Topical Anaesthetic (or “numbing gel” in dentist-speak) is used to numb the gums or other tissues before an injection, so you won’t be able to feel the needle glide in.
- Topical Anaesthetic is put on tissues like gums or skin and numbs the surface of the tissue.
- Local Anaesthetic is injected with a needle and numbs the nerves of the actual tooth (or teeth).
How does it work?
Numbing gel contains an anaesthetic agent. A q-tip/cotton bud or cotton roll (depending on location and dentist preference) is used to apply a small amount of numbing gel to the injection site before the injection.
In the UK, lidocaine (aka xylocaine) at a concentration of 5% is widely used (for example Xylonor Gel by Septodont).
Until fairly recently, benzocaine 20% used to be the most common topical anaesthetic. But because some people are allergic to benzocaine, many dentists now use lidocaine instead.
Does it really work?
Yes it does, but there’s a slight snag. It needs to be left on for long enough to take effect. Numbing gel usually starts working within 1 to 2 minutes for lidocaine (or 30 seconds for benzocaine). But in sensitive areas of the mouth like the palate, it should ideally be left on for longer for best effect: 2 to 5 minutes for lidocaine (or 2 to 3 minutes for benzocaine) 1.
Does the numbing gel guarantee a comfortable injection?
Actually, most discomfort during injections is due to the local anaesthetic being given too quickly, as well as the bevel of the needle not being angled correctly. It is important to give it slowly and steadily to avoid any discomfort (although this also depends on which area is being numbed – some areas are much more sensitive than others).
So while the numbing gel doesn’t guarantee a comfortable injection, it can certainly play a big part, especially in sensitive areas of the mouth.
What types of topical anaesthetic are there?
Topical anaesthetic comes in lots of forms (spray, patch, ointment/gel, solution). The ingredients are the same, but they are good for different purposes. Gel is good for numbing the gums prior to an injection. Spray is good if you are prone to gagging, and can be used before x-rays, for example.
Some topical anaesthetics come in yummy flavours such as strawberry, mint, cherry, berry, tropical fruit, or bubble gum.
I’ve heard about a numbing gel that can be used instead of injections. Is this true?
Topical anaesthetics are good for numbing the gums, but they’re no use for numbing the actual teeth. This is because they only numb soft tissues. Topical anaesthetics doesn’t really affect the nerves that transmit sensations from your teeth to your brain. To put these nerves to sleep, a local anaesthetic needs to be used.
For some people, topical anaesthetics can be a useful alternative to local anaesthetics for deep cleaning (also known as scaling and root planing), depending on how sensitive your teeth and gums are, and whether or not injections cause you a lot of stress.
Oraqix (2.5% lidocaine and 2.5% prilocaine) is a non-injectable gel anaesthetic that is put into the space where the teeth meet the gums in order to numb the soft tissues.
My dentist doesn’t use the numbing gel. What should I do?
Some dentists are really good at giving painless injections even without numbing gel. This is especially true for upper back teeth and lower front teeth. But if you’d like the numbing gel, just ask if they have it! It’s not impolite to do so, nobody is going to get upset if you say something along the lines of “I’m worried that the prick might hurt. I’ve read about this numbing gel, could you use something like that?”.
I’m allergic to ester “caines” like benzocaine.
Allergy to ester “caines” is more common compared to the amide “caines” used in injections. Luckily, because benzocaine is not absorbed into the body system, any allergic reaction is usually localised to the spot where the contact occurs. But if you have a known allergy to benzocaine, let your dentist know – lidocaine can be used instead.
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Needle Phobia – This page also provides information on topical anaesthetics for IV sedation, including Ametop and EMLA cream.
- H.S. Lee (2016). Recent advances in topical anaesthesia. J Dent Anesth Pain Med. 2016 Dec;16(4):237-244.