(Afternoon tea pics 1647.7: Kuraray Clearfil Majesty ES-2 Universal U)
Peripheral rim fractures are often seen as a part of the Poisson effect, where solids can seemingly compress and exhibit elastic deformation, according to my mentor Dr. Graeme Milicich. Amalgam restorations do not bond to the peripheral walls and as such do not contribute any flexural resistance to the residual walls under function. If an amalgam margin approximates a marginal ridge too closely (the area which is most under tension/flexural stress when subjected to occlusal and lateral excursive load), often hairline fractures can appear.
My protocol when approaching these is to complete the exploratory occlusal preparation and to assess whether the crack permeates past the DEJ. If it does, it is considered a superhighway for bacterial ingress and if it does not, I leave it alone for now.
#RiskBenefitRatio #PeripheralRimFractures Graeme Milicich
