Explain bone grafting please. Where are you getting this bone?

Bone grafts are when
additional bone is added to a portion of your mouth in order to save, restore,
or place new teeth when existing bone levels are poor. There are different
types of sources that can be used: from your own body (through surgical
methods), donor bone, or bovine bone.

Great question.  This topic has textbooks on it.  I'll try to be brief in this summary.   Bone grafting is a procedure used to increase the volume of bone in a horizontal and/or vertical dimension.   Bone used may come from autogenic ( own bone), allogenic ( others bone), xenogenic ( animal sources) or artificial/ chemical sources.  If it's autograft then the most common sources are jawbone or chin bone, hip bone, tibial bone or more rarely calvarium(skull) bone.  Allograft usually comes from pre screened cadaver bone that has been irradiated.  Xenografts are most commonly bovine(cow) or porcine(pig) and more recently equine(horse).  These are usually only matrix or mineral and do not contain live cells.  The artificial stuff may be ceramic or calcium sulfate like materials.  Whatever material is being used it's resorbed by the body and replaced with your own bone.  Depending on the material some may be left behind and some materials are 100% resorbed.  Often we use growth factors to help in healing these may be your own that are obtained from drawn blood like PRGF or PRP and some come prepared from donors and contain BMPsAll the materials work and it's the surgeon that decides what material best works in his/her hands.  Hope this was not overly confusing and somewhat helpful.  

Without going into much detail it's really simple, 4 main categories:1. Autograft - comes from the patient.2. Allograft - same species (donor bone)3. Xenograft - different species (animal bone)4. Alloplast -  chemical bone substitutes (not exactly bone, but work well) Each material has it's pros and cons. What's being used depends on surgeon, procedure and sometimes on patient's preference.

Bone grafting is essentially a scaffold. Wherever there is a bone defect, the site is opened and a powdered grafting material is placed in the ultimate desired shape of bone. Blood mixes with this powdered material and clots. This mixture is now a scaffold - your body invades this scaffold and builds new bone in place of the scaffold. The source of the bone graft depends on the type of the graft. Some bone grafts are synthetic - meaning they are man-made in a factory. Other bone grafts come from bone banks and are made from cow bone or human cadavers; this bone is very strictly sterilized and treated before being used in humans.

Bone Graftingis the replacement or
augmentation of the portion of the jaw bone that anchors the teeth. It's a
surgical procedure that's often done to reverse the loss or resorption of bone
that may have occurred due to tooth loss, trauma, disease or ill-fitting
dentures, and to rebuild the bone structure beneath the gums in preparation for
the placement of dental implants or other tooth replacements

When bone graft is
implanted in the jaw, it doesn't just simply fill a void in the bone; it may
also help promote new bone growth in that location. When successful, bone
grafting can restore both the height and width of your jaw bone. Bone grafts
are placed by material provided from"Bone banks" and it is a procedure that helps you
get Dental Implants when your jawbone is shrinking.