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.
Meryam Khda et al. EJO advanced access. DOI https://doi.org/10.1093/ejo/cjac061
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.”
“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.
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.
Emeritus Professor of Orthodontics, University of Manchester, UK.