Prof. Ruggero Rodriguez y Baena
Department of Oral Sciences
School of dentistry – University of Pavia (Italy)
Abstract:
Immediate and early loading techniques request a precise choice of the fixture installation sites on the basis of the wax image of the implant-supported prosthesis. The fragility of the healing bone tissues make the prosthesis construction hard because they must distribute the occlusal loads to the bone without overloads. The fixture must be distributed along the edentulous crest and the prosthesis must split all the fixture avoiding the micromovements that could stimulating a fibrous scare formation. Moreover, if the fixtures are well distributed and positioned the technician can build the prostheses more easily and a more passive fitting can be reached.
The fixtures installation can be driven by an acrilic surgical stent created either on the diagnostic waxing or on the existing prosthesis. In any case the fixtures position must be selected depending on the bone morphology and density. In case of routine and easy cases, there are no impediments to a radiographic pre-surgical evaluation only by the traditional radiographical techniques (intraoral and panoramic). These techniques give just bidimensional informations on the maxillary structure. The third dimension analysis can be done with the TC Dentascan that can give both qualitative and quantitative informations. Nowadays there are dedicated softwares that allow the dentist to import the TC images on the PC creating 3D images of the bone.
During the TC examination, the patient must wear a radio opaque stent to relate the radiographic measurements to the patient mouth. On this basis the surgeon can make a surgical simulation on the 3D structures. Stereolithography give the possibility to build surgical guide that can help the implantologist during the fixtures installation. We cannot overlook the forensic importance of the virtual surgical planning because these studies can prevent the surgeon in making mistakes and damage important anatomical structures (nerves, maxillary sinus, etc.). In fact the demonstration that the surgeon has executed the surgical virtual planning can protect from the charge to having neglected the iatrogenic damage prevention.
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