You’ve worn a mouthguard to protect your teeth. An instrumented mouthguard does that too — but it also carries miniature sensors that record what happens to your head every time you take a hit.
The basics
A standard mouthguard is a custom-fitted piece of polymer that absorbs some of the force when your jaw is struck and stops your teeth from chipping or your tongue from being bitten. It does very little to protect your brain.
An instrumented mouthguard (often shortened to “iMG”) adds two small sensors into that same polymer:
- A triaxial accelerometer, which measures how fast your head is speeding up in three directions.
- A triaxial gyroscope, which measures how fast your head is rotating in those three directions.
Together they record what biomechanists call 6-DOF kinematics — six numbers per timestamp that describe everything your head is doing during the milliseconds around an impact.
Why mount it on the teeth, of all places?
The upper jaw is fixed rigidly to the skull, so a sensor mounted there moves with the brain. The same is not true of helmets, skin patches, or earpieces — those can shift during a tackle and produce misleading numbers. This is why World Rugby and the Rugby Football League now recommend or require iMGs in elite trials and pilot programmes, and why outlets like the BBC have been reporting on early adopters across rugby union, women’s rugby, and football academies.
What they look like in use
During a match, the iMG records every event in which the head exceeds a small acceleration threshold (typically around 5 g). Each “event” is a window of about 100 ms of high-frequency data. That window — its peak acceleration, its rotational velocity, its overall shape — is what tools like trace* then translate into a per-region brain-strain estimate.
Recordings are either streamed in near real-time to a touchline tablet or downloaded after the match.
What an iMG cannot do (yet)
- It does not diagnose concussion. Two players can take similar hits with very different outcomes. The mouthguard tells you how hard the head was loaded; whether that load caused injury is a clinical question.
- It does not tell coaches when to remove a player — though many programmes use threshold alerts as a prompt to check, never as a decision in themselves.
- It misses indirect head loading from whiplash unless the impact is sharp enough to cross the trigger threshold.
The point of an iMG isn’t to replace the medics on the touchline. It’s to give them, the coach, the parent, and the athlete an objective record of what the head has experienced — match by match, season by season, career by career.
Sources & further reading
- BBC — Smart mouthguards in rugby (2023).
- World Rugby — Instrumented mouthguard specifications.
- Jones, B. et al. (2022) — Ready for impact? A validity and feasibility study of instrumented mouthguards. British Journal of Sports Medicine.
- Jones, C. et al. (2023) — Validation of the Protecht instrumented mouthguard. Sensors 23 (16), 7068.