The human mouth is a challenging place to attempt any restorative procedure. There are temperature, acidity, and other chemical changes all the time. Teeth and the restorations we create for them are also challenged by a constant barrage of mechanical forces.
It's almost as if the dental academicians of a century ago should have chosen the word "resurrection" rather than "restoration", especially given the technology of the day.
Here, though, in this photograph, I've caught the essence of dental amalgam's weakness as a restorative material- it does not bond or adhere to the surrounding tooth structure. We had just removed an old amalgam when the photo was taken. There is a vertical fracture- partial and still restorable- running down the tooth on the left side of the photograph.
Another factor that plays into such a fracture is that amalgam seals by corrosion and this process peaks at the two year point, rendering teeth with older amalgams much more prone to fracture. Yet another issue- the flexibilities of tooth and amalgam fillings at all temperatures are also quite different. (The orange dot in the photo is the top of a prior root canal treatment with gutta percha.)
A tooth can certainly fracture when repaired with any material, adherent or not. Yet with dental amalgam "of a certain age", this becomes statistically very likely.
There are anti-amalgamists and politicians who seem to be one taco short of a combination plate in their stance on this dental material ("Amalgam, Politicians, and All the Pink Trees", Nov 4). I object to their disregard of science and medical research. Yet we do have beautiful alternative treatments now including composite resins, onlays and crowns that protect teeth from these vertical fractures quite well. There are also intensive studies being done by dentists such as Ray Bertollotti, David Alleman and Pascal Magne where the goal is to restore just what's damaged in a tooth, no more; when this approach matures even crowns may seem old fashioned and overkill for many situations where teeth have been damaged by decay.