The best way to break a tooth is to put an amalgam filling in it!
Australia is embarrassingly, still teaching dental students to use mercury amalgam in 2022. It is claimed to be the best, strongest and longest lasting filling material. Poisoning from the mercury that is released from the amalgam is still denied. NO systemic effects are recognized in this country. We are still stuck in the old mentality of mechanics only. I dropped amalgam way back in 1991. All of the alternative materials then were better than amalgam and lasted longer. The mechanics argument has no legs to stand on and is only supported by an antiquated private trade club.
In 2009, Sweden completely banned the use of mercury including in amalgams.
Quintessence International is one of the most respected international dental journals.
In 1995 the editor-in-chief of Quintessence (Volume 26, Number 3,1995), Dr Richard Simonsen wrote:
“Amalgam should never be used
as a restorative material in paediatric dentistry.”
Why? Because better alternatives are available.
“Amalgam should never be used as a first time restorative material.”
Why? Because better alternatives are available.
“Move Over Amalgam – At Last”
Dr. Harold Loe, the Director of the National Institute of Dental Research ( NIDR), who stated in the September, 1993 edition of “Dental Products Report”:
“That first filling is a critical step in the life of a tooth. Using amalgam for the first filling requires removing a lot of the tooth substance, not only diseased tooth substance but healthy tooth substance as well.
So, in making the undercut you sacrifice a lot, and this results in a weakened tooth.
The next thing you know the tooth breaks off, and you need a crown. Then you need to repair the crown…and so it continues to the stage where there is no more to repair and you pull the tooth.
With the first filling you should do something that can either restore the tooth or retain more healthy tooth substance. Use new materials-composites or materials you can bond to the surface without undercuts. You can do this with little removal of the tooth substance so that the core of the tooth is still there.”
Comparison of Filling Techniques And Their Consequences
Amalgam fillings do not stick to the tooth. To retain the filling in the tooth, the cavity must be prepared with ‘undercuts’. These undercuts not only lock in the amalgam filling but also cut off the nutrient supply to the dentine above the cut. Therefore the tooth structure above and to the side of the filling becomes brittle.
All metals in the mouth will undergo some corrosion. Amalgam also corrodes at a reasonably fast rate. When amalgam corrodes it also expands and it does so in all directions. The force created by this expansion will often create minute fractures in the tooth, that is already more brittle due to the shape of the cavity preparation. Some times the cracks are so severe, that a whole cusp will break off. Especially with larger fillings this is common. The best way to break a tooth is to put an amalgam filling in it! At this stage the patient returns to the dentist to report that all they were eating was some soft bread and the tooth broke!
To repair such a problem, the dentist will usually drill a small hole into the dentine and insert a self-tapping screw – called a pin. The pin is reinforcement for the amalgam filling which will go back in. Even if this pin is made of titanium it will undergo corrosion when in contact with amalgam. Again the corrosion will cause an enlargement of the pin (sometimes up to five times its diameter) which will then crack the tooth further – but this time lower down the root surface.
This tooth is now a candidate for a crown because the filling, which has to go back into the tooth, is now so large that it cannot sustain the forces of chewing for very long.
Composite fillings do stick to the tooth. They are bonded chemically and mechanically to the tooth. They do not require a cavity, which is undercut and therefore do not require such a large or damaging cavity. In fact a composite filling can be used to rebuild a broken cusp without the use of pins or other mechanical support. I personally have not used a pin for years and have had great success with such restorations.
Studies comparing the fracture resistance of the tooth when filled with amalgam or composite indicate that amalgam will weaken the tooth structure whereas bonded composite fillings will strengthen the tooth. There is absolutely NO reason to continue the use of mercury amalgam!
Secondary Decay Under Fillings
Secondary decay is just another way of saying “the decay that you find under a filling”. It is given such a name because dentists believe that their fillings will stop decay, especially if it is amalgam. This bit of misinformation, which is often touted about by the dental associations, is that secondary decay is much greater with composite fillings than amalgam.
This is completely false.
When amalgam corrodes it not only does so on the chewing or exposed surfaces, but also corrodes on the side, which is in contact with the tooth- the deep part of the cavity. The corrosion products react with the calcium and phosphorous in the tooth, with the formation of hydrochloric acid. This acid then dissolves the tooth structure which is called secondary decay. The newer term for this is Crevice Corrosion. This does not happen with composites.
In other words, just to hit you over the head with this, the amalgam filling is responsible for the decay that is found under it!
There are many studies comparing the fracture resistance of a tooth, when filled with amalgam or composite. They clearly show that amalgam will weaken tooth structure whereas bonded composite fillings will strengthen the tooth. [i],[ii],[iii],[iv],[v]
[i] Longevity of dental restorations in selected patients from different practice environments. Mahmood-S; Smales-RJ Aust-Dent-J. 1994 Feb; 39(1): 15-7
[ii] Three-year follow-up of five posterior composites: in vivo wear.
Willems-G; Lambrechts-P; Braem-M; Vanherle-G J-Dent. 1993 Apr; 21(2): 74-8
[iii] Clinical evaluation of a highly wear resistant composite. Dickinson-GL; Gerbo- R; Leinfelder-KF Am-J-Dent. 1993 Apr; 6(2): 85-7
[iv] Replacement of missing cusps: an in vitro study. LC; Smith-BG J-Dent. 1994 Apr; 22(2): 118-20
[v] Longevity of dental restorations in selected patients from different practice environments. Mahmood-S; Smales-RJ Aust-Dent-J. 1994 Feb; 39(1): 15-7
