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Two main actions stimulate the release of mercury vapor from amalgam fillings—disrupting the oxide layer that thinly covers their surface and heating the filling. In most cases, the two happen simultaneously. For example, many common actions will remove the microscopically thin oxide layer and heat the filling at the same time, such as brushing, eating, chewing gum, and tooth grinding. The amount of mercury vapor released when an amalgam filling is heated is determined by the type, intensity, and length of stimulation, and whether it has a high or low copper content. (High copper amalgams release up to 50 times more mercury than low copper ones.) Mercury vapor release is highest while the filling is being actively stimulated. Once the stimulation stops, it gradually decreases, but the filling still releases mercury vapor for up to 90 minutes. The following are the most common methods of stimulation, along with recommendations for reducing the amount of mercury released. These are listed in order of importance.

Tooth Grinding

It’s estimated that 90 percent of the population grind their teeth at some time during their lives, and as many as 20 percent grind them extensively and continuously.

Tooth grinding dramatically increases the release of mercury vapor from amalgam fillings by both disrupting the oxide layer and dramatically heating the fillings.

Of course, the extent of tooth grinding, and thus the amount of mercury vapor released, varies from person to person.

This will depend on: the number and size of the fillings:

  • whether or not the bite allows for a direct tooth-to-filling or filling-to-filling
  • contact the intensity and duration of the grinding

Since the majority of tooth grinders do most of their grinding at night, mercury vapor release will take place for many hours, exposing the body to high levels of mercury during this period. While non-grinders get a respite from mercury exposure during sleep, tooth grinders receive their highest dose of mercury during this time.

A tooth grinder with only a few amalgam fillings can release significantly more mercury than a person who has many more amalgams but doesn’t grind. More mercury is released during tooth grinding than at any other time, except when amalgam fillings are placed, removed, or polished.


If you’re a tooth grinder and need to delay having your mercury amalgam fillings removed, ask your dentist to make you a soft night-guard to prevent tooth-to-filling or filling-to-filling contact.

If the delay in removing your fillings will be longer than a year, ask for a more durable, longer-lasting night-guard.

Using a night-guard will significantly reduce your mercury vapor exposure and can also help relieve muscular stress and tension caused by grinding. Some people don’t know if they grind their teeth, but if you’re unsure, speak to your dentist about it, as he or she will be able to determine if you do.

Chewing Gum

Chewing gum increases the amount of mercury vapor released from amalgam fillings by up to 54 percent when compared to non-chewers. The key factor here is time—the longer you do anything that stimulates the release of mercury vapor, the more will be released. Other factors being equal, a frequent gum chewer who has a few amalgam fillings will be exposed to much more mercury vapor each day than a person who has more fillings but doesn’t chew gum.

The total amount of mercury released depends on how long, how often, and how vigorously the gum is chewed.


Simple answer. Don’t chew gum until all your mercury fillings have been removed and replaced.


Brushing your amalgam fillings, especially with a hard toothbrush and abrasive toothpaste, can increase mercury vapor levels in the mouth to more than 10 times the amount that some regulatory agencies allow in the workplace. The actual amount released is determined by the hardness of the bristles, how often you brush, the pressure used, and the duration of brushing.

The amount of mercury vapor released also depends on whether you use an electric or manual toothbrush.

When used for the same amount of time, an electric toothbrush will stimulate the release of more mercury vapor than a manual  one. This is because the bristles on an electric toothbrush are usually harder and generate many more strokes per minute. Thus, even if you use an electric toothbrush for a shorter period of time, the total amount of mercury released from the brushed fillings will still be significantly higher than from manual brushing.


You don’t need to be concerned about decay developing on the surface of an amalgam filling, but it can develop at the margins where the filling meets the tooth. Until your mercury fillings are removed, brush the margins of your filling (where it meets with the tooth) lightly and quickly, and avoid brushing all  other surfaces of the filling.

Rinsing with room-temperature water after brushing to cool down the fillings will help minimize the amount of mercury released.


While clenching doesn’t appreciably heat amalgam fillings, it can cause an increase in mercury vapor release if this action brings a gold filling into continuous contact, or proximity, with an amalgam filling.

For example, if you have a gold crown on an upper tooth and clenching brings it into direct contact with an amalgam filling on the lower opposing tooth, a battery-like effect called a “galvanic current” can result. This current can cause the release of high levels of mercury, even though the amalgam filling isn’t being heated. The current can exist even if the teeth are not in contact, but the closer the two different types of fillings are to each other, the more powerful the current—resulting in the release of more mercury vapor.


If you know you’re a clencher and have gold fillings in contact or proximity with amalgam fillings (ask your dentist if you’re not sure), use a night-guard until the amalgam fillings are safely removed.

Hot Liquids and Foods

Drinking hot liquids and eating hot foods can significantly heat amalgam fillings and increase the release of mercury vapor. This form of filling stimulation is significant for people who drink large amounts of hot coffee or other hot beverages throughout the day.


This is easier said than done, but until your amalgams have been removed, it’s best to cool liquids and foods to room-temperature or rinse your mouth with room temperature water as soon as possible after eating or drinking.


Snacking throughout the day heats the fillings by the abrasion/heating effects of chewing, consequently increasing the release of mercury vapor. The amount released depends on the number of snacks per day and how long the snacking lasts.


Don’t snack between meals until your amalgams are removed, unless you have special dietary requirements, or eat foods that don’t require chewing, such as juices, smoothies, or pureed foods.

Chewing Abrasive Foods

Chewing any food will heat amalgam fillings and stimulate the release of mercury. But abrasive foods such as nuts and seeds are more likely to do so because they easily disrupt the oxide layer, erode more amalgam particles from the fillings, and quickly heat the fillings to a higher temperature.


Avoid abrasive foods until your fillings are removed. If abrasive foods are an essential part of your diet, you can minimize the amount of chewing by grinding nuts and seeds in a blender or food processor or using nut/seed butters.

Cleaning and Polishing Amalgams at the Dental Office

Many dental offices use a cavitron or other ultrasonic cleaner to clean teeth. During an ultrasonic dental cleaning, heat is generated due to friction created between the tooth and the ultrasonic waves emitted from the cleaning tip. These instruments are routinely used in many dental offices to clean teeth and, if used on amalgam surfaces, can significantly increase the temperature of the fillings, which in turn can dramatically increase the amount of mercury vapor released.


Ask your dentist or dental hygienist not to use an ultrasonic cleaning device on the surfaces of your amalgam fillings. Handheld cleaning instruments can be used selectively in the margin areas, minimizing the amount of heat generated during cleaning. It’s also important not to have the surfaces of your amalgam fillings polished after cleaning, as polishing dramatically heats the filling and increases the release of mercury vapor and amalgam particles. (Not using an ultrasonic cleaner on amalgams will also help minimize the dental hygienist’s exposure to mercury vapor.)

Acidic Foods and Drinks

Acidic foods and drinks such as citrus fruits, pickles, sauerkraut, tomatoes, mustard, vinegar, acidic fruit juices, and soft drinks can etch the surfaces of amalgam fillings and cause the release of elemental mercury.


Limit consumption of these items until your amalgam fillings have been removed. If you must drink acidic beverages, use a straw, as it will keep the acidic liquid away from the fillings. Always remember to rinse your mouth with water after consuming acidic drinks and food.

Hot Baths and Saunas

Anything that increases the temperature of the oral cavity will heat your fillings and increase the amount of mercury vapor they release.


Hot baths and saunas have great value. If you enjoy them, you can keep your fillings cool by rinsing your mouth with room-temperature water every 5–10 minutes or so.


Smoking can increase the temperature in the mouth during inhalation and, consequently, increase the amount of mercury vapor released. Although the amount released can be small, be aware of this fact if you smoke. Smoking also has a more direct and harmful effect on the immune system by increasing your exposure to cadmium, another very toxic heavy metal. Many symptoms of chronic cadmium poisoning are similar to those of chronic mercury poisoning. By placing additional stress on the immune system, smoking can reduce your body’s ability to eliminate mercury.


If you’re a smoker, I highly recommend that you seriously consider stopping.

Rinsing with Cool Water

Regardless of the type of stimulation, you can reduce your exposure to mercury vapor by always rinsing your mouth with room-temperature water after any activity that increases the fillings’ temperature. It will be more effective if you leave the water in contact with the fillings for at least 30 seconds or so. If you spit out the water after rinsing instead of swallowing it, you’ll also remove mercury that’s mixed with saliva. Not swallowing it will prevent any elemental mercury from being transformed into organic or methyl mercury in the mouth or intestine.

Following these recommendations can significantly reduce your exposure to mercury vapor while your amalgam fillings are still in your teeth. But please, don’t be lulled into thinking that the above precautions will eliminate your need to have these poisonous fillings removed.

What’s Next?

Thinking about having your amalgam fillings removed? Remember that once you’ve had your silver fillings removed, your body still needs to purge itself of the accumulated mercury.

This article was contributed by Dr. Tom McGuire, DDS. Visit Dr. McGuire’s website on mercury exposure. Dr. McGuire also has a book available on next steps that can help put you back on the road to optimum health including a mercury detox program.


If you have any questions about amalgam (silver) fillings that you have, please contact Brit Phillips DDS at Mira Vista Smiles and let us know your concerns. Dr. Phillips is a whole health dentist and cares about your total health and well being. Call 817-361-1999 and speak with our helpful dental team today!