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Dental Anatomy

Why Your Dentist Can’t Get You Numb

Jun 27, 2011

Did you know that over four million dental injections are given every year in the United States? The failure rate is estimated to be anywhere from 5 to 15%. that means that there are anywhere from 200,000 to 600,000 dental injections that don’t get the patient numb. That means that people get poked by their dentist with a needle and don’t end up getting numb about every minute.

It’s no wonder that a lot of people come into my dental school and tell me something similar to, “My dentist has trouble getting me numb – I usually need a lot of novocaine in order to get numb.” As a side note, we normally use lidocaine, not novocaine as many patients believe.

So why do so many dental anesthetic injections not work – why can’t your dentist get you numb?

Seven Reasons Why Your Dentist Can’t Get You Numb

An article published in the January 1991 issue of the Journal of the American Dental Association sheds some insight into this issue by giving five reasons why dental injections sometimes don’t work. I also found a couple of others and added them onto the list below.

1 – Anatomic Variations

Everyone is different. Some people’s jaw flares out wider than others, making it hard to visualize where that person’s nerve is. Some people have a longer jaw or extra muscle and/or fat around their jaw. In patients that are missing lots of teeth in the back of their mouth, it’s harder to visualize where the nerve is. Also, young patients can have different anatomy depending on their stage of growth, making it hard to get the anesthetic in the right spot.

2 – Technical Errors by the Dentist

Dentists aren’t perfect! Sometimes we can put the needle in the wrong place and give the anesthetic too low, too high, or too far to the side. Also, we might not put the needle in deep enough, or we may accdentally deposit the anesthetic in a blood vessel, which is why your heart can beat fast when getting a dental injection.

3 – Anxious Patients

Some anxious patients may think that they aren’t numb and jerk away in fear when we start to drill. In cases like this, I usually tap around their gums on the numb side and then on the side that isn’t numb to let them feel the difference and realize that they really are numb.

4 – Inflammation or Infection

When people have swelling in an area, it can be harder to get them numb. One theory says that the acidic tissue makes it harder for the anesthetic to take effect. Antoher theory says that since the patient has been in pain for so long, use tramadol pain medicine, they have an increased sensitivity to pain which makes it harder for them to get numb.

5 – Defective Anesthetic Solutions

I haven’t had experience with this one, since my dental school has a pretty good quality control program to ensure that the dental anesthetic stays potent. However, sometimes a dentist may use dental anesthetic that has expired or was improperly stored or manufactured. This made me realize that I should always go with a respected brand name of dental anesthetic and not get the cheaper stuff to save money. There’s no point in cutting corners if it will inconvenience my patients.

6 – Having Red Hair

People with red hair have more difficulty succumbing to the numbing effects of dental anesthetic. They also have a greater fear of the dentist.

This article published in the July 2009 Journal of the American Dental Association states, “People with naturally red hair are resistant to subcutaneous local anesthetics and, therefore, may experience increased anxiety regarding dental care.”

7 – Having Joint Hypermobility

Those who suffer from Ehlers-Danlos Syndrome can be insensitive to local anesthetics used in dentistry. You can check out this article for more information on local anesthetic failure in those with joint hypermobility.

Conclusion

If your dentist can’t get you numb, more than likely there is a specific reason. In my experience, I’ve found that there are many people who have slightly different anatomy in their jaws which makes it harder to position the needle so that the anesthetic gets deposited where their nerve is located.

Do you have any questions, questions, comments, or concerns about getting numb at the dentist? If so, feel free to go ahead and leave a comment below. Thanks for reading!

The Differences Between Baby Teeth and Permanent Teeth

Pediatric Dentistry

Feb 7, 2011

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Baby Teeth and Adult Teeth Differences — ©Timothy W. Stone/Shutterstock.com

Have you ever noticed that baby teeth look like they’re whiter than adult teeth? Or maybe you knocked out a baby tooth when you were a child, but when you had a similar accident when you were older, your permanent tooth got chipped rather than getting knocked out.

The two scenarios above can be explained by the differences between adult and permanent teeth.

There are many differences between baby teeth and permanent teeth, but before I get into all of the differences, take a look at the photo above of the little girl swimming.

Now, take a closer look at her teeth in the photo below:

In the picture to the left, there are six permanent teeth that are visible. Can you spot them?

They are the two top front teeth, the two bottom front teeth, and the two molars on the bottom in the very back of her mouth.

These permanent teeth stand out in more ways than one. I’ll cover all these differences between baby teeth and permanent teeth below.

As you read, feel free to refer back to this picture to get a visual representation of some of the more noticeable differences that I talk about below.

The Differences Between Permanent Teeth and Baby Teeth

1 – The enamel and dentin are thinner in baby teeth, and the pulp is bigger relative to the rest of the tooth. This means that if your child gets a cavity, it will travel much faster to the nerve of the tooth. This is one more reason why it’s important to take your child to the dentist before they turn one year old and get routine checkups thereafter.

Not sure what enamel, dentin, and pulp are? Read my previous article about the anatomy of a tooth.

2 – Permanent teeth are more yellow than baby teeth. Take a quick look at the picture above and you’ll see that the six permanent teeth that are visible don’t look nearly as white as the other baby teeth.

3 – Baby teeth have shorter roots – because of this they aren’t anchored as well into the bone and may fall out more easily if your child falls on a hard step or hits their mouth on the coffee table. The shorter roots also give the permanent teeth more room to develop underneath the baby teeth and make it easier to dissolve the roots of the baby teeth when the permanent teeth are ready to come into the mouth.

Find out what to do when a baby tooth gets knocked out.

4 – Baby teeth fall out – If you take good care of your adult teeth you can keep them for your entire life. Just because baby teeth fall out, it doesn’t mean that they aren’t important. If you’ve been staying up late at night pondering this question, click the following link to find out why baby teeth are important.

5 – Permanent teeth have mamelons. Mamelons are the small bumps that give the permanent incisors a serrated look when they first come into the mouth. If you look closely at the girl in the picture above, you can see the little bumps on the edges of her four permanent front teeth. Mamelons quickly wear away as long as the teeth fit together properly.

Learn more about what mamelons are and what to do if you still have them as an adult.

Conclusion

As you can see, there are definitely some differences between adult and permanent teeth. These differences can not only affect the appearance of the teeth, but can also affect what happens to a tooth when you suffer an injury to the mouth.

Do you have any questions about baby teeth or permanent teeth? I’d love to hear what you have to say in the comments section below! Thanks for reading.

A Popping Click When You Open Your Jaw Is Pretty Common

Jun 16, 2010

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Popping and Clicking in Jaw is Normal — ©Absolutimages/Shutterstock.com

If you experience a popping sound, a grating sound, or a click when you open your mouth, you’re not alone.

Many people have slight problems with their jaw joint, which is formally known as the temporomandibular joint, or TMJ for short. Whenever we want to open our mouth, our jaw glides down and forward to allow our mouth to open.

The rounded end of the jaw bone that glides down is called the condyle. Between the condyle and our skull, there is a small, soft, lubricated disk that allows our jaw to open smoothly. This is called the articular disk.

Sometimes, that disk may not be big enough, or it may not be the right shape to allow the jaw bone to smoothly glide forward and down when you open your mouth. When this happens, it is a condition known as crepitus.

Crepitus is a word that is used to describe the grating, crackling, and/or popping sounds that are heard around people’s joints.

Unfortunately, not everyone has jaw joints. When I open my mouth, my jaw slides down and out nicely on the right side, but on my left side, there is a loud popping noise. Luckily this only happens when I open my mouth really wide, so it doesn’t affect me when I chew gum or eat (unless it’s a really big hamburger!)

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The Anatomy of a Tooth

Anatomy

Mar 8, 2010

Have you ever wondered what makes a tooth so strong?

The anatomy of a tooth is very simple compared to the human body. Every tooth in your mouth has two major portions: a crown and a root.

The crown of the tooth is normally the portion that you can see inside your mouth. It is covered in a glassy, white-colored substance called enamel, which is the hardest substance in the body.

The root is the part of the tooth that you can’t see unless you have severe gum disease. It is what anchors the tooth in the mouth and supports all of the forces that are placed on the tooth while food is being chewed. The root is covered by a very thin layer of a substance called cementum. The cementum anchors the tooth to the bone by way of the periodontal ligament.

Here is a large diagram that illustrates the anatomy of a tooth:

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