Light Therapy Relieves Tooth Sensitivity by Reducing Substance P in Dental Nerves | Research

The takeaway

Photobiomodulation (light therapy) at both 660nm and 808nm reversed dentin hypersensitivity in rats by reducing substance P expression, suppressing glial activation, and promoting tissue repair.

Complete reversal of sensitivity in 3 sessions
Both 660nm and 808nm PBM eliminated acid-induced dentin hypersensitivity by reducing substance P

What the researchers found

PBM at 660nm and 808nm reversed dentin hypersensitivity by reducing substance P in the dentin-pulp complex and trigeminal ganglia, suppressing glial activation (GFAP), and increasing osteopontin expression for tissue repair.

Why it matters

Dentin hypersensitivity affects up to 57% of the population. Understanding that light therapy works by reducing pain-neuropeptide signaling and promoting repair — not just symptom masking — validates its use as a mechanistic dental treatment.

The numbers in context

660nm and 808nm; 1J, 3.5 J/cm2, 100mW, 10s, 3 sessions; SP reduced in pulp + TG; GFAP reduced; OPN increased at 14d

How the study worked

Rat model: 45-day acidic isotonic drink ingestion to induce dentin hypersensitivity. PBM: 660nm or 808nm, 1J, 3.5 J/cm², 100mW, 10s, 3 consecutive daily sessions. Nociceptive behavior assessed at 24h, 48h, 72h, and 14 days. Immunohistochemistry for substance P, GFAP, and osteopontin.

Who was studied

Rats with isotonic drink-induced dentin hypersensitivity

What this study cannot tell us

Rat model — dental anatomy and pain processing differ from humans. Single acid exposure model may not represent all clinical causes of dentin hypersensitivity. Specific laser parameters may need optimization for human clinical use.

How to read the evidence

Well-designed preclinical study with behavioral, immunohistochemical, and molecular outcome measures. Provides strong mechanistic evidence for PBM in dental pain.

When this study was published

Published in 2021, advancing understanding of photobiomodulation's mechanisms in dental pain management.

The bigger picture

Photobiomodulation is increasingly used in dentistry but its mechanisms have been poorly understood. This study shows it works through specific neuropeptide and glial pathways, providing a scientific foundation for clinical protocols and opening possibilities for treating other pain conditions involving substance P.

Questions still open

Does photobiomodulation reduce substance P in human dental tissues?
What are the optimal laser parameters for treating dentin hypersensitivity in patients?
Could PBM's substance P-reducing mechanism be exploited for other painful conditions?

Common questions

How does laser therapy help with sensitive teeth?

This study shows it works by reducing substance P — a pain-signaling molecule — in both the tooth and the nerve ganglion that processes dental pain. It also calms supporting nerve cells and promotes repair processes in the tooth. This means it's treating the underlying cause, not just masking pain.

Which type of laser is better for tooth sensitivity?

Both red (660nm) and near-infrared (808nm) lasers were equally effective in this study, completely reversing tooth sensitivity within 3 treatment sessions. Both wavelengths reduced substance P and promoted tissue repair through the same mechanisms.

Read the original research

Involvement of substance P, osteopontin and satellite glial cells on photobiomodulation-induced antinociceptive effect in an experimental model of dentin hypersensitivity.

Lasers in medical science, 36(6), 1297-1305

View on PubMed ↗Publisher’s paper ↗

Citation

de Oliveira, Victhor Teixeira; Ferrara-Jr, João Ignácio; Matielo, Heloísa Alonso; da Silva Alves, Adilson; Britto, Luiz Roberto; Aranha, Ana Cecilia Corrêa; Dale, Camila Squarzoni. (2021). Involvement of substance P, osteopontin and satellite glial cells on photobiomodulation-induced antinociceptive effect in an experimental model of dentin hypersensitivity.. Lasers in medical science, 36(6), 1297-1305. https://doi.org/10.1007/s10103-021-03246-9