Diagnostic Code 9909 · 38 CFR §4.150
The coronoid process is a thin, triangular projection at the top front of each side of the mandible (lower jaw). The temporalis muscle — one of the main muscles that closes your jaw — attaches to the coronoid process. Losing this structure weakens the mechanical leverage of the temporalis muscle, reducing your bite force and making chewing less effective. Veterans may lose the coronoid process from combat trauma, blast injuries, jaw fractures, or surgical removal due to tumors or to treat jaw ankylosis (fusion). The VA rates this condition based on whether the loss is on one side (unilateral) or both sides (bilateral), since bilateral loss affects more chewing function.
| Rating | Criteria |
|---|---|
| 20% | Bilateral (both sides) loss of the coronoid process. Loss on both sides reduces the attachment points for both temporalis muscles, significantly weakening bite force and chewing ability. |
| 10% | Unilateral (one side) loss of the coronoid process. Loss on one side reduces the attachment for one temporalis muscle. Some bite force reduction occurs but the opposite side partially compensates. |
CT scans or panoramic X-rays showing the absence of the coronoid process on one or both sides are essential. Surgical records documenting the cause of the loss — combat injury, fracture, tumor removal, or surgical coronoidectomy — are needed. Service treatment records establishing the in-service cause are required. If the loss was from a coronoidectomy to treat jaw ankylosis, include the records of the underlying condition and its service connection.
A coronoidectomy is the surgical removal of the coronoid process, sometimes performed to treat jaw ankylosis (fusion of the jaw joint) or to relieve restricted jaw opening caused by the coronoid process impinging on surrounding structures. If this surgery was performed to treat a service-connected jaw condition, the resulting bone loss is service-connected as well.
The condyloid process (rated under DC 9908) is the rounded knob that forms the TMJ — the actual jaw joint. The coronoid process (DC 9909) is a separate projection where the temporalis muscle attaches. They serve different functions: the condyloid process enables jaw movement, while the coronoid process provides leverage for bite force.