What could be causing jaw pain on the left side in an adult, possibly with a history of dental issues or Temporomandibular Joint (TMJ) disorders, that occurs only when opening the mouth?

Unilateral Left-Sided Jaw Pain with Mouth Opening

Your left-sided jaw pain occurring only with mouth opening is most likely temporomandibular disorder (TMD), which affects 5-12% of adults and is the most common non-dental cause of facial pain. 1, 2

Immediate Red Flags to Exclude

Before proceeding with TMD management, you must rule out life-threatening conditions:

• If you are over 50 years old, giant cell arteritis must be excluded immediately, as it can mimic TMD and cause irreversible vision loss if untreated. 1, 3, 2 Look for jaw claudication (pain with chewing that improves with rest), temple tenderness, scalp tenderness, visual changes, or new headaches. 2, 4 If any of these are present, obtain ESR and CRP within hours and start high-dose corticosteroids immediately. 2, 4

• Progressive worsening pain with any palpable mass requires urgent imaging within 1-2 weeks, as cancer can present as progressive facial pain. 1, 4

• Acute dental infection or abscess requires immediate dental intervention and cannot be managed without addressing the underlying pathology. 3, 5

Clinical Examination Findings to Assess

Your healthcare provider should specifically evaluate:

• Palpate the masseter and temporalis muscles bilaterally for tenderness, trigger points, and hypertrophy. 2 Manual trigger point therapy provides approximately twice the minimally important difference in pain reduction if trigger points are identified. 3

• Assess jaw opening range and quality of movement, listening for clicking, popping, or crepitus in the temporomandibular joint. 1

• Examine all teeth and oral structures for decay, mobile teeth, wear facets (indicating teeth grinding), and gum disease, as dental pathology is the most common acute cause of jaw pain. 1, 3

• Test all three branches of the trigeminal nerve for sensory changes, as numbness suggests neuropathic causes requiring different management. 2

Primary Treatment Pathway for TMD

Conservative management should be exhausted for at least 3-6 months before considering any invasive procedures. 3

First-Line Conservative Therapies

• Supervised jaw exercises and stretching provide approximately 1.5 times the minimally important difference in pain reduction and should be your primary physical intervention. 3

• Manual trigger point therapy by a physical therapist with TMJ expertise provides one of the largest reductions in pain severity. 3

• Patient education and self-management: Avoid jaw overloading activities (chewing gum, hard foods, wide yawning), maintain a soft diet, apply heat or cold therapy, and understand that improved self-efficacy leads to fewer symptoms. 1, 3, 2

• NSAIDs (ibuprofen, naproxen) are first-line medications for pain relief and inflammation reduction. 3, 6

Additional Pharmacological Options

• Muscle relaxants may help overcome muscle spasm when other approaches fail. 3, 6

• Neuromodulatory medications (amitriptyline, gabapentin) can be considered for chronic refractory pain lasting beyond 3-6 months. 3, 6

• Never combine NSAIDs with opioids, as this increases risks without clear additional benefits. 3

Critical Interventions to AVOID

• Occlusal splints (night guards) are conditionally recommended AGAINST despite their widespread use in dental practice, as evidence for effectiveness is limited. 3, 7 If your dentist recommends one, understand it should not be your primary treatment.

• Avoid irreversible procedures like permanent alterations to your bite or tooth structure, as these can cause irreparable harm. 3, 7, 6

• Discectomy (surgical disc removal) should be avoided. 3

• Do not proceed to invasive procedures before exhausting conservative options for at least 3-6 months. 3

Psychological and Comorbidity Considerations

TMD is strongly linked with depression, catastrophizing, anxiety, back pain, fibromyalgia, and other chronic pain conditions. 1, 2 These psychological factors significantly increase the risk of chronicity and must be addressed. 2, 4 Cognitive behavioral therapy (CBT) improves coping strategies and quality of life. 2, 6

When to Seek Specialist Referral

• Dentist first for evaluation and management if any dental pathology is suspected, as treating TMJ symptoms without addressing underlying dental issues will result in treatment failure. 3

• Physical therapist with TMJ expertise for manual trigger point therapy and jaw mobilization. 3

• Multidisciplinary team (oral and maxillofacial surgeons, orofacial pain specialists) if conservative treatments fail after 3-6 months. 3, 6

• Pain management specialist for intractable pain unresponsive to conservative interventions. 3

Alternative Diagnoses to Consider

If your pain pattern differs from typical TMD:

• Trigeminal neuralgia presents as paroxysmal attacks of sharp, shooting, electric shock-like pain lasting seconds to minutes, triggered by light touch, eating, or brushing teeth, with pain-free intervals between attacks. 1, 2, 4 This requires MRI imaging and treatment with anticonvulsants like carbamazepine or gabapentin. 1, 2

• Salivary gland stones cause intermittent pain characteristically occurring just before eating, with tender gland on palpation. 1, 4 Ultrasound imaging confirms diagnosis. 4

• Post-traumatic trigeminal neuropathic pain occurs within 3-6 months of dental procedures or trauma, presenting as continuous burning or tingling pain. 1, 8 This requires neuropathic pain medications. 1