Prosthetics on implants with fixed structures in the immediate loading protocol as an alternative to removable dentures.
Most patients agree with the use of removable dentures in the upper jaw with the provision that the portions of the hard palate in this case remain free of the prosthesis plates and the prosthesis themselves are not unduly movable. After the loss of all teeth the patients tend to solve this problem as quickly as possible, trying nevertheless to avoid the installation of a full denture. They think that a full denture is an obsolete treatment method. The needs of such patients may be met by implantology.
In the case described in this article, removal of teeth and replacing them with cortical fixation implants and implants with surface «Osmoactive» was performed. Because cortical implants have a polished surface and are smaller in diameter their placement can be carried out into the wells immediately after the extraction of the teeth. The next day after the operation a temporary prosthetic was placed and six months after surgery a permanent dental fixed prostheses made of zirconium dioxide was placed. Using cortical osseointegrated implants with thin polished parts allows immediate execution of prosthesis works straight after tooth extraction, as well as in the event of an adverse condition of the bone. Cortical osseointegrated implants can be fixed in the cortical bone of the jaw in several places.
In the past decade sophisticated coupling elements were developed between the teeth which carried out the fixation and the prosthesis. The disadvantage of this type of prostheses is that the teeth involved in these structures are subjected to excessive load. Moreover, they should provide a high degree of anatomic retention of the crowns bearing coupling elements. In this case, we offered the patient a fixed prosthetic structure of zirconia dioxide with fixation on implants with immediate loading. After discussing of several possible methods of treatment, the patient decided to place implants.
MATERIALS AND METHODS
Under local anaesthesia all the teeth on the upper and lower jaws have been removed without tilting mucous periosteal flap. Osteotomy was performed with the help of vertical mills. With the help of the erbium laser granulation tissue from the wells of the extracted teeth were removed and disinfection of the wells of the extracted teeth was performed. BCS implants were placed into the wells of the extracted teeth. These implants are integrated into the region on the outer cortical bone of the alveolar ridge. At the site of the first premolar BCS implant was installed. The second BCS implant is placed in the maxillary tuberosity. Implants are fixed together with a fixed dental prosthesis. The aim was to provide a cortical fixation of osseointegrated implants of cortical bone in the bottom of the maxillary sinus, the bottom of the nasal cavity and the tuber of the upper jaw.
In the mandible a combined placement of implants with a rough surface into the alveolar bone of the previously deleted teeth was performed and into the wells of just extracted teeth the installation of implants with polished surface was held. Transfer caps were put on all the implants, a cast was taken, and then a temporary bridge made of plastic was installed.
Within 48 hours an adverse condition of the masticatory system of the patient has been eliminated by installing a stable permanent structure fixed to the implants. The treatment proceeded steadily without complications and there was no need to make any changes. The desires of the patient were satisfied completely.
Figure 1 View of the dentition of the upper and lower jaw before the surgery. The remaining teeth do not provide a sufficient degree of fixation for crowns, which the prosthesis is based on. In the course of preparation to the surgery intraosseous infection with symptoms of inflammation was diagnosed and bone loss was noticeable. The picture was taken on October 26, 2011.
Figure 2 Eighteen months after the implant placement in the picture there is a stable state of the bone tissue
and the absence of foci of bone resorption
Figure 3 Permanent construction of zirconium dioxide. View after a year and a half
after the implant placement.
Traditional approaches used in implantology offer the installation of large diameter implants, as well as considerable time to healing after implant placement in the wells of the extracted teeth without load. The use of conventional screw implants is considered impractical in cases when a tooth extraction with healing with secondary intention is performed. The reason is that their surface subjected to sandblasting or etching, which greatly contributes to the penetration of bacteria. Consequently, in the traditional approaches while installing these implants certain healing time is provided making it possible for the immature bone tissue to tighten the holes under sterile conditions. The application of our approach is made possible by the use of suitable implants having the following characteristics: delicacy, polished vertical parts, the lack of thread and other fasteners in place of a possible bacterial attack. This type of cortical osseointegrated implants used in this case satisfy these requirements.
For the secure implementation of immediate loading protocols two approaches are now widely used: The first approach (described in this article) suggests cortical and macromechanical fixation of implants. It is known that a cortical bone is sufficiently resistant to resorption (due to its structural features). Furthermore, the bone is able to withstand large loads due to the high degree of mineralization. This approach is based on a strategy of orthopaedic surgeons and the principles of fracture treatment. When choosing optimally suitable implants the width of the bone should be considered (for lateral implants), and the distance between the alveolar crest and an opposing cortical plate (for cortical screw osseointegrated implants). Integration along the vertical part of the implant does not have much impact on the success of its implementation, but it is natural that over time it will begin in this area. The second approach involves corticalization of the cancellous bone through conical implants with fastening by a thread. The corticalized (compressed) bone loses its ability to initiate osteon remodelling. In this regard, a compressed bone area cannot become a place of formation of new osteones, but only its purpose.
The implants used in this approach are characterized by either increased surface area (in the processing of sandblasted) or the presence of large fasteners (e.g., threads), or both at the same time. The width of the implant is determined depending on the available bone (3 to 5 mm.) And the length of the implant, in most cases varies between 10-15 mm. In cases of tooth extraction, bone lateralization of the alveolar ridge is not made, since it requires large-diameter implants. If the holes remain open due to the immediate load of the implants, the use of implants with a rough surface makes the procedure more risky. For this reason, we prefer to use implants, fixed in cortical areas: as it prevents the development of infection and loss of stability in the case of a quick start functioning.
We believe that in order to prevent infection of the wells of the removed teeth at the initial stages, the implants installed in the non-sterile oral cavity must pass certain processing (polishing), at least in their crestal part. For preventing periimplantitis diameter of the penetration of the implant into the mucosa should be as small as possible. Such a construction is contrary to the traditional approach to the formation of "projecting Profile" for the implant crown. The usage of "projecting profile" approach is different only in some cases, for example when sufficient vertical and horizontal bone, as well as in those areas where the teeth adjacent to the implant left, which help to maintain the level of vertical and horizontal bone. Nevertheless, our approach has been successfully used in practice, avoiding risky bone augmentation procedures.
Installing implants in immediate loading mode in cases of a tooth extraction requires repositioning of the bridge but after a few weeks: it is impossible to foresee the complete degree of gum size reduction in the development of the prosthesis design, moreover, remodelling reduces vertical and horizontal dimensions of the bone. Consequently, cementing must be performed by using a temporary cement (e.g., Temp Bond). In some cases, after the healing of the bone and the soft tissue is necessary to replace the prosthesis completely. If you use an identical metal bar or frame to create the "second bridge", you can be sure that it will not pressure the implant (in a state of passivity).
The patients' need to conduct immediate restoration procedures after tooth extraction can be satisfied only when using the lateral and vertical cortical osseointegrated implants. Depending on the condition of the patient's mouth cavity after removal of the teeth both screw implants with fixation in cortical bone and bicortically fixed implants can be used separately or simultaneously. In this approach the bone augmentation is not required. If there is no vertical bone, we use horizontal bone stock and fix the implant in the vestibular and oral cortical bone at the lower and the upper jaw, palatal cortical bone of the alveolar ridge of the upper jaw, side or (and) basal boundaries of the maxillary sinus or cortical bone of the nasal cavity bottom.