Amalgam restorations

An amalgam restoration for many, many years was considered one of the strongest and most commonly used restorative material available. While effective and certainly strong an amalgam restoration is wrought with problems.

 Some of these problems include:  

• Mercury is used in the material to help make it pliable and hold the other metal material together. While the amount of  mercury in these restorations is minimal, some consider the mercury in amalgam restorations to have a detrimental effect on one’s health.

• Expansion and contraction of the material. As with most metals, the amalgam restoration does expand and contract slightly with temperature changes. This puts pressure on the surrounding tooth surfaces causing the tooth to form cracks 

• Mechanical Retention. The typical way an amalgam restoration was placed was to use mechanical retention. This means for the filling to stay in place more of the tooth needed to be removed, the more tooth that is removed the weaker the tooth becomes and can break.

• An amalgam restoration would take 24 hours to set to its maximum strength and often if not careful the filling would fracture before reaching it’s maximum strength.

• Over time the margins of the restoration wears/ chips away allowing decay causing bacteria to leak underneath the restoration. The tooth looks sound on the outside but underneath decay is spreading, eventually causing a tooth ache and possible killing the nerve of the tooth.

 
As with everything else in todays society technology has improved, making these amalgam restorations unnecessary. Today we use a composite resin material that is bonded or glued into place (not relying on mechanical retention). The composite restoration is set fully whilst in the dental chair using a special curing light, so it is OK to eat your favourite foods as soon as the numbness wears off.

Here is an example of what can happen underneath an old amalgam restoration… Note in the top photo the black cracks showing either side where the black amalgam has been removed. The cracks and dentine are stainned black due to corrosion byproducts (in essence rust!) and leakage from the old black amalgam filling that was removed.
 
       

 
It is common to find this underneath an existing old amalgam filling. The hairline cracks that are extending down the sides of this tooth are caused in part, by the expansion and contraction of the amalgam filling material, causing stress on the surrounding tooth surface. A crown is now needed on this tooth to act as a thimble and keep the tooth from flexing any more. If the amalgam filling was left then the crack in the tooth could extend causing the tooth to split. Once this happens often there is nothing that can be done to save the tooth.
 
 
If you are at all concerned about your existing amalgam restorations, please contact us, we are happy to discuss the treatment options available to you.