Why is the physiologically correct position in centric relation the most superior position in the joint space itself?
Now, if you're like me and you went through dental school earlier, maybe 20 years ago, you were probably taught that centric relation was actually a distalized position of the condyles.
It was a very frustrating experience not only for the dentist, but also for the patients because you're trying to put the mandible and the condyle into a very unnatural position.
Think about these three things:
- The anatomy of the condyle
- Centric relation as being a healthy, normal condyle disc assembly seating axillary fully into the glenoid fossa
- The triangulization as we move to the medial aspect of the glenoid fossa
Now if you think about the joint anatomy and the joint being distalized, there are no muscles to the distal temporomandibular joint. The only way that it can get there is through force, and the only way that it can be distalized is the condyle needs to move downward and backwards from that superior axillary seated position within the joint itself. So a distalization is just simply not possible unless it's forced.
When we think about seating the condyle in centric relation, we want to be using bimanual manipulation to make sure that the fingers are providing a force in the long axis of the condyle that seats the joint or condyle up in the glenoid fossa, and then using our thumbs to provide that torquing motion as we turn that doorknob to fully seat the condyle up into the glenoid fossa.
So anatomically, the only position that makes perfect sense is that most superior aspect of the glenoid fossa as the condyle seats into centric relation.
I hope that helps you as you start to three-dimensionally think about the joint in the future, and I look forward to seeing you down the road.
To learn more about the TMJ and joint disorders, consider the course Functional Occlusion - From TMJ to Smile Design and TMD Patients: Diagnosis and Treatment.
Photo Credit: BiteFX