Mandibular techniques compared
| Technique | Landmarks and depth | Anesthetizes | Positive aspiration (Malamed) |
|---|---|---|---|
| Inferior alveolar nerve block (IANB) | Height of the coronoid notch (about 6–10 mm above the mandibular occlusal plane), about three-quarters of the way from the notch to the pterygomandibular raphe; barrel over the opposite premolars; 20–25 mm to bone | Mandibular teeth to the midline, body of the mandible, buccal tissues anterior to the mental foramen; lingual nerve with it: anterior two-thirds of the tongue, floor of mouth, lingual gingiva | About 10–15% |
| Buccal (long buccal) nerve | Distal and buccal to the last molar, in the mucosa | Buccal gingiva and mucosa of the mandibular molars | Low |
| Mental | Mucobuccal fold at or anterior to the mental foramen (between the premolars) | Lower lip, chin and buccal gingiva anterior to the foramen | Moderate |
| Incisive | Same as mental, with 2 minutes of pressure to push solution into the foramen | Pulps of premolars, canine and incisors plus mental nerve tissues | Moderate |
| Gow-Gates | Mouth wide open; insert distal to the maxillary second molar at the level of its mesiolingual cusp; aim along the line from the corner of the mouth to the intertragic notch; about 25 mm to the condylar neck | IAN, mental, incisive, lingual, mylohyoid, auriculotemporal and usually buccal nerves | About 2% |
| Vazirani-Akinosi (closed mouth) | Teeth together; needle parallel to the maxillary occlusal plane at the mucogingival junction of the maxillary molars; about 25 mm from the tuberosity; bevel away from the ramus; no bone contact | Same as an IANB plus lingual and usually mylohyoid | Under 10% |
When the IANB fails
- Common causes: injecting too low (below the mandibular foramen), accessory innervation (mylohyoid nerve, cross-innervation of incisors from the opposite side), a bifid canal, and acute pulpitis.
- Fixes: repeat higher, add a buccal or mylohyoid injection, use Gow-Gates or Vazirani-Akinosi, add articaine buccal infiltration for first molars, or use intraosseous or PDL injections.
- Vazirani-Akinosi is the technique of choice when trismus limits opening.
- Bone contact during an IANB confirms depth; if no bone is felt, the needle is probably too far posterior (near the parotid). Withdraw, redirect, and do not inject.
⚠️ Common traps
- Injecting an IANB without contacting bone: risks depositing solution into the parotid gland (transient facial palsy).
- Expecting the buccal molar gingiva to be numb after an IANB: add a buccal nerve block.
- Using the closed-mouth technique only when the patient can open: Vazirani-Akinosi is for limited opening.
- Confusing mental (soft tissue only) with incisive (pulps of anterior teeth).
Mini-quiz
- Which mandibular block has the lowest positive aspiration rate?
- A patient with trismus needs mandibular anesthesia. The technique of choice is:
- During an IANB, no bone is felt at full depth. The safest action is:
- Which injection gives pulpal anesthesia of a mandibular canine without a full IANB?
- The usual depth of needle penetration for an adult IANB is about:
Answer key: 1 A · 2 C · 3 C · 4 A · 5 C