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The benefits of using local anaesthesia are well understood, however if poor technique is used these advantages are far outweighed by the potential risks and complications arising from its use. The greatest concern when injecting local anaesthetic is damage to a nerve or intravascular injection. Damage to the nerve can be minimized by using a fine (27gauge), short bevel needle with a gentle technique. The bevel should be orientated in the same direction as the nerve fibers in order to reduce the chance of cutting through the nerve fibers. When inserting the needle, avoid side to side movement, and if the needle touches bone, withdraw and replace the needle to avoid the damaged tip snagging on the nerve fibers. A smaller volume, injected slowly, should be used when injecting into a canal to avoid excessive pressure on the nerve to avoid neuropraxia. Penetration of a blood vessel is a frequent complication due to the presence of the large blood vessels in the neurovascular bundle. Using a fine needle in the way described above will help reduce the risk of a haematoma forming. Always aspirate before injecting the agent to reduce the risk of injecting intravascularly, which can lead to serious consequences.   

The benefits of using local anaesthesia are well understood, however if poor technique is used these advantages are far outweighed by the potential risks and complications arising from its use. The greatest concern when injecting local anaesthetic is damage to a nerve or intravascular injection. Damage to the nerve can be minimized by using a fine (27gauge), short bevel needle with a gentle technique. The bevel should be orientated in the same direction as the nerve fibers in order to reduce the chance of cutting through the nerve fibers. When inserting the needle, avoid side to side movement, and if the needle touches bone, withdraw and replace the needle to avoid the damaged tip snagging on the nerve fibers. A smaller volume, injected slowly, should be used when injecting into a canal to avoid excessive pressure on the nerve to avoid neuropraxia. Penetration of a blood vessel is a frequent complication due to the presence of the large blood vessels in the neurovascular bundle. Using a fine needle in the way described above will help reduce the risk of a haematoma forming. Always aspirate before injecting the agent to reduce the risk of injecting intravascularly, which can lead to serious consequences.   

The trigeminal nerve provides sensory innervations to the teeth and associated soft tissues. Knowledge of the applicable anatomy is useful to understand where to deposit the local anaesthetic agent to achieve the best results. Five most commonly used regional blocks are described below.

The trigeminal nerve provides sensory innervations to the teeth and associated soft tissues. Knowledge of the applicable anatomy is useful to understand where to deposit the local anaesthetic agent to achieve the best results. Five of the most commonly used regional blocks are described below.

==Mental Nerve Block==  

==Mental Nerve Block==  

Superficial injection will anaesthetize the buccal soft tissues and lower lip rostral to the middle mental foramen. If the needle is introduced into the foramen, and advanced caudally, then sensation to the canine and incisors may be blocked. Care must be taken when inserting the needle so as not to cause damage to the neurovascular bundle. The preferred technique is to perform an inferior alveolar (mandibular) block to achieve anaesthesia for the mandibular teeth.  

Superficial injection will anaesthetize the buccal soft tissues and lower lip rostral to the middle mental foramen. If the needle is introduced into the foramen, and advanced caudally, then sensation to the canine and incisors may be blocked. Care must be taken when inserting the needle so as not to cause damage to the neurovascular bundle. The preferred technique is to perform an inferior alveolar (mandibular) block to achieve anaesthesia for the mandibular teeth.  

'''Technique''': The middle mental foramen can be palpated through the lip frenulum just mesial to the 2nd premolar, in the ventral third of the mandible. The anaesthetic agent can be infused at the foramen and digital pressure applied to keep the agent local. The needle can also be introduced from a rostral to caudal direction, into the canal very carefully and the agent injected slowly. It is essential to aspirate prior to injecting. In small dogs and cats the canal is often too small to inject directly into the canal.  

'''Technique''': The middle mental foramen can be palpated through the lip frenulum just mesial to the 2nd premolar, in the ventral third of the mandible. The anaesthetic agent can be infused at the foramen and digital pressure applied to keep the agent local. The needle can also be introduced from a rostral to caudal direction, into the canal very carefully and the agent injected slowly. It is essential to aspirate prior to injecting. In small dogs and cats the canal is often too small to inject directly into it.  

==Inferior Alveolar Nerve Block==  

==Inferior Alveolar Nerve Block==  

Anaesthetising the inferior alveolar nerve will provide loss of sensation of the hard and soft tissues of the ipsilateral mandible. The nerve enters the mandible at the level of the mandibular foramen. The mandibular nerve divides into three branches – the lingual nerve, the inferior alveolar nerve and the mylohyoid nerve. If the anaesthetic agent is deposited too far caudally, the other branches may also be affected, and may cause complications arising from loss of sensation to the tongue.   

Anaesthetising the inferior alveolar nerve will provide loss of sensation of the hard and soft tissues of the ipsilateral mandible. The nerve enters the mandible at the level of the mandibular foramen. The mandibular nerve divides into three branches – the lingual nerve, the inferior alveolar nerve and the mylohyoid nerve. If the anaesthetic agent is deposited too far caudally, the other branches may also be affected, and may cause complications arising from loss of sensation to the tongue.   

'''Technique''': There are two approaches to this block – intra-oral or extra-oral. Either way, the mandibular foramen is palpated on the lingual aspect of the mandible, caudal and ventral to the last molar. It is not always possible to feel the foramen itself but usually the neurovascular bundle can be felt as a soft, string- like structure. When injecting intra-orally, the nerve or foramen is palpated with one hand whilst the syringe and needle are held in the other hand. The needle is advanced in a caudal direction, below the mucosa, with the bevel of the needle positioned towards the bone, to the position of the neurovascular bundle. Aspirate before injecting. For the extra-oral approach the neurovascular bundle is located as in the intra-oral approach and the needle is inserted perpendicularly, just medial to the body of the mandible, with the bevel facing the mandible. In the dog a useful landmark in helping to locate the position of where to insert the needle is the depression on the caudal border of the ventral mandible. The foramen can also be located halfway along an imaginary line drawn between the last molar and the angle of the jaw.     

'''Technique''': There are two approaches to this block – intra-oral or extra-oral. Either way, the mandibular foramen is palpated on the lingual aspect of the mandible, caudal and ventral to the last molar. It is not always possible to feel the foramen itself but usually the neurovascular bundle can be felt as a soft, string-like structure. When injecting intra-orally, the nerve or foramen is palpated with one hand whilst the syringe and needle are held in the other hand. The needle is advanced in a caudal direction, below the mucosa, with the bevel of the needle positioned towards the bone, to the position of the neurovascular bundle. Aspirate before injecting. For the extra-oral approach the neurovascular bundle is located as in the intra-oral approach and the needle is inserted perpendicularly, just medial to the body of the mandible, with the bevel facing the mandible. In the dog a useful landmark in helping to locate the position of where to insert the needle is the depression on the caudal border of the ventral mandible. The foramen can also be located halfway along an imaginary line drawn between the last molar and the angle of the jaw.     

==Infra-Orbital Nerve Block==

==Infra-Orbital Nerve Block==

This branch of the trigeminal nerve supplies the teeth and gingiva of the maxilla. The nerve exists from the infraorbital foramen which can be palpated just dorsal to the third premolar. An arterial pulse is often visible intra-orally at the foramen. Superficial injection at the foramen will anaesthetize the oral mucosa and upper lip rostral to the foramen. It will not anaesthetize the teeth. To anaesthetize the maxillary teeth, the needle should be inserted into the canal.  

This branch of the trigeminal nerve supplies the teeth and gingiva of the maxilla. The nerve exits from the infraorbital foramen which can be palpated just dorsal to the third premolar. An arterial pulse is often visible intra-orally at the foramen. Superficial injection at the foramen will anaesthetize the oral mucosa and upper lip rostral to the foramen. It will not anaesthetize the teeth. To anaesthetize the maxillary teeth, the needle should be inserted into the canal.  

'''Technique''': The needle is inserted into the foramen and advanced caudally with the needle parallel to the axis of the bone. In cats and brachycephalic dogs the canal may only be a few millimeters and inserting the needle into the canal may result in penetration of the eye. Always aspirate before injecting. There should be no resistance felt when injecting. Use a small volume, injected at low pressure to avoid neuropraxia.  

'''Technique''': The needle is inserted into the foramen and advanced caudally with the needle parallel to the axis of the bone. In cats and brachycephalic dogs the canal may only be a few millimeters and inserting the needle into the canal may result in penetration of the eye. Always aspirate before injecting. There should be no resistance felt when injecting. Use a small volume, injected at low pressure to avoid neuropraxia.  

*Include an opioid in the premedication.

*Include an opioid in the premedication.

*Use local anesthetics prior to surgery and/or administer additional opioids intraoperatively.

*Use local anesthetics prior to surgery and/or administer additional opioids intraoperatively.

*Give opioids and/or NSAIDs postoperatively. Local anesthesia (administered at the end of a procedure) will also provide postoperative analgesia.

*Give opioids and/or NSAIDs postoperatively. Local anaesthesia (administered at the end of a procedure) will also provide postoperative analgesia.

*Administer NSAIDs during recovery.

*Administer NSAIDs during recovery.

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[[Category:Dental Surgical Procedures]][[Category:To Do - Dentistry preMars]]

[[Category:Dental Surgical Procedures]][[Category:To Do - Mars Check]]