What is the recommended injection site for local anesthesia during a lower incisor tooth extraction?

Local Anesthesia for Lower Incisor Extraction

For lower incisor tooth extraction, use bilateral mental/incisive nerve blocks with 4% articaine (with 1:100,000 epinephrine), injecting 0.6-1.2 mL per side at the mental foramen, supplemented with labial and lingual infiltration if needed. 1, 2

Primary Injection Technique

Mental/Incisive Nerve Block

• Locate the mental foramen (typically between the first and second premolars, approximately 1 cm above the inferior border of the mandible) and inject at this site 1
• Use 4% articaine with 1:100,000 epinephrine as it provides significantly higher success rates (32.5% for lateral incisors, 55% for canines) compared to 2% lidocaine for anterior mandibular teeth 1, 2
• Administer 0.6-1.2 mL per side for bilateral mental nerve blocks 1
• This technique avoids the complications of inferior alveolar nerve blocks (lower success rates, risk of aspiration, nerve injury) while providing adequate anesthesia for extraction 3

Supplemental Infiltration

When Mental Block Alone is Insufficient

• Add buccal (labial) and lingual infiltrations in the mandibular incisor region, as combining infiltrations significantly increases success rates 2
• The infiltration technique works effectively in the anterior mandible due to the thinner cortical bone and proximity to the mental foramen 2, 4
• Use the same 4% articaine solution for infiltration, as it is more effective than 2% lidocaine for mandibular infiltration 2

Dosing and Safety

Maximum Dose Calculations

• Adults: Maximum 7.0 mg/kg of articaine with epinephrine (4% articaine = 40 mg/mL) 5, 6
• Children: Maximum 7.0 mg/kg with epinephrine (reduce by 30% if under 6 months of age) 5, 6
• For a typical lower incisor extraction using bilateral mental blocks plus infiltration, total volume rarely exceeds 3-4 mL (120-160 mg), well below toxic thresholds for most adults 6

Critical Safety Measures

• Aspirate before each injection to avoid intravascular administration 5, 6
• Use incremental injections rather than bolus dosing 5, 6
• Lower doses in highly vascular areas due to increased systemic absorption 5, 6

Expected Onset and Duration

• Onset: Articaine provides faster onset than lidocaine for anterior teeth (typically within 3-5 minutes for mental block) 1
• Duration: Expect 10-20 minutes of pulpal anesthesia for incisors with mental block alone, though soft tissue anesthesia lasts approximately 4 hours with 4% articaine 7, 1
• If the procedure extends beyond 10 minutes, supplemental infiltration will be necessary 1

Common Pitfalls and How to Avoid Them

• Avoid relying solely on inferior alveolar nerve block for lower incisors, as it has lower success rates and unnecessary risks for this procedure 3
• Do not use 2% lidocaine when 4% articaine is available, as articaine is significantly more effective for mandibular anterior teeth 1, 2
• Do not forget lingual infiltration if the mental block alone proves insufficient, as bilateral infiltration (buccal and lingual) dramatically improves success 2
• Monitor for early toxicity signs including circumoral numbness, facial tingling, metallic taste, and slurred speech 5, 6