The fact of the matter is that no artificial material can adequately perform the job of your natural teeth.  Constant pressure exerted on our teeth from chewing, grinding and biting down on hard foods wears down on fillings.  The fact of the matter is that all fillings will eventually wear away, crack, become chipped or fall out.  The average lifespan of a filling is 5-15 years (it is said that fillings last even less time when they are white). 

Once some sort of damage is sustained to the tooth or its filling bacteria can form.  Since you can't clean inside the cracks of a filing, the bacteria feed on the food debris and form the acid that causes tooth decay. Decay under a filling can escalate quickly without you noticing any pain or sensitivity.

These problems can be prevented by having your fillings checked regularly and by getting your fillings replaced when problems are found.  Listed below are even more reasons and benefits for having old fillings replaced.

Leaking
When fillings become worn around the edges or pull away from the tooth enamel it is called leaking.  Leaking allows for bacteria to enter and be stored in the mouth in the inaccessible leaks that are in the edges around the filling.  Damage caused from leaking often goes unnoticed because there are no noticeable symptoms present until this decay reaches the nerve of the tooth.
When the damage does reach the nerve of the tooth it often causes severe decay and pain.  Obviously, it is important to keep the tooth and filling clean so as to prevent the development of another cavity. Worn fillings need to be restored as soon as possible in order to stop the decay from forming and the bacteria from spreading.

Biting and chewing
Cracks can develop in fillings simply from everyday biting and chewing forces.  The average human jaw has the ability to exert hundreds of pounds of pressure!  Chewing on particularly hard foods can magnify the problem.  If for no reason but simple chewing your food, your fillings can become worn, cracked and in need of replacement.

Crowns
When a tooth has had repeated trauma and a simple filling is no longer sufficient to protect and give strength to the tooth a crown is used.  Crowns are used to protect especially weak teeth from fractures and/or breakage

Looks can be deceiving
Damaged teeth are not always apparent.  Although decay can discolor a tooth, often times problems with fillings can exist without any apparent signs or symptoms.  Your dentist has the tools to be able to examine and evaluate the health of your tooth enamel.  In fact, dentists have a cavity detecting dye that can be rinsed over the mouth.  This dye sticks to areas that are decayed and rinses clean from areas that are healthy.

X-rays
More evidence for the benefits of replacing old fillings can be seen from X-rays taken to see decay that doesn't show on the surface.

Grinding or abnormal force
Cracked, broken, or fillings that are worn from unusual use will need to be replaced.  Activities such as nail-biting, tooth grinding (bruxism) or using your teeth to open things, will make filling damage more likely and a damaged filling can allow food debris and bacteria in your mouth to seep down and cause damage to the tooth itself.

If you're like most adults of today, you have a few fillings somewhere in your mouth.  And the chance that those fillings are silver (also known as amalgam) is even higher, especially if they're older fillings.  Nowadays there is another option of fillings: white composite fillings.  You may wonder what the pros and cons of each type of fillings are.  This article is here to inform you of just that: the pros and cons of silver amalgam fillings, and then a brief mention of the pros and cons white composite fillings. 

Pros of silver amalgam fillings
    Amalgam fillings are relatively inexpensive and they are usually covered by most dental insurance companies
    Amalgam fillings are very strong and usually do not break due to heavy chewing on the filled tooth

Cons of silver amalgam fillings
    Amalgam fillings contain mercury and some other metals.  Although there has never been a study to prove the relationship between the mercury in amalgam to any medical dangers, it is well known that mercury in and of itself is a very deadly metal.
    Amalgam fillings have been known to leave people's teeth more sensitive to hot and cold temperatures.  This is due to the metal expanding or shrinking with the temperature of the food or drink that we consume.
    Amalgam fillings do not harden immediately, so you may not chew on the tooth with the filling for several hours after the filling has been placed.
    A significant amount of healthy tooth area is removed when getting an amalgam filling.  The dentist needs more space to prepare for the filling when using amalgam.  This can be damaging to the remaining healthy parts of the tooth.
    Not all dentists work with amalgam filings anymore.  So if you choose to get amalgam fillings and then switch dentists, it's possible that s/he will not be able to work with your fillings.

Pros of white composite fillings
    White composite filling material contains acrylic and glass particles, no mercury, so there is no danger of mercury poisoning ever occurring. 
    White composite looks much more natural than amalgam filling.  Sometimes you can't even tell that you have a filling there.  When you smile, no one will have to see silver fillings, just nice, white teeth. 
    White composite fillings are less stress on your teeth than amalgam fillings because the dentist does not need to remove as much area of healthy tooth.  This keeps the tooth stronger and less likely to experience further problems.
    White composite fillings are usually "light cured" today, meaning that the acrylic material remains a liquid until a very bright light is shined on it, causing it to harden.  Using a "light cured" method allows for your filling to be chewed on almost immediately. 

Cons of white composite fillings
    White composite fillings may be slightly more expensive than amalgam fillings, however, most people find that they are usually well worth the cost. 
    Not all dentists work with white composite fillings. 

There are pros and cons to both amalgam fillings and composite fillings; although it seems that white composite fillings have a few more benefits.  They are definitely the up-and-coming method of filling cavities.  This is not to say, however, that you should demand white composite fillings from your dentist.  Composite fillings require a different type of training to place them and not all dentists are well trained in the process.  Be sure that if you choose to get white composite fillings, that your dentist feels comfortable placing them. 

Unfortunately, fillings don't last forever. While they do last a long time - typically up to 15 years - there is a chance that at some point, your filling may fall out. Because there is decay under the filling, there is generally some pain associated with this.

Fillings fall out for a number of reasons. The filling may not have been placed properly, meaning it wasn't fit tightly enough into the tooth or the bond that holds it in was not strong enough, making the filling more susceptible to falling out. Or, it could simply be because the filling is old and weakened.

If your filling falls out, you should make an appointment with the dentist immediately. In the meantime, however, there are a number of things you can do to minimize the pain until you can get to the dentist:

    First of all, call and make an appointment with the dentist and ask to be seen as soon as possible. Even if you are not experiencing pain, the filling needs to be fixed. Neglecting to see the dentist can result in the growth and spread of infection, which can result in more painful, expensive procedures than fillings, like a root canal. Many dentist offices set aside slots for emergencies, or will be able to fit you in right away, depending on the severity of the pain.
    If possible, save the piece of filling that has fallen out. In some cases, the dentist can re-cement the filling instead of having to drill more teeth away for the new filling.
    Rinse your mouth with warm water, and then gently brush and floss the teeth to remove any debris from the filling. Do not brush or floss too hard around the tooth that lost the filling, as the tooth will probably be cracked and hard brushing and flossing could be painful.
    If you have any, take a piece of dental wax and soften it by rubbing it between your fingers. Place a small piece of the wax over the exposed tooth to prevent it from exposure to air and debris until you can see the dentist. This will also help to alleviate any pain while protecting the tooth from further damage. Even if the tooth area doesn't hurt, you should still cover the area for protection.
    If the tooth is painful, take an over-the-counter pain reliever such as Tylenol, Advil, or ibuprofen.
    Until you see the dentist, avoid eating on the side the missing filling is on as much as possible. If the missing filling is painful, this won't be too hard.

Once you get to the dentist, he or she will be able to determine the best step to take in order to fix the filling. When a filling is lost, typically there is some sort of decay still remaining around the filling. If this is the case, the dentist may do some drilling and put in a new filling altogether. If there is no decay, the dentist will determine what caused the filling to fall out in the first place, and then either fix the broken filling or replace it with a new one.

Most people would agree that a white or porcelain filling looks better than a silver filling.  But of course how a tooth looks is not always what is most important.  Although there are advantages to having newly filled teeth done with the white filling there are some distressing disadvantages to having already existing silver fillings replaced by white fillings.  It is a personal decision and some are willing to face the discomfort and risks to have a smile that they do not feel self-conscious about.  In any case before you make a decision, you should speak to your dental health professional and review advantages and disadvantages of the options that are available to you.

Advantages of White Fillings:
    No more "mouth-full-of-silver" look whenever you smile big enough for someone to see into your mouth.
    There is some vanity involved when it comes to having all of your silver fillings replaced.  Many times, you will have already started having your fillings filled with the white material and are changing out your old silver ones so that all the teeth in your mouth match.

Disadvantages of Silver Fillings
    Many people are concerned about the amount of mercury in silver fillings.
    Some are allergic to the mercury in the amalgam filling.
    Teeth turn gray from the silver seeping through the tooth enamel itself.   Although this is normal with fillings that were made of the silver amalgam from the 1970's.  Teeth can begin to look much like teeth that are "dead" or that have sustained some sort of damage.
    Unfortunately silver filling discoloration will usually get darker and darker with time.

Disadvantages of White Fillings
    Serious dental work is possible and when you have serious dental work there is a higher likelihood of future problems.
    The dentist may decide to have you come in on two separate days so that only one side of your mouth is numbed at a time.  But this means setting aside the time for multiple dentist visits that can be several hours in length.
    The process of removing old silver fillings meant that the silver was not only removed but space needed to be made for the new white filling. This translates into more drilling and more whittling down at the teeth to find a good surface for the new filling to adhere to.
    Some teeth have to be drilled so much to remove the silver filling that a crown must be made for the tooth.  Wearing down the teeth can lead to cracks, sensitivity and hidden fractures in the future.
    Replacing silver fillings with white ones means disturbing the balance of your mouth.  The surface of your teeth will most likely change and with that comes a different bite.  Because biting and chewing exert so much force there can be problems with your jaw or even just problems eating your food.
    During the replacement process teeth left untouched for years are exposed to air and a new filling material.  In addition the tooth has to become accustomed to a new material and a new fit making nerve ending particularly sensitive.
    White fillings are said to not last as long as silver fillings.

Advantages of Silver Fillings
    Last twice as long as white fillings
    Avoid the additional dental work and risks of having the old silver fillings removed and replaced.

Many people, at one point or another during their lives, will need to get a filling to cover up the spots in the tooth that have been eroded by tooth decay. While most fillings last a long time - generally around 5 to 10 years, if they are placed correctly and taken care of - they will on occasion fall out.

There are a number of reasons why old fillings fall out. In some cases, a filling will fall out because of an error on the dentist's part. The filling may not have been placed properly, meaning it wasn't fit tightly enough into the tooth. Other times, the cavity being filled is contaminated with saliva when the filling is placed. This weakens the bond used to hold the filling in place, and if the bond is not strong enough, the filling can fall out.

Old fillings also begin to leak and crack over time. Cracks can occur soon if the filling has not been shaped properly. So, for example, if the filling is higher than the rest of the surface of the tooth, the force of biting and chewing is placed directly on the filling. This can cause the filling to crack.

Leaking fillings occur when the side of the filling doesn't fit tightly enough against the tooth. This can allow debris and saliva to leak in between the filling and the tooth, which can lead to even more decay.

Fillings aren't designed to last forever, and in some cases, fillings just wear out. As fillings wear, food and debris can seep under them, causing decay and pain and more expensive problems. Regular visits to the dentist to have your fillings checked will help you to know when your fillings need to be replaced.

What if my filling falls out?
If you have an old filling that falls out, the following steps should be taken:
    First of all, call and make an appointment with the dentist and ask to be seen as soon as possible. Even if you are not experiencing pain, the filling needs to be fixed. Neglecting to see the dentist can result in the growth and spread of infection, which can result in more painful, expensive procedures than fillings, like a root canal.
    If possible, save the piece of filling that has fallen out. In some cases, the dentist can re-cement the filling instead of having to drill more teeth away for the new filling.
    Rinse your mouth with warm water, and then gently brush and floss the teeth to remove any debris from the filling. Do not brush or floss too hard around the tooth that lost the filling, as the tooth will probably be cracked and hard brushing and flossing could be painful.
    If you have any, take a piece of dental wax and soften it by rubbing it between your fingers. Place a small piece of the wax over the exposed tooth to prevent it from exposure to air and debris until you can see the dentist. This will also help to alleviate any pain while protecting the tooth from further damage.
    If the tooth is painful, take an over-the-counter pain reliever such as Tylenol, Advil, or ibuprofen.