What is Local Anaesthesia? | Dental Treatment Guide




Local anaesthesia is defined as the localised numbing of a target area. This is often used in dentistry, as your dentist wants to prevent you feeling pain in a specific area. The local anaesthesia allows you to remain conscious throughout the procedure but without you feeling any pain or discomfort.

Local anaesthetic is available in a number of different types. It can be administered via a spray, drops or an injection. However, in general the most common route of administration is by injection to the area requiring numbing. This works as the anaesthetic selectively targets nerves to block them transmitting pain signals and sending them to the brain.

The level of anaesthesia can be controlled to regulate how long the pain block lasts for as well as the level of numbness. This is meticulously controlled by concentration, amount administered as well as the actual solutions used in the anaesthetic. Generally, local anaesthetic lasts up to eight hours.

What anaesthetic do dentist use?

Many dentists use a local anaesthetic known as Lidocaine although this is just one of many available. An easy way to know whether the medication your dentist is talking about is an anaesthetic is to listen out for "-caine" at the end of the name. This may bring the name Novocain to mind, as it is a well-known type of medication used for localised numbing. However, dentists no longer use this drug as it caused too many allergic reactions and did no last as long as other available local anaesthetics.

What is contained in local anaesthetic?

Obviously there is a drug aimed primarily at numbing the area into which it is injected, however there is also a liquid component, which contributes further to the anaesthetic's effect. In this liquid there is often:

  • Vasoconstrictor – A vasoconstrictor is a type of drug that acts on your blood vessels to narrow them. By doing this, the numb effect of the local anaesthetic will last a longer amount of time.
  • Chemical – Certain chemicals are included in local anaesthetic to protect the vasoconstrictor drug from being broken down.
  • Sodium hydroxide – This particular component is included to enhance the numbing effect of the drug.
  • Sodium chloride – This part of the liquid is used to aid the introduction of the numbing drugs into the blood.

The use of local anaesthetic injections at the dentist

The dentist has two types of local anaesthetic injections available for use depending on the procedure being performed. Firstly is a block injection that is used to numb a whole section of your mouth, like the left side of your upper jaw. Alternatively, the dentist may use an infiltration injection to numb a more local, specific area.

If you are at the dentist to undergo a procedure that requires local anaesthetic, you will need the part of your mouth concerned to be dried. This is done using simple cotton or just air. Once dry, the dentist will often apply a numbing gel so you will not feel the injection. Once his gel has had time to have an effect, your dentist will carefully inject the anaesthetic. Any pain felt here is often due to the drugs moving into the mouth tissues rather than the actual needle.

The numb effect of the local anaesthetic injection often lasts up to eight hours. This means that a lot of the time, by the time you leave the dentist clinic, your mouth may still be numb. This can hinder certain everyday tasks such as talking or eating. Although this can often be quite amusing to yourself and others around you, it can also cause some problem. You must still be aware that you have had a procedure and you should take care to avoid biting the area that has been numbed, as it could inadvertently cause damage.

Potential side effect of local anaesthetic injections

As with many drugs, local anaesthetic has potential side effects attached to its use. The actual probability of these side effects happening vary from person to person but it is always important to ensure that you are aware of them. These possible side effects and complications include:

  • Temporary problems with eating, drinking and talking immediately after receiving the injection.
  • You may feel dizzy, suffer blurry vision or endure a short-term loss of your muscle control and coordination - this may be seen as twitching.
  • It is possible that you might get a headache or feel nauseas or even vomit.
  • Some people lack the ability to recall the actual treatment.
  • An allergic reaction may occur and symptoms to look out for include a rash, tingling of the skin (especially the lips) and breathing problems.
  • In extremely rare circumstances, nerves can suffer damage if the needle accidently hits them.
  • Haematomas may occur where the injection was administered. This is a swelling full of blood that occurs if the needle strikes a blood vessel.
  • The numbing drugs can have an effect on facial areas away from your mouth, such as your eyelids. This can sometimes lead to the inability to blink although this will wear off as the anaesthetic does.
  • Your heart may beat at a quicker than normal rate due to the vasoconstrictor component.

You should tell your dentist prior to your treatment if you have any allergies. You must also inform them of any concerns you may have and if there are any questions on your mind, now is the time to ask them. If you are taking any medication, please tell your dentist the name and dosage as it may interfere with the local anaesthetic. These medications include over-the-counter drugs like ibuprofen or paracetamol as well as medically prescribed drugs.