What is an example of microtrauma causing TMD?

• A. Bruxism
• B. Overloading the joint during heavy chewing
• C. Parafunction or poor posture
• D. High-impact trauma to the jaw

Answer: (C)

Microtrauma comes from repetitive, submaximal forces over time that accumulate and irritate TMJ structures and the jaw muscles rather than from a single, high-energy event. Parafunction (nonfunctional clenching, grinding, or other habitual jaw positions) and poor posture create ongoing, abnormal loading and sustained muscle activity, which steadily stresses the TMJ and surrounding tissues. Over weeks to months, this repeated strain can lead to pain, joint dysfunction, and disc or muscle changes characteristic of TMD.

In contrast, a high-impact trauma to the jaw is a macrotrauma—an acute, single injurious event—and heavy chewing, while potentially contributing to strain, often represents episodic loading rather than the continuous, low-grade stress that defines microtrauma. Bruxism is a parafunctional habit and fits the microtrauma mechanism, but the broad category of parafunctional activity or poor posture best exemplifies the repetitive, small-scale stresses that drive microtraumatic changes in TMD.