When you chew you are putting a lot of pressure on your teeth (approximately 150 newton centimetres of torque). Surprisingly, for something so solid, a tooth will twist and bend a little under this pressure. The first part of this video shows how a rubber band ball distorts when squashed. Teeth squash a tiny amount when bitten on. The next part of the clip shows a chewing machine used to measure how teeth distort or squash when chewed on. In this example a dental crown is being tested to see how it behaves when chewed on. In tests on teeth (in vitro), a tooth with a medium sized amalgam filling will flex 26 times more than a tooth with a similar sized bonded white filling. In fact the tooth with a bonded white filling will flex almost the same amount as a healthy tooth. This is because the white filling not only fills the cavity, it also bonds the tooth back together again biomimetically, so the tooth & white filling are swaying & twisting as one. Essentially the teeth tested with the amalgam fillings are twisting & bending in all different directions i.e. the cusps are moving away from each other & the amalgam filling is jiggling around in the cavity as the mercury amalgam is just a hole filler & does not “glue” anything to anything.
http://www.milforddentists.co.nz/blog...
