The TMJ open‑mouth position is the maximal comfortable opening of the lower jaw where mandibular condyles rotate then translate forward onto the articular eminences, often moving relative to the articular disc. It’s used in assessment and rehabilitation of TMJ disorders. End‑range opening (about 35–50 mm interincisal) can strain the joint, ligaments and muscles and may cause pain, clicking, or locking.

Common radiographic views for temporomandibular joint assessment include panoramic (orthopantomogram) for overall anatomy; transcranial (lateral) views in closed and open mouth to evaluate joint space and mobility; axiolateral/transpharyngeal (oblique) views for condylar profile; and AP axial (Towne) or submentovertex projections for condylar fractures or position. CT or MRI is used when more detail is required.

The opening click occurs when the mandibular condyle moves over a displaced articular disc as the mouth opens; the closing click happens when the disc slips out of position again during mouth closure. These sounds stem from disc displacement with reduction or ligament laxity in the temporomandibular joint. They may be intermittent and painless, but persistent pain, locking, or limited opening needs professional evaluation.

Yes. Many people with temporomandibular joint (TMJ) problems can still open their mouths, though movement may be limited, painful, click, or lock intermittently. Severe cases can cause restricted opening ("closed lock") or occasional locking open. Resting the jaw, soft foods, gentle exercises, heat/ice, and over‑the‑counter pain relief often help; seek dental or medical assessment if symptoms persist.

The correct closed-mouth resting position: lips gently together, jaw relaxed with teeth slightly apart (a small “freeway” gap), and tongue resting against the roof of the mouth with the tip just behind the upper front teeth. Breathe through the nose, avoid clenching, and keep facial muscles relaxed. This posture supports nasal breathing, airway health, and proper jaw alignment.

Sit upright with head neutral. Ask the patient to open their mouth as wide as possible without pain. Measure the interincisal distance between the upper and lower central incisors with a ruler or caliper (mm). If there’s an overbite, subtract overlap. Record unassisted and, if needed, assisted opening. Normal range is about 35–55 mm; <35 mm suggests limited opening.