Local anaesthesia means a no pain sensation in a particular area supplied by a specific nerve. The correct term is local analgesia but commonly not used? It is given with the help of 2 ml or 5 ml single use disposable syringes.
The anaesthesia is an inseparable part of surgery. It provides maximum patient comfort and cooperation. Without anaesthesia, the advancement in surgeries could not have been achieved. In 3rd molar surgery a patient may opt for general anaesthesia or local anaesthesia. The local anaesthesia may be supplemented with sedation for increased comfort.
Local anaesthesia has the following advantages over general anaesthesia.
Despite the huge number of advantages, the local anaesthesia does have certain disadvantages. They are as follows.
The local anaesthetic solutions mainly contain the following contents.
Local anaesthetics inhibit the generation of electrical impulses and their conduction along the neuronal axon membrane, by reversible blockade of sodium ion channels.
There is a continuous imbalance of sodium and potassium ions between the cytoplasm of neurons and the intercellular fluid. This is maintained at about 25 times more potassium intracellularly and 15 times more sodium in interstitial space.
The molecule of local anaesthetic agent enters the neural cell through neurilemmoma from interstitial fluid by a simple diffusion process. Then in the acidic environment of a neural cell, it breaks itself in its components and acts on the sodium influx gate and blocks it, thus blocking the generation of action potential, thus blocking signal conduction along the nerve cell membrane. The local anaesthesia cannot act on sodium influx gates from outside the nerve cell. It must enter the nerve cell.
The anaesthesia is an inseparable part of surgery. It provides maximum patient comfort and cooperation. Without anaesthesia, the advancement in surgeries could not have been achieved. In 3rd molar surgery a patient may opt for general anaesthesia or local anaesthesia. The local anaesthesia may be supplemented with sedation for increased comfort.
Advantages of Local Anaesthesia
Local anaesthesia has the following advantages over general anaesthesia.
- It is safe, efficient and predictably effective in almost all patients.
- It is inexpensive.
- It is easy to administer.
- For healthy patient, no monitoring is needed by equipment
- The patient does not lose consciousness with an intact gag reflex during anaesthesia.
- Procedures under local anaesthesia, hospitalization is not needed, therefore, for patients’, it is convenient.
- To administer local anaesthesia, no preoperative fasting is required.
- A patient can be discharged immediately without waiting for recovery or an escort.
Limitations of Local Anaesthesia
Despite the huge number of advantages, the local anaesthesia does have certain disadvantages. They are as follows.
- It cannot be used in a non-cooperative patient; for example, younger children.
- It cannot be used in a patient with fear of needles.
- It cannot be used in an anxious or nervous patient.
- It is only suitable for short procedures which are of less than 30-minute duration.
- It cannot anesthetize the locally inflamed tissues.
Composition of Local Anaesthesia
The local anaesthetic solutions mainly contain the following contents.
- Local anaesthesia base.
- Hydrochloride salt for solubility and stability.
- Buffering agents.
- Preservatives; e.g., Methyl Paraben
How does local anaesthetics prevent the conduction of dental pain?
Local anaesthetics inhibit the generation of electrical impulses and their conduction along the neuronal axon membrane, by reversible blockade of sodium ion channels.
There is a continuous imbalance of sodium and potassium ions between the cytoplasm of neurons and the intercellular fluid. This is maintained at about 25 times more potassium intracellularly and 15 times more sodium in interstitial space.
Mechanism of action
The molecule of local anaesthetic agent enters the neural cell through neurilemmoma from interstitial fluid by a simple diffusion process. Then in the acidic environment of a neural cell, it breaks itself in its components and acts on the sodium influx gate and blocks it, thus blocking the generation of action potential, thus blocking signal conduction along the nerve cell membrane. The local anaesthesia cannot act on sodium influx gates from outside the nerve cell. It must enter the nerve cell.
Question: What happens when the area surrounding the nerve gets inflamed?
Once the tissue is inflamed, the interstitial fluid becomes acidic in nature. In an acidic environment, the local anaesthetic molecule breaks down. A broken local anaesthetic molecule cannot pass through the cell membrane by a simple diffusion process and thus cannot produce its effect.
This is the reason a local anaesthetic cannot produce its effect in an inflamed tissue or is not so effective in an inflamed area.
Question: Why does LA not function efficiently in an inflamed environment?
Answer: The molecule of local anaesthetic agent enters the neural cell through myelin sheath from interstitial fluid by a simple diffusion process. Then in the acidic environment of a neural cell, it breaks itself in its components and acts on the sodium influx gate and blocks it, thus blocking the generation of action potential, thus blocking signal conduction along the nerve cell membrane. The local anaesthesia cannot act on sodium influx gates from outside the nerve cell. It must enter the nerve cell.
Question: What happens when the area surrounding the nerve gets inflamed?
Once the tissue is inflamed, the interstitial fluid becomes acidic in nature. In an acidic environment, the local anaesthetic molecule breaks down. A broken local anaesthetic molecule cannot pass through the cell membrane by a simple diffusion process and thus cannot produce its effect.
This is the reason a local anaesthetic cannot produce its effect in an inflamed tissue or is not so effective in an inflamed area.