The four stages of Temporomandibular Joint (TMJ) internal derangement, as described in a progressive model, are as follows:
Stages of TMJ Internal Derangement
Internal derangement of the TMJ is often considered a progressive condition. It's commonly categorized into four stages that describe the progression of disc displacement. These stages help clinicians understand the extent and nature of the problem. The four distinct stages are:
| Stage | Description |
|---|---|
| 1 | Disc displacement with reduction: The disc is displaced when the jaw is closed, but it returns to its normal position when the mouth is open. |
| 2 | Disc displacement with reduction and intermittent locking: The disc reduces with jaw opening, but the jaw may intermittently lock. |
| 3 | Disc displacement without reduction: The disc is displaced and no longer returns to its normal position when the jaw is opened. |
| 4 | Disc displacement without reduction and degenerative joint changes: The displaced disc is accompanied by degenerative changes in the joint. |
These stages represent a progression of the condition, with early stages being less severe and generally more treatable. It is important to note that not all individuals progress through each stage.
- Stage 1 (Disc Displacement with Reduction):
- The articular disc is displaced when the jaw is closed.
- During jaw opening, the disc returns to its normal position, often with a clicking sound.
- Stage 2 (Disc Displacement with Reduction and Intermittent Locking):
- Similar to stage 1, the disc is displaced when the jaw is closed, and it reduces upon jaw opening, often with a clicking sound.
- In this stage, the patient begins to experience intermittent locking of the jaw.
- Stage 3 (Disc Displacement Without Reduction):
- The disc is displaced when the jaw is closed, and it does not return to its normal position during jaw opening.
- This lack of reduction causes limitations in jaw movement.
- Stage 4 (Disc Displacement Without Reduction and Degenerative Joint Changes):
- Similar to stage 3, the disc remains displaced.
- In addition, degenerative changes within the joint begin to appear, such as osteoarthritis.
Understanding these stages helps in diagnosing and planning treatment for TMJ disorders. Progression through these stages can be influenced by various factors and may not be linear.
