DENTAL GROSS ANATOMY CASE 4.2 (POSTERIOR SUPERIOR ALVEOLAR NERVE BLOCK)

HISTORY A 52 yo man, Francis McKean, went to his dentist because of severe pain in his left maxillary molars. The dentist found that the 2nd and 3rd maxillary molars had fractured crowns and thought that the remaining root portions should be extracted. A posterior superior alveolar nerve block was administered. The needle was placed just distal to the maxillary 3rd molar and was advanced superiorly and posteriorly ~ 2cm into the infratemporal region. Immediately after deposition of the anesthetic Mr. McKean felt the left side of his face swell up. The dentist realized what had happened and explained that he had probably penetrated a venous structure causing a hematoma. This complication might have been avoided by using an aspirating technique. No extractions were attempted because of the facial swelling. Mr. McKean was prescribed antibiotics and asked to return in one week to re-attempt extraction.

Would a posterior superior alveolar nerve block be suitable for extraction of other upper teeth? 1. Would a posterior superior alveolar nerve block be suitable for extraction of other upper teeth?   No. The maxillary incisors and canine are innervated by the anterior superior alveolar nerve and the premolars by the middle superior alveolar nerve.

INNERVATION OF MAXILLARY TEETH Anterior superior alveolar n. Mucosa of maxillary sinus Dental and gingival branches Middle superior alveolar n. Posterior superior alveolar n.

2. Where does the posterior superior alveolar nerve arise from and where does it enter the maxilla? 2. Where does the posterior superior alveolar nerve arise from and where does it enter the maxilla?   The posterior superior alveolar nerve arises from V2 in the pterygopalatine fossa. It enters the posterior (infratemporal) aspect of the maxilla through the posterior superior alveolar foramen (foramina).

INNERVATION OF MAXILLARY TEETH V ganglion Sensory root of V Infraorbital n. Anterior superior alveolar n. V3 V2 Mucosa of maxillary sinus Dental and gingival branches Middle superior alveolar n. Posterior superior alveolar n.

What venous structure was penetrated by the needle?   Pterygoid plexus of veins.

POSTERIOR SUPERIOR ALVEOLAR NERVE BLOCK Pterygoid plexus Maxillary a. PSA nerve and foramina Maxillary 2nd molar

4. Are there any special concerns about infection of this venous structure? 4. Are there any special concerns about infection of this venous structure?   Yes. The pterygoid plexus communicates with the cavernous sinus in the cranial cavity via an emissary vein through the foramen ovale, and with the inferior ophthalmic vein in the orbit through the inferior orbital fissure. Infection could therefore spread into the cranial cavity or orbit via these routes.

Emissary vein communicating with cavernous sinus through foramen ovale Posterior superior alveolar v. Pterygoid plexus Inferior alveolar v.

5. What important structure is related to the roots of the maxillary molars and must be taken into consideration when performing their extraction? What important structure is related to the roots of the maxillary molars and must be taken into consideration when performing their extraction? Maxillary sinus. (Note: The teeth related to the floor of the sinus vary from the three molars to the molars, premolars and canine.)  

Opening into middle nasal meatus Maxillary sinus Roots of teeth

END OF CASE 4.2