Implants in Orthodontics
Temporary orthodontic implants that are placed in the median suture of the palate in an insertion angle of about 45 °, can be used to record reciprocal orthodontic forces. Here, after the bone implant site is prepared in the bony palate and the implant placed.
Construction parts for easy fixation of orthodontic elements can be used to retrusion of the anterior teeth, anterior tooth inclination or amending the mesial movement of molars with the aim to avoid extraoral orthodontic auxiliaries, such as the headgear. These temporary implants are removed after the completion of orthodontic treatment by means of trephining.
Extra-oral implants in epithetics
Influencing factors are the size of the defect, the tissue bed and the edges of the defect area. It is considered to be advantageous when the defect size is sufficiently large, the fabric is not pre-irradiated bed and having the edges of the defect area a healthy wide margin with stable soft tissue and muscular without agitation. Disadvantageous to small defects, pre-irradiated areas which are then often have a thin, dry and / or irritated skin and border areas which are subject to a muscular movement.
As epitheses materials the following are used:
- Polymethymethacrylate´s to produce resection prostheses and intraoral obturators,
- permanent soft silikon materials to manufacture prostheses. These are individually configurable in their coloring and can be supplemented with natural hair. Eye epitheses can be provided with individualized glass bodies to substitute the corpus vitreum.
The fixation of prostheses can
- using bonding techniques (adhesive),
- by combining it with a spectacle frame
- or carried by implants.
The topographic positioning of implants for facial prosthesis depends on the defect localization, the size of the epithesis and the bone in the area of the defect edge. Endosseous implants are suitable for the temporal bone, the bony orbital frame, the zygoma, the aperture piriformis and the pterygoid process. The bones of the facial skeleton are 2.5 to 5.5 mm thick, so that special short implants of larger diameter are used. The implants should be advertise in parallel in order to facilitate the fixation of the epithesis. Two or three web-connected, powered telescope or retroauricular magnet anchored implants can secure the support of a epithesis of the outer ear. 4 implants either web-connected or equipped with magnetic attachments used - for fixation of eye epitheses will be inserted in the cranial and lateral bony of the orbital rim.
For fixing of mid facial epitheses of nasal defects and partial or total upper jaw defects a fixated by at least three implants placed parallel to each other and additionally another perpendicularly inserted implant at the basis for a web framework are required.
Implants
Since the recognition of dental implantology by the parent company of all dental societies in Germany, the DGZMK 1992 dental implantology has developed into a reliable and diverse part of dentistry. We now know that at the appropriate indication, proper treatment and appropriate follow-up of implant-supported dentures accompanies its owner for decades. In addition, in the mouth, orthodontic, maxillofacial area, the use of anchoring the so-called prostheses, which is the artificial replacement of a previous by a genetic defect, accident, or lost due to a tumor exposed parts of the face such as eyes, a nose or an ear is relevant.
The focus is not only how common a few years ago, the restoration of masticatory function but to achieve an aesthetically perfect and lasting results, that is a denture which the patient viewer and as such is not recognized. This also means that should the planning and implementation of this therapy done carefully and disciplines to find the best way for the individual case.
Implants often allow the introduction of a fixed prosthesis when there is insufficient or no possibilities of stabilization in the remaining residual dentition. Bridge structures can involve simultaneously teeth and implants, thus the range of prosthetic solutions is increased significantly. Today preferably helical implants with different surface treatments are used. After a 3-6 month healing - in favorable situations bones also significantly shorter or even directly after implantation - Kronen-/Brückenkonstruktionen but with these implants can also be loaded with telescopes or mounting flanges for a removable denture.
For the introduction of such implants usually only a small outpatient procedure under local anesthesia is necessary, which is comparable to the load of a tooth extraction. When adequate bone anchoring without preparatory measures is possible.
Unfortunately, it often comes to clinical situations which make it impossible for the implants to the ideally planned to anchor positions. This is due to atrophy of the so-called hard and soft tissue, so the decline in these tissues (eg due to prolonged absence of teeth). Biologically speaking, the tooth-bearing portion of the alveolar ridge for tooth loss is returned, because the force is applied is lost to the bone through the root and no chewing forces on the teeth to the jawbone be transferred. The bone begins to shrink in all dimensions, that is, the height and width of the alveolar ridge is reduced to the extent that a conventional prosthetic treatment is difficult to impossible. If in such extreme situations, there is no anatomical suffiency treatment of weakened bone must come from an increased risk of fracture of the mandible.
A build up of hard and / or soft tissue for implantation to be made - in all patients prior to the implantation of a structure of the tissue is considered necessary in the must in such cases or preparing the same - depending on the extent of bone resorption. With limited amount of bone needed this can caseation from the area (for example, from the mandible: chin, jaw angle) are obtained. If more volume is needed, for example, can also be a removal of pelvic bones to be the tool of choice. Again, it is important that the treatment algorithm, ie, the sequence of treatment steps has been discussed before treatment with all stakeholders. On average, may be the placement of the implants and then after 100 more days of the functional loading of the implants after a latency period of about 100 days after the initial procedure (bone formation). This prevents the parts of the brain area built up, it is similar to the alveolar ridge after tooth loss, lost again. So you nutz the implants inserted in order to achieve an approximately equal load distribution in the transplanted bone like natural teeth. Thus, a re-constructed brain area of bone loss is largely avoided. The consulting, organization and management of implant and implant interested patients is performed in our practice in implant clinic specially installed interdisciplinary, involving all disciplines involved in the treatment. After a clinical examination usually takes place roughly exploratory X-ray examination, which is sufficient in general for some advice on the dental implant options in an individual case. This also of course already created documents (eg X-rays) can be brought.
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Augmentations
In addition to ensuring general medicine shear conditions when planning dental rehabilitation with implants, of course, the respective regional bone situation is of great importance. Without a suitable local bone bearing implants can not be inserted sufficient statistic in the sense of "backward planning". If the space in bone stock is inadequate, the optimization is the first task.
Possibilities of optimization of the bone bed are given by using the body's own materials, through the use of bone substitute materials (BS) and membranes or in conjunction with all the above options, as well as by distraction osteogenesis.
Cause of a primarily non-performance implantation bone stock can be:
- genetic defect,
- trauma
- after tumor resection,
- and the general atrophy of the jaws after loss of the dentition.
After tooth loss outweighs the reduction of the width of the maxillary alveolar ridge (sagittal resorption typ), in the lower jaw of the height reduction of the alveolar ridge (vertical resorption typ). Resorptions are less pronounced, after the initialyear of tooth loss, i.e. after incorporation of a dental prosthesis. In the maxilla, the alveolar ridge can dwindle down to a few millimeters thick bone lamella. For the repair of bone defects autogenous bone is still considered to be the ideal graft material.
Guidelines for bone grafting
- The recipient region must have an adequate blood supply. This is extremely important for the preservation of all living cells of the transplant surface ensured.
- Between graft and host bone, a direct bone contact area must be existing. This facilitates bone resorption and bone formation by "creeping substitution".
- The recipient region must have an adequate blood supply. This is important for the preservation of all living cells is ensured on the graft surface.
The repair of autologous graft
Bone repair is based on three basic mechanisms:Osteogenesis: the ability to form in the graft of the surviving bone osteoblasts.
Osteoconduction: The introduced graft serves as a lead structure for the sprouting of vessels from the adjacent bone stock. The newly formed bone deposits on the transplanted tissue.
Osteoinduction: Osteoinduction effect of bone proteins (growth inducing factors for example = bone morphogenetic protein, BMP) to reach the pluripotent mesenchymal cells, with the ingrowth end vessels in the bone graft. Under the action of these proteins wachstumsinduzierenden the pluripotent Mesenchymzellem differentiate into cartilage, or bone-forming cells. The biological transplant healing depends on the storage tissue and the mechanical rest.
The healing of the graft always runs in multiple phases, used in the first two weeks initially resorptive process and only occurs consecutively with the capillary ingrowth from the surrounding tissue bearing the beginning of the repair. Graft osteoblasts, which are supplied with blood by diffuse, survival in this first phase and begin osteoneogenesis.
By the third week, the second phase begins. Osteoclastic bone cells penetrate the ingrowth end of the storage vessels into the graft tissue and resorb the bone graft. Below osteoblasts build new bone on (woven bone). In the subsequent period, the entire free transplanted bone is resorbed and replaced successively.
In the following, it is in the third phase from the 4th Week under functional stress to the remodeling of the bone into lamellar bone braid. The raised mounting operations lead to a loss of volume, so that always a certain over-contouring of the bone graft is necessary.
We know that not functionally loaded bone is resorbed over a relatively short period of time. It is also known that the last phase of bone healing, so the trabecular pattern in clarifying functional integration of the graft is favored over a load introduction by implants. These processes are not or only insufficiently to develop, if the quality of the transplant bed is restricted hinschtlich the vascularization of the adjacent bearing bone and the surrounding soft tissues.
This can for example by a previous radiotherapy, massive inflammation or multiple previous surgeries, which led the case for extensive scarring. The decision whether an intraoral bone harvesting is sufficient or extraoral donor site must be sought should already take place within the implant planning.
Similarly, the question of the time of implant placement should be taken when osteoplastic replacement in individual cases. The synchronous implant placement is possible if sufficient stability of the implant is given into the local residual bone.
If this condition, it is time to act two. The implantation is carried out in this case after an installation phase of the bone graft of four to six months. Advantage of simultaneous implant placement during the implantation of bone graft is that even after the required four to six months of healing of the bone graft and the implants can be a functional load of the built-bone on the kaufunktionell loaded implants, thus early for adequate functional loading of the augmented mandible leads. The absorption rate in bony integrated implants from the second year after autologous bone grafting is indicated by 0.2 mm per year.
Choice of the augmentation
Clinically it should be considered already in the planning phase which präopertativen bone replacement material is suitable for the individual case. Here, the autologous bone is by definition also be seen as a bone substitute material such other materials. Once the basic mechanisms of bone healing were explained with the use of an autologous graft in the preceding paragraph will be presented briefly below, the specific characteristics and indication of the most common bone substitute materials.
Bone substitute materials (= BS) must be characterized by biocompatibility. Long-term safety also includes the degradation products arising from the degradation. Bone substitute materials general posses osteoconductive and rare -inductive properties.
All on the market at the time BS are characterized by two specific properties:
- With respect to their biological behavior, which is to be assessed as Osteoconductive.
- Respect to their formulation, which is always in particulate form.
From a materials science point of view BS must be divided into defect fillers of the long term stability such as for example hydroxylapatites, the resorbable BS´s, which are substituted by de novo bone formation, so the onlyserve as temporary defect filler. These include phase-pure, unsintered hydroxyapatite, and the alpha-and beta-tricalcium phosphates, which may release large amounts of calcium ions and / or implant particles due to their solubility and hence have high demand of phagozytosis.
In allogeneic transplants donor and recipient are not genetically identical but belong to the same species (man-man). There is a possible risk of infection by pathogens transfer from the donor to the recipient. In addition, the risk of infection which reason we use at the site of implantation up to 20% no quantifiable allografts.
Xenogenic bone grafts derived from another species (eg, cattle, pigs) and are genetically different. They are used today only after appropriate treatment, eg Pyrolisation to turn immunological risks. For the usefulness of these materials, the course prescribed large interconnector animal cavities play an important role, entering the bearing bone ingrowth from forming osteocytes on the track vessels and all the material can be penetrated by de novo bone formation. The cavities are filled with new formed bone, the autogenous bone connected to the BS like a wallpaper.
Intraoral donor sites for autogenous bone grafts avascular
As oral donor sites in the mandible are suitable:- symphysis,
- angle of the jaw,
- mandibular border,
- retromolar region.
Extra-oral donor sites for autogenous bone grafts avascular
Common donor sites of avascular bone grafts are:- anterior and posterior iliac crest
- skull
- tibia
Clinical augmentation
Due to a relatively thin cortical layer and an additional loose cancellous bone of the upper jaw has primarily an more unfavorable implant bed than the lower jaw. For the atrophic maxilla different augmentation procedures for widening and internal and external ridge structure were developed. To widen the alveolar ridge one can laterally apply an autogenous corticocancellous bone graft. The stabilization of the bone graft is done by osteosynthesis screws. An implant insertion is made secondary to bony incorporation of the bone graft. When it comes to vertical alveolar ridge augmentation one has to take into consideration that is resolves in a reduction of the vertical distance between the upper and lower jaw, which has to be considered with regard to the prosthetic restoration. This dimensional changes can be done either through a so-called vertical augmentation or by a interpositional osteoplasty. The stabilization of the bone grafts can be performed in the horizontal augmentation by simultaneously implant placement or using osteosynthesis crews fixed to the residual. In these two-stage procedures three to four months after the augmentation the implant is placed.Pre-prosthetic Surgery
Sometimes it is with removable dentures to improve retention through surgery on the soft tissues necessary in patients, for example, has passed in the described decrease of earlier tooth-bearing jaw portion of the oral vestibule in the upper and lower jaw and floor of the mouth in the area of the mandible. Here, the shape of the mouth vestibule significantly improve the integration of a prosthesis (vestibuloplasty).
Similar measures may be also in already existing implant treatment appears when an inflammation permanently endangered the preservation of the implant. There is always a good time performing the action for long-lasting success with decisive. The Präprothetik also includes the surgical removal of unwanted structures in the functional edge (tapes) or storage area (fibroids) of the prosthesis, which are responsible for a continuous loosening.