Are the non-metal crowns as strong as metal crowns?
A. Yes and no. Define “strong.” I am assuming “strong” in this question means fracture resistant. Also in dentistry, the more important property is the fatigue strength as we continually use crowns and bridges on a daily basis. Fatigue strength is different from impact strength in that fatigue strength tests are done through a cyclic loading whereas impact strength is tested with one large impact force. However, when determining the fracture toughness of a material, it is more important to know the tensile strength of the material. More brittle materials are more susceptible to defects in the material and will fracture quicker under a loading. As loading in our mouth during chewing is not always straight down the root (we call it “axial loading” vs “non-axial loading”) it is important to know their “strength” under non-axial cyclic loading. We generally generate about 90 to 180 lb of biting force during a regular chewing cycle, and it would be more accurate to look into studies that ar