Local Anesthesia in Oral Surgery - According to Stanley F. Malamed

Overview

1. Local Anesthetic Agents

Classes

• Amide type (all modern agents): Lidocaine, Mepivacaine, Prilocaine, Articaine, Bupivacaine, Ropivacaine
• Ester type (largely obsolete): Procaine, Tetracaine

Key agents per Malamed:

Maximum Recommended Doses (MRD)

• Lidocaine: 4.4 mg/kg (max 300 mg = 8.3 cartridges)
• Mepivacaine: 4.4 mg/kg (max 300 mg)
• Articaine: 7.0 mg/kg (max 500 mg = 13 cartridges)
• Bupivacaine: 1.3 mg/kg (max 90 mg)

2. Vasoconstrictors

• Epinephrine (1:50,000, 1:100,000, 1:200,000) - most potent, most effective
• Levonordefrin (1:20,000) - used with mepivacaine

3. Maxillary Injection Techniques

3.1 Supraperiosteal (Local Infiltration)

• Needle: 25 or 27 gauge short
• Technique: Insert at mucobuccal fold adjacent to target tooth, bevel toward bone, advance to apex
• Volume: 0.5-1.0 mL
• Use: Single tooth anesthesia for the maxilla

3.2 Posterior Superior Alveolar (PSA) Nerve Block

• Anesthetizes: Maxillary 3rd, 2nd, 1st molars (excluding MB root of 1st molar in ~28% of patients), overlying buccal periodontium and mucosa
• Needle: 25 or 27 gauge short
• Insertion: Mucobuccal fold over maxillary 2nd molar, needle directed superiorly, posteriorly, and medially at 45° angles
• Target: Pterygomaxillary space
• Depth: 16 mm
• Volume: 0.9-1.8 mL
• Aspiration rate: 3.1% (highest of any maxillary injection - risk of pterygoid venous plexus)
• Complication: Hematoma in infratemporal fossa

3.3 Anterior Superior Alveolar (ASA) / Infraorbital Nerve Block

• Anesthetizes: ASA + MSA nerve distributions (maxillary incisors, canines, premolars, buccal soft tissue, lower eyelid, nose, upper lip)
• Needle: 25 gauge long
• Target: Infraorbital foramen (located 6-10 mm below infraorbital rim)
• Volume: 0.9-1.2 mL

3.4 Anterior Middle Superior Alveolar (AMSA) Block

• A Malamed-described technique using a single palatal injection
• Anesthetizes maxillary premolars through central incisors from palatal approach
• Delivered via computer-assisted anesthetic device (e.g., Wand/STA system)
• Advantage: No facial numbness - ideal for aesthetic procedures

3.5 Palatal Injections

4. Mandibular Injection Techniques

1. The cortical plate of mandibular bone in adults is very dense
2. The IA nerve must be located in soft tissue before it disappears into the mandibular foramen - this is a "blind" injection

4.1 Inferior Alveolar Nerve Block (IANB) - "The Halsted Approach"

• Anesthetizes: All mandibular teeth to midline ipsilaterally, lower lip, chin, buccal tissue from premolars forward, body of mandible, periosteum, PDL
• Needle: 25 gauge long (Malamed recommends 25 over 27 gauge for blocks - less deflection, safer aspiration)
• Landmarks: Coronoid notch (concavity felt on anterior border of ramus), pterygomandibular raphe
• Insertion point: 6-10 mm above the mandibular occlusal plane, at the medial border of the mandibular ramus (pterygomandibular triangle)
• Barrel of syringe positioned over contralateral premolars, parallel to mandibular occlusal plane
• Depth: ~20-25 mm until bone is contacted, then withdraw 1 mm
• Aspiration: MANDATORY - 10-15% positive aspiration rate
• Volume: 1.5 mL slowly (over ~60 seconds)
• Onset: 3-5 minutes

• Lip tingling/numbness (mental nerve territory)
• Tingling of tongue (lingual nerve - anesthetized simultaneously)

• Needle: 25/27 gauge long
• Insertion: Mucosa distal and buccal to last mandibular molar
• Volume: 0.3 mL
• Aspiration rate: only 0.7%

4.2 Gow-Gates Mandibular Nerve Block

• Anesthetizes: Entire mandibular nerve distribution - IA, lingual, buccal, mental, incisive, mylohyoid, auriculotemporal nerves (true V3 block)
• Advantage: Higher success rate (~95%), no separate buccal or lingual blocks needed, low aspiration rate (<2%)
• Disadvantage: Longer onset (3-5 minutes vs 3-5 minutes IANB, but up to 10 min in some patients), requires wide mouth opening
• Needle: 25 gauge long
• Target: Lateral aspect of condylar neck (below insertion of lateral pterygoid muscle)
• Landmark: Tragus of ear + corner of mouth line; insertion at mesiobuccal cusp of maxillary 2nd molar height
• Volume: 1.8 mL
• Position after injection: Patient keeps mouth open for 1-2 min to allow diffusion

4.3 Vazirani-Akinosi Closed-Mouth Block

• Indication: Trismus (limited mouth opening), failed IANB, patient anxiety with wide opening
• Anesthetizes: IA, lingual, buccal, mylohyoid nerves
• Needle: 25 gauge long
• Technique: Mouth CLOSED, muscles relaxed. Needle inserted parallel to maxillary occlusal plane between coronoid process and maxillary tuberosity, at height of mucogingival junction of maxillary molars. Bevel away from bone (toward mandibular ramus). Advance ~25 mm (half mesiodistal width of ramus).
• Volume: 1.5-1.8 mL
• Limitation: No aspiration possible (closed mouth), higher failure rate

4.4 Mental and Incisive Nerve Blocks

• Mental nerve block: Anesthetizes lower lip, chin, buccal premolar area
• Incisive nerve block: Also anesthetizes anterior mandibular teeth (incisors, canines, premolars)
• Landmark: Mental foramen - located between apices of mandibular premolars (typically below 2nd premolar)
• Needle: 25 or 27 gauge short
• Volume: 0.6 mL; apply digital pressure after injection to force solution into foramen for pulpal anesthesia

5. Supplemental Anesthesia Techniques

5.1 Intraligamentary (PDL) Injection

• Needle inserted into PDL space at 30° angle
• Uses specialized high-pressure syringe or computer-assisted device
• Rapid onset (~30 seconds), short duration (10-20 minutes)
• Indicated as supplemental technique; not as primary

5.2 Intraosseous (IO) Anesthesia

• Direct deposition into cancellous bone via small perforation through cortex
• Systems: Stabident, X-tip
• Onset: ~30 seconds
• Very effective for mandibular molars that fail IANB
• Epinephrine causes transient tachycardia - warn patients

5.3 Intrapulpal Injection

• Last resort when all else fails
• Needle sealed into pulp chamber under pressure
• Immediate onset, short duration
• Uncomfortable until solution is flowing under pressure

5.4 Buffered Local Anesthetics (The Onset® Approach)

• Raises pH of solution closer to physiologic pH
• Reduces sting on injection
• Faster onset
• More reliable block
• Protocol: Administer buffered IANB → check pulpal anesthesia with EPT/Endo-Ice at 2 minutes → if block successful, proceed; if not, re-administer

6. Complications of Local Anesthesia

Local Complications:

Systemic Complications:

Ocular Complications (rare):

7. Special Considerations in Oral Surgery

Infected Tissue ("Hot Tooth")

1. Acidic pH of infected tissue (pH 5-6) keeps local anesthetic in ionized (RNH+) form - cannot penetrate nerve membrane
2. Increased vascularity causes rapid systemic absorption
3. Inflammatory mediators lower neural firing threshold

Patients on Anticoagulants

• Infiltration preferred over blocks (lower hematoma risk)
• However, research shows mandibular blocks can be safely performed in anticoagulated patients (INR up to 3.5) without interrupting therapy

Patients with Bleeding Disorders (hemophilia, von Willebrand)

• PSA and IANB carry risk of serious hematoma with airway compromise
• Factor replacement recommended before blocks in severe cases
• Infiltration preferred when possible

Pediatric Patients

• Weight-based dose calculation mandatory
• Mepivacaine 3% (no vasoconstrictor) preferred for short procedures
• Lower volumes needed
• Self-inflicted trauma to anesthetized lip/cheek is a significant pediatric concern - advise parents

8. Key Malamed Principles (Summary)

1. "Every injection is BLIND" - once needle penetrates mucosa - anatomical knowledge and technique are paramount
2. Always aspirate before injecting (especially IANB, PSA, Gow-Gates)
3. Always inject slowly - 1 mL/min to reduce tissue trauma and pain
4. The Gow-Gates block has a superior success rate to IANB and should be the block of choice for comprehensive mandibular anesthesia
5. Articaine by maxillary infiltration is superior for molars with flared palatal roots
6. Buffered lidocaine improves onset and reduces injection discomfort
7. Mandibular molars in irreversible pulpitis = most challenging anesthesia scenario; supplemental IO or intrapulpal injection often required
8. A dentist administers approximately 30,000 IANBs over a 20-year career - mastery is essential
9. Always confirm anesthesia before beginning a procedure