Guided Bone Regeneration in the aesthetic zone

Introduction


Dental implants seem to be the number one alternative when it comes to restoring the missing teeth. The high osseointegration success and the predictability are the features that lead to a long-term aesthetics with the tissue composition and the peri-implant bone. The success of the implant depends on the adequate amount of the available bone and if the resorption process is noticed, it may be a serious and significant challenge for the clinical praxis. It is very important for patients to know that tooth removal can lead to remarkable changes later on the bone tissue. In the first to three years, a 50% of the alveolar ridge could be lost. If the tooth is extracted traumatically or if there were some endodontic or periodontal pathologic changes, the bone loss is exacerbated. Cases similar to this often need bone augmentation in order to design ideal aesthetics and gingival contours. There are different materials and techniques which are used for restoring the volume of the bone tissue which would support the dental implants in the future period. The most frequently outlined methods in the dental searches are:

  • Guided Bone Regeneration (GBR),
  • Inter-positional inlay grafting,
  • Onlay veneer grafting,
  • Distraction osteogenesis, and
  • Ridge splitting technique.

The most commonly used procedure for tissue reconstruction is guided bone regeneration. The concept of this method is that the regeneration of the bone defects is by the application of occlusive membranes which by mechanic way exclude the non-osteogenic cells from the local soft tissues, and at the same time, allowing the osteogenic cells which come from the parent bone to stop the osseous wound. The studies found in the dental literature show that bone regeneration is improved only when the soft tissue into osseous defects is impeded mechanically. Two perspectives are described in guided bone regeneration process- the simultaneous and the staged perspective. In the first simultaneous perspective, the fixture placement and the GBR are done simultaneously and this method is indicated in narrow ridge defects. In the second staged perspective, the GBR is utilized for increasing the alveolar bone before the fixture placement.

The GBR technique


Guided Bone Regeneration (GBR) is a procedure that describes the bone growth which is achieved by maintaining the space and preventing the growth of the soft tissue into the area by using a resorbable or non-resorbable membrane. This way the bone regeneration is achieved. The procedure could be done together with the implant placement or during a surgical operation prior to the placement of the implant. There are various different types of membranes materials that have been utilized in the process of GBR. But, the most important considerations about choosing the right membrane are the following: GBR Technique

  • Biocompatibility: This means that there is no interaction between the tissue and the material
  • Cell occlusion properties: Prevention of the invasion of the fibrous connective tissue
  • Integration by the host tissues
  • Clinical management and space designing ability


  • Resorbable Membranes There are two types of membranes used in the GBR technique. The non-resorbable membranes are not degraded by specific enzymes when placed in the human body which is not a case when resorbable membranes are used. The non-resorbable membranes need a second surgical procedure for their removal. The usage of these membranes could lead to a complete failure of the reconstruction treatment. The mentioned disadvantages have inspired the scientists to develop the resorbable membranes. For applying the guided bone regeneration procedure, the absorbable collagen membranes are most commonly used in the dental clinics. The best advantage of using this type of membrane is that it doesn’t require a second intervention to be removed. The membrane is created by a unique procedure that makes a longer resorption suited to GBR process. It is about six months. This material is made of a fibrillar matrix structure in order to give strength for suturing the membrane. The composition of this membrane is excellent for supporting the idea of GBR concept.

    Another type of bone augmentation is with the usage of intraoral block graft technique. It mainly involves autogenous block bone grafts provided from the ramus, more exactly, from the posterior part of the mandible or from the chin (symphysis). These blocks are used for horizontal and in some cases vertical ridge augmentation in both jaws. Another type of block grafts is the non-autogenous blocks known as block allografts or block allogenous.

    Bone Augmentation The bone augmentation is also available with the usage of polytetrafluoroethylene and titanium mesh (Ti-mesh). They give a rigid-space maintaining barrier and at the same time, they reduce the possibility of complications and also the compatibility with the soft tissue. Titanium is used in the past because of its high compatibility and rigidity. Keep in mind that the manageability of the Ti-mesh gives the possibility of three-dimensional reconstruction of the bone defects.

    The “box” technique is a new and advanced technique for bone augmentation. This method utilizes absorbable materials that are naturally processed by the human body. The “box technique” was performed by the Dr. Andrea Menoni in November 2008. It is very interesting that this intervention doesn’t need the usage of the autologous bone of the patient in the regeneration procedure, and because of this the surgical sessions are minimized. This popular technique is a regenerative one because it is able to convert the bone volume defect into a typical container (“the box”).

    The container can be filled easily with the preferred filler material allograft or xenograft. Remember the fact that this technique allows the regeneration of the bone in three space dimensions and at the same time avoids the bone grafting procedure to the patient and also minimizes the number of surgical interventions. Besides Prof. Khoury developped a similar mehode, using cortical plates instead as box frames. The aim of this prosthetically guided bone regenerative technique is the notion of “restitution ad integrum”. This means that it helps to fully restore the bone volume to its prime and original condition and not only functionally but aesthetically as well. The key guide of this innovative technique is to be aesthetically and prosthetically guided. Choose the box technique because of the following reasons:

    • This is the first technique for bone augmentation that is aesthetically guided
    • The technique allows restoring the bone volume in the aesthetic zone
    • The box technique utilizes absorbable materials thermoplastic transparent and loads resistant
    • This technique does not require bone grafting to the patient
    • The box technique allows an easy and quick transfer of the insertion of the implant
    • This technique offers a reduced surgical impact such as trauma when compared to the other techniques for bone augmentation.

    When this procedure is performed it is good to know that it can be done in one visit. Six to eight months after the procedure, the patient can start his second procedure for the dental implant placement.

    Another possible option for bone augmentation is with milling parts of a bone and to make them fit exactly to the defect. This is done with milling devices. This system delivers the exact bone grafts that the oral surgeon needs and at the same time, reducing the need for further preparation of the patient’s bone.

    There is a double membrane technique for bone augmentation procedure. It is composed of collagen membrane and high-density polytetrafluoroethylene (dPTFE) membrane. The guided bone regeneration procedure utilizing the double-membrane technique may give a positive clinical outcome.

    Conclusion


    In a case where the dental clinician wants to insert an implant in the esthetic zone in the maxilla, he should notice the conditions of the upper jaw. In cases where a restoration is needed of the maxillary anterior partially edentulous ridge, a GBR technique may be used. When the procedure is properly done, it is expected the outcome of the implant placement be aesthetically completed. Always choose a well-trained and experienced dental professional for achieving the best result.



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