Major & Minor Bone Grafting
Over a period of time, the jawbone associated with missing teeth atrophies or is reabsorbed. This often leaves a condition in which there is poor quality and quantity of bone suitable for placement of dental implants. In these situations, most patients are not candidates for placement of dental implants.
Today, we have the ability to grow bone where needed. This not only gives us the opportunity to place implants of proper length and width, it also gives us a chance to restore functionality and esthetic appearance.
Major Bone Grafting
Bone grafting can repair implant sites with inadequate bone structure due to previous extractions, gum disease or injuries. The bone is either obtained from a tissue bank or your own bone is taken from the jaw, hip or tibia (below the knee.)
Sinus bone grafts are also performed to replace bone in the posterior upper jaw. In addition, special membranes may be utilized that dissolve under the gum and protect the bone graft and encourage bone regeneration. This is called guided bone regeneration or guided tissue regeneration.
Major bone grafts are typically performed to repair defects of the jaws. These defects may arise as a result of traumatic injuries, tumor surgery, or congenital defects. Large defects are repaired using the patient’s own bone. This bone is harvested from a number of different sites depending on the size of the defect.
The skull (cranium), hip (iliac crest), and lateral knee (tibia), are common donor sites. These procedures are routinely performed in an operating room and require a hospital stay.
Sinus Lift Procedure
The maxillary sinuses are behind your cheeks and on top of the upper teeth. Sinuses are like empty rooms that have nothing in them. Some of the roots of the natural upper teeth extend up into the maxillary sinuses. When these upper teeth are removed, there is often just a thin wall of bone separating the maxillary sinus and the mouth. Dental implants need bone to hold them in place. When the sinus wall is very thin, it is impossible to place dental implants in this bone.
There is a solution and it’s called a sinus graft or sinus lift graft. The dental implant surgeon enters the sinus from where the upper teeth used to be. The sinus membrane is then lifted upward and donor bone is inserted into the floor of the sinus. Keep in mind that the floor of the sinus is the roof of the upper jaw. After several months of healing, the bone becomes part of the patient’s jaw and dental implants can be inserted and stabilized in this new sinus bone.
The sinus graft makes it possible for many patients to have dental implants when years ago there was no other option other than wearing loose dentures.
If enough bone between the upper jaw ridge and the bottom of the sinus is available to stabilize the implant well, sinus augmentations and implant placement can sometimes be performed as a single procedure. If not enough bone is available, the sinus augmentation will have to be performed first, then the graft will have to mature for several months, depending upon the type of graft material used. Once the graft has matured, the implants can be placed.
Ridge Expansion or Augmentation
In severe cases of maxillary and mandibular bony atrophy, the ridges of the upper and lower jaw have resorbed and bone graft is required in order to increase the height and width of these areas. Techniques used to restore the loss of bone dimension in the jaw ridge include; split ridge technique, onlay bone graft, distraction of alveolus. These procedures are often done prior to the placement of dental implants.
Bone graft can be harvested from many different areas which include; the anterior or the posterior iliac crest (hip graft), the jaw bone, the cranium, the ribs as well as the knee (tibia).
Anterior or Posterior Iliac Crest (Hip Graft)
Quantity of 30 to 60 cc of bone can be obtained from the anterior iliac crest. This is often done via a small incision done in the anterior portion of the hip, taking bone therefore from the inside of the iliac girdle versus the outside. This creates less discomfort. At present, this technique is covered under the New-Brunswick Medicare Service. This requires a hospital stay of minimum one night and both corticocancellous bone may be obtained. This bone is often placed in either the maxilla or the mandible in order to increase the ridge height and width as well as increase the quality and quantity of bone and the elevation of the maxillary sinuses. Discomfort is noted in the anterior region which will last anywhere between a few days to a few weeks. Precautions in order to prevent pocket numbness are always taken as well as hematoma formation. Some patients may have a drain placed at the end of the surgical procedure in order to prevent hematoma formation. The posterior iliac crest can also be harvested.
- This is often done on the lateral aspect of the spinal column and bone is harvested from the posterior iliac region. A greater quality and quantity of bone of the cancellous bone can be obtained. This is often used in large bony reconstruction of the mandible or maxilla.
Jaw Bone Harvest
- In some cases, where a smaller amount of bone is required, bone could be obtained from either the posterior mandibular region in the area of the wisdom teeth to the chin region or parasymphysis. Both corticocancellous bone could be obtained and this is often reserved for smaller bone grafting at a extraction site or even in the perinasal region for the anterior maxillary area. Bone is harvested and placed immediately to the required site. Bone is always secured into place using bone screws. Often, platelet rich plasma or PRP will be used at the same time. This will increase the quality and quantity of bone performed.
- Often for reconstruction of a temporomandibular joint, a costocondylar rib is often taken. This is often the 6th or 7th rib from the contra lateral side in order to obtain a more ideal situation. Rib can also be used for infraorbital reconstruction, nasal reconstruction as well as some areas of the alveolus, depending on the other sites to be evaluated. The sequelae and complications of this surgical procedure are explained in detail during the consultation and the preoperative examination. One has to remember that pneumothorax and paresthesia are 2 complications that can occur.
Cranial Bone Graft
- The lateral portion of the cranium is often used in bony reconstruction of orbital rims as well as certain portions of the maxilla, often used with a muscular flap. These bring a cortical or cortex type of reconstruction rather than cancellous bone.
Tibial Bone Graft
- Tibial bone graft is often used for sinus reconstruction. This often is taken from the tibial plateau and a fair amount of bone can be harvested anywhere between 15 to 25 cc. This is often of medullary or cancellous type of bone, which is packed and reinjected into the specific sites. This bone graft is always mixed with PRP in order to increase the bone quality and quantity.
- One has to remember that any of the non intraoral bone harvesting requires meticulous cleaning of the wounds postoperatively, care to allow healing and therefore no immersing under water, increase activity as tolerated.
The sequelae and complications of bone grafts:
One has to understand that 25 to 30% of bone grafts from these different sites are often lost or resorb prior to implant insertion.
Nerve – Repositioning
The inferior alveolar nerve, which gives feeling to the lower lip and chin, may need to be moved in order to make room for placement of dental implants to the lower jaw. This procedure is limited to the lower jaw and indicated when teeth are missing in the area of the two back molars and/or and 2nd premolar, with the above-mentioned secondary condition. Since this procedure is considered a very aggressive approach (there is almost always some postoperative numbness of the lower lip and jaw area, which dissipates only very slowly, if ever), usually other, less aggressive options are considered first (placement of blade implants, etc.)
Typically, we remove an outer section of the cheek side of the lower jawbone in order to expose the nerve and vessel canal. Then we isolate the nerve and vessel bundle in that area, and slightly pull it out to the side. At the same time, we will place the implants. Then the bundle is released and placed back over the implants. The surgical access is refilled with bone graft material of the surgeon’s choice and the area is closed.
Alveolar Distraction Osteogenesis
This principle developed many years ago by an orthopedic surgeon named Ilizarov, creates alveolar lengthening by including a latency period for the distraction followed by small movements of a magnitude of .5 to 1 mm a day to increase the height of bone loss. This unique technique allows a transport of bony segment to be moved and therefore increasing the quality and quantity of bone. This bone is from the same site and therefore tends to show less resorption of bone postoperatively.
One can see the alveolar distraction osteogenesis being applied in both the maxilla and the mandible with, at times, onlay grafting as well in order to increase the width of the bony segment. Small appliances are placed in the mouth with daily activation.
The sequelae and complications of these surgical procedures can include:
- Lack of desired height.
- Loss of bony segment.
- Neurosensory changes.
The advantage of an alveolar distraction is that both soft and hard tissue are mobilized and increased during the procedure.
These procedures may be performed separately or together, depending upon the individual’s condition. As stated earlier, there are several areas of the body that are suitable for attaining bone grafts. In the maxillofacial region, bone grafts can be taken from inside the mouth, in the area of the chin or third molar region or in the upper jaw behind the last tooth. In more extensive situations, a greater quantity of bone can be attained from the hip or the outer aspect of the tibia at the knee. When we use the patient’s own bone for repairs, we generally get the best results.
In many cases, we can use allograft material to implement bone grafting for dental implants. This bone is prepared from cadavers and used to promote the patients own bone to grow into the repair site. It is quite effective and very safe. Synthetic materials can also be used to stimulate bone formation. We even use factors from your own blood to accelerate and promote bone formation in graft areas.
These surgeries are performed in the out-office surgical suite under IV sedation or general anesthesia. After discharge, bed rest is recommended for one day and limited physical activity for one week.