Infra-orbital nerve block.
The infra-orbital nerve block in veterinary dentistry works well to block the maxillary teeth and the buccal soft tissues associated with them. The nerve anaesthetised is the infra-orbital and anterior superior alveolar nerves. Indications for this nerve block would include treatment of the maxillary teeth, treatment of the soft tissues of the anterior portion of the mouth. The most common reason for failure to achieve adequate anaesthesia may occur when the tip of needle is not in the correct position. Complications may include a haematoma but this is rare, as it is a relatively simple technique with easy to find landmarks.
This is an intra-oral injection. A 30 gauge short needle is recommended. The lip should be lifted to reveal the teeth and buccal mucosa. Before injecting make sure: depth of needle is adequate to reach foramen, any deviation of the needle away from the foramen, orientation of the bevel. The bone is palpated approximately 0.5mm in cats and 1-2cm in dogs dorsal to the maxillary third premolar tooth. An outward bulge can be palpated which is the buccal border of the infra-orbital foramen. The bone caudal to this bulge is the border of the infra-orbital canal. The palpable hollow, cranial to the bulge, is the foramen of the canal and the point where you wish to deposit the local anaesthetic. Maintain your finger on the edge of the bulge, applying tension to the tissues. The bevel of the needle is orientated towards the bone. Insert the needle through the mucosa just dorsal to the muco-gingival line at the level of the second premolar tooth in a caudal direction towards the infra-orbital foramen. Advance the needle slowly until bone is gently contacted. The point of contact should be the upper rim of the infra-orbital foramen. The general depth of penetration is to the level of the distal root of the maxillary 4th premolar tooth. Aspirate. Slowly deposit 0.1mls (cat) and up to 1ml (dog) over 30 seconds. Maximum volume is 1 cartridge per 10 kg body weight total volume from all sites. Little or no swelling should be visible. You should be able to feel the solution under your finger in the dog. Move your finger over the exit of the foramen and slowly withdraw the needle. Maintain direct finger pressure for 30 seconds then release.
Infra-orbital nerve exiting the rostral foramen of the infra-orbital canal (blue line) in a dog.
Infra-orbital nerve block in a dog. Insertion of the needle through the buccal mucosa towards the rostral foramen of the intra-orbital canal.
Infra-orbital nerve exiting the rostral foramen of the infra-orbital canal (blue line) in a cat.
Infra-orbital nerve block in a cat. Insertion of the needle through the buccal mucosa towards the rostral foramen of the intra-orbital canal.