Pain Peptide Substance P Found in Gum Fluid During Invisalign Orthodontic Treatment | Research

The takeaway

The neuropeptide substance P was detected in gum fluid around teeth being moved by Invisalign aligners but not in unmoved control teeth, linking orthodontic forces to pain-signaling peptide release.

SP present in treated teeth, absent in controls
Within the same patients, substance P was found only around teeth experiencing orthodontic forces, providing direct evidence that tooth movement triggers neuropeptide release.

What the researchers found

Substance P (SP), a pain-signaling neuropeptide, was detected in the gingival crevicular fluid of teeth undergoing orthodontic movement with the Invisalign technique, but was not found in control teeth from the same patients that were not being moved. This is one of the first studies to demonstrate substance P release specifically during clear aligner orthodontic treatment.

Why it matters

Understanding the role of neuropeptides like substance P in orthodontic pain and inflammation could lead to better pain management strategies during treatment. Substance P is a key mediator of pain signaling and inflammation, so its presence in gingival fluid during tooth movement confirms that orthodontic forces activate neuropeptide-mediated inflammatory pathways in the periodontal tissues.

The numbers in context

n=4 subjects · GCF collected with paper cones · 60-second sampling time · SP present in treated teeth · SP absent in control teeth

How the study worked

In this pilot study, gingival crevicular fluid (GCF) was collected from four young subjects undergoing Invisalign orthodontic treatment. Paper cones were placed in the gingival sulcus for 60 seconds to collect samples from both teeth being actively moved and control teeth in the same patient that were not undergoing movement. Samples were analyzed for substance P content.

Who was studied

4 young subjects undergoing orthodontic treatment with Invisalign technique

What this study cannot tell us

This is a very small pilot study with only 4 subjects, making the results preliminary at best. No quantitative substance P measurements are reported — only presence or absence. The study design lacks statistical analysis due to the small sample size. Only the Invisalign technique was tested, and results may differ with other orthodontic methods. The sampling methodology (paper cone absorption) may have limited sensitivity.

How to read the evidence

This is a very small pilot study (n=4) with qualitative rather than quantitative measurements. It provides preliminary evidence that generates hypotheses but cannot establish definitive conclusions about substance P's role in orthodontic treatment.

When this study was published

Published in 2013, this pilot study identified substance P in orthodontic GCF. Subsequent research has likely further explored neuropeptide involvement in orthodontic pain and inflammation.

The bigger picture

Substance P is one of the most studied neuropeptides in pain and inflammation research. This pilot study extends its known role to orthodontic treatment, adding to the evidence that tooth movement activates neurogenic inflammation mediated by peptides. Understanding these pathways could eventually lead to targeted pain management approaches for orthodontic patients, potentially using substance P receptor antagonists.

Questions still open

Does the amount of substance P released correlate with the degree of orthodontic force applied or the level of pain experienced?
Could substance P receptor antagonists reduce orthodontic pain without interfering with tooth movement?
Is substance P release different between clear aligners (Invisalign) and traditional bracket-and-wire orthodontics?

Common questions

What is substance P and why is it important in pain?

Substance P is a neuropeptide — a small protein made by nerve cells — that plays a central role in transmitting pain signals from the body to the brain. It is also a potent vasodilator (widens blood vessels) and promotes inflammation. When released in tissues, it contributes to the pain and swelling associated with injury or mechanical stress, such as the forces applied during orthodontic treatment.

Does this mean Invisalign causes more pain than other orthodontic methods?

Not necessarily. This study only looked at Invisalign and found substance P release, but substance P is likely released during any type of orthodontic tooth movement. The study did not compare Invisalign to traditional braces, so no conclusions about relative pain levels between methods can be drawn.

Read the original research

Changes of substance P in the crevicular fluid in relation to orthodontic movement preliminary investigation.

TheScientificWorldJournal, 2013, 896874

View on PubMed ↗Publisher’s paper ↗

Citation

Levrini, Luca; Sacerdote, Paola; Moretti, Sarah; Panzi, Silvia; Caprioglio, Alberto. (2013). Changes of substance P in the crevicular fluid in relation to orthodontic movement preliminary investigation.. TheScientificWorldJournal, 2013, 896874. https://doi.org/10.1155/2013/896874