The TMJ Trinity

The upper and lower jaw bones, the teeth, and the temporomandibular joints (TMJs) form the TMJ Trinity. These three structures have unique characteristics and are interrelated and dependent upon each other. As the word “trinity” implies, all three structures are equally important. This is not a “trilogy” of sequential or linear

importance, but a trinity of three equally interrelated dimensions of form and function.

Let me explain using an analogy: The Door.

It has three basic functional and structural parts: the hinges, the frame, and the lock (or doorknob). When all the parts are properly aligned and working well, the door can easily be closed with the gentle push of a finger. We all know of doors that do not work this way. You might have a door that you must lift the knob a little to make it close into its hasp, or a door with a “sticky frame” that requires a tug or push to open or close, or a door with noisy hinges that rattle or squeak. Would you expect a door with rusty or loose hinges to work better if you changed the lock or trimmed the frame? Of course not! Unless the hinges are stable, the correct position of the lock and frame is uncertain. Likewise, if the lock and/or frame are misaligned or “sticky,” the hinges will become stressed and strained until they bend, break, or become loose. The problem door remains a nuisance because it does not correctly open, shut, or lock.

So how is a door fixed to work well for a long time? By correcting one variable at a time. First, evaluate the hinges to ensure they are strong, stable, and well-aligned. Next, check the door in its frame. Plane it or adjust the trim so there are no “catches,” it is “squared,” and it closes evenly within the frame. Lastly, place the lock/doorknob so it is centered and aligned within its hasp. You should now be able to open and close the door with just a finger or two.

Just like the body, age will take its toll on a door. With time and use, the door may sag and become less easy to close or lock. The door becomes a slight nuisance because it must be lifted a little to close properly. This may not seem significant because it can still open and close, it just requires a little extra effort. But what happens over time? The hinges become stressed, the lock seems to get a bit worse, and the frame sticks. Sometimes when the weather is hot and humid, the door (especially wooden and fiberboard ones) will swell and become problematic, requiring an extra tug to open or close. Next season, when the air is dry again, the door may work “better” but not fully return to what it used to be. The point is that the door may require minor maintenance to keep it working well, but if neglected, future repairs become more complicated and expensive.

Also, and most importantly, each of the three parts of the door has its own individual qualities. Unless all three parts work harmoniously, there will be problems in one, two, or all three parts.

The Face. In reference to the door analogy, consider the TMJs as the hinges, the bite (meshing of the teeth) as the lock/doorknob, and the alignment between the upper and lower jaws as the way the door fits within its frame. Yes, there are other parts of the face such as the muscles, nerves, gums, and tongue. These structures are also important, but they usually have a secondary role relative to the TMJ Trinity.

Long-term facial and jaw functional stability depends upon proper alignment and structural health within the TMJ Trinity.

The overwhelming majority of TMJ disorders (dislocated discs, condylar degeneration, limited jaw opening, and joint noises) originate from dental malocclusions (bad bites) and misalignment (growth discrepancies) between the upper and lower jaws. In fact, a large percentage of malocclusions (what appears to be only a bad bite) are due to a combination of both irregular tooth position within bone and growth problems between the upper and lower jaws. The first symptoms that motivate people to seek help from a doctor are usually pain within the face, head, and jaws, or locking of the jaw. (Pain is a great motivator!)

As a surgeon, I am frequently consulted by people requesting that I evaluate their facial pain and jaw movement problems. I often tell these individuals that, as a surgeon, I am a good diagnostician and I can fix their TMJs so that their jaws can open, but that is not the total solution to their problem. Like the door, long-term success (function and stability) depends upon identifying and correcting the sources of their TMJ disorders: problems within their bones and bite. Indeed, most TMJ surgery would not be needed if there were proper bite and bone alignment/function. And again like the door, fixing the bite and bony problems cannot be expected to improve severe TMJ disorders. Instead, correction begins with fixing the hinges, then reevaluating and correcting the problems within the bite and bones.

As you now realize, diagnosing and correcting problems and disorders in the face may be complicated and time-consuming. Long-term success is predicated upon controlling one variable at a time with the goal of attaining stable TMJ function, bone alignment, and tooth position. This usually requires the combined skills and excellent communication between several dental specialists including the restorative dentist, orthodontist, and oral and maxillofacial surgeon. Each specialist provides a unique role in ensuring the optimal health of the TMJ Trinity.

Thank you for visiting Dr. Gallagher's Blog. We hope you found our articles informative and helpful on your journey to better oral and maxillofacial health. Our commitment is to provide you with the latest information and support, ensuring you feel confident and well-prepared for any procedure or treatment. If you have any questions or need further assistance, please don't hesitate to contact our office. Stay tuned for more updates, tips, and expert advice from Dr. Gallagher and his team. Your health and well-being are our top priorities.

Additionally, be sure to watch our YouTube channel, TMJ Tour, for detailed videos and insights on TMJ and other jaw-related conditions.