This document discusses measuring a patient's temporomandibular joint (TMJ) range of motion as part of a new patient exam. It recommends recording three opening movements (comfort, active, passive) which takes 20 seconds, and lateral and protrusive movements, adding another 40 seconds. Normal ranges are provided. The TheraBite range of motion scale is placed on the lower incisors to measure opening, and on the upper incisors for lateral and protrusive movements. Recording baseline TMJ measurements takes under a minute but provides important future reference if jaw issues arise.

1. TMJ MOTION MEASUREMENTS
Dr Maher FOUDA

2. Reference:

3. TMJ Muscle
Range of
Motion
Measurements
A patient’s
range of
motion
measurements
should be
recorded as
part of every
new patient
exam.

4. TheraBite range-of-motion
(ROM) scale. When measuring
mouth opening, the notch at
the lower left portion of the
scale is stabilized on the
superior aspect of the lower
incisors. Once stabilized, the
instrument is rotated up toward
the inferior aspect of upper
incisors until contact is made
between the scale and the
upper incisors. The instrument’s
scale is then read and the
opening range obtained.

5. This adds anywhere
from 20 seconds to a
new patient exam if you
only record the three
opening movements,
which are “comfort,
active, and passive.” If
you measure right and
left lateral and
protrusive movements,
you might be adding 60
seconds to your exam
time. Yes, it’s that quick

6. Normal Range
of Motion
Opening: 40 to
60 mm. If a
patient opens to
55 mm with
either the
comfort or
active opening,
there is no need
to obtain the
Passive
opening.

7. Additionall
y, do not
have a
patient
open past
60 mm
and do not
push a
patient
open past
60 mm.

8. If they can
open to 60
mm or you
can push
them to 60
mm, then
they have an
excellent
opening range
of motion.
Lateral: 8 to
12 mm
Protrusive: 8
to 12 mm

9. Place the notch of the
range of motion scale
on the midline of the
mandibular
centrals, and take the
following three
measurements:
Comfort: ask the
patient to open
“comfortably without
pain.”
Opening Movements

10. Active: ask the patient to
open as wide as they can
even if it hurts.
Passive: with the patient in
the Active opening, the
doctor then pushes the
patient open using their
thumb on the maxillary
centrals and the index or
middle finger on the
mandibular centrals
Opening Movements

11. With the arrow of
the range of motion
scale centered on
the maxillary
centrals, have the
patient move to the
left by tapping the
mandible on the
left, which causes
the patient to move
to the side that you
are tapping.
Lateral Movements

12. Measure the
distance
traveled. Rep
eat this for
the right side
by tapping
the right side
of the jaw.
Lateral Movements

13. Protrusive
Movement
Fold the range of motion
scale in half at the black
triangle on the lateral scale.
Measure the overjet, then
ask the patient to move their
jaw forward “like a bulldog”
and measure that number.
Record those two numbers
as separate numbers such as
“2+8” so that you know the
overjet plus how far they can
protrude forward from their
centric occlusion.

14. Protrusive
Movement
Note in your chart if any
of the movements cause
pain and if any of the
movements replicate
their jaw pain. If a
movement does cause
pain, have the patient
point with one finger
where the pain occurs.

15. Protrusive
Movement
If the patient ever has
a future problem with
opening and/or
moving their jaw, you
now have a baseline
of what their normal
movements are. Do
you think it is worth
spending up to one
additional minute of
your time to record
these measurements?

16. Protrusive
Movement
You will if you
ever have a
patient who
has a problem
especially if
they think you
created it with
an injection or
by keeping
them open too
long.