Dental Corner: Using intraoral regional anesthetic nerve blocks - Veterinary Medicine
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Dental Corner: Using intraoral regional anesthetic nerve blocks


VETERINARY MEDICINE



Figure 2. As seen with this cat's skull, the position of the needle with the caudal infraorbital nerve block could cause orbital injury in a cat. For this reason, this block is not recommended in cats.
Five regional anesthetic blocks can be used depending on the area of the oral cavity to be anesthetized. Except for the caudal mandibular block, the blocks are easy to learn. It is helpful to have a skull to refer to when performing a block to help visualize the anatomic landmarks. Make sure to insert the needle with the bevel facing out, and try to avoid repeatedly inserting the needle. Because of the lag with the onset of anesthesia, perform these blocks 10 to 15 minutes before beginning the procedure. The time between regional anesthetic injection and surgery can be used for scaling, oral and dental charting, taking intraoral radiographs, or performing other painless procedures.

Cranial infraorbital nerve block

A cranial infraorbital nerve block anesthetizes only the ipsilateral incisors and canines of the maxilla. For this technique, 0.2 to 0.4 ml bupivacaine (0.5%) is injected into the opening of the infraorbital foramen, which is apical to the distal root of the maxillary third premolar. Palpate the foramen through the oral mucosa, hold the syringe almost parallel to the maxilla with the needle directed caudally, insert the needle 1 mm into the foramen, aspirate to ensure the needle is not in a blood vessel, and inject the bupivacaine rapidly (Figure 1). In cats, do not attempt to advance the needle into the foramen because the feline infraorbital canal is short, and needles placed into the foramen can cause orbital trauma.

Caudal infraorbital nerve block


Figure 3. The proper needle placement for the caudal infraorbital nerve block, which will block the entire unilateral maxillary arch on the side injected.
A caudal infraorbital nerve block anesthetizes all ipsilateral teeth of the maxilla. This block is not recommended in cats because of the short canal and the potential for orbital injury (Figure 2). Insert the needle 2 to 3 mm into the infraorbital foramen, and place a finger over the entrance to the foramen. Inject 0.4 to 0.8 ml (usually 0.4 for small dogs, 0.6 ml for medium-sized dogs, and 0.8 ml for large dogs) bupivacaine (0.5%) into the foramen, causing the bupivacaine to flood the infraorbital canal and exit through the caudal opening of the canal (Figure 3).

Middle mental nerve block


Figure 4. The proper needle placement for anesthetic injection at the middle mental foramen, which is apical to the mesial root of the mandibular second premolar.
A middle mental nerve block anesthetizes all ipsilateral incisors and canines of the mandible. Inject 0.2 to 0.4 ml bupivacaine (0.5%) at the middle mental foramen, which is apical to the mesial root of the mandibular second premolar (Figure 4).

Caudal mandibular nerve block

A caudal mandibular nerve block anesthetizes all ipsilateral teeth of the mandible. This procedure is challenging to perform accurately, so laboratory instruction is recommended before performing this block on patients.


Figure 5. The proper needle placement for the caudal mandibular nerve block.
Inject 0.8 to 1 ml bupivacaine (0.5%) at or near the mandibular foramen, which is on the lingual (inside) aspect of the mandible above the mandibular notch. The mandibular notch can be palpated caudal to the last molar on the ventral surface of the mandible. Insert the anesthetic needle through the skin, walk it off the ventral mandible, and advance it dorsally to the region of the mandibular foramen (Figure 5).


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Source: VETERINARY MEDICINE,
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