Is bone graph nesasary?

Hello,
Last week I had 2 teeth pulled one was on the bottom left side and the other was on top righ( it was actually a wisdom tooth that had grown in all the way) but my question to you is was it nesasary to have gotten a bone graph after he pulled them? Also what is the purpose for a bone graph? I paid 400.00 dollars for those graphs so I want to make sure they were needed.. On the bottom  left tooth that was extracted I am going to get a bridge, if that helps.
Thank you for your time..

[Jerome Tsang, DDS]

You should probably ask your dentist for your specific situation.

A bone graft is placed immediately after removal of a tooth to preserve the jaw bone.  The jaw bone is stimulated to grow to a certain height when a tooth is in it but when the tooth is removed, the jaw bone will slowly resorb and shrink away.  The preservation is bone is key since replacing it is difficult and sometimes unlikely to happen at all.  With the development of dental implants, everyone wants to preserve bone in case at a future time, an implant can be placed in the jaw bone to replace missing teeth.