I had crown being done a few years ago, but I noticed that part of the crown started to feel strange about 3 months ago, and I felt like there is a break at the back inside of the crown. Last night, when I brushed my teeth, almost 1/3 of the back side of the crown falling out. I went to a few dentists in the past & had some crowns being done , & this never happened before. How can a big part of the crown breaking like that? I am very suspicious the materail of the crown is of very poor quality. Now I have to spend my time & money again to fix my teeth.