Irreversible Pulpitis

Irreversible pulpitis is severe inflammation of the dental pulp that cannot heal even when the stimulus is removed. It presents as spontaneous, lingering pain and is a very common cause of acute dental pain.

Two forms are described. Symptomatic irreversible pulpitis has spontaneous or lingering pain, and the asymptomatic form is found on examination of a deeply carious tooth without pain. Without treatment the pulp becomes necrotic and apical periodontitis follows.

Pathophysiology. Bacterial invasion of the pulp, or heavy mechanical injury, causes neutrophil infiltration and microabscess formation. Pressure rises in the rigid pulp chamber, compressing vessels and driving ischaemia.

C-fibre activation by inflammatory mediators produces dull, throbbing, poorly localised pain, and inflammatory mediators lower the activation threshold of nociceptors, which explains reduced response to local anaesthetic.

Severe pain that is spontaneous or provoked, throbbing, lasting minutes to hours, lingering for more than 30 seconds after hot or cold stimuli, and worse on lying down at night. The pain may be referred to the ear, temple or opposite jaw, and the patient may be unable to name the tooth.

Hot stimuli may aggravate and cold may relieve pain in late disease. The tooth may be tender to percussion when inflammation reaches the periodontal ligament. A deep cavity, large restoration, crack or recent trauma is usual.

Swelling, fever, trismus or difficulty swallowing indicates a spreading infection and needs urgent evaluation.

• Diagnosis is clinical, from the spontaneous or lingering pain and the response to testing.
• Cold test: an exaggerated response lingering for more than 30 seconds. Electric pulp test: responsive at a low reading. Heat test where needed to find the tooth.
• Percussion and palpation: tenderness in advanced disease. Mobility and probing to exclude periodontal disease.
• Periapical and bitewing radiographs: deep caries or restoration near the pulp, a normal periapical area or widened periodontal ligament space.
• Local anaesthetic test to find the source of pain when the tooth is unclear, with infiltrations or ligament injection in sequence.

Differential diagnosis.

• Reversible pulpitis
• Acute apical periodontitis and acute apical abscess
• Cracked tooth syndrome
• Maxillary sinusitis
• Trigeminal neuralgia and other neuropathic orofacial pain
• Pericoronitis and periodontal abscess
• Referred cardiac or temporomandibular pain
• Dry socket in a patient with a recent extraction

• Definitive treatment is removal of the inflamed pulp: pulpectomy with root canal treatment, full pulpotomy with a calcium silicate cement in mature teeth with selected cases (success about 85 to 95% at 1 to 3 years), or extraction.
• Emergency care: access cavity, pulp removal (pulpectomy) and a dressing of calcium hydroxide, under local anaesthesia, to relieve pain at once.
• Local anaesthesia:
  • Maxillary teeth and lower premolars and incisors: articaine 4% with adrenaline 1 in 100 000, 1.7 mL, buccal infiltration, repeated with a palatal injection (maximum articaine 7 mg/kg).
  • Mandibular molars: inferior alveolar nerve block with lidocaine 2% with adrenaline 1 in 80 000, 1.8 mL (maximum lidocaine with adrenaline 7 mg/kg to 500 mg), plus buccal articaine infiltration. When anaesthesia is inadequate give an intraligamentary or intraosseous supplement.
  • Adrenaline limit of 0.04 mg in significant cardiovascular disease, with an aspirating technique and slow injection.
  • Ibuprofen 400 to 600 mg orally 1 hour before treatment improves anaesthetic success.
• Analgesia until treatment: ibuprofen 400 mg every 6 to 8 hours with food (maximum 2400 mg daily, avoided in renal impairment, peptic ulcer, anticoagulant use and late pregnancy) together with paracetamol 1 g every 6 hours (maximum 4 g daily, 3 g in low weight, liver disease or alcohol excess). A short course of both for 48 to 72 hours is more effective than either alone.
• Antibiotics do not relieve pain from pulpitis and are not indicated without swelling or systemic spread.

Special groups. Pregnancy: treat in the second trimester when possible, use paracetamol, and use lidocaine with adrenaline in usual dental doses. Anticoagulated patients need the INR checked within 24 hours of invasive procedures, and local haemostasis.

Monitoring. Review 1 to 2 weeks after emergency treatment, complete the root filling and coronal seal, and take periapical radiographs at 6 and 12 months. Persistent pain after treatment suggests a missed canal, fracture or non-odontogenic cause.

Referral and escalation. Refer to an endodontist for calcified canals, a cracked tooth, failed treatment or complex anatomy. Emergency referral for spreading infection, trismus or airway threat.