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Composite Fillings

Is Blue Dental Light Harmful?
©Nejron Photo/

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.

Chipped Tooth Fixed Filling

Breaking one of your front teeth is something that nobody wants to go through, but unfortunately it is a common occurrence.  Luckily, modern dentistry is able to make these teeth look normal after a tooth fracture has occurred.  Chipped teeth can be repaired with crowns, veneers, and ordinary white composite fillings.

Today in my pre-clinical lab, we fractured a tooth on purpose and then repaired it.  I took some pictures of the finished result so you can see how it looks.  My professor had us mount some natural teeth in a yellow plaster.  When we got to the lab, he had us cut a few millimeters of tooth structure off of an incisor to simulate a front tooth that had been chipped.  Front teeth can be chipped when someone trips and hits their mouth on a hard object, during fights, or for many other reasons.

I worked on the middle tooth in the photos below.

Composite Filling Dry
Above is the finished tooth in the middle. When it’s dry, it’s easy to see the difference between the filling and the natural tooth. In the bottom photo, I drew a red line showing where the natural tooth ends and the filling begins.

In the bottom photo, you can see a red line.  Everything below that red line is the composite filling, and everything above it is natural tooth structure.

In both of these photos, the tooth is dry, so it is easier to differentiate between the white filling and the natural tooth structure.  The composite filling is also easier to differentiate in this example because we only have a couple of shades of composite available to us in the pre-clinic lab.

I took a second photo of the filling after getting the teeth wet.  This better simulates the real world since our teeth live in a very wet environment in the mouth.

Class IV Composite Filling Wet
Here is the finished tooth. I put some water on it to simulate saliva. When the filling is wet (as it is in the mouth), it appears more aesthetically pleasing.

You will notice that it is a lot harder to see the difference between the natural tooth structure and the composite filling when the tooth is wet.

When you compare it to the tooth on the right, you can see that the colors match pretty well; it is more yellow at the top, and gets whiter as you go down the tooth.

If I’d have used the right shade of composite (and if I had a few more years of experience!), it would be nearly impossible for the untrained eye to detect the difference between the composite filling and the natural tooth structure.

Have you ever chipped a tooth?  Did you get it repaired?  If you have any comments or questions, please leave them below in the comments section below.

High Filling Pain

If you’ve ever received a filling at the dentist’s office, you probably vaguely remember the dentist putting a piece of colored paper in your mouth and telling you to bite together.  Then, the dentist probably asked, “Does that feel too high?”

Filling is too HighSince the mouth is generally numbed during a filling, it’s often hard to tell if a filling is too high while you’re sitting in the dental chair.  Also, the sooner we tell the dentist that it feels alright, the faster we can get out of their office and on with our life!

Sometimes, a few days after receiving a filling you may notice that your filling is a little too high.  When you bite together, the filling and its opposing tooth may be the first teeth to touch.  It may create an uneven bite.  However, the worst side-effect of a high filling is pain!

Why Does a High Filling Hurt and Cause Pain?

A Tooth With Symptomatic Apical Periodontitis Due to a High  FillingThe tooth is supported in bone by a thin layer of tissue called the periodontal ligament.  When you have a filling that is too high, the tooth gets pressed down a lot harder and it makes this ligament very tender.

All of the tissues of our body can get tender when put under stress.  For example, if you work outside in the garden all day pulling weeds without any gloves on, your hands will get red and inflamed.  As a result, the body sends an extra amount of blood to your hands to help them heal.  They gets red, inflamed, and very tender as part of the healing process.  This is what happens with the periodontal ligament when it gets compressed much more than usual due to a high filling.

The technical term for this is symptomatic apical periodontitis or acute apical periodontitis.

In the image to the right, you can see a high filling on the left side of the molar tooth.  I made the filling yellow so it will stand out.

In the bottom left, you can see that the periodontal ligament has widened and become red and inflamed.  This is the source of your pain when you have a high filling.

How to Stop the Pain Caused by Symptomatic Apical Periodontitis

In order to stop the pain, the cause must be removed.  That means you need to call your dentist and tell them that the filling is too high.  The process of grinding it down and re-checking your bite should only take a few minutes and most dentists probably won’t charge for it — after all, the filling was high in the first place because they didn’t grind it down enough to begin with.

How Long Will It Be Until the Pain Stops?

After the dentist has ground down the filling, the peridontal ligament will still need some time to heal from the additional stress that was placed upon it.

This healing process can take anywhere from a one day to two weeks.  As a general rule, if you are still in pain after more than two weeks you should make an appointment with your dentist, as this could be a sign that something else is wrong with your teeth.

I have a friend who recently experienced symptomatic apical periodontitis as a result of a filling that was too high (he was the inspiration for this post.)  He went back and had it adjusted and it was still too high.  He went back again, and the dentist took it down a little bit more.  After that, he said it was feeling better.

Don’t be shy about calling your dentist – the quicker that a problem is resolved, the less likely it is to develop into something more serious.

Has this ever happened to you or your dearly-loved ones?  Please leave a comment below and share.

Silver Fillings Last Longer than White Fillings

In my last two articles, I addressed the length of time that White (Composite or Tooth-Colored) fillings last and the length of time that Silver (Amalgam) fillings last.

In this article, I simply wish to summarize the results and show a graph comparing the length of time that you can expect your fillings to last.

Amalgam (Silver) Fillings Last Longest

Amalgam fillings tend to last around 12 years, while a composite filling only lasts about 6 years.

Here is a graph that shows the percentage of remaining fillings after a certain amount of years.  It has been constructed using the data from Chadwick B, Dummer P, Dunstan F , et al. The Longevity of Dental Restorations.

A Graph Comparing the Length of Time That Amalgam and Composite Fillings Last
A Graph Comparing the Length of Time That Amalgam and Composite Fillings Last. 

Does This Mean Amalgam Fillings Are Better?

A Beautiful SmileNo.  Amalgam fillings are less costly and generally last longer, but they aren’t very aesthetic.  Most people don’t want everyone to see a big chunk of silver on their teeth when they smile.  As a general rule, composite fillings are usually best for the front teeth that most people will see.  For teeth in the back, the stronger, long-lasting amalgam fillings are usually recommended.

How Long White Composite Fillings Last
©Ermolaev Alexander/

Last week, I wrote about how long amalgam (silver-colored) fillings last.  While many people have amalgam fillings in their mouths, others prefer white fillings because they are less-noticeable and made of different materials.  As you can imagine, most people don’t want to walk around with a big silver filling on one of their front teeth!  Unfortunately, while tooth-colored (also called composite resin) fillings are more aesthetically pleasing than the silver amalgam fillings, there is a trade-off — they simply don’t last as long.

The Average Tooth-Colored Filling Lasts About Five to Seven Years

A Composite Filling Courtesy of Michael Ottenbruch on Wikimedia Commons
A Composite Filling

There have been many studies done to discover how long composite resin fillings last.  I would like to share three of them here.

The first study involved a study of 659 dentists in Finland.  Finland is one of the European nations that is trying to phase-out amalgam fillings due to health concerns from the mercury that they contain, and are shifting towards composite fillings.  These dentists placed over just under 5,000 composite fillings during the study period.  This particular study found that composite fillings last less than five years.

The next study followed just one dentist in Belgium.  He placed 115 composite fillings from 1982 to 1999.  The study found that the composite fillings that this dentist placed over that period of years lasted on average just under 8 years.

Those isolated studies work pretty well, but the sample size isn’t the largest.  To address this problem, a group of researchers scoured 16 electronic databases, and 36 dental journals in 2002 to find all of the studies performed on the longevity of different types of restorations.  They found 73 studies looking at how long composite fillings last.  You can find a summary of their findings here.  From the data they collected, I put together the graph below which shows the estimate of the longevity of composite fillings.

How Long Composite (Tooth-colored) Fillings Last
A graph showing the percentage of composite restorations still in existence for a given number of years after they were placed.


Composite fillings between five and seven years, on average.  As technology improves, composite fillings will only get better.  I believe that someday, composite fillings could last longer than amalgam fillings.  New methods of bonding composites to tooth surfaces are being researched every day.   The duration of composite fillings will only increase as time goes on.