Photo of Topical Anesthetics in different flavours

Topical Anesthesia (or “numbing gel” in dentist-speak) is used to numb your gums or other tissues before an injection, so that you can’t feel the needle glide in.

  • Topical Anesthetic = an anesthetic agent that is applied externally to tissues like gums
  • Local Anesthetic = an anesthetic agent that is injected with a needle

How does it work?

Cotton-Tip Applicators

Numbing gel contains an anesthetic agent, most commonly benzocaine (usually at a concentration of 20%). A cotton swab or q-tip is used to apply a small amount of gel to the injection site.

Does it really work?

Yes it does, but there’s a slight snag. It needs to be left on for about one minute, in order to be really effective. Studies have shown that application of topical anesthetic to the injection site for 2 to 3 minutes leads to profound soft-tissue analgesia (Stern & Giddon, 1975). The problem is that some manufacterers’ instructions say it only needs to be left on for 10-15 seconds, which is not enough time for numbing to take place (Gill & Orr, 1979). So if you read somewhere that “the numbing gel doesn’t work for me”, it’s probably because it wasn’t left on for long enough. So it’s important to leave it on for long enough, especially in sensitive areas like the palate.

Does the numbing gel guarantee a comfortable injection?

Actually, most discomfort during injections is due to the local anaesthetic being given too quickly. It is important to give it slowly and steadily to avoid any discomfort (although this also depends on which area is being numbed). Especially in days gone by, some dentists also used pretty blunt needles, which hurt. If you’re particularly scared of injections, the best way to find a dentist who gives painless ones is by asking around. Also ask the dentist – they tend to be amazingly forthright about their ability (or inability) to give painless injections…

My dentist is using a spray, not a gel – what is going on?

Photo of numbing gels in different flavors

Topical anesthetic comes in lots of forms (sprays, patch, ointment, solution). The ingredients are the same, but the gel seems to be popular these days. Topical anaesthetics are available from many companies, and sometimes come in yummy flavors like strawberry, mint, cherry, banana, berry, tropical fruit, and bubble gum.

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 for 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?”. If necessary, explain that it would make you feel less anxious.

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 localized to the spot where the contact occurs. But if you have a known allergy to benzocaine, let your dentist know. An alternative topical anaesthetic is lidocaine. The reason why benzocaine is the topical anaesthetic of choice is the risk of accidental overdose is lower with esters compared to amides (especially on larger areas).

I’ve heard about a numbing gel that can be used instead of injections. Is this true?

You’re probably referring to Oraqix. Because their slogan is “needle-free dental anesthesia”, many people think that Oraqix can be used instead of injections. That’s not the case – Oraqix really is nothing other than EMLA cream and a special applicator for a treatment called scaling and root planning (deep cleaning). It’s very good for numbing your gums, but it’s no use for numbing the actual teeth. This is because Oraqix (like all topical anesthetics) only numbs soft tissues. It 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.

However, some dentists have reported that Oraquix also seems to work for sensitivity during dental cleanings due to sensitive teeth. The most common cause of sensitive teeth is that the enamel (the outermost part of the tooth) has worn away and that the next layer (the dentin) is exposed. The dentin is made up of thousands of microscopic passageways that lead to the tooth’s nerve center. So when your teeth come in contact with something cold, hot or sweet, the tubules carry the sensation to the tooth’s nerves and can cause pain.

Further Reading

Needle Phobia