| The moment patients hear their dentist or surgical | | | | Depending on the amount of bone present at the |
| specialists mention "bone grafts", often you see the | | | | time of surgery, the implant can be placed at the |
| backs of patients as they rapidly head for the door. | | | | same time or in a secondary procedure 5-6 months |
| Often times patients are never truly educated on | | | | later. |
| why bone grafts are needed. Not every dental | | | | Often times patients are more concerned with the |
| implant case requires bone grafting, but a fair number | | | | harvest site or the taking of the bone graft rather |
| of them do. Patients must understand that bone | | | | than the placement of the graft. Are there other |
| provides the foundation for the support of the | | | | options besides using the patient's own bone? Yes, |
| implant. The bone, depending on the type of | | | | there are other alternatives to consider. One option is |
| restoration desired, must have adequate height, | | | | an allograft block. It is a block of bone taken from a |
| width and positioning for dental implant placement. | | | | human cadaver and treated to remove all disease |
| Additionally, the bone normally has to be at or near | | | | and protein that cause rejection. However in most |
| the same level as the adjacent bone. | | | | cases, the amount of resorption is unpredictable. |
| Imagine the bone being the foundation for the | | | | What that means, is it is hard to determine how |
| construction of a house. It must be solid and level. It | | | | much of the bone graft will actually stay behind. |
| isn't that different in the mouth. After you have an | | | | Additionally, some times the bone can incorporate but |
| extraction or have a tooth missing for some time, | | | | never get fully turned over by your body. Typically |
| the bone deteriorates (atrophies). The alveolar bone | | | | when allografts are placed, they are resorbed by |
| (the bone that houses teeth and their roots) | | | | your body and replaced by your natural bone within |
| atrophies typically in width greater that in height, but | | | | the matrix of the graft placed. Your skeleton is not |
| both components are involved. If the bone is too | | | | static and constantly rids itself of old bone and turns |
| thin, an implant cannot be placed because the body | | | | over new bone. This process happens to about 0.7% |
| of the implant will not be covered by bone | | | | of your skeleton everyday. The area that has the |
| circumferentially. If the bone is not high enough, the | | | | most turnover is the mouth where the teeth and |
| implant could be too close to adjacent anatomic | | | | periodontal ligament meet the bone. With these |
| structures. Moreover, even if an implant could be | | | | allograft blocks and with xenografts, some of the |
| placed, but the bone is not at the same level as the | | | | graft material occasionally never gets turned over |
| adjacent bone, the implant may not be hygienic, it | | | | and can have a poor blood supply. Implants placed |
| may be very unaesthetic and/or create a periodontal | | | | into this bone can suffer bone loss and failure. The |
| issue for the patient. A general rule of thumb for | | | | other option is human recombinant bone morphogenic |
| implants surgeons, is to reconstruct the foundation | | | | protein. Commonly called BMP, this protein actually |
| for the implant back to ideal prior to placing an | | | | signals the body to put bone where the protein is |
| implant or implants. | | | | placed. For sinus lifts, a collagen membrane is soaked |
| There are many types of bone grafts. Normally, | | | | in BMP and placed into the sinus. After 6 months or |
| when a tooth is removed, banked bone (called an | | | | so, implants can then be placed. Success rates are |
| allograft) or a xenograft (bone from another species, | | | | relative on par with autogenous bone grafts. Patients |
| typically bovine or cow) is placed into the socket. | | | | often elect this procedure when they wish to avoid |
| Additionally a resorbable collagen membrane is placed | | | | bone harvesting. The only negative is the cost of the |
| over the bone to prevent the gum tissue from | | | | protein which can be a few thousand dollars by itself. |
| invading the socket site. Occasionally, in an extraction | | | | When there isn't enough bone that can be obtained |
| site without grafting, the gum tissue invades into the | | | | from the mouth, the bone must be harvested from |
| socket before bone can heal and some loss of width | | | | elsewhere. Typically for dental implant procedures, |
| more so than height occurs. The bone graft to | | | | bone can be obtained from the anterior (front part |
| preserve the socket is called an alveolar preservation | | | | of the hip), the tibia (big bone of the lower leg), or |
| procedure. Normally after three to four months, the | | | | the skull. The hip and the tibia are typically used. |
| implant can then be placed. | | | | Some of these procedures can be done in the office, |
| If the bone is too thin and/or too short, autogenous | | | | but some require hospitalization. Other options to |
| bone grafting is usually needed. Autogenous bone | | | | bone grafting can be distraction osteogenesis. The is |
| grafting is typically taking bone from one part of the | | | | where a cut in the bone is made and freed up from |
| body and transferring to another. For most situations | | | | the mandible or maxilla but still left attached to the |
| in the mouth, bone can be taken from non-tooth | | | | tissue one side. Therefore the freed up piece of |
| bearing areas (at or above the wisdom tooth site | | | | bone still has a blood supply. The freed up part of |
| called the ramus), from the front part of the chin, | | | | the bone, called the transport bone, is attached to a |
| the site where the upper wisdom tooth once was | | | | device with screws and the other end of the device |
| (tuberosity), the malar buttress (where the bottom | | | | is attached to part of the bone where the freed |
| of the cheek bone meets the upper jaw), or from | | | | piece came from. Slowly over time, the device is |
| tori. Tori are naturally occurring bone outcroppings of | | | | activated and slowly spreads apart. If done properly, |
| the upper and/or lower jaws. This anomaly is seen 5 | | | | as the bone segments are moved apart, bone fills in |
| to 10% of the population. The site where the bone is | | | | gap and "new" bone is grown. The difficulties with |
| taken is called the harvest site. The donor site, | | | | the procedure is controlling the direction of the |
| where the bone is to be placed, is prepared to | | | | transported bone segment, the patient tolerating the |
| accept the block of bone or particulated bone. | | | | device for several weeks and the transported bone |
| Particulated or ground up or scraped bone is placed | | | | is occasionally too thin for implants and requires |
| into a defect or into a titanium mesh or titanium | | | | further grafting. |
| reinforced Gore-Tex (PTFE-Polytetrafloroethylene). If | | | | In the lower jaw, if there is not enough height, one |
| a block of bone is taken, once the donor site is | | | | other option beside bone grafting is nerve |
| prepared, the block is secured to the site using | | | | lateralization. If the bone is wide enough, what |
| titanium or stainless steel bone screws. After a period | | | | typically limits vertical placement of implants is the |
| of healing, typically 5-6 months, the mesh, Gore_tex | | | | position of the inferior alveolar nerve canal. This is an |
| or bone screws are removed and the implant(s) are | | | | intrabony canal that houses the nerve that supplies |
| placed. | | | | feeling to the lower teeth and to the lip and chin. It is |
| Bone of the upper back jaw often does not atrophy | | | | the nerve that makes your lip and chin feel fat after |
| horizontally significantly. However, vertical atrophy | | | | the dentist numbs your lower arch for treatment. To |
| causes the alveolar bone to shrink upwards and | | | | gain height for implants, the nerve canal can be |
| approaches the bottom portion of the maxillary sinus. | | | | unroofed from the side and moved away, the |
| Then a decision has to be made whether to add | | | | implants placed and then the nerve redraped. |
| bone vertically to the upper jaw (maxilla) or elevate | | | | Obviously there is some risk of nerve damage in this |
| the sinus. The sinus is a hollow cavity of the skull | | | | procedure and is usually a secondary consideration to |
| lined by a membrane (Schneiderian membrane). The | | | | bone grafting. |
| membrane consists of respiratory epithelium or | | | | When patients understand why bone grafts are |
| ciliated columnar epithelium. The cilia are little hairs that | | | | needed, the case acceptance rates improves |
| beat and clear the sinus of fluid and mucus. When | | | | dramatically. Patients must have a firm understanding |
| there isn't enough bone present, the sinus can be | | | | of the procedure and reasoning behind procedures to |
| elevated and bone placed under the membrane. The | | | | reduce their reluctance to proceed. Understanding |
| procedure consists of an approach to the sinus from | | | | that creating the ideal foundation for implants |
| either the alveolar ridge (where the tooth was) or | | | | improves dental implant success, longevity, function |
| from the side (cheek side of the jaw). Access is | | | | and greatly reduces post-implant complications, |
| made into the sinus without tearing the membrane | | | | motivates patients not to compromise their dental |
| and elevating the membrane off of the bone. The | | | | implant treatment plan. Therefore, dentist and |
| mobilized membrane creates the matrix to contain | | | | specialist must take their time to explain not only the |
| the bone graft. The bone graft can be an | | | | procedure but the reasoning behind bone grafting for |
| autogenous, an allograft, and/or a xenograph. | | | | dental implants. |