Local Anesthesia, Pain Management, and Endodontic Pharmacology
Achieving anesthesia in endodontics
The inferior alveolar nerve block fails more often in mandibular molars with irreversible pulpitis than in any other situation - reported failure rates are high. Inflammation lowers the threshold of nociceptors, upregulates sodium channels on nerve membranes and creates a local acidosis that traps the anaesthetic base in its ionised form. Repeating an identical block rarely helps; instead use a supplemental technique: buccal infiltration with articaine, intraligamentary injection, or intraosseous delivery. Articaine 4% has better bone diffusion than lidocaine 2%, which explains its use for buccal infiltration and its reported (debated) association with lingual nerve paraesthesia after blocks.
Safety and doses
Know maximum doses for a healthy adult: lidocaine 2% with 1:100,000 epinephrine about 4.4 mg/kg (roughly 7 cartridges), articaine 4% about 7 mg/kg, mepivacaine 3% about 6.6 mg/kg, bupivacaine 0.5% about 1.3 mg/kg. Epinephrine is limited to about 0.2 mg. Prilocaine and benzocaine can cause methemoglobinemia. True amide allergy is rare; most adverse reactions are psychogenic or vasovagal.
Analgesia and antibiotics
Preoperative NSAIDs (ibuprofen 400–600 mg) or a combination of ibuprofen and acetaminophen reduce postoperative pain; take the first dose before treatment. Opioids are rarely indicated. Antibiotics are not indicated for irreversible pulpitis or a localized abscess without systemic involvement; drainage and treatment provide definitive relief. Antibiotic prophylaxis is reserved for specific cardiac or immunocompromising conditions.
Rule of thumb: in a 'hot' tooth, change the technique, not the number of repeats - supplemental anesthesia plus a preoperative NSAID.