Do you need a second bone graft at time of implant placement when you have had a bone graft a few months earlier?

 No two situations are exactly the same. That being said, typically only one bone graft procedure is necessary if this is a straightforward situation.There are times however, when additional  bone graft  procedures may be required due to the amount of bone that needs to be replaced and how well your body regenerates the necessary bone. I hope you found this information to be helpful,Dr. Champagne

it is not indicated in all cases. but yes, in many cases we place bone graft to maintain or to increase bone height around implant. there are chances crestal bone loss after implant placement, and its good for implant also. 

Hello
Dental implants require the bones below them for support and for the implant to integrate correctly into the mouth. People who have been edentulous (without teeth) for a prolonged period may not have enough bone left in the necessary places. In this case, the bone can be taken from the chin or from the holes for the implants or even from the iliac crest of the pelvis and inserted into the mouth under the new implant.
Regards.

It is sometimes necessary to have the second bone graft if there is not adequate healing from the first graft.

Usually, a bone graft is not necessary at the time of implant placement if the previous graft has completely regenerated. However, in some cases, there may not be sufficient bulk after grafting for ideal thickness when placing an implant. This can be due to several reasons; your body didn't regenerate the graft fully, some of the graft resorbed, there was tension in the area...