Name two common etiologic risk factors for TMD.

• A. Parafunctional habits (bruxism) and occlusal disharmonies.
• B. Recent antibiotic use and hydration levels.
• C. Excessive sun exposure and diet high in fiber.
• D. Vaccination history and sleep position.

Answer: (A)

Common etiologic risk factors for TMD involve how the jaw is used and loaded. Parafunctional habits like bruxism—grinding or clenching the teeth—place repeated, excessive forces on the temporomandibular joints and the surrounding muscles. This overload can lead to muscle pain, tightness, and changes in joint function, including disc displacement or joint noise. Occlusal disharmonies, meaning a bite that isn’t properly aligned, create uneven or abnormal loading of the TMJ and masticatory muscles. Over time, this can provoke pain, restricted movement, and dysfunction. Together, these mechanical factors are widely recognized as two of the most common and modifiable etiologic risk factors for TMD.

The other choices don’t fit as etiologic factors for TMD. Recent antibiotic use and hydration levels aren’t established drivers of TMD, and factors like sun exposure or a high-fiber diet don’t influence TMJ pathology. Vaccination history and sleep position aren’t considered core etiologic factors for TMD, though sleep position can affect symptoms rather than cause the condition.