Tags Posts tagged with "pulp"


Why Teeth Hurt
©Vladimir Gjorgiev/Shutterstock.com

There are several easy answers to the question, “Why do teeth hurt?”  For example, teeth hurt because you don’t take care of them.  But, that’s not what I want to talk about in this article.  I want to talk about why it is that teeth hurt so much.  They’re so small, yet if you’ve ever had a toothache that kept you up at night, you know that teeth can hurt almost as much as any other feeling of pain you’ve ever felt.

Teeth Hurt Because They Are So Hard

Why Teeth HurtTeeth hurt because they are so hard.  When the tissue inside of the tooth (the pulp) gets hurt, it has no room to expand.  Here’s an example.  Let’s say someone punches you in the shoulder.  Your shoulder might get warm and swollen.  Your shoulder has room to get bigger.

Now let’s say that someone punches your tooth and chips the bottom of it.  The force of the blow will likely irritate the pulp of your tooth and cause it to get warm and swollen.  Here’s the problem, when the pulp gets swollen, it wants to get bigger, but there’s nowhere to go!  The pulp is encased in a hard shell known as the dentin and enamel of your tooth.  Pressure builds up inside of your tooth.  Suddenly, the tooth that was hurting due to the initial trauma is now also hurting because of the pressure.

Not sure what the difference between pulp, dentin, and enamel is?  Read my article about the anatomy of a tooth.

Here is what happens in technical terms when the pulp becomes inflamed.  It’s a quote taken from the book, Cohen’s Pathways of the Pulp by Hargreaves:

Inflammation in the pulp takes place in a low-compliance environment composed of rigid dentinal walls. Compliance is defined as the relationship between volume (V) and interstitial pressure (P) changes: C = Δ V/ Δ P. Consequently, in the low-compliant pulp, an increase in blood or interstitial volume will lead to a relatively large increase in the hydrostatic pressure in the pulp. The acute vascular reactions to an inflammatory stimulus are vasodilatation and increased vascular permeability, both of which will increase pulp interstitial fluid pressure and may tend to compress blood vessels and counteract a beneficial blood flow increase.

Other Parts of Our Body Experience Similar Pain Levels

Why Teeth HurtThe dental pulp isn’t the only tissue that experiences high levels of pain when it is inflamed.  Most places in the body that are enclosed in a rigid structure experience lots of pain.

This is why headaches can be so painful, the skull is rigid and there’s no room for the swelling to go.

Another example is when you smash your fingernail and you get lots of inflammation underneath the fingernail.  Some people have even gone so far as to burn or poke holes through their fingernails to relieve the pressure that builds up.


Teeth hurt because when the pulp gets even slightly injured, it wants to expand and there’s no room for it to expand.

Do you have any questions related to tooth pain?  Leave them below in the comments section.  Thanks for reading!

Is Blue Dental Light Harmful?
©Nejron Photo/Shutterstock.com

Recently, Christopher, a thirteen-year-old reader from Michigan wanted to know if the blue light that dentists use to cure fillings and sealants can hurt your teeth when used for a long period of time.

Blue Dental Curing LightHe told me that when he was at the dentist’s office getting sealants placed on his back teeth, they shined a light in his mouth.  After the sealants were put on, the dental assistant hardened (cured) the sealants by shining a blue light on them.  He noticed that after the blue light had shut off automatically, the dental assistant would press the button to get it to turn on again and continue curing the sealants.

Christopher wanted to know if the blue light can burn, irradiate or otherwise hurt someone’s teeth when used longer than it should be.

About the Blue Dental Curing Light

Before I answer Christopher’s question, here’s a little background information for those who aren’t familiar with the blue dental curing light.  When a dentist puts a white filling (or a sealant, or a light-cured filling material) in your mouth, it is in a liquid or semi-solid state so that the dentist can put it exactly where it needs to go and shape it correctly.  In order for the material to harden so that it can withstand the forces of chewing, it needs to be cured.

Curing the material is accomplished by shining a blue light on it.  Not just any blue light will do.  It has to be a certain shade of blue.

The blue dental curing light emits light at a wavelength of around 450 to 490 nm, a blue light.  You can read more about the visible light spectrum here.

The very first light-activated filling materials used ultraviolet light.  Fortunately, today dentists only use materials that are cured by visible light as the use of UV cured materials has pretty much died out due to the dangers posed by ultraviolet light.

Can the Blue Dental Curing Light Hurt Your Teeth?

Blue Dental Curing LightFortunately, the blue dental curing light normally won’t hurt your teeth.  Most of the modern curing lights use a blue LED light for curing.  In some of the old models, the tip could get really hot.  This heat could cause damage to the dental pulp — the innermost tissue composed of nerves and blood vessels inside of your tooth.

A good test to see if the curing light is too hot is to hold your finger 2-3 mm away from the curing light for 20 seconds.  If your finger gets too hot, then the curing light could do damage to the teeth.

The Blue Dental Curing Light Can Hurt Your Eyes!

One of the major dangers of the blue dental curing light is that it can hurt your eyes!  When we were learning how to do white fillings, our professors always advised us to never look at the blue light.

Here’s what the book Craig’s Restorative Dental Materials says about this:

Although there is minimal potential for radiation damage to surrounding soft tissue inadvertently exposed to visible light, caution should be used to prevent retinal damage to the eyes.  Because of the high intensity of the light, the operator should not look directly at the tip or the reflected light from the teeth.

The orange filter that you can see on the curing light above filters out the visible light, allowing the dentist or assistant to see what they are doing without looking directly at the light.


To answer Christopher’s question, there could be some harm in holding the light on your teeth for too long if it heated up your teeth.  Since you probably weren’t numb when the sealants were placed, you would have felt pain if your teeth had gotten too hot.  Other than that, as long as they didn’t shine the light in your eyes, no damage was done, since they used visible light rather than ultraviolet light.

The dental assistant probably just wanted to make sure that the sealant was hardened all the way, and didn’t want to leave any room for doubt.

Do you have any questions or comments about the blue dental curing light used in dentistry?  If so, feel free to leave them in the comments section below.  Thanks for reading!

By the way, I really enjoyed researching for this article.  If you have any dental questions, no matter how odd you think they are, feel free to contact me and I’ll either answer your question via email or in an article here at Oral Answers.

Anatomy of a Tooth

Have you ever wondered what makes a tooth so strong?

Anatomy of a ToothThe 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: