Among the listed factors, which is often linked to TMD due to repetitive jaw use or parafunctional activity?

• A. Posture
• B. Occlusion
• C. Parafunction
• D. Stress

Answer: (C)

The main concept being tested is that parafunctional activity—repetitive or nonfunctional use of the jaw—frequently contributes to temporomandibular disorder. When the jaw muscles are repeatedly activated or held in a clenched, grind-like state, especially during sleep or stress, the constant load leads to muscle fatigue and hyperactivity, and places abnormal stress on the TMJ. Over time this can cause pain, tenderness, headaches, and dysfunction such as limited opening or disc-related symptoms. Parafunction is the word that specifically describes these repetitive, nonessential jaw activities like bruxism (grinding) and clenching, which is why it best explains the link to TMD. While posture, occlusion, and stress can influence TMD risk, they don’t capture the repetitive jaw-use mechanism as precisely as parafunctional activity does.