Procedure overview
Sometimes it becomes necessary to use whole blocks of bone, which are held in place by fixation screws while the body “integrates” the graft. Bone powder may be used as a filleting material around the abrupt edges of a block graft. Blocks can either be harvested from the patient at the time of the graft (known as an “autograft”), or may be obtained from a tissue bank that supplies human block cortical bone (“allograft”).
What steps are involved
Step 1: Anesthetic
The area to be grafted is anesthetized by injecting local anesthetic around the nerve(s) that supply sensation to the surgical area. If the patient is going to supply the bone for the graft, there will be a second surgical site at the donor area. Common sites for retrieving a block of cortical bone include the “ramus” area of the lower jaw, a “plug” of bone from the chin, the tibial plateau (i.e. lower leg bone), the iliac crest (i.e. hip bone), and (less commonly) the calvarium (skull). This page does not provide information on “donor site” surgical procedures. Only the area to be grafted is discussed. Note: It is possible that the need for harvesting blocks of bone from the patient may soon be irrelevant, due to promising developments involving the use of stem cells. See “Questions”.
Step 2: Preparation and surgical access
The extent of the defect is studied visually and on X-rays. An incision is made to expose the underlying bone defect, and the soft tissue is retracted for visibility (Figures 1a, 1b, and 1c).
Step 3: Block graft preparation
The length and width of the bone defect is measured, and the block graft is trimmed to the corresponding dimensions.
Step 4: Bone screws
The graft is held in place with small bone screws which can be removed after the graft has healed and integrated into the host (i.e. “your”) bone (Figure 2).
Step 5: Filleting
The gaps and irregularities around the block graft are filleted with powdered bone (Figure 3).
Step 6: Closure
The soft tissues are repositioned over the graft. Usually, the soft tissue must be modified to cover the newly widened bone, using a technique called “periosteal scoring”. In this technique, accordion-like pleats are incised on the bone-interfacing side of the soft tissue— a toughened layer called “periosteum”. This allows it to be stretched over the graft. The incision is then closed and sutures are placed.
Step 7: Post-operative instructions
Your dentist should give you specific post-operative instructions, taking into account your unique medical and dental situation. You should request that the instructions be given in writing. Although they may seem simple at the time of your appointment, questions frequently come up later.
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