Hygiene Atlas

Atlas · Plate VIII · Pharmacology and Local Anesthesia · 11

Injection techniques

The inferior alveolar block deposits near the mandibular foramen in the pterygomandibular space and has the highest rate of positive aspiration; a long buccal injection adds the buccal gingiva of the molars. The PSA block carries the highest hematoma risk. Use 25- or 27-gauge needles for blocks, never insert to the hub, aspirate before every deposit and inject about 1 mL per minute.

High-yield facts · 20

  1. Needle gauge: higher number = smaller diameter. 25 and 27 gauge are used for blocks; 30 gauge is not recommended for blocks (deflects, poorer aspiration).S16T1
  2. Long needle about 32-35 mm; short needle about 20 mm. Never insert a needle to the hub (breakage risk).T1
  3. Inject slowly: about 1 mL per minute (a full 1.8 mL cartridge over about 60 seconds or more).T1
  4. Aspirate before every deposit and in two planes; positive aspiration is most common with the IA block (about 10-15%).S15T1
  5. Inferior alveolar block: target is the pterygomandibular space near the mandibular foramen; insertion depth about 20-25 mm with a long needle.S15
  6. IA block success rate is about 80-85%; it anesthetizes the mandibular teeth to the midline, body of the mandible, buccal soft tissue anterior to the mental foramen, plus the lingual nerve area.S15
  7. Long buccal block: buccal gingiva of mandibular molars, injected distal and buccal to the last molar.S16S69
  8. Mental block: injected near the mental foramen (usually between the premolars); numbs buccal soft tissue anterior to the foramen and the lower lip.S68
  9. Incisive block: same site as mental with pressure; adds the premolar, canine and incisor pulps.S16
  10. Gow-Gates block targets the condylar neck and numbs nearly all V3 branches; mouth wide open; lower aspiration rate (about 2%).S16
  11. Vazirani-Akinosi is a closed-mouth mandibular block for limited opening (trismus).S16
  12. PSA: numbs maxillary third, second and most first molars (except, in some patients, the MB root of the first molar); depth about 16 mm; highest hematoma risk.S16T1
  13. MSA: maxillary premolars and the MB root of the first molar; absent in many people.S16
  14. ASA (infraorbital) block: maxillary incisors, canine and often premolars plus the lower eyelid, side of the nose and upper lip.S17
  15. Greater palatine block: posterior hard palate to the canine area on that side.S16
  16. Nasopalatine block: anterior palate from canine to canine; injected beside the incisive papilla; usually the most painful injection.S16
  17. AMSA block (from the palate midway between the premolars) numbs the maxillary incisors to premolars without facial numbness.S16
  18. Supraperiosteal (local) infiltration works well in the maxilla and in children because the bone is thin and porous.S16
  19. Most common local complications: hematoma, trismus (often from medial pterygoid trauma), paresthesia, transient facial paralysis, soft-tissue biting in children.S14S16
  20. ADA cartridge color bands: lidocaine 1:100,000 red, 1:50,000 green; mepivacaine 3% tan, 2% with levonordefrin brown; prilocaine plain black, with epi yellow; articaine gold; bupivacaine blue. (verify against current packaging)T1

Facts are written in our own words; each tag links to its source. Values marked "sources vary" differ between references, so check the one your program uses.