A solid block of the patient’s own bone is harvested from a second surgical site and fixed onto a deficient ridge to rebuild width and/or height before implant placement.
It’s indicated where the alveolar ridge is too thin or too short – horizontally, vertically, or both – to place an implant in a prosthetically correct position, and where the defect is too large or too shaped for particulategraft and membrane (guided bone regeneration) alone to reliably restore.
Because it’s the patient’s own living bone, it remains the reference standard for volume and predictability of gain, at the cost of a second operative site.
CBCT imaging of both the recipient defect and the chosen donor site to confirm adequate bone volume and map vital structures (mental foramen/nerve, inferior alveolar canal, tooth roots).
A mucoperiosteal flap is raised over the deficient ridge, the site debrided, and the recipient bone perforated (decortication) to encourage blood supply and healing into the graft.
A separate intraoral flap is raised at the symphysis or ramus. The outline of the block is marked and cut with a fine saw or piezoelectric instrument to a controlled, shallow depth.
The block is carefully levered free with osteotomes, preserving as much cortex and attached cancellous bone as possible, then placed in sterile saline.
The donor site is smoothed, haemostasis achieved, sometimes packed with collagen or residual bone chips, and closed in layers (this heals independently of the graft site).
The block is contoured to fit the recipient ridge and rigidly fixed with one or more titanium bone screws (occasionally plates), keeping it in close contact with the underlying bone.
Any residual gaps around the block are often packed with particulate bone graft, and a resorbable membrane may be placed over the construct.
The recipient flap is released and closed without tension over the graft – this is critical, as exposure is the main cause of graft failure.
Typically 4–6 months of undisturbed healing while the block revascularises and integrates with the native ridge.
The site is reopened, fixation screws removed, graft integration confirmed, and the dental implant(s) placed – either at this visit or, if more maturation is needed, at a later stage.
Schematic — lower jaw, front view. Shaded zones show the two common donor areas: the symphysis (chin, between the mental foramina) and the ramus (back corner of the jaw, both sides). Dots mark the mental nerve exit points, the key structure to protect when harvesting from the symphysis. This is a simplified diagram for orientation, not an anatomical or clinical reference image.
Both are intraoral sites accessed without any skin incision. The choice depends mainly on how much bone is needed and where the recipient defect is.
Larger volume, good mix of cortical and cancellous bone.
BEST SUITED FORLarger defects, anterior maxilla, cases needing more height as well as width.
KEY STRUCTURES AT RISKSmaller volume, predominantly dense cortical bone.
BEST SUITED FORLocalised, moderate width defects – commonly posterior mandible or premolar/canine region.
KEY STRUCTURES AT RISKChoose symphysis when a larger, thicker block is needed and some added donor-site sensitivity risk is acceptable.
Choose ramus when the defect is more modest, and lower donor-site morbidity is the priority.
Both sites carry a genuine, non-trivial risk of temporary – and a small risk of permanent – altered sensation, which must be discussed explicitly with the patient beforehand.
Autogenous bone is the only material that is osteogenic (contains living bone-forming cells), as well as osteoinductive and osteoconductive. Every alternative below lacks the osteogenic property, which is the main reason autogenous block remains the benchmark for larger, shape-critical defects.
Schematic – cross-section of a fixed block graft. The block is screwed to the recipient ridge, gaps packed with particulate graft, and sometimes covered with a membrane before tension-free soft tissue closure.
| MATERIAL | REGENERATIVE PROPERTIES | DONOR SITE | PREDICTABILITY FOR LARGE/SHAPECRITICAL DEFECTS | OTHER CONSIDERATIONS |
|---|---|---|---|---|
| Autogenous block (symphysis/ramus) + | Osteogenic + osteoinductive + osteoconductive | Yes – second surgical site, added morbidity | Highest – gold standard | Limited volume available; longer surgery; best long-term volume stability |
| Xenograft (e.g. bovine-derived) + | Osteoconductive only | None | Lower as a stand-alone block; more predictable as particulate + membrane for smaller defects | Very slow resorption (good for long-term volume maintenance); unlimited supply; some patients decline for religious/ethical/dietary reasons; theoretical (very low) disease transmission risk |
| Allograft (processed human donor bone) + | Osteoconductive, some osteoinductive if demineralised | None | Moderate – generally used as particulate rather than load-bearing block | No donor site; very low but non-zero disease transmission risk; some patients decline on ethical/religious grounds |
| Synthetic / alloplast (e.g. beta-TCP, hydroxyapatite) + | Osteoconductive only | None | Lowest for large defects alone; often combined with autogenous chips or growth factors | No biological/disease risk; unlimited, consistent supply; weakest regenerative capacity of the group; resorption/remodelling rate varies by material |
The block may partially or, rarely, completely fail to integrate – most often linked to soft tissue exposure/infection during healing.
If the recipient site flap opens, the graft can become exposed to the mouth, raising infection and failure risk.
At either the donor or recipient site; usually manageable but can compromise graft take
Expected after any bone surgery; typically peaks at 2-3 days and settles over 1-2 weeks.
Temporary – and occasionally permanent – numbness or altered feeling in the chin, lower lip, or lower front teeth from mental/incisive nerve disturbance.
Numbness of the lower lip/chin if the inferior alveolar nerve is irritated; generally less frequent than with symphysis harvest.
Rare chin ptosis (drooping) if the mentalis muscle isn’t precisely resutured at a symphysis donor site.
A small risk at the symphysis if the harvest extends too close to the apices of the lower front teeth.
More common after ramus harvest; usually temporary.
Your jawbone doesn’t have enough width or height in one area to support a dental implant safely and in the right position. We’re going to take a small block of bone from another part of your own jaw – either your chin or the back corner of your jaw – and fix it onto the area that needs building up.
Your own bone gives the most reliable and predictable result for a defect of this size and shape, because it contains living cells that actively help form new bone – something artificial or donor materials can’t fully replicate. The trade-off is a second small surgical site.
We’ve recommended [symphysis / ramus] because [it gives enough bone for the size of area we need to rebuild / it’s a smaller, more localised area to fix and this keeps the second surgery site as minor as possible].
Swelling, bruising and discomfort at both sites for one to two weeks.
A real possibility of temporary numbness in your chin, lip, or teeth near the donor site – occasionally this doesn’t fully recover.
A small risk the graft doesn’t take as well as hoped and needs further treatment.
Both sites heal over the following weeks. The graft itself needs around four to six months to properly join with your own bone before we can safely place the implant.
We could use a synthetic or donor/animal-derived bone graft instead, which avoids a second surgical site but generally isn’t as predictable for building up an area of this size – and may mean a less certain final result. We can discuss whether that trade-off makes sense for you.
Puresmile Borehamwood Dental & Implants
020 8953 3665
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