In many instances, an implant site in the upper or lower jaw does not offer enough bone volume or quantity to accommodate a dental implant of proper size or in the proper place.
This is usually a result of bone resorption that has taken place since one or more teeth (if not all) were lost. Bone Grafting or Guided Bone Regeneration -GBRprocedures usually try to re-establish bone dimension, which was lost due to resorption. A bone graft normally takes at least four to six months to heal, before a dental implant can be placed into it.
There are times also that multiple grafts may be needed to produce the amount of bone needed. This is dependant on a persons health and amount of bone being grafted.