SOMETIMES your dentist needs to numb a part of your mouth. In order to do this, he or she injects medicine into your gum or inner cheek. This medicine is called local anaesthesia.

Lidocaine is the most common local anaesthetic that dentists use. There are many others. They all have names ending in “-caine”.

Many people think of Novocain as the classic numbing drug. But Novocain is not used anymore. Other drugs last longer and work better than Novocain. These drugs are also less likely to cause allergic reactions.

The numbing drug is only one part of what’s injected. The liquid in the injection can also include:

• A type of drug called a vasoconstrictor. This drug narrows your blood vessels. This makes the numbness last longer.

• A chemical that keeps the vasoconstrictor from breaking down.

• Sodium hydroxide, which helps the numbing drug work.

• Sodium chloride, which helps the drugs get into your blood.

There are two kinds of numbing injections: Block injection and infiltration injection. A block injection numbs an entire region of your mouth, such as one side of your lower jaw. An infiltration injection numbs a smaller area. This is the area near where the injection was given.

If you need local anaesthesia in order to have your dental treatment done, your dentist will dry part of your mouth with air or cotton. Many dentists then swab the area with a gel to numb the skin.

Then your dentist will slowly inject the local anaesthetic. Most people don’t feel the needle. Instead, the sting they feel is caused by the anaesthetic moving into the tissue.

An injection of local anaesthesia can last up to several hours. After you leave the dentist’s office, you may find it difficult to speak clearly or eat. Drinking from a straw can be messy. Be careful not to bite down on the numb area. You could hurt yourself without realising it.

Side effects

Local anaesthetics are the most common drugs used in the dental office. Side effects are very rare.

One possible side effect is a haematoma. This is a blood-filled swelling. It can form when the injection needle hits a blood vessel.

The numbing medicine sometimes causes numbness outside of the targeted area. If this happens, your eyelid or mouth can droop. You will recover when the drug wears off.

If you are unable to blink, you may need to have your eye taped shut until the numbness wears off. The anaesthetic usually lasts for only a couple of hours. In some people, the vasoconstrictor drug can cause the heart to beat faster. This lasts only a minute or two. Tell your doctor if this has ever happened to you.

Finally, the needle can injure a nerve. This can lead to numbness and pain for several weeks or months. The nerve usually heals over time.

Concerns

It is rare to have an allergic reaction to a local anaesthetic. Be sure to tell your dentist about all the medicines you take. This should include over-the-counter drugs and any herbs or vitamins you take. Also, tell your dentist about any reactions you have had with medicines, no matter how minor the reaction was. Some drugs can interact with local anaesthetics.

Dr Sharon Robinson DDS has offices at the Dental Place Cosmetix Spa, located at shop #5, Winchester Business Centre, 15 Hope Road, Kingston 10. Dr Robinson is an adjunct lecturer at the University of Technology, Jamaica, School of Oral Health Sciences. She may be contacted at 630-4710. Like their Facebook page, Dental Place Cosmetix Spa.