In the world of TMD, cortical erosion most often refers to erosion and breakdown of the condyle (the top of the jawbone). It can also mean breakdown of the socket that holds the condyle. Basically, cortical erosion refers to a bony degeneration that occurs over time and this can lead to the condyles and joints being very prone to breakage eventually. This is why treating TMJ disorder should be done in a timely fashion- i.e. don’t wait!
In most cases, when the MRI is ordered of the TM joints, it is patently clear when there is cortical erosion of either the condyle or the fossa (socket for the condyle). The radiologist will most likely indicate that the articular disc (that protects the condyle) is displaced and thus the condyle is now exposed and is bone on bone in the fossa. This is not a good situation and can lead to all sorts of pain, asymmetry, and other problems in the head/neck region. Think of it like this: If the disc is slipped off the top of the condyle, it can no longer protect your condyle from banging into the socket bone-on-bone. Diagnosis: OUCH!
The cortical erosion of the condyles and fossas can also be diagnosed with the X-ray called CBCT (Cone-Beam Computed Tomography). The CBCT allows the dentist or the radiologist to look very precisely at the condyle and fossa and if erosion has begun it can be clearly seen in the images. Even though some people do not like taking the CBCT due to the radiation, it is really important to do these images every few years to follow up on the cortical erosions.
So, what does one do when cortical erosions are present? Well, in most cases it’s called ‘watchful waiting’ where the doctor checks the range of motion on a regular basis to make sure the erosions are not doing more obvious damage. You should wear your mouth appliance(s) accordingly to protect the joints. And every few years, just re-take the images and compare them to the previous images.
Unfortunately, if things worsen, surgery is sometimes all that is left to offer to a person with severely damaged joints. There are several types of surgery. The simplest surgery is called plication of the articular discs. This means just moving the slipped discs back into the proper position to reduce the risk of bone-on-bone damage to the condyle and fossa. The next level of surgery entails what is called menisectomy – removal of the damaged discs. If the discs are fully removed, this enhances the risk of bone-on-bone, condyle to fossa, banging or pounding. As long as the appliance (splint) is worn, this is not a problem. Unfortunately, if things get worse, then TJR (Total Joint Replacement) is indicated. This is a big surgery but very rarely indicated.
As with most health issues: Treat early and keep a careful watch on your health!