What is Jaw Tracking?

by Nate Krey

Jaw Tracking is the ability to track mandibular movements.  This can be useful in function and in rest (and everywhere in between).  Some of the various tests done with jaw tracking are Range of Motion (ROM), Velocity, Freeway Space Measurement, Mastication and Speech Analysis.  ROM is important to determine a baseline for a patient as well as give us clues as to what might be wrong with a patient.  Restrictions and/or asymmetries can give us an inside into whether we are dealing with an intracapsular (inside the joint) or extracapsular (muscle or occlusal based) problem as well as be useful in determining maximum medical improvement to end treatment.  Maximum Opening, lateral excursions, and protrusions (which can be very useful for clinicians making sleep appliances) are usually measured in this test.  Deviations and deflections also give us an insight into what might be happening inside the patients jaw joint. 

Velocity is a test in which the patient is asked to move their jaw at certain speeds, much like a “stress test” in cardiology.  From this test we can see if the patient can reproduce a consistent pattern or if they produce “slow downs” or asymmetries that might lead us to believe there is a muscle or joint problem.  Freeway Space is used to determine if the patient has a normal physiologic rest position, if their teeth touch when they swallow (which can suggest a tongue thrust {which might be an airway issue}), what their closing trajectory looks like, and what we have to work with for “freeway space.” 

Mastication is the study of one of the most important things we do to survive…chewing.  People who have normal joints have normal chewing patterns.  People that chew their food efficiently have less digestion problems and are overall healthier than those who struggle to chew their food.  We study how effectively people chew their food and see if there are ways to improve their chewing.  This is also helpful in designing new dentistry.  If a person is having significant dentistry done, it is important to give them a more effective chewing scheme, just as important as it is to give them the esthetic result they desire.  Speech is also used for function and esthetics.

Jaw Tracking can also be used simultaneously with JVA so that we know when a disk is reducing or displacing.  Some believe that the earlier a disk recaptures, the easier it is to treat.  Next time, I will be talking what protocols to use to effectively implement JVA and Jaw Tracking!