Does constriction of the dental arch result in sleep-disordered breathing? 

It has been suggested that tooth extraction as part of orthodontic treatment and arch constriction may cause sleep-disordered breathing. When considering the role of extractions in orthodontics, we know that extraction treatment does not generally reduce the volume or change the shape of the upper airway. However, when teeth have been over-retracted or the arch has been constricted, there remains a possibility that this could influence breathing. But this is mostly conjecture.

This new pilot study looked at the effects of dental arch constriction on SDB. I found the results interesting. They provide an argument against some of the nonsense circulating about the effects of orthodontics.

A team from Canada, did this study. The Angle Orthodontist published the paper. 

What did they ask? 

The aim of this study was 

“To characterise the presence of functional changes of the airway with level three polysomnography while using an appliance simulating airway constriction” 

What did they do? 

They conducted a single-blind, prospective, randomised crossover study in healthy adults. 

The PIC0 was 

Participants 

Healthy adults were recruited from the student and staff population of the Faculty of Dentistry. 

They had standardised demographic and anthropometric data collected and orthodontic records. This included a lateral cephalogram and an intraoral scan of the dentition. 

Intervention

This was a vacuum-formed retainer designed to constrict the arches. Constriction was simulated by adding a 5 mm thickness to the lingual and palatal aspects of all the teeth in both upper and lower arches. This resulted in a 1cm constriction overall.

Control 

A vacuum-formed retainer. 

Outcomes. 

The primary outcomes were Respiratory Events Index (ROI) This was derived from data obtained from a portable sleep monitor at home. 

Other outcomes were oxygen desaturation index (ODI), SpO2 measured with a pulse oximeter. The Epworth Sleepiness Scale and morphological data. 

Each participant underwent three sleep studies. The initial study was conducted at baseline, before any appliances were fitted. Patients were then randomly assigned by computer-generated randomisation to an intervention sequence arm, and they wore either the control appliance or the constricting appliance for six days. After this period, a second home sleep study was conducted. 

The participants then crossed over and used the other appliance for another six days. This was followed by a third sleep study. 

They analysed their data with a relevant univariate statistical test. 

They conducted a sample size calculation for a pilot study, which suggested they needed 12 participants per group. As a result, they attempted to recruit 24 participants, with an additional 11 to account for potential dropouts. 

What did they find? 

They recruited 35 healthy participants with an average age of 28.5 years for the study. By the end of the study, 34 participants had completed all required data collection. When analysing their data, there were no statistically significant differences in REI at any stage of the study. 

Similarly, when they examined ODI, they did not find any statistically or clinically significant differences. There did not find any differences in the Epworth sleepiness scores. 

The overall conclusion was 

“Simulated severe constriction of the dental arches does not affect respiratory function during sleep as measured by at-home polysomnography.” 

What did I think? 

This was a good, ambitious study that employed quite novel techniques. They used an interesting and relevant method to simulate dental arch constriction. We might think that this does not fully represent the gradual arch constriction that can occur with “retractive orthodontics”. Nevertheless, I believe this was a reasonable approach.

I have considered whether the rather sudden constriction might have influenced the results. I cannot help feeling that rapid constriction would have a greater impact than a slow constriction resulting from any orthodontic treatment. This is because the airway is given sufficient time to adapt to the constriction. However, I am not an expert on this matter, and my thoughts are purely conjecture.

We also need to acknowledge that this study is a pilot with a relatively small sample size; however, given the small effect sizes detected, we would argue that they are unlikely to change substantially with a larger sample. Still, I would prefer to see a larger study before drawing any firm conclusions.

The authors also mention that they relied on participants’ cooperation and did not measure the duration of appliance wear. This factor could, of course, influence the results. 

Final thoughts. 

We need to consider whether we can generalise these findings to real-world clinical care. I believe they offer some evidence that the constriction of arches does not impact breathing.

Nonetheless, we should interpret the results of this study with caution, but they provide useful preliminary data to guide further research and enhance our understanding of this important issue. 

Now that you have read this blog post.

Last year, I requested donations to support my blog, and thankfully, I received an overwhelming response. With your help, I was able to raise sufficient funds to keep my blog going for another year. 

Now, I’m seeking your support again to help me cover the blog’s running expenses for the upcoming year. The funds will cover web hosting, software upgrades, email lists and general running costs. 

I believe that if every reader contributes a small amount, I can cover the yearly running costs. Your help will be much appreciated.

To make a donation, just use the form below. You can use the set-amount buttons or the free-field button to enter other amounts.

Then the easiest way to pay is to tap the Apple Pay button. If you want to use another payment method, click the “next” button and enter your details. This will take you to credit cards, PayPal, and other payment methods.