Infections causing Trismus could be of odontogenic or non odontogenic in nature.Pain can also be caused due to excessive pressure affecting adjacent tissues and irritation of trigeminal nerve, which leads to masseteric muscle spasm causing Trismus.Chronic infections involving this supporting tissue may irritate free nerve endings causing masseteric muscle spasm.As with other dental infections pericoronitis also can cause reflex irritation of trigeminal nerve throwing masseter muscle into spasm causing Trismus.This is commonly caused by dental caries which manages to penetrate through the enamel and dentine of the teeth to reach the pulp.Dental infections if left unchecked can cause spread of infection into various neck spaces causing cervical cellulitis / mediastinitis.Non odontogenic infections causing Trismus:
These include tonsillitis, tetanus, meningitis, parotid abscess and brain abscessWhen Pulp becomes inflamed due to infections it causes excessive pressure build up within the Pulpal cavity causing dental pain.This causes excessive dental pain.