A bit of tooth came off?? :S?

Looking in the mirror and I noticed quite alot of plaque it seemed to be on the back of my tooth so I scraped it off with my finger and then I felt like my tooth root was out a bit and I picked at it and it came off soo easy :S was it a part of my tooth? What should I do? My teeth ain't perfect and that's my fault so don't lecture me please....I would say my teeth are a light yellow :(