Trismus after block (trauma/infection risk not managed)
What it is
After a mandibular block (especially inferior alveolar nerve block, IANB), the patient develops trismus (restricted mouth opening / "lockjaw"). The clinical mistake is to: • Not recognize it early • Not treat it symptomatically (pain control + heat + jaw exercises) • Miss infection/hematoma red flags • Give poor advice (patient stops moving the jaw → stiffness persists) Trismus can occur when the medial pterygoid (most commonly) is traumatized or irritated during IANB.
Why it happens
Mechanisms repeatedly described in dental anesthesia literature: • Intramuscular needle penetration/trauma → muscle spasm and pain-limited opening (commonly medial pterygoid) • Intramuscular hematoma in the pterygomandibular space → irritation/spasm • Multiple injections in the same region within a short time • Technique errors (wrong needle positioning) and, less commonly, low-grade infection
The full clinical mistake entry includes
- How to avoid it — the prevention protocol
- The clinical tip experienced clinicians use
- The documented reference behind the mistake
More clinical mistakes
Dentalverse is an educational resource for dental students and dentists. This page is a study reference — it is not medical advice and does not replace clinical judgment. Always follow your institution's protocols and your supervisor's guidance.