Jaw Deviation on Opening
Watch yourself open slowly in a mirror. The midline of your lower teeth should travel more or less straight down. If it swings off to one side, that path is telling you something specific about which side is restricted and whether the restriction is releasing.
Deviation and deflection are different signs
Deviation means the jaw veers off centre partway through opening and then returns to the midline at full opening — typically an S-shaped path. It usually indicates a disc on one side that is temporarily obstructing until it recaptures. Deflection means the jaw moves off centre and stays there at full opening, which suggests a restriction on that side that is not releasing at all.
Which side is the problem
As a general rule the jaw moves toward the restricted side, because the unrestricted side continues to translate forward while the restricted side cannot. A jaw that deflects consistently to the left at full opening points toward a left-side restriction. This is a rule of thumb rather than a diagnosis, and it is interpreted alongside the rest of the examination.
Why the path is worth documenting
The opening path is one of the few TMJ signs you can observe and track yourself. A deviation that becomes a deflection is a meaningful change — it suggests a disc that was recapturing has stopped. Noticing that shift early is genuinely useful, because early closed lock responds better than established closed lock.
Common questions
- Is a small deviation normal?
- Minor variation in the opening path is common and not automatically a problem. A consistent, obvious deviation — especially with joint noise, pain, or reduced opening — is worth having examined.
Not sure where to start?
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Book An AppointmentRelated Care
All TMJ Conditions- Locked JawA jaw that catches, or will not open or close.
- Limited OpeningReduced range before pain or a hard stop.
- BruxismClenching and grinding, awake or asleep.
- Clicking & PoppingJoint noise, with or without pain.
- Disc DegenerationWear and displacement inside the joint.
- Jaw TightnessMuscles that never fully release.