Archives for February 2015

Doc, That Shot Hurt – Part I

As a dentist in private practice, I probably administer local anesthetic about ten times a day. Or to state this in terms that patients like to use, I probably give about ten shots each day. Sometimes more, sometimes less.

Very often, my patient will say something like “Wow, I barely felt that! You’re good.” But other times, I’ll hear “Wow, that hurt! My last dentist didn’t hurt me like this!”

The degree to which you will feel the shot while in the dental chair is dependent upon a number of factors. In fact, there are so many factors that they will be spread across two blog posts. Here’s part 1:

1. Location, Location, Location!

roof of the mouth or palate shot photograph

Any injection on the palate will hurt!

Just as the real estate saying goes, location is probably the number one factor in determining how much, if at all, a dental injection will hurt.

It is universally agreed upon by both dentists and patients that the shot on the roof of the mouth (more formally known as a palatal injection) hurts the most. Why? First off, the type of gum tissue present does not allow for topical anesthetic to work effectively. Secondly, the tissue is so tight and firm that the local anesthetic fluid has literally nowhere to go – making it very painful as the fluid is pushed in.

Conversely, other areas, such as on the outside of an upper tooth, we can make almost painless. You would literally not even know the injection occurred. This, however, assumes other factors are taken into account (those factors are outlined here and in the next post).

2. Topical Anesthetic

topical anesthetic used for dental injections photo

Topical Anesthetic

Topical anesthetic, more frequently referred to as “numbing jelly,” will reduce the initial “pinch” of the injection.

How does it do it?

The jelly is actually an anesthetic – just a viscous form similar to what is injected. When applied to the inside of the mouth, it will numb the area in approximately 1 minute. By making the superficial layers numb, the initial sensation of the pinch of the needle is either eliminated or reduced.

Most dentists use standard topical anesthesia these days. Some dentists, myself included, will use a high powered version that is compounded at a local pharmacy. When used properly, this type can almost completely eliminate the sensation of the needle.

If your dentist does not use topical anestheisa, you should request it. It makes a BIG difference.

3. Temperature

thermometer photo showing temperature affects pain from dental shots

Temperature of the local anesthetic affects how much you feel it.

This should be very obvious. Dental anesthetic is typically at room temperature – approximately 68 degrees Fahrenheit – and your body temperature is approximately 98 degrees Fahrenheit. Don’t you think that the 30 degree difference in temperature will make the shot be more painful?

If you answered yes, you are correct. And many research studies have confirmed this. It can make such a difference that there are actually local anesthetic warmers that dentists can buy.

Having used warmers before, I can attest that they appear to make a difference in how much you feel. But again, this assumes all other techniques are being used.

4. Presence of an Infection

Occasionally, a patient will have a significant dental infection that requires treatment. In many of those cases, an injection needs to made directly into the infected site.

pericoronitis photo where the dental shot will hurt

An injection into this infected tooth – with pericoronitis – will hurt.

Infected tissue is already hypersensitive. And the patient is already extremely distressed. And in many cases, there is a buildup of pus which is causing an increase in pressure. So what happens when you inject 1.8 cc of a local anesthetic into the infected area? You feel pain. This is because of the hypersensitivity, the likely buildup of pus underneath, and the stress.

So, injections into infected areas will always hurt, no matter what I or any other dentist try to do.

5. Choice of Local Anesthetic

First off, we dentists no longer use novocaine. In the United States, there are many different type of local anesthetics available. These include lidocaine, articaine, mepivicaine, bupivicaine, and many others. Some come with epinephrine and some come without.

According to some research studies, the choice of local anesthetic can affect how much pain you feel. This is because of differences in pH (the acidity). In humans, the pH at the injection site is typically 7.4. Doesn’t it make sense that the closer the local anesthetic is to 7.4 the less pain you will feel?

Lidocaine local anesthetic used for dentist shots

Some research says lidocaine hurts more than other local anesthetics!

One local anesthetic, prilocaine (brand name Citanest), has a pH of between 6.0 and 7.0. Many other common local anesthetics have pHs of approximately 5.0. So it stands to reason that prilocaine will hurt less because its pH is much closer to our body’s normal pH.

Well, one study confirms this finding, while another study finds no difference in type of anesthetic.

You might be asking then, why don’t all dentists use prilocaine? Prilocaine does not last as long as other local anesthetics. And many dentists (myself included) feel it is not as effective in getting patients properly numb. So many dentists elect not to use it.

Believe it or not, there are 5 more reasons why some shots hurt more than others. Part II can be found here.