What are the chances that my tooth will break in half?!

Awhile ago I was eating at the olive garden, just some bread sticks and all of a sudden a huge chunk of my very back tooth came out!. It didn't hurt really up to that I think!. I had a silver crown put on that!. But a bit later I had my braces come off and on one of my front teeth a small bit kinda came off with it!. Because my teeth (my former I guess dentist says) are soft and I didn't have very good brushing habits!. But that was back in March and lately I guess it's been rather sensitive!. Its like a line kind of chip and I'm paranoid that just like my other tooth it will break in half!. What are the chances of that happening!? Why did my tooth have a huge chunk come out anyway before!? My former dentist was old and recently retired but there's a new dentist that took over his practice!. His daughter, people have told me to change dentist but I can't because until December I have no more insurance because it ran out!. Me and my parents have no money to pay for it until then!. Www@Answer-Health@Com

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