Changes

Spring-held mouth gags can cause cerebral ischaemia and blindness in cats, and their use should be avoided. This risk may be compounded by hypotension and hypoxaemia. Gags can cause damage to the teeth, especially if the plane of anaesthesia is light and the animal begins to chew.

Spring-held mouth gags can cause cerebral ischaemia and blindness in cats, and their use should be avoided. This risk may be compounded by hypotension and hypoxaemia. Gags can cause damage to the teeth, especially if the plane of anaesthesia is light and the animal begins to chew.

==Loco-Regional Anaesthesia (pic3)==

==Loco-Regional Anaesthesia==

The local anaesthetics most commonly used in veterinary dentistry belong to the aminoamide group. This includes lidocaine, mepivacaine, bupivacaine and ropivacaine. The choice of drug is usually dependent on the onset of action and duration of effect. The duration of effect may also depend on the site where the local anaesthesia is used – in very vascular areas, the drug may have less duration of action as it is resorbed quicker. The activity of local anaesthetics is dependent on the diffusion of the unionized form through the cell membrane, and the amount of unionized form is pH-dependent. Tissues with low pH will promote the presence of the ionized molecule, thus decreasing the action of the drug. Inflamed or infected tissues have a lower pH and thus the local anaesthetic agent may be less effective if injected into these tissues.  

The local anaesthetics most commonly used in veterinary dentistry belong to the aminoamide group. This includes lidocaine, mepivacaine, bupivacaine and ropivacaine. The choice of drug is usually dependent on the onset of action and duration of effect. The duration of effect may also depend on the site where the local anaesthesia is used – in very vascular areas, the drug may have less duration of action as it is resorbed quicker. The activity of local anaesthetics is dependent on the diffusion of the unionized form through the cell membrane, and the amount of unionized form is pH-dependent. Tissues with low pH will promote the presence of the ionized molecule, thus decreasing the action of the drug. Inflamed or infected tissues have a lower pH and thus the local anaesthetic agent may be less effective if injected into these tissues.  

Bilateral or multiple blocks are often required, which impacts on the total volume available for use. For the selected drug, calculate the maximum safe dose and divide the volume available between the blocks planned.  

Bilateral or multiple blocks are often required, which impacts on the total volume available for use. For the selected drug, calculate the maximum safe dose and divide the volume available between the blocks planned.  

The benefits of using local anaesthesia are well understood however if poor technique is used these advantages far outweigh 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, with draw 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 most commonly used regional blocks are described below.

==Mental Nerve Block==  

==Mental Nerve Block==