Reduced oral aperture and mandibular mobility/trismus are relatively common conditions that can be encountered in patients attending general dental practice, community dental practice and district general or dental teaching hospitals. All dental specialties may see patients with these conditions, and regardless of which environment or specialty, both patient and clinician may experience significant problems. The purpose of this opinion-based paper is to identify and review the causes of such conditions, to review the development of problems encountered for patients and clinicians, and to identify options to treat or manage the conditions.