeutic strategy, but shouldn’t override what might be in a child’s best short/long-term interest in QOL. Skeletal maxillary transverse deficiency, which is very often detectable by/before 30 months of age(Cohen, JAMA-Dec.1922), is a frequent craniofacial co-morbidity with other problems associated with overall general health. A ‘wait and see’ strategy based upon data from a study similar to the one recently reviewed here, would seem difficult for me to defend. So, please Ernest, consider my original question posed to prof. O’Brien, ‘….in young kids who might present in the full primary dentition with crowded U/L incisors, deep/narrow palatal vaults and a v-shaped maxillary arch,…..similar to posterior dental cross-bites, do you think that some, or all, of these additional/aforementioned malocclusion traits could also auto-correct?’

  10. Looking back at the article published in EJO in 2017 by Masucci et al. where they found that crossbites were present in 34% of the mixed dentition cases that had been previously treated for the same problem in primary dentition, it seems better not to do anything and wait. According to the article covered in this blog post, without treatment in primary dentition, only 23% are left with a crossbite in mixed dentition, and with treatment in primary dentition, 34% need retreatment. It could be a good example that sometimes the best treatment is no treatment?!!

  11. It is a very interesting study but I miss the differential diagnosis. I have seen many childrend with a crossbite in the decidiuos dentition ,some had only a crossbite in some molars.many had a functional sideshift after a thumbsucking habit ore mouthbreathing-habit and in thes cases I could see a reposition into the midline when guiding the mandible in a retral condylar position. in some cases there was a selfcorrection during development auf permanent dentition. In only very rare cases I could find a functional sideshift in patients after the pubertal growth-spurt. So I treated my patients after eruption of first molars and beginning incisal toothchange. I often saw a developping crossbite of upper later incisors in patients with functional sideshift and could treat both problems with one treatment of 6 months..I think,that a functional sideshift can result in asymmetric condylar growth. Patients with a skelettal deviation with class 2 ore class 3 occlusal relation and asymmetric condylar growth never had a spontaneous selfcorrection.

  12. Referring to “Developmental Aspects of TM Joint Disorders, Feb 24 & 25, 1984”. The chapter by Prof. Birgit Thilander “TM Joint Problems in Children” (with excellent and numerous references) highlights that children who present with posterior cross-bite which includes a postural shift are at higher risk for skeletal asymmetries and TMD later in life. The important issue is the presence of a centric, postural shift.
    Cochrane review, 2005. Authors’ conclusions
    The evidence from the trials reported by Lindner (1989); Thilander (1984) suggests that removal of premature contacts of the baby teeth is effective in preventing a posterior crossbite from being perpetuated to the mixed dentition and adult teeth. When grinding alone is not effective, using an upper removable expansion plate to expand the top teeth will decrease the risk of a posterior crossbite from being perpetuated to the permanent dentition.
    The comparisons of treatments made in the trials reported by Asanza (1997); Sandikçioglu (1997); Mossaz-Joëlson (1989); Ingervall (1995); Schneidman (1990) were inconclusive so recommendations for clinical practice can not be made based on the results of these trials. However, these trials were small and inadequately powered so further studies, with appropriate sample sizes, would be required to assess the relative effectiveness of these interventions.

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