 An occasionally irregular blog about orthodontics
We are seeing an increasing number of studies examining the effects of breathing on skeletal growth and other important factors. These developments are good news for those of us seeking evidence on these relationships. This new paper in the high-impact AJO-DDO examined the effects of removing adenoids on respiration, craniofacial development, and posture.
A team from Istanbul, Turkey, did this research
What did they ask?
They did this study to
“Assess changes in respiratory patterns, craniofacial development, and head and neck and overall body posture in children who have undergone early adenoidectomy and those who have not”.
They provided an extensive, yet, traditional literature review on this subject. Importantly, they noted that mouth breathing is traditionally associated with a distinct craniofacial appearance (adenoids facies). They drew attention to a comprehensive review published in 2025, which showed that mouth breathing induces craniofacial morphological changes and significant alterations in mandibular, lingual, and palatal positioning. However, this was published in a predatory journal. The conclusions of this study are very different from those of a recent paper on a similar subject, published in the AJO in 2025.
I guess at this point you are sensing the direction that this blog post is taking!
What did they ask?
They wanted to
“Evaluate children presenting with respiratory obstruction because of adenoid hypertrophy”.
What did they do?
To answer this question, they conducted a retrospective cross-sectional study. They looked at three distinct groups of participants.
- Group 1 were patients who were diagnosed with adenoid hypertrophy who presented at a later stage and were planned for removal of their adenoids.
- Group 2 were patients with respiratory obstruction because of adenoid hypertrophy who had undergone early surgery and completed 3 years post-operative follow-up.
- Group 3 comprised subjects with no pathology or systemic disease causing respiratory obstruction, and they exhibited normal nasal breathing.
They evaluated all the groups at one time point. All the children in the study were aged 6 to 10 years. The median age of each group was 8 years.
They used the following outcome measures:
- The NOSE scale. This consists of five questions that assess patients’ respiratory symptoms.
- Peak nasal inspiratory flow (PNIF). This provided quantitative data on respiration.
- The head and neck posture.
- A comprehensive orthodontic clinical examinations, including:
- Radiographic records
- Panoramic radiographs
- Lateral cephalogram and analysis
- PA head and hand/wrist X-rays
- Tooth measurement from dental casts
They did a power analysis using the gonial ratio (S-Go/N-Me %) from a similar study. The clinically significant difference they aimed to detect was 0.4%. As a result, we can assume that the gonial ratio is the primary outcome of the study.
What did they find?
The team carried out an extensive analysis of their data. I felt that these were the main points.
When they examined differences in the outcome measures between the groups, they found no differences in any of the postural measurements.
They conducted univariate analyses of 32 Cephalometric measurements. This increases the likelihood of achieving statistical significance and potential false positives. They found statistically significant differences in 7 out of the 32 cephalometric measurements. But these were very small, and I felt that they were not clinically significant.
There were no differences in the dental cast measurements.
However, the later adenoidectomy group had greater nasal obstruction (NOSE score) and lower PNIF. But, the NOSE scores were all within normal limits.
Their overall conclusion was that.
“Early adenoidectomy improves respiratory and craniofacial growth, resembling normal breathing. Delayed surgery leads to persistent mouth breathing and negative growth outcomes”.
What did I think?
This was an interesting study that aimed to answer a clinically relevant question. However, it is also a good example of how a cursory reading of an abstract and a paper can lead to misinterpretation of the results and conclusions.
The authors collected a large amount of data on 34 outcome measures and ran simple univariate statistics between the groups. This increases the chance of false positives. They then concentrated their discussion and conclusion on these differences. However, this did not include their primary outcome of gonial ratio, which was not different between the groups.
This was a traditional cephalometric trawl looking for statistical significance and concentrating the discussion on the “significant” measures totally ignoring the other 25 “non significant” outcomes.
When I examined the cephalometric data, most statistically significant differences between the groups were small. I did not find any clinically significant differences. The authors’ discussion and conclusions were based on statistical significance rather than effect size. However, they noted that we should interpret the study cautiously, given the small effect sizes. Nevertheess, this was not reflected in their conclusions.
I think it is also very relevant to consider the findings in this paper alongside a recent systematic review. I have posted about this review previously. In this systematic review, the authors identified an effect of adenoid removal on skeletal parameters, but it was very small and likely not statistically significant.
It was also interesting to see that they based their sample size on a small difference in gonial ratio. I presume that this was the primary outcome of the study. However, when they analysed this outcome, there were no differences between the groups for genial ratio. This raises questions about the study’s power.
My conclusions.
The data in this study support the conclusions of the previous systematic review. As a result, I feel that this study would have benefited from closer statistical refereeing and less emphasis on statistical rather than clinical significance.
Some readers may feel that I am being to critical and this post represents my confirmation bias. This is not the case I have simply carried out a critical appraisal.
I also realise that I have now done several posts on breathing. However, it appears that research is increasing in this area and it is important that we appraise it. Next week I am doing a post about aligners. The post Does this new study suggest that adenoidectomy effects facial development? appeared first on Kevin O'Brien's Orthodontic Blog.
Content mobilized by FeedBlitz RSS Services, the premium FeedBurner alternative. | 
