Quiz #3: Maxillary Anesthesia

MSA Injection

Errors:

• Deposition distal or mesial to apex of 2nd premolar

• penetration depth too shallow (not near apex of 2nd premolar)

• too lateral away from bone

• scraping bevel along bone

• not enough anesthetic

• watch out for dense bone associated with the zygomatic process of the maxilla

Note:

• may also innervate the maxillary sinus (4.28% of population)

• may serve as a supplement to the PSA for anesthesia of the MB root of 1st molar

• Penetration depth: 4-6mm (depends on anatomy)

• may touch bone associated with the zygomatic process of the maxilla

ASA Injection

Errors:

• deposition distal to canine eminence

• penetration depth too shallow (not near apex of canine)

• too lateral away from bone

• scraping bevel along bone

• not enough anesthetic

• midline cross-over: may need to inject above the central incisor on the opposite side

Note:

• Penetration depth: 4-6+mm (depends on anatomy)

SP Injection

Contraindications:

• tissue infection

• dense bone

• multiple teeth/large tissue area

Errors:

• penetration depth too shallow (not at apex of target tooth)

• too lateral away from bone

• scraping bevel along bone

• not enough anesthetic

Note:

• The penetration point involves bisecting the long axis of the tooth!

• Penetration depth: 3-5mm (depends on anatomy)

IO Injection

Errors:

• penetration site too lateral or too medial (aim in line with pupil!)

• deposition site too inferior to infraorbital foramen (you MUST contact bone and use a LONG needle!)

• not enough anesthetic

Indications:

• pulpal anesthesia on the mx anterior and premolar teeth

• pulpal anesthesia on more than two teeth

• inflammation which contraindicates an SP injection

• SP injection is ineffective due to dense cortical bone

Contraindications:

• treatment of one/two teeth only

• need for hemostasis

Note:

• if the needle buzzes the nerve bundle, stop advancing, pull back 2mm, aspirate, and inject

• penetration depth: 12-25mm depending on anatomy

• alternatives: ASA & MSA; SP

PSA Injection

Errors:

• penetration depth is too lateral, distal, or shallow

• scraping the bevel along the bone

• not enough anesthetic

• deposited anesthesia too far laterally and anesthetized the mandibular nerve instead

Indications:

• pulpal anesthesia for more than one tooth

• bone too dense for SP

• periodontal/surgical procedures requiring anesthesia of buccal tissue and bone adjacent to the molar teeth

Contraindications:

• hemophiliacs at risk of hemorrhage

• infection/inflammation

Note:

• may also numb the mucous membrane of the maxillary sinus

• positive aspiration ≠ hematoma

  • PSA has the HIGHEST risk of post-injection hematoma

  • hematomas can happen when you enter the pterygoid plexus and nick the maxillary artery

• you are entering the pterygomaxillary fossa

• insertion depth: 13-16 mm depending on anatomy (“hubba-hubba” = stop penetrating when the hub is parallel with the CEJ of the 2nd molar)

GP Injection

Errors:

• too fast/too much deposited: ischemia and necrosis

• too fast deposit: sloughing

• soft palate anesthetized

Contraindications:

• inflammation/infection at injection site

Note:

• insertion depth: 5-6mm depending on anatomy

• hematomas are rare

• deposit 0.4-0.6 mL (1/4-1/3 cart) over 30 sec

NP Injection

Errors:

• too fast/too much deposited: ischemia and necrosis

• sterile abscess

• too fast deposit: sloughing

• soft palate anesthetized

• inserted directly into incisive papilla/penetrated foramen

Contraindications:

• inflammation/infection at injection site

Note:

• you will see tissue blanching

Local Infiltration

Field Block

Nerve Block

Hematomas