Have you ever had a new filling or crown placed that felt kind of foreign? It was smooth as silk, it wasn’t pointy and the bite felt just right. But yet, it was different. Your tongue acted like it would never get used to it, constantly running circles around the newness of it.
Do you remember what happened to it? Yup. You forgot about it. A day or two later, it didn’t feel new. How does that work? I mean, two days ago you were pretty sure that you were going to need to call the dentist. There had to be something wrong with this weird new filling. But now you’re not even sure what tooth it is. How bizarre is that?
It’s actually not bizarre at all! In fact, it means your nervous system is working just perfectly.
Neural adaptation or sensory adaptation is a change over time in the responsiveness of the sensory system to a constant stimulus. That’s a very fancy way of saying, “you just get used to it.” Our nervous system is constantly taking in all kinds of sensory data. What we hear, what we see, what we smell, taste and feel are all giving constant input to our brain. The thing is, not all of this information is all that important at any given time. So the brain has to be able to filter out the stuff that isn’t important while keeping track of the sensory information that is.
Once the brain and nervous system has figured out which information isn’t important at the moment, or salient, it can filter this information out. That way the brain can focus on more important sensory input.
"this is going to be cold!"
My favorite example of this adaptation has to do with swimming in the lake. Each 4th of July weekend for as long as I can remember my cousins and I spend as much time as we can in the lake. Even in early July, when the temperature is in the mid-80′s that lake always feels really cold. At first. If you creep into the lake slowly, just a couple steps at a time, it stays excruciatingly cold. But the longer you’re in, and the more of your body gets wet, the less cold the water feels. Pretty soon, we’re splashing around in the water like it was a bathtub. What happened? Did the water change temperature? Probably not. We just got used to the temperature.
There are probably great survival reasons for our brain to be wary of the shocking cold we feel when we make our way into the lake. We have to maintain our temperature between certain parameters and if our brain feels like this is threatened, it’s going to continue to sound the alarm. After you spend a little time in the water and your survival doesn’t seem threatened, the temperature stops being such a salient stimulus. Your brain begins to focus on other things, like the squishy bottom of the lake or your cousin attempting to dunk you.
So, back to that new crown or filling. It feels new and weird for a little while because it’s a constant and different stimulus to what your brain had been used to up to that point. The longer it stays there without causing a big problem, the more your nervous system discounts the stimuli coming from the touch receptors in your lip, cheek and tongue. Over time, the new filling begins to feel like the norm. Most of the time my patients have gotten very comfortable with their provisional (temporary) crowns and will have to go through the same process with their new crown.
So the next time you have some dental work done and your tongue keeps telling you that there’s something funny going on, just remember that it’s just like jumping into the lake. After a little while, you’ll get used to it!
Did you find this post interesting? Silly? Earth shaking? I’d love to hear about it! You can share any Mead Family Dental post with a “Like” on Facebook, a “+1″ on Google+ or you can even “Tweet” it with Twitter! All you need to do is hover over the heart shaped button next to the title of the post. Or you can leave a comment by clicking on the balloon shaped icon next to the title.
If you’re looking for a dentist in Saginaw, we’re always happy to accept new patients! You can request an appointment online or call the office at (989) 799-9133. And, as always, you can email me at alan@meadfamilydental.com. I always answer my own emails!
I recently wrote about some new research that connected dental x-rays to a common brain tumor called a meningioma. Unfortunately, the news media took the “connection” from the research and made some pretty sensational claims. It made a lot of dentists pretty mad and it made a lot of patients pretty nervous.
Today I got a suggestion from a Facebook friend:
“Al, I’ve seen the phrase ‘levels of radiation that are so small as to be insignificant’ used a fair bit in the last few years. Particularly in relation to the Japanese disaster and the observation of levels of radiation around the world due to it…I think it would be instructive to have hard numbers to compare to background and other common sources that are considered safe.”
I agree. I’ve been explaining how safe x-rays are to patients for so long, I’ve kind of forgotten about the actual amounts of radiation that we expose them to. So let’s talk a little bit about radiation.
Electromagnetic radiation like visible light and x-rays travels in waves. And I have a cool graphic of it.
Electromagnetic radiation, or EMR, is any form of energy that travels in a wave. Visible light, radio waves, microwaves and x-rays are all forms of EMR that are common to us. The different types of EMR are characterized by their wavelength and frequency. Longer wavelength radiation like radio waves and have a lower frequency and are considered “low energy.” The shorter the wavelength the higher the frequency of the energy and generally these are “higher energy.” Very high energy like x-rays and gamma rays that can cause an electron to break away from an atom are considered ionizing radiation. These are the kinds of radiation that can cause health problems. Too much ionizing radiation can cause damage to the DNA in a person’s cells, which can lead to tumor formation and even cancer. The high energy state of x-rays is also what makes them so useful for seeing structures inside the body. Visible light is stopped by the skin and soft tissues around your bones and teeth, but x-rays can penetrate through them to show us things that we cannot see with visible light alone.
Harm from radiation sources is “dose dependent,” which means that more is worse. So in order to maintain safe levels of radiation in the dental office we need to know what kind of dose that we’re giving. The dose of radiation is measured in millirems or mrem. You can actually calculate common radiation doses using this chart from the American Nuclear Society.
So what is a “safe” level of radiation dosage? According to the American Nuclear Society the average level of radiation per person in the United States is 620 mrem/year. The safe allowable dose for people that are exposed to radiation in their work (nuclear plant workers, radiology technicians) is 5000 mrem/year.
Here are some examples of radiation dosages for different common exposures:
1 bitewing or PA dental x-ray: 0.5 mrem
2 hours in a jet plane: 1 mrem
1 panoramic dental x-ray: ~3 mrem
living in a stone, adobe or concrete house (instead of wood frame): 7 mrem/year
a full mouth set of dental x-rays: 9 mrem
chest x-ray: 10 mrem
1 pack of cigarettes each day: 36 mrem/year
chest CT scan: 700 mrem
whole body CT scan: 1000 mrem
These numbers reflect conventional film x-rays. Many dentists use digital x-ray technology which needs significantly less radiation to make x-ray images. In some cases the amount of radiation needed is 80% less than conventional film radiography, which would yield even lower radiation doses.
How much is too much?
Even though dental x-rays have an incredibly low dose of radiation, it makes sense to limit the amount of radiation as much as possible. Patients with a proven track record of low decay rate are an example of a type of patient that may not need diagnostic x-rays each year. Other diagnostic methods like high magnification with intense lighting, evaluating saliva flow and dietary evaluation can help determine a patient’s risk for new decay. For patients who have experienced cavities recently or new patients that don’t have a track record with their dentist, taking dental x-rays on a regular basis is necessary diagnostic tool.
So what’s a patient to do? How do you know if an x-ray is necessary? You need to ask your dentist. And if you don’t feel like your dentist is hearing you, perhaps you need to find another. Having a relationship with a dentist whose opinion you trust is a great way to know that you’ve found a good balance between too many x-rays and not enough information to prevent dental problems.
Did you find this post helpful? Zealous? Wonderful? I’d love to hear about it! You can share any Mead Family Dental post with a “Like” on Facebook, a “+1″ on Google+ or you can even “Tweet” it with Twitter! All you need to do is hover over the heart shaped button next to the title of the post. Or you can leave a comment by clicking on the balloon shaped icon next to the title.
If you’re looking for a dentist in Saginaw, we’re always happy to accept new patients! You can request an appointment online or call the office at (989) 799-9133. And, as always, you can email me at alan@meadfamilydental.com. I always answer my own emails!
You brush your teeth to get the plaque off of them, right? And if you remove the plaque then you won’t get cavities, right?
Um…kind of.
The model dentistry has been explaining to patients forever is that plaque causes cavities and that if you can just remove the plaque then you’ll have healthy teeth. Unfortunately, it’s really not that simple.
Unless you’ve just had your teeth cleaned, like 2 minutes ago, your teeth are actually covered in a biofilm. It happens if you brush three times a day and floss like a maniac or if you haven’t seen a toothbrush in years. Biofilms form on most any surface that’s wet. Slime on the hull of a boat, coated rocks in a stream and the plaque covered surface of teeth are all examples of a biofilm.
Biofilms are actually microscopic communities of bacteria and the slimy matrix they make to stick to surfaces. A biofilm will “mature” over time and then spread. The plaque that dentists and hygienists talk about is actually a biofilm that’s large enough to be seen with the naked eye. Dental plaque/biofilm is actually made up of many types of bacteria. Some of the bacteria (Streptococcus mutans, for instance) found in this biofilm are the bad guys that can eat sugar and turn it into acid which can then cause tooth decay. Other bacteria (Streptococcus sanguinis) found in the plaque are actually known to make the biofilm less hospitable to the acid loving bacteria. So it doesn’t necessarily follow that biofilm = cavities. Someone who does a good job of brushing and flossing will generally keep the size of the biofilm smaller and potentially makes the biofilm “healthier” by increasing the % of bugs that don’t produce acid.
less beautiful and more common biofilm
O.K. Doc…I’m following you. Not all plaque is bad plaque. So why can’t they get rid of the bad bugs and leave the good bugs? Well, I’m glad you asked! There was a preliminary study out of UCLA about a mouth rinse that can do just that! Since it’s a preliminary study that means that real clinical trials to prove efficacy haven’t been done. They have some promising results on a small group of patients treated with a mouth rinse that can supposedly target S mutans (the bad bugs) in the plaque. According to one article there will be clinical trials starting in 2012.
If you like this post, I’d love to hear about it! You can share any Mead Family Dental post with a “Like” on Facebook, a “+1″ on Google+ or you can even “Tweet” it with Twitter! All you need to do is hover over the heart shaped button next to the title of the post. Or you can leave a comment by clicking on the balloon shaped icon next to the title.
If you’re looking for a dentist in Saginaw, we’re always happy to accept new patients! You can request an appointment online or call the office at (989) 799-9133. And, as always, you can email me at alan@meadfamilydental.com. I always answer my own emails!
What's the deal with silver fillings? Why is it that we see news stories every once in awhile questioning the safety of dental amalgam? The answer, in a nutshell, is Mercury.
The element Mercury (Hg) is highly toxic. Think broken thermometers and fluorescent light bulbs. Avoiding Mercury exposure is highly recommended. As an element, Mercury is poisonous.
Another element, Chlorine (Cl), is also highly toxic. Yet, when combined with the element Sodium (Na) you get a chemical that is common, safe and in reasonable doses, delicious. Common table salt is a chemical compound called Sodium chloride (NaCl) and is perfectly safe to eat in moderate amounts. But no one in their right mind would go out of their way to ingest Sodium or Chlorine on their own. The same goes for Mercury.
"Silver fillings" aren't really fillings made of Silver. They are a combination of Mercury, Silver, Copper, Tin and other trace metals. Silver fillings are placed by thoroughly mixing these ingredients. The ingredients mix and form an alloy of the metals. This alloy is different than any of the ingredients individually. In other words, there isn't just Mercury, Silver, Tin or Copper in there. It's a whole new chemical compound made up of all of these metals. It's kind of like concrete. You start with cement, sand, stone and water. The final product is concrete. You can't go back and take the ingredients out of concrete without breaking down the concrete chemically.
The bottom line is that there's no such thing as "Mercury fillings." Dental amalgam has Mercury in it that is chemically combined with other metals to form an alloy. One of the properties of Mercury is it's ability to form an alloy like this at room temperature.
Can dental amalgam "leak" Mercury? Yes. There can be a very slight release of mercury from amalgam fillings. A study conducted by measuring the Mercury vapor levels inside the mouth over a 24-hour period in patients with at least nine amalgam restorations showed the average daily dose of inhaled mercury vapor was 1.7 µg (micrograms), which is approximately only 1% of the threshold limit value of 300 to 500 µg/day established by the World Health Organization. So there is Mercury released from fillings, but it's a very tiny amount.
What about Mercury exposure from dental amalgams causing diseases? The American Dental Association has weighed in regarding the safety and efficacy of dental amalgam. Scientific evidence concludes that the use of dental amalgam is safe. There is no evidence to support removing silver fillings in an effort to cure or prevent other diseases.
Dental amalgam has undoubtedly saved millions of teeth in its 100+ years of use. Until relatively recently there haven't been inexpensive options to restore teeth that could hold a candle to silver fillings. They're durable as heck and they're relatively easy and inexpensive to place.
Are there any problems with dental amalgam? I actually see two.
They're ugly. When polished they can be shiny and smooth, but they don't look like a tooth. They look like metal, which they are.
In order to place a silver filling you need to remove a lot of tooth structure. In a tooth that's never been filled before, this means that you're cutting away more tooth structure than you need to.
To me, those are the main down sides to using dental amalgam. Perhaps these down sides deserve their own post (stay tuned!) I place very few dental amalgams any more because I'm confident that I can place an excellent bonded resin restoration (a.k.a: composite) in any situation that I might have used amalgam.
But my reasons for using composite fillings has nothing to do with Mercury. In my mind, the Mercury is a non-issue.
Do you have questions or comments about this post? Can this Saginaw dentist be of service to you in any way? I'd love to hear from you at my email: alan@meadfamilydental.com. Or give us a call at the office at (989) 799-9133! We'd love to be your Saginaw dentist! And don't forget to "like" us on Facebook!
I recently bought a bottle of water at Walgreen. The brand was “Iceland Pure Spring Water” and it featured “pH 8.88″ prominently on the label. I read a little further to find:
“…it has one of the naturally lowest mineral contents of any water and a high pH of 8.88. Icelanders live longer than any other nationality; we believe their secret to long life is their water.”
This is an interesting claim. My research (if you want to call finding a cool chart Wikipedia chart research) shows Iceland coming in 3rd to Japan and Hong Kong. FYI…the U.S. comes in tied for 36th place with Cuba and Denmark. So the claim that Icelanders live the longest is in dispute, but what about the pH of their amazing spring water? Could it account for longevity? Should I be worried about my pH?
pH is a measurement of acidiy or alkalinity in an aqueous (water based) solution. A solution that is high in acidity has a low pH and a solution that is more alkaline has a higher pH. pH is measured on a 14 point scale with 0 being the lowest pH (most acidic) and 14 being the highest pH (most basic or alkaline). A pH of 7 is considered neutral, neither majority acid or alkaline. This 14 point scale is logarithmic, which means that each number on the scale is 10 times higher or lower than number above it or below it. For instance, a substance with a pH of 3 is 10 times more acidic than a substance with a pH of 4 and 100 times more acidic than something with a pH of 5.
The pH of the human body is variable depending on the part of the body you’re talking about. The stomach has a pH of about 1…very acidic. This is useful in breaking down the food into smaller, more digestible pieces. Lysosomes, the small bags of chemicals found inside cells are used to break down damaged cell parts. They can have a pH of 4-4.5. Our blood is at a relatively steady pH of 7.34-7.45. The body keeps the pH of our tissues relatively constant completely separate from our diet.
Our mouths are a bit of an exception. The pH can range quite significantly in our mouths due to the presence of acid producing bacteria. Some of the bacteria in our mouths can turn the carbohydrates that we eat into acid. I’ve talked quite a bit about this inpreviousposts. This acid can dissolve the surface of the tooth if it reaches a critical pH. The critical pH, or the pH at which tooth structure begins to dissolve is 6.7 on the root surface of the tooth and 5.2 on the enamel. Diet, habits and saliva flow have a lot to do with how well an individual defends against pH drops in the mouth. But these localized oral pH fluctuations are not the same as pH change of the body.
You often hear claims that the pH of your body being off or unbalanced are the cause of disease. Whether these claims are indirect like my water bottle or more direct as in some blogs or books, they need to be looked at critically. Most of these claims have no basis in science or actual physiology. Beware of diets or claims that talk about “changing your body pH.” Often they direct you to test your saliva to evaluate your body’s pH. That would be akin to checking the inside of your furnace to evaluate what the temperature of your house is! Your body has very specific control mechanisms for regulating your pH through the lungs and kidneys. Your diet makes no difference with regard to your body’s pH, except in your mouth!
Some disease states can result in pH changes. Diabetics can experience diabetic ketoacidosis, which can lower the pH of the blood. This is a consequence of their inability to use sugar in their bodies. However, in healthy individuals this is not a concern.
So, do I think my Iceland Pure Spring Water at a pH of 8.88 will prolong my life? Not really. However, it was cold and delicious and made it so I wasn’t so thirsty. So it did what I was hoping it would!
Do you have comments or questions about this or any of my other posts? Do you like what you see on my blog? Leave a comment here on the blog or feel free to email me at alan@meadfamilydental.com. This Saginaw dentist writes all the posts and answers his own email. Thanks for taking the time to read!
