It’s nice to see some sense about mouth breathing and orthodontics 

This post is by Martyn Cobourne, who condenses his views on orthodontics and mouth breathing. He counters some of the nonsense we are currently seeing in orthodontics.

Introduction

A really excellent editorial by Sanjivan Kandasamy just published in the AJODO this month: dismantling some of the myths associated with breathing, posture and facial growth. I particularly like the discussion of the often quoted but experimentally flawed ‘classic’ papers by Linder-Aronson and Harvold investigating adenoidectomy in children and forced-nasal breathing in monkeys, and their extreme effects on facial growth and induction of the ‘adenoid face’. I would argue that the questionable findings of these investigations have been further demonstrated by systematic reviews failing to show extremes of facial growth in association with mouth breathing or indeed, obstructive sleep apnoea (OSA) as reported by  Katyal et al, 2013; Fagundes et al, 2022; Finke et al, 2023).

The onslaught of airway orthodontists

The tsunami of orthodontists claiming that orthodontic management of mouth breathing and sleep disorders in children through early maxillary expansion, functional appliances and myofunctional therapy is seemingly never-ending. These strategies are advocated through opinion articles, conference presentations and poor research. The evidence that maxillary expansion at any age can induce significant anatomical (and more importantly) physiological effects on the airway is low-quality and unconvincing as found by Buck and also Niu. Indeed, there is a better evidence base showing that functional appliances do not induce clinically significant additional mandibular growth, whilst the evidence relating to myofunctional therapy is almost non-existent. Anyone interested in the complex subject of mouth breathing, airway and indeed, OSA should make the excellent AAO guidance on orthodontics and management of OSA mandatory reading. 

Oversimplification of theory

The problem with any theory that ends in excess is that it over-simplifies the reality – particularly in relation to biology. Whether you claim to be an ‘airway orthodontist’, or ‘airway dentist’ (heaven forbid), believing that the oro-facial environment is entirely responsible for abnormal facial growth and development – be that incorrect tongue posture, nasal breathing or some combination of the two, ignores the fundamental importance of genetics. 

A genetic example

I thought it would be useful to use some images of a mouse line we are currently studying in our laboratory.

One is a wild type (on the left) and one is mutant for a gene called Wnt5A  (many thanks to Daniel Stonehouse-Smith for the images). The nature and function of the protein encoded by this gene is not important, but without this single functioning gene, the craniofacial phenotype (and indeed, the limb phenotype) of these mice is significantly disrupted, clearly demonstrated in the craniofacial region by the truncated maxilla and mandible. The environment does not cause this, it is primarily the result of genetic background and demonstrates the huge influence of genetics and gene function on craniofacial development.

Some clinical common sense is required

Clearly, the environment is also important for normal craniofacial growth and development; nobody would deny this. There may well be a role for adjunctive orthodontic therapy in the multidisciplinary management of breathing disorders, nobody is dismissing that. However, craniofacial growth and development represents a complex inter-relationship between genetic, epigenetic and environmental factors. The sooner we accept this and cease making claims based on questionable evidence or fantasy, the less our patients will be misled, unnecessarily treated, or even harmed. This editorial is an excellent reference point for anybody interested in sensible further reading on this unnecessarily controversial subject.

Now, a message from Kevin

Can you help me do something good?

I am raising funds for Maggie’s Cancer Support Centres. I will be walking 22 miles across the U.K. moors in memory of my dear friend Dr Betsy Bennett. Sadly, she passed away from leukaemia at only 61. I want to honour her by using the power of this blog to raise a substantial amount. If everyone who reads this blog donates £5.00, we will raise an amazing amount! The donation button is at the bottom of this section.

Betsy was a psychologist. We collaborated in Pittsburgh and North Carolina. Her kindness and personality touched everyone she met. She introduced me to research on patient and psychological outcomes, which changed my research direction. I’m so grateful to have known her. 

What is Maggies?

Maggies is a fantastic charity. There are 24 centres in the UK, welcoming 100+ visitors into each centre every day. I volunteer at the Manchester Centre.

The centres offer free practical and emotional support to anyone whose lives are affected by cancer. They depend entirely on charitable donations and concentrate on issues such as financial worries, housing, stress management, treatment side effects, and family support. They provide this support through one-on-one sessions or group discussions. 

It would be wonderful to provide them with substantial support to help them sustain their incredible work.