Questions about Local Anaesthetic

Your dentist has told you that your child needs a local anaesthetic at their next visit. You may be worried and have questions. We will discuss many of the common questions in this blog post:

What is local anaesthetic?
Local anaesthetic is a type of medicine given as an injection to temporarily numb a specific area of the mouth.
How does it work?
Local anaesthesia blocks pain by stopping pain signals being carried by nerves to the brain. This causes a complete loss of pain sensation to a specific area, without affecting the rest of the body. Pressure sensations may still be felt.

Why is local anaesthetic (LA) used in dentistry?

Although shallow fillings can often be completed without LA, it is required for deeper cavities, treatment involving the nerve of the tooth and tooth extractions, among other procedures. Local anaesthetic makes painless procedures possible and therefore makes treatment easier and more comfortable.


What is the difference between local and general anaesthetia or sedation?
General anaesthesia (GA) is used when a patients needs to be asleep for an operation or procedure – this can only be done by a trained anaesthetist in a fully equipped hospital.

In conscious sedation, a sedative is given either by mouth (tablet or liquid), injection, or inhalation (gas and air). The patient remains awake and responsive but is more relaxed and less anxious. Local anaesthetic is often used in addition to sedation or GA.

Local anaesthetic does not affect consciousness. Only the specific area of the body being numbed is affected.


Is Local Anaestheic safe?

Local anaesthetics are used routinely every day for dental treatment all over the world, with relatively few problems.
As with all medication, care and attention must be taken to ensure local anaesthetic is used safely. Good dentists will use safe techniques carefully and inject slowly. To ensure a safe dose a child’s size and weight need to be taken into account, as the maximum safe dose is lower for children than for adults.
Allergies to commonly used dental local anaesthetics are extremely rare. Allergies to preservatives used in LA have been known, although they are not common.
Epinephrine (adrenaline) is commonly added to local anaesthetics as it increases the duration of the numbing effect and also reduces bleeding. For patients with significant heart or thyroid problems LA without epinephrine may be used.
From what age can children be given LA?
Very young children are sometimes unable to cooperate for treatment with local anaesthetic. This is because they do not understand the numb feeling or the reason for it. With reassurance and explanation appropriate to the child’s age, some children as young 3 years old can accept treatment with local anaesthetic. For young children who unable to cooperate, temporary treatment may be done to make the child comfortable until they are able to accept further treatment. If there is severe infection treatment under general anaesthetic may be required.

What if I or my child are worried about the injection?


Anxiety about injections is common and understandable. Finding a good dentist who is understanding and sympathetic will go a long way in reducing anxiety.  Relaxation or distraction techniques can be used. For very anxious patients, conscious sedation with inhaled nitrous oxide and oxygen may be an option. Talk to your dentist about your anxieties but try not to convey your worries to your child. In our experience at Small Bites we have found that the children are often are less anxious than their parents!

How can the dentist make it easier for my child?


Local anaesthetic should ideally be used when a child is cooperative and has accepted other treatment well.
Explanation and reassurance are very important. For a young child the dentist may say that they are going to give some special medicine or “sleepy juice” to make the tooth go to sleep for a while, so that they don’t feel any pain while the tooth is fixed. Older children with more understanding may be told that this involves an injection.
A numbing gel placed on the gum for a couple of minutes before the injection often works very well, so that the injection is hardly felt. At Small Bites we also use a very fine needle which minimizes pain or discomfort during injection.

It is necessary to wait 5 or 10 minutes to give the local anaesthetic time to work before starting treatment.

How long does the numb feeling last for?
This will depend on the technique used but usually between 1 and 3 hours. It should be explained to the child that their lip/cheek (and sometimes also tongue) will feel strange. The affected area will feel swollen/bigger but not look any different.
What precautions should I take after my child has had local anaesthetic?
Tell you child that the numb feeling will take some time to wear off. Care should be taken that they do not bite their lip or tongue during this time. Hot food and drink and any food that they need to chew should also be avoided until the feeling has returned.

If you have any other questions you can either talk to your dentist or leave a comment below.

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