Initial Record

Orthodontic therapy to treat anterior crowding and traumatic occlusion to upper left central

What is guided bone regeneration?
Guided bone regeneration(GBR) is the term refer to the concept of using various type of bone implants in conjunction of barriers of different types in periodontal surgery to promote regeneration of new bone. The bone graft can be autogenous, allograft, xenograft, and/or synthetic material. The barrier is constructed of biocompatible material, exhibits occlusive properties to prevent fibrous connective tissue invasion of the space, provides some degree of protection from bacterial invasion should the membrane become exposed to the oral environment, provides suitable space which osseous regeneration can occur, and finally, is capable of tissue integration to help stabilize the healing wound, creating a seal between bone and material to prevent connective tissue leakage into the defect, and retards the migration of epithelium around the material. Moreover, the difference between the barrier used for GBR and that of GTR (guided tissue regeneration) would be the bioavailability of the membrane over the graft site, i.e., the membrane resorption rate. In GBR, the membrane is preferred to resorb at the slower rate than in GTR.

• Autogenous bone graft: a graft taken from one site to another in the same individual.The common donor sites are the chin, the exotoses, the mandibular lingual ridge, the edentulous ridge, the lingual surface of maxilla or mandible at least 5mm away from the roots.
• Allograft: taken from the same species such as undecalcified freeze dried bone allograft (FDBA), the decalcified freeze dried bone allograft (dFDBA). In the case of FDBA, it can provoke an immune response.
• Xenograft: bone from different species such as bovine or calf bone, demineralized to reduce the immune response.
• Synthetic bone graft: surface active biomaterial such as Biogran. Biogran consists of 300-355 um diameter bioactive glass granules. As a result of its optimal size range, it transformed into hollow calcium phosphate bone growth chambers. Each bone growth chambers within a bony defect provides a new protective environment in which cells differentiate into osteoblasts, which give rise to new bone. Multiple ossification sites throughout the defect within the Biogran granule provides chambers for which new bone growth takes place.

All these types of graft offers osteoconductive and osteoinductive properties. Allograft, xenograft, and synthetic graft may provoke an immune response due to being a foreign body. Autogenous bone graft demonstrated osteogenic property and does not invoke an immune response, therefore it is the most favorable. Biogran also demonstrated osteogenesis with multiple ossification sites within the Biogran granules.

What are the desired properties in selecting a bone graft material?
Shallhorn described the selection of criterias for an ideal type of bone graft as biological acceptability, inductive effect, predictability, clinical feasibility, minimal operative harzard, minimal operative sequelae, and patient acceptance. It is very difficult to find a material which possesses all these ideal properties, thus we must carefully evaluate the bio-characteristic of each material and its application. Sometimes, combination of the graft materials have been shown to be favorable in term of clinical success.

The inductive effect of bone graft materials can be categorized into three properties. They are:

• Osteogenesis: occurs when graft survive the transplantation and contribute to the repair process.
• Osteoinductive: occurs when two or more tissues of different natures or properties become intimately associated, resulting in alteration of the developmental course of tissue, i.e., bone is formed in the area it should not be formed. Urist et al. (1967) noted enhanced osteoinductive effects when bone was demineralized to expose the matrix protein.
• Osteoconductive: occurs when the graft served as the functional matrix for the ingrowth of capillaries in new connective tissue and forming bone (the trellis effect). The graft provide a cytoskeleton of which the capillaries can grow into, followed by resorption of dead bone or of the synthetic bone matrix and the deposition of new bone lamellae.

Other factors favor the inductive effect are small particle size, increased surface area, ease of resorption, demineralization.

What are the surgical technique used in GBR?
Robinson described the technique using mixture of small, crushed bone particle and blood that he termed osseous coagulum. The crush, small particles increases the surface areas which then increases the inductive effect. The graft site should be free of all the soft granulation tissue. All fibers must be removed to open the marrow spaces and permit intimate contact between the graft material and the bone.The graft site should be decortical, i.e., small holes in bone are made with sharp curette or small round bur to permit rapid regeneration of bone, rapid anastomosis of graft and bone, and rapid proliferation of granulation tissue with undifferentiated messenchymal cells. The graft material then is packed in small increment, removing excess fluid as we finished each packing. The graft material should be slightly overfilled, but not too much as flap closure would be difficult. Barrier should be applied to prevent ingrowth of connective tissue into the defect and also epithelial migration. Graft and membrane barrier should be covered completely (100%) by the flap. Vertical mattress suture can be done with ePTFE suture (Goretex) to prevent wicking of bacteria into graft site. Postoperatively patient can be placed on doxycycline, tetracycline, and/or periostat. Peridex mouth rinse may also be used. Suture can be removed in two weeks.

Today, with the advance in the area of platelet concentrate technology allowed for the increase in availability of growth factors in the area of bone regeneration. With the platelet concentrate collection system(PCCS) in our office, we can collect platelet from as low as 55mL of blood. The platelet concentrates contains all the growth factor which is very favorable in the inductive effect. Healing from the surgery with PCCS have been phenomenal, with healing time shortened as much as one week. The fibrin in the platelet concentrate also aid tremendously in clot stabilization, which is one of the important criteria in wound healing. I preferred to perform the surgery with PCCS in every difficult situation especially in individual with systemic problems.

What are the application of GBR?
Guided bone regeneration is used in various applications. They are:

• Grafting to increase bone width and height in the future implant site.
• Concurrent grafting surrounding the newly placed implant to improve bone to implant contact areas.
• Ridge augmentation for denture retention in the lower posteriors area
• Regenerates bone width for the area underneath the pontic of a bridge
• Placement of grafts in surgical procedure such as apicoectomy, cyst removal, sinus lift with Tatum lateral wall approach

What is required for a successful guided bone regeneration surgery?
The success of guided bone regeneration lies on the following factors. These factors are very similar with those of guided tissue regeneration. They are:

• Use of an appropriate grafting material or combination of the graft material. My favorite is the mixture of Biogran and Bio-Oss or Biogran and dFDBA.
• Use of an appropriate barrier membrane. Membrane selection should be base on biocompatibility, ease of adaptation to the defect, tissue integration, creation of space for bone regeneration, and bioavailability during the crucial regenerative period (preferrably 6 months in the sinus lift case).
• Surgical technique in flap reflection, debridement of defect, graft placement, membrane placement, and adaptation.
• The use of bone graft with osteogenesis, osteoinductive and osteoconductive property to further stimulation of migration, differentiation, and maturation of new bone. Note that the bone graft will serve as a functional matrix to maintain the space for new future bone. The material itself will resorb.
• The use of platelet concentrate collection system (PCCS).
• Stabilization and close adaptation of membrane to the surrounding bone can be aided with bone screw or tack (resorbable or nonresorbable)
• Primary flap closure
• Eliminate of all the systemic and local etiology which may lead to surgical complication (autoimmune disease, diabetes, occlusal trauma, poor oral hygiene)
• The use of adjunctive therapy postoperatively such as periostat may help in regeneration result.
• Other important factors are plaque control and patient 's repair potential.

If we control all the factors above, the outcome should be very successful in regeneration of new bone in the area.

On the right hand column is an example of a case using guided bone regeneration to augment the maxillary sinus case. The patient came to our office requesting treatment for his recurrent periodontitis. Upon examination, we decided to provide posterior support to his dentition with implants placed bilaterally. Radiograph examination indicated of Misch category of SA4, with inadequate bone height and width in the maxillary posterior region (Please select Implant Dentistry, Sinus Lift under services menu for more information). Note that upper right premolar also shows periapical abscess. Root canal therapy is carried out prior to the grafting of the posterior region. Due to severity of the bone graft, platelet concentrate collection system from 3i is used. 60cc of blood was collected intravenously and from that we harvest about 35cc of platelet. Mixture of autogenous, Bio-Oss, and Biogran graft is used. Ossix membrane also was placed. We also fabricated a collagen membrane using our platelets and place over the ridge area to further augmented the width of maxillary posterior. Result is shown below with patient demonstrated excellent healing in two weeks. Implant can be placed from 10-12 months later.

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