Tooth fillings are often made of gold or porcelain because these materials are:
b. nonreactive
That means that they don't corrode or rust and they are resistible to staining.Their thermal conductibility is low.
Explanation:
Porcelain-fused-to-metal crowns. PFM crowns are an approximately esthetic improvement that has been in use for more than 40 years. In one way, they blend the best of both worlds, a crown made of “refined or noble” metal (gold or platinum), which is strong, fits correctly and is bonded/bonded to the tooth.
The correct option is D. Lumen is used to quantify the amount of total light energy that a source is putting out in all direction, thus, it refers to luminous output of a light source. Initial lumen refers to the luminosity of a light when it was first turned on; the luminosity is highest at this point.
