A new study shows that some “developing malocclusion” resolves spontaneously.
Wouldn’t it be wonderful if we could intercept the development of malocclusion during the late mixed dentition stage? This has been a long-standing goal for orthodontists. However, this topic has sparked controversy, as phase I interceptive treatment is becoming more popular. This contrasts with the traditional approach of watchful waiting, where treatment is postponed until the dentition is fully established.
I wonder if our focus on intercepting malocclusion has caused us to overlook essential knowledge about facial growth, which is usually covered in the first chapter of orthodontic textbooks and during the early stages of our dental specialty training. Specifically, which aspects of malocclusion tend to self-correct with facial growth? This new paper offers valuable insights on this topic, and I recommend that all practitioners read it.
A team from Brazil did this study. The AJO-DDO published their paper.
Diego Patrik Alves Carneiro, et al
AJO-DDO: Advanced access. https://doi.org/10.1016/j.ajodo.2025.02.006
What did they ask?
They did this study to investigate
“The intermaxillary and intraarch relationships of mixed to permanent dentition over a four year follow up period”.
What did they do?
The team carried out a longitudinal study of a sample of children transitioning from mixed to permanent dentition over a four-year period.
They examined a sample of 785 children aged 8-10 years in the late mixed dentition in 2018.
They measured intra-arch features such as crowding, spacing, and maxillary midline diastema during this examination. Intermaxillary features were any sagittal, vertical, and transverse discrepancies.
In 2022, they contacted all the children who participated in the study’s first stage. They excluded children whose parents did not consent and anyone who had received orthodontic treatment.
What did they find?
They evaluated 352 of the original sample of 786 children. This was a response rate of 44.9%. They found that there were statistically significant changes across all the variables that they measured. These were the important clinical features that improved
Crowding
Improved in 69% who had crowding in both arches
Maxillary diastema
Decreased in 74%
Overjet
43% of the children with increased overjet had a normal overjet at T2.
Posterior Crossbite
70.5% who had a crossbite at T1 had a normal relationship at T2
Anterior Open Bite
74% of those who had AOB had a normal overbite at T2.
Class II relationship
29% of those who originally had a Class II molar relationship had a Class I relationship at T2.
Their conclusion was
“Significant favourable changes were observed from the mixed to the permanent dentition”.
What did I think?
This research significantly enhances our understanding of the transition from mixed to permanent dentition. While the findings may not be entirely new, they are still important. After reading this recent paper, I revisited my 40-year-old copy of Proffit’s book, specifically Chapter 4 on dental development and growth. In this chapter, he emphasizes that favourable changes in dentition result from the growth of the mandible and maxilla. We should all know this. It appears, however, that we may have overlooked these fundamental facts or perhaps were never fully aware of them in the confusion of those early months of specialty training.
In line with other longitudinal studies, there was a significant dropout rate of participants. This should be considered when interpreting the findings. It would have been beneficial if the authors had included information about those who did not participate in the second clinical examination.
I would have liked to see more information about the initial severity of malocclusion. For example, this could have provided data on the proportion of large overjets that resolved, resulting in a more precise understanding of the findings.
The most compelling conclusion is that many features targeted for early intervention seem to resolve on their own. For instance, 70% of posterior crossbites resolve spontaneously. This finding raises questions about the necessity of early expansion if such resolution occurs without treatment. Although, this is somewhat controversial.
Final comments
This paper raises important questions about the effects of early treatment. It makes me wonder if the outcomes of some early intervention treatment significantly differ from the effects of normal growth. As usual, Proffit was right; we must not overlook our foundational knowledge.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Per Prof O’Brien’s comment, “I would have liked to see more information about the initial severity of malocclusion. For example, this could have provided data on the proportion of large overjets that resolved, resulting in a more precise understanding of the findings.”
This data would also apply to posterior cross-bite and Class 2 malocclusion. One should be aware this article is not in agreement with Bishara, et. al. AJO/DO, 1988 longitudinal study of molar relationship from the deciduous dentition to the permanent dentition of 121 subjects from the Iowa Longitudinal Growth Study. From that article, “The present findings have some important clinical implications regarding treatment and its timing. As an example, none of the sides that started with a distal step (Class II) in the deciduous dentition were able to self-correct. These findings and observations support a frequently repeated axiom: “Once a Class II, always a Class II.”
Reviewing Diego Patrik Alves Carneiro’s references, it’s curious that he does not include Bishara’s research.
“What did I think”
First of all I read the article in order to not make wrong decision.
The spontaneus correction at posterior crossbite (Which is very high ratio 70.5%) is suspicious.
There are neither enough explanation nor discussion about the occurence of this correction in the text.
I think this correction is not skeletal. This correction occurs because of the transforming of the dedicious molars to permanent premolars whose erupts more buccaly results more wider maxillary arches that corrects posterior cross-bite. As I explained, the correction here is dentoalveolar rather than skeletal.
For that reason the conclusion “posterior cross-bite corrects spontaneously in Childeren between 8-10 ages” is not a correct decision.
We must follow up these cases and must sent the skeletal ones to ENT for upper airway examination and consultation.
I agree with this, as practionioner and specialist. It was my first think. Was it skeletal or dento alveolar? Maybe in this 55,1 was the sketal cases? The next study that shows how hard is to to do reliable study
Thank you for this work. My first concern when i was reading you is: what about the functionnal dimension? I would be very interesting in knowing the ratio in this sample of oral breather /mouth breather/tongue trust.
First, I would like to express my admiration for Professor Kevin O’Brien and sincerely thank him for reviewing our study.
We have been following the comments on the blog and recognize the importance of providing a response.
To begin with, it is important to highlight that our study is an observational, population-based epidemiological study. As such, we did not assess the severity of malocclusions because there is no validated instrument for this purpose in the mixed dentition. This limitation makes it challenging to determine malocclusion severity in this context.
Regarding transverse problems, our study categorized cases as having a “normal transverse relationship,” “posterior crossbite,” or “Brodie bite.” However, I must emphasize that these occlusal conditions were evaluated strictly from an epidemiological perspective. When a transverse problem was identified, we were unable to differentiate the severity of its presentation—whether it involved a single tooth, multiple teeth, or the entire posterior segment.
Our group acknowledges the study’s limitations and is committed to addressing these aspects in future research.
Hi Kevin:
I agree it’s an interesting study but what made me smile is when you said “After reading this recent paper, I revisited my 40-year-old copy of Proffit’s book”. What now? 🙂 But seriously, why does the orthodontic specialty still believe in the orthodontic prophets (no pun intended)? It appears that orthodontic thinking is still mired in Darwinian genetics and Newtonian mechanics. Guys, the human genome was sequenced in 2003 – so why are we still relying on 20th century concepts that have not withstood the test of time? Is it time to update the basis of orthodontic theory?
Singh GD. Outdated definition. Brit Dent J 2007;203,174
As a practicing orthodontist of 40+ years I am glad to see this paper get recognition.
I am not a big proponent of most cases need early intervention. In many cases giving the patient time to grow and mature may not correct the early malocclusion, but it certainly can improve it and alter treatment needs.
However, in my experience there are certain issues that do not improve with time and growth. These should be addressed early. To wit- skeletal crossbite, some anterior open bites ( with tongue thrust, narrow maxilla and/or breathing issues), Class III skeletal growth among others.