When teeth are lost, as the time passes, the bone starts to lessen. As well as the patient who uses removable prostheses or complete dentures, through the years bone volume diminishes because these prosthesis are supported on the gum and bone.
Nowadays graft procedures have became to be integral part of implant reconstruction, this is, if the potential site for the implant placement does not offer enough bone volume or quantity, due to bone destruction caused for one or more missing teeth. Bone graft procedures try to restore bone dimension lost by decay.
Long time ago bone lack made impossible implants placement, now we have the capability of creating bone where we need, also to give the opportunity of placing proper dimension implants and in addition our prosthesis become better in appearance and functionality.
Materials to increase bone
We have five different categories: ºAutogenous bone ºAllograft ºXenograft ºAlloplastics ºGrowing factors
Autogenous bone is considered as the ideal graft. It is transplanted from a donor site to a receiving site of the same patient. The greatest ranks of success have been obtained with autogenous grafts. There is not any rejection reaction and microscopic structure fits perfectly. The only disadvantage is that it must be taken from another part of the body that means a more complicated surgery. For oral Implantology purposes we can used bone from other part of the jaw (chin or the back portions of the jaw) to avoid extra oral wounds.
Allograft is defined as the graft among individuals from the same species, but with different genetic composition, normally it is corpse bone. This bone has to be put under many treatments to reach its neutrality and immunity and so, avoid diseases contamination of receptor.
Xenograft is defined as tissue graft between two different species (bovine origin bone).
Alloplastics generally include synthetic graft material that does not come from animal or human origin. Normally hydroxiapathite.
Growing factors are natural proteins found in our body and stimulate growing of certain tissues, these are bone morphogenetic proteins (BMPs), and they can be a potential substitute as material for autogenous grafts.
Sinus Elevation
After teeth loss maxillary sinuses grow in volume and eliminate valuable bone of the maxilla ridge. This process is called neumatization of the maxillar sinuses.
The previous process makes it difficult but not impossible endosseous implant placement.
Sinus elevation is used to elevate the low part of the sinus; bone is grafted underneath to create enough space to place one or more dental implants. This procedure has been successfully performed for more than two decades and it is considered an accepted and predictable method of bone graft. An autogenous graft gives the best and fastest results. An autogenous graft takes about 4 or 6 months in maturing inside the sinus, an allogenic bone graft, alloplastic graft or xenogenetic graft can take 8 or more months. Sinus elevation procedures and implant placement can be performed in only one procedure, as long as enough bone exists between the upper maxilla edge and the sinus base available to stabilize well the implants. In the case that there is not enough available bone, sinus elevation has to be performed first, and then let it to mature for several months (depending upon the material used). Once the graft has mature, implants can be placed.
Here it is shown the normal bone height underneath the sinus, when teeth exist
Decay of the bone when premolars and molars are lost
Graft placement inside the maxillar sinus to be able to place implants
Placed Implants
Crowns on the implants
Case 1
Now, we are presenting some x-rays from a 55 year old patient, where it appreciates bone lack underneath the maxillar sinuses, caused for the missed teeth, as we mentioned, this bone lost process is normal and it is not pathological. Then we observed the x-ray where the procedure of sinus elevation is done and the graft placement can be appreciated with the implants already placed.
Here the little bone quantity under the maxilla sinuses is observed
Note the placed graft obtaining a greater height for the implant placement
Case 2
Now, Here are a 47 year old patient’s x rays, who have lost a second premolar and two upper left molars.
The little bone quantity underneath the maxillar sinus can be observed
Here we observe the maxillar sinus elevation procedure. Note the great bone quantity for the next implants placement
Block grafts
Also known as Onlay graft. This Kind of graft is designed to reestablish bone lost in a particular area, due to decay. One autogenous bone portion (normally from the chin or from the back site of the jaw, is attached to the site with osseous defect.
Subsequently, the area is closed and allows it to mature for a maturation and healing period, this bone will be incorporated in the receiving place to be integrated and mineralized, and then implants can be placed.
In the case of bigger areas, more autogenous bone portions will be needed, taken from the patient’s hip or shin-bone. At this point other implants modalities can be used (subperiostical, ramusframe) to avoid this surgical procedure.
This procedure is widely used to treat osseous edges with too much bone decay in upper and low maxilla. It is normally needed before the implants placement to assure the implant positioning and for a better aesthetics of the future prosthesis.
Donor Zone
Receiving Zone
Patient with congenital lateral absence. Note the great bone depression
Here we observed the bone increase due to a chin block graft
Although this procedure is highly used nowadays with great success, we are constantly trying to increase and facilitate graft procedures, as well for the patient as for the surgeon.
Ridge expansion
This technique is used to recover lost bone dimension when maxilla edge is too thin to place conventional implants. Maxilla edge is literally expanded by mechanical means. A series of expansors or osteotomes are forced in implant site, these expansors are struck inside the edge by a surgery. This compresses the bone spongy part and it makes the outer crust to come out. At this point implants can be placed immediately inside the created site.
Bone Spreading Osteotomos
Other grafts procedures.
In this category the other grafts procedures are included. For example when an implant is immediately placed in the extracted tooth site. Most of the time there is some discrepancy between the implant and the site diameter, leaving an space between the implant wall and the bone wall, these spaces are usually filled with graft bone material.
Upper lateral Fracture
Implant immediately placed after the root extraction
Another procedure is when an implant is placed inside the bone and it is not completely covered by bone and there is an exposure of the implant’s screw-thread. In most of the cases they are covered or grafted with membrane. While the implant is integrated to the bone, the membrane allows the bone to be reshaped and to grow underneath avoiding soft tissues cells to be inhibited from their process.
