Mercury from fillings contributes 3 to 4 times more mercury to our bodies than all the environmental sources combined.
Many people still don't realize that the majority of the new cavities we see in children today occur just in the center of the molar teeth. The tiny groves there are flaws which invite early decay. By the age of 6 a child has 4 permanent first molars.
Mercury fillings require the removal of the middle third of the tooth. The material itself is weak and cannot be used in a thin layer. The dentist must drill deeply into the softer dentin area of the tooth and drill undercuts into the healthy tooth even where there is no disease. This approach was developed in 1908 by G.V. Black. As a result of this kind of filling, the tooth is now weakened by 75%.
Mercury fillings also expand after being placed in the tooth. The bigger the filling the more they expand. If any moisture gets into the filling they expand rapidly. Temperature can also cause expansion. All this expansion within the tooth eventually results in fracture.
Once broken the tooth may require a root canal or crown or extraction. Often the fracture is so severe that in spite of all efforts the tooth is lost.
Metall free fillings:
Composite fillings materials (with porcelain particles)
Lab processed composites fillings
Lab processed porcelain fillings
Last two have solved the wear and placement problems of the composite fillings.
The cheapest Choice:Composite Filling Materials
If you are restoring a tooth for the first time then composite filling materials will not only strengthen the tooth as well as provide greater longevity and beauty than the mercury/silver ones but, more importantly it is far less damaging to the healthy tooth.
The majority of initial composite fillings require only minimal natural tooth removal and not only restore decayed areas but also seal up weak spots so decay will not penetrate the other surface groves.
Sealed surfaces ARE protected as long as the sealant lasts. When it wears out it can easily be reapplied until the child grows out of this cavity prone period. However, the composite sealant must be placed before decay begins. On the average 36% of the children today are cavity free. However, those children raised in the southwest are much more likely to be cavity free than those from the northeast. No single cause can be found for these differences.
Earlier Composites
Earlier Composites were not strong enough for replacing big mercury/silver fillings in the hard-biting back teeth. As a result, stronger and better light cured materials have been developed,yet technical problems still exists in placing these restorations. They shrink 1% to 3% upon setting and lack the crushing strength to withstand the enormous biting forces some people can generate. Sensitivity and recurrent decay results from the shrinkage and excessive wear is the result of low strength.
Progress for the 1990's: Indirect Composites
Since the mid-80's a new system, called indirect composites combines the best of the composite and the strength of a natural tooth. This inlay process is much easier on the patient (and dentist) and has virtually eliminated the two major drawbacks to the composite restoration.
If you want to replace amalgam, please read first this :
The IAOMT recommended patient protection procedure for mercury/silver replacement is to:
First: Protect the patient's breathing zone. Drilling out old fillings can release enormous amounts of mercury into the air. If the patient is given a nasal hood this exposure can be prevented. Many dentists recommend a rubber dam..
Second: The dentist should cut the fillings in half or quarters with a small burr and lots of water then remove the pieces. This avoids excessive drilling of tooth or grinding on the old fillings.
Third: The tooth is cleaned and shaped with a diamond burr, some undercuts may be removed, and an accurate impression is made. Here technique may differ from office to office. Dentist will temporize the tooth with a light cured temporary composite and send the patient home.
Fourth : Dentist then make a model of the tooth preparation in out lab and fill the preparation with a good quality posterior composite. This filing is first set with light and then heated or baked at 270o F for 14 minutes. Once baked the filling is then etched with acid and sand blasted so it can be bonded to the tooth.
Last: The patient returns usually in a day or two and the temporary is removed. The tooth is cleaned and prepared for bonding. The Bowen system is currently the strongest in attaching the new filling to enamel and dentin. With the newest generation of dentin bonding the filling can be essentially welded to the remaining tooth structure. Once completed the bite is adjusted and margins polished. This restoration can be virtually invisible to the naked eye and feels wonderful.
Some situations will still require a full (or partial) crown but almost any tooth that can hold a filling now can be restored with this procedure.
The baking process more completely cures the filling and greatly increases the crushing strength.
Minimal uncured chemical resin is left and the result is a much stronger wear resistant and far less toxic filling. In addition the shrinkage takes place outside of the mouth and the small gap that results will be filled with a thin layer of composite resin cement. The welding of the filling to the tooth makes the tooth stronger and more resistant to fracture.
Conclusion
Children born today need never have the mercury packed into their teeth that we did.
Those of us who already have the large mercury/silver fillings must consider how best to restore our teeth.
The larger the cavity the worse a composite filling will hold up. Excessive wear especially becomes a problem for some brands when used in molar teeth. If the decay has penetrated deeply in between the teeth composites can leak and are more difficult to place. Lab processed composites and porcelain fillings appear to have solved both the wear and placement problems.
As to expense, the initial cost of a filling must be weighed against the long term expense. Fillings which require the dentist to remove excessive amounts of good tooth structure are not cheap. Which is best?
My first recommendation is to prevent the cavity if at all possible. Seal out decay. If the damage is already done then repair it with the most durable material available and try harder to prevent the next cavity. As Hippocrates said, "First and foremost do no harm". I don't think he would have approved either toxic fillings or drilling away the good tooth.
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