One of the most common questions that every patient diagnosed with TMD will have is “What is the difference between TMJ and TMD?”. Many patients wonder because these terms have been used interchangeably in many forums, even by medical professionals. Let us look at the answers.
What does TMJ Stand For?
For those short on time, the short answer is that the acronym refers to the Temporomandibular Joint.
Open your jaw all the way and shut it. This simple movement would not be possible without the Temporomandibular joint (TMJ). This is the most complex and most frequently used joint in the human body. It is located in front of each of your ears, where your skull and lower jaw meet. On average, it opens and closes 10,000 times a day!
To understand where the joint is located, put your finger on the triangular structure in front of your ear. Then move your finger just slightly forward and press firmly while you open your jaw all the way and close it. You can also feel the joint motion in your ear canal.
TMJ is a hinge and gliding joint that connects the lower jaw (mandible) to the temporal bone of the skull. The round upper end of the lower jaw (the movable part of the joint) is called the condyle. The socket (the fixed part) is called the articular fossa. Each TMJ has a disc made of cartilage between the ball and socket. The disc cushions the load and absorbs the stress while enabling the jaw to open widely and rotate or glide.
TMJ is basically a complex system of muscles, ligaments, discs and bones working in coordination to perform several important functions. The joints on each side are essential for chewing, speaking, yawning swallowing and opening or closing of jaw. When you bite down hard, you put force on the object between your teeth and on the joint. In terms of physics, the jaw is the lever and the TMJ is the fulcrum. When that joint has issues such as deterioration, arthritis, inflammation or is not properly aligned it may result in what the medical community refers to as TMD or TMJD. It is the only joint in your body designed to bring bone (teeth) to meet another bone (teeth) without any padding (cartilage).
What does TMD Stand For?
TMD is the acronym used by the medical community to refer to a temporomandibular joint disorder, temporomandibular joint syndrome or temporomandibular joint dysfunction. Some trained treatment providers will also refer to this as TMJD which would be the most specific and medically correct acronym. We have found that is the least used by dentists and least searched term by patients.
Temporomandibular disorders (TMD) occur as a result of problems with the jaw, the jaw joint and surrounding facial muscles that control chewing and moving the jaw.
The Temporomandibular Joint is different from the body’s other joints. The combination of synchronized as well as three-dimensional movements of the paired joints distinguishes them as the most complicated joints in the body. They also differ in biological composition from other weight-bearing joints, like the hip or knee.
Due to its complex movement and unique makeup, the jaw joint and its controlling muscles can pose a tremendous challenge to both patients and treatment providers like neuromuscular TMD dentists when problems arise. While symptoms normally come from one side of the jaw both joints may be involved. Depending on the severity, TMD symptoms can affect a person’s ability to speak, chew, swallow, make facial expressions, and even breathe adequately at night.
Temporomandibular disorders are often incorrectly called TMJ, which actually stands for Temporomandibular Joint. Part of the reason for the confusion between the two terms is that they are often used interchangeably by both doctors and patients.
In actuality, TMJ refers only to the jaw joints themselves and TMD to the pain and disorders occurring from TMJ issues. However it can become even more confusing for people with a TMJ issue as it is rarely referred to as MPD.
What is Myofacial Pain Dysfunction (MPD)?
TMD falls in 3 main categories depending on the part affected:
- Muscles (Masseter, Temporalis, Medial and Lateral Pterygoid muscles)
- Internal derangement of joint (displaced disc, dislocated jaw, condyle injury)
- Arthritis (degenerative/ inflammatory disorders)
TMD problems where the muscles are affected leading to pain and discomfort are classified as Myofacial pain dysfunction (MPD).
Classic features of MPD are as follows
- Pain in the jaw, temples, face, pre-auricular area, or inside the ear at rest or during function.
- Pain in response to palpation of three of the following muscle sites: posterior temporalis, middle temporalis, anterior temporalis, origin of masseter, insertion of masseter, posterior mandibular region, submandibular region, lateral pterygoid area, and tendon of the temporalis;
- At least one of the painful sites is on the same side as the pain.
However in a broader sense, Myofacial Pain Dysfunction (MPD) refers to the muscle pain related to TMD. It refers to pain and inflammation in the body’s soft tissues. It is a chronic condition that affects either a single muscle or a muscle group.
(“Myo” is the prefix that refers to muscle, and the fascia are the layers of connective tissue that surround the muscles.)
WHAT ARE THE VARIOUS SYNONYMS FOR TMD?
The list of synonyms for TMD is extensive and confusing. But ultimately they all refer to disorders of the Temporomandibular Joint system. The various terms used interchangeably with TMD (Temporomandibular Joint Disorder) are as follows:
- TMJD (Temporomandibular Joint Dysfunction)
- TMDS (Temporomandibular Joint Disorder Syndrome)
- FAM (Facial Arthromyalgia)
- MPD (Myofacial Pain Dysfunction)
In addition to these terms, there are many other examples like:
- Temporomandibular joint pain dysfunction syndrome;
- Temporomandibular joint syndrome;
- Temporomandibular dysfunction;
- Temporomandibular syndrome;
- Craniomandibular dysfunction;
- Masticatory myalgia;
- Mandibular dysfunction
Sometimes the preferred terms are influenced by geographic location like
- in the United States, the term “TMD” is preferred
- in UK, the term “Pain Dysfunction Syndrome” is commonly used
An older name for TMD is “Costen’s syndrome” referring to Dr. James B. Costen, an otolaryngologist, who wrote extensively on the topic, starting in 1934, and was the first to approach the disorder in an integrated and systematic way. This approach was later later adapted by Dr. Bernard Jankelson, who many credit as the innovator in Neuromuscular dentistry.
TMD is a painful, frustrating and limiting condition. Hence it is important that you consult with a TMD dentist since they have an appreciation and special post dental school training of proper physiologic function of both hard and soft tissues e.g. jaw and muscles and can help you manage the condition and apply proper treatment.