In brief: Many people having All-on-4 need no bone graft, because the tilted back implants are anchored in denser bone further forward. A graft is needed when the front of the ridge is too thin, when extraction sockets need support, when an old implant site has lost bone, or when All-on-6 needs extra height under the sinus. A CBCT scan decides which applies to you.
What a bone graft does
A bone graft adds material where the jaw is too thin or too short to hold an implant. The material acts as a scaffold: the body's bone-forming cells grow into it and, over months, it is replaced or incorporated by new bone.
The aim is enough bone around the implant for primary stability, the firm mechanical grip at placement that healing depends on. An implant that is loose in the bone at surgery is unlikely to integrate, however well it is placed.
Why All-on-4 often avoids grafting
After teeth are lost, the back of the upper jaw shrinks and the sinus above it tends to expand downward. In the lower jaw, the nerve canal limits depth at the back. Standard upright implants in these areas often need a sinus lift or a graft.
All-on-4 tilts the two back implants, often up to about 45 degrees, so their tips sit in denser bone in front of the sinus or nerve. This is why many people with moderate bone loss can have a fixed bridge without a graft. If you have been told you need a graft before All-on-4, it is reasonable to ask which site needs it and what the scan shows there. Our All-on-4 dental implants page explains the implant layout.
When grafting is needed
Socket grafting at extraction sites
When failing teeth are removed on the day of surgery, the empty sockets may be filled with graft material. Without support, socket walls shrink within weeks and the ridge narrows, which can affect implant positions and the gum line under the bridge. Done at the same visit, this usually adds no time to treatment.
A thin or short front ridge
Tilted implants still need bone at the front of the jaw. In people who have had no teeth for many years, or who lost bone to severe gum disease, the front ridge itself can be too thin. Ridge augmentation then builds width or height first.
Sites of failed implants
When an old implant fails or is removed, bone is lost around it. If a planned implant position falls in that area, a local graft may be needed before or during placement.
Sinus lift, more often for All-on-6
All-on-6 places implants further back along the arch, where sinus expansion has often reduced height. A sinus lift raises the sinus membrane and places graft material beneath it. Our article on sinus lift and bone graft differences compares the two procedures.
Where bone in the upper jaw is too limited even for grafting to be practical, zygomatic implants anchor in the cheekbone and can avoid grafting altogether.
Types of graft material
- Your own bone (autograft): contains living bone cells and integrates well. Small amounts can be collected from the implant drilling site itself. Larger blocks from the chin, the back of the lower jaw or the hip need a second surgical site and are kept for bigger defects.
- Donor bone (allograft): processed human bone from a tissue bank, sterilised for safety. Often used for sockets and moderate defects.
- Bovine bone (xenograft): purified cattle bone mineral. It resorbs slowly, so it holds space well in sinus lifts and ridge grafts.
- Synthetic materials: hydroxyapatite or beta-tricalcium phosphate. A choice for small, contained defects and for patients who prefer not to receive animal-derived material.
The choice depends on the size and shape of the defect and on your preference, and is explained at planning.
Where PRF fits in
Platelet-rich fibrin (PRF) is made by spinning a small sample of your own blood. The fibrin gel can be mixed with graft particles to hold them together, or laid over the site as a membrane. It contains growth factors released over the following days.
Studies report that PRF can help soft tissue heal and may reduce swelling after surgery; results for extra bone formation are mixed. Because it comes from your own blood, there is no risk of rejection. Read more on our tissue regeneration page.
How grafting affects the timeline
- Socket grafting with same-day implants: usually no extra time.
- Socket grafting before implants in that site: usually about three to four months of healing.
- Sinus lift: often four to six months before implants go into the grafted area, unless enough bone exists to place them at the same time.
- Larger ridge augmentation: often four to nine months, depending on size.
The end result is the same fixed bridge; only the schedule changes. Where a waiting period is needed, a temporary prosthesis is planned so you are not without teeth.
Grafting is done under local anaesthetic. Socket grafts usually cause little extra soreness; larger grafts may mean swelling and discomfort for several days, controlled with prescribed medicines.
Getting the assessment right
A panoramic X-ray shows bone height in two dimensions but not width or density. A 3D CBCT scan shows all three, along with the sinus and nerve, and is the basis for deciding whether a graft is needed and where. If you already have a recent CBCT, the files can be reviewed before your visit.
Unsure whether your bone is enough for All-on-4 or All-on-6? Book a Consult at our Bandra West or Kemps Corner clinic.
