Occlusion and Temporomandibular Disorders
Occlusion and temporomandibular disorders tests whether you can distinguish normal adaptation from pathology and choose reversible care. The board emphasizes centric relation, occlusal interferences, and DC/TMD-style diagnosis.
Core rules
- Centric relation is a condyle-to-fossa position, not a tooth contact; maximum intercuspation is a tooth-defined position.
- A clinically useful CR record uses an anterior-superior condylar position with a light, unforced arc.
- Interferences in CR, working, or nonworking side can produce instability, but not every interference causes TMD.
- TMD diagnosis includes myalgia, arthralgia, disc displacement with or without reduction, and degenerative joint disease.
- First-line care is conservative: education, self-care, splint therapy, and physical therapy; avoid irreversible occlusal grinding without a clear diagnosis.
Worked example
A patient has a reproducible click on opening and closing, no pain, and normal opening. The likely diagnosis is disc displacement with reduction. Reasoning: reciprocal click and normal range fit that category; imaging is not routine; conservative care and monitoring are appropriate.
Traps
Equating a click with a need for equilibration is a common error. Grinding all teeth to CR without records can worsen function. Missing limited opening or deviation suggests disc displacement without reduction. Ignoring sleep bruxism and medication effects leads to failed splint therapy. Treating pain as purely occlusal overlooks myofascial and psychosocial factors.