Is mouth breathing in children really a warning sign for orthodontic intervention? A recent review challenges long-held beliefs and urges clinicians to revisit the evidence.
For decades, mouth breathing has been associated with a wide range of dentofacial concerns, including long faces, retruded mandibles, high-arched palates, and even behavioural and cognitive issues such as ADHD.
This has created a clinical environment where concern over mouth breathing is common, but clarity on how to manage it is less so. The review by Kandasamy, published in the American Journal of Orthodontics and Dentofacial Orthopaedics (June 2025), provides a timely re-evaluation of the evidence behind these practices.
So, does the evidence truly support an interventive approach?
Key Findings
Kandasamy’s review focused on several key studies that have historically shaped beliefs around mouth breathing.
One of the most cited is a study by Harvold and colleagues, in which nasal obstruction was induced in rhesus monkeys. The animals developed notable skeletal changes, seemingly supporting the link between airway obstruction and altered facial development. However, as Kandasamy points out, rhesus monkeys are obligate nasal breathers — unlike humans, who can switch between nasal and oral breathing with minimal compensatory changes. This key biological difference raises questions about how transferable the findings are to human children.
The review also looked at research by Linder-Aronson on adenoids and airway obstruction. While these studies helped popularise the concept of “adenoid facies,” they often relied on subjective methods to classify breathing mode. Notably, children with significantly enlarged adenoids did not always exhibit the expected vertical facial growth patterns. This inconsistency weakens the proposed causal link between nasal obstruction and altered facial morphology.
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The Question of Early Intervention
Even when nasal obstruction is suspected, the choice of treatment varies. Some clinicians advocate early myofunctional therapy or maxillary expansion with the aim of improving airway function and guiding growth. These approaches have gained popularity among those seeking to “correct” mouth breathing early.
However, the evidence base is not strong. Kandasamy’s review suggests that while certain interventions may produce short-term changes in function or form, they do not appear to significantly influence long-term mandibular growth patterns. In fact, expansion performed in the absence of clear transverse discrepancies may inadvertently increase vertical facial dimensions, particularly in children with long face tendencies or lip incompetence.
This raises a concern: could some interventions intended to help actually complicate a child’s growth pattern?
Rethinking the Diagnosis
A major challenge in this area is how we define and identify “mouth breathers.” The label is often applied based on clinical features such as open lips or increased vertical proportions, but these are not reliable indicators on their own.
Children (as adults) frequently alternate between nasal and oral breathing, during physical activity, while sleeping, or when unwell. This variability makes it difficult to assess breathing patterns accurately without objective data. Kandasamy’s review stresses the importance of recognising when nasal obstruction is genuinely present, and recommends that such cases be assessed with the help of ENT specialists, rather than managed solely through orthodontic intervention.
Implications for Clinical Practice
For clinicians, the review serves as a prompt to reconsider how we interpret and respond to mouth breathing in young patients.
The desire to intervene early is understandable, particularly when parents are concerned about facial appearance or sleep quality. But without clear clinical indications, aggressive early orthodontic treatment aimed at “correcting” mouth breathing may not be warranted — and in some cases, may even be counterproductive.
Instead, a multidisciplinary approach is encouraged. When nasal obstruction is suspected, referral for ENT assessment and appropriate medical management should come before considering orthodontic solutions. This helps ensure that treatment is aligned with the actual cause, not simply the appearance.
Study Limitations
As with all reviews, Kandasamy’s article depends on the quality of the original studies. Many of the key papers were conducted decades ago, often with small sample sizes and limited long-term follow-up. The use of subjective measures to assess breathing mode further complicates interpretation.
There is also a lack of consensus on standard diagnostic criteria for mouth breathing in children, an area that would benefit from clearer definitions and more rigorous research. Until then, clinicians must be cautious in how they interpret the available evidence and communicate findings to families.
About Dr. Jamal
Dr. Jamal Giri is an orthodontist and associate professor at B.P. Koirala Institute of Health Sciences in Nepal. He obtained his orthodontic training from the Institute of Medicine, Tribhuvan University, Nepal, in 2014.
Currently pursuing a PhD at the University of Adelaide, Dr. Jamal’s research focuses on the genetic and environmental factors influencing malocclusion development. He also holds a postgraduate certificate in clinical education from the University of Edinburgh and a master’s in medical education from the University of Nottingham.
Dr. Jamal teaches on the Diploma in Orthodontics and Dentofacial Orthopaedics at the London Dental Institute.
Read More
Kandasamy S. Mouth breathing and orthodontic intervention: Does the evidence support keeping our mouths shut? American Journal of Orthodontics and Dentofacial Orthopaedics. 2025;167(6),629-634.
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