Bone grafting is often closely associated with dental restorations such as bridge work and dental implants. In the majority of cases, the success of a restoration procedure can hinge on the height, depth, and width of the jawbone at the implant site. When the jawbone has receded or sustained significant damage, the implant(s) cannot be supported on this unstable foundation and bone grafting is usually recommended for the ensuing restoration.
There are several major factors that affect jaw bone volume:
Periodontal Disease – Periodontal disease can affect and permanently damage the jaw bone that supports the teeth. Affected areas progressively worsen until the teeth become unstable.
Tooth Extraction – Studies have shown that patients who have experienced a tooth extraction subsequently lose 40-60% of the bone surrounding the extraction site during the following three years. Loss of bone results in what is called a “bone defect”.
Injuries and Infections – Dental injuries and other physical injuries resulting from a blow to the jaw can cause the bone to recede. Infections can also cause the jaw bone to recede in a similar way.
Reasons for bone grafts
Bone grafting is a highly successful procedure in most cases. It is also a preferable alternative to having missing teeth, diseased teeth, or tooth deformities. Bone grafting can increase the height or width of the jawbone and fill in voids and defects in the bone.
There are essentially two basic ways in which bone grafting can positively impact the health and stability of the teeth:
Jaw Stabilization – Bone grafting stabilizes and helps restore the jaw foundation for restorative or implant surgery. Deformities can also be corrected and the restructuring of the bone can provide added support.
Preservation – Bone grafting can be used to limit or prevent bone recession following a tooth extraction, periodontal disease, or other invasive processes.
Initially, the dentist will thoroughly examine the affected area in order to assess the general condition of the teeth and gums. If periodontal disease is present or the adjacent teeth are in poor condition, these factors will be fully addressed before the bone grafting procedure can begin. The dentist will also recommend panoramic x-rays in order to assess the precise depth and width of the existing bone. On occasion, a CAT scan may be recommended to determine the bone condition. Depending on these results, the dentist may also anesthetize the area and explore into the gum in order to determine what kind and how much bone is required.
What Does Bone Grafting Involve?
There are several types of bone grafts. Your dentist will determine the best type for your particular condition.
Autogenous Bone Graft - Harvested from the patient’s own body (usually from the posterior part of the lower jaw or the chin). This method is usually preferred because it produces the most predictable results.
Allograft Bone Graft - Cadaver or synthetic bone is used in this type of graft.
Xenograft - Cow bone is used in this type of graft.
The bone grafting procedure can often take several months to complete. Bone is typically harvested from your own body (or on rare occasions obtained from a “bone bank”) and added to the affected site. This bone will fuse with the existing bone and the migration of cells will cause firm adhesion and cell growth. Supplementing the jaw with bone will result in greater bone mass to help support and anchor the implant(s).
During the surgery, the dentist will numb the grafting and extraction sites using local anesthetic. A small incision will be made to prepare the site for the new bone and it will be anchored into place. On occasion, a synthetic membrane may be used to cover the new bone. This membrane prevents soft tissue and bacterial invasions, and encourages new bone growth. The surgery does not require an overnight stay, and you will be provided with comprehensive instructions for your post-operative care. The dentist will prescribe medications to help manage infection, discomfort and swelling.
Periodontal disease is the leading cause of bone loss in the oral cavity, though there are others such as ill-fitting dentures and facial trauma. The bone grafting procedure is an excellent way to replace lost bone tissue and encourage natural bone growth. Bone grafting is a versatile and predictable procedure which fulfills a wide variety of functions.
A bone graft may be required to create a stable base for dental implant placement, to halt the progression of gum disease or to make the smile appear more aesthetically pleasing.
There are several types of dental bone grafts. The following are the most common:
Autogenous bone graft – In this type of graft the bone is removed from elsewhere in the body and implanted in the mouth. Common donor sites for bone grafting include the iliac section of the pelvis, the chin and the posterior third molar areas of the jaw. If large amounts of bone need to be harvested, the hip or the shin bone (tibia) is generally used.
Allograft – Synthetic bone (man made) can be created in the laboratory and used in the bone grafting procedure. Bone can also be obtained from a bone bank (cadaver bone).
Xenograft – This is the implantation of bovine (cow) bone. A xenograft is perfectly safe and has been used successfully for many years. Ample bone can be obtained and no secondary donor site is necessary.
Reasons for bone grafting
There are a wide variety of reasons why bone grafting may be the best option for restoring the jaw bone.
Dental implants – Implants are the preferred replacement method for missing teeth because they restore full functionality to the mouth; however, implants need to be firmly anchored to the jawbone to be effective. If the jawbone lacks the necessary quality or quantity of bone, bone grafting can strengthen and thicken the implant site.
Sinus lift – A sinus lift entails elevating the sinus membrane and grafting bone onto the sinus floor so that implants can be securely placed.
Ridge augmentation – Ridges in the bone can occur due to trauma, injury, birth defects or severe periodontal disease. The bone graft is used to fill in the ridge and make the jawbone a uniform shape.
Nerve repositioning - If the inferior alveolar nerve requires movement to allow for the placement of implants, a bone grafting procedure may be required. The inferior alveolar nerve allows feeling and sensation in the lower chin and lip.
What does bone grafting treatment involve?
Bone grafting is a fairly simple procedure which may be performed under local anesthetic; however if large amounts of bone area need to be grafted, general anesthetic may be required.
Initially, the grafting material needs to either be harvested or prepared for insertion. A small incision is made in the gum tissue and then gently separated from the bone. The bone grafting material is then placed at the affected site.
The bone regeneration process may be aided by:
Gum/bone tissue regeneration – A thin barrier (membrane) is placed below the gum line over the grafting material. This barrier creates enough space for healthy tissue to grow and separates the faster growing gum tissue from the slower growing fibers. This means that bone cells can migrate to the protected area and grow naturally.
Tissue stimulating proteins – Enamel matrix proteins occur during natural tooth development. Emdogain is a matrix protein product which is usually placed on the affected site before the gum is sutured. It mediates the formation of accellular cementum on the tooth which provides a foundation to allow periodontal attachment to occur. Tissue stimulating proteins help to create lost support in areas affected by periodontal defects.
Platelet-rich growth factors –A high platelet concentration liquid can be used to create a blood clot at the site of a wound. It has recently been discovered that PRGF also stimulates bone growth – meaning a denser graft in a shorter time period.
The gum is sutured in place and a follow up appointment will need to be made within 10 days to assess progress. Bone grafting is a highly successful treatment and a good base for further periodontal restorations.
If you have any questions about bone grafting, please ask your dentist.