The comparison of usefulness prosthetic rehabilitation with removable and fixed suprastructures on endosseous...

Advanced atrophy bone in edentulous jaws is a serious problem for conventional prosthodontics. The advent of implantology, as well as guided reconstruction of bones, has opened new possibilities for conventional prosthodontic suprastructures. The turning point in implantology occurred in the sixties and was promoted by a Swedish orthopaedist Brånemark. Nowadays, implants are inserted routinely without creating any significant problems to a skillful maxillofacial surgeon. This study was performed in 73 patients who had 77 prosthodontic suprastructures (fixed suprastructures in 58 and removable in 15 patients) placed on a total of 331 implants. Three types--blade, cylindrical and screw implants, were used. Patients with both total and partial defects had typical removable and fixed suprastructures installed. All patients were followed radiologically and clinically. Pantomographic images taken at different stages of the study served to measure bone atrophy near the implants. The atrophy of bones near implants supported by removable prosthodontic suprastructures was compared with fixed suprastructures. Dental bridges were made and supported by implants and by the patient's own teeth at the same time. Removable suprastructures, however, were supported mainly by implants connected with bars or implants with ball attachments. The prothesis saddle rested on the epithelium of the oral cavity. Following location of the implants, lower and upper jaws were divided into four regions. Statistical data served to determine in which of the four regions atrophy of bones was most and least advanced taking into consideration the type of implant and type of prosthodontic suprastructure. Record was made of the region, stage and implant which underwent explantation. Radiographs taken before and after implantoprosthetic rehabilitation demonstrated that atrophy of bones did not occur in 106 cases. Six patients underwent reconstruction of bones near the implants. Statistics showed that fixed prosthodontic suprastructures are superior to removable as far as jaw rehabilitation is concerned. Atrophy of bones near implants supported by fixed suprastructures was smaller. Nevertheless, usefulness of the removable suprastructures cannot be questioned. Not only do they represent an effective solution, but are far less expensive than fixed. Statistics revealed that the best regions to install implants include the presinusal (I) and interforaminal regions (II). The least advanced atrophy of bones occurred near screw implants (0.8 mm in region I, 0.7 mm in region II, 0.3 mm in subantal region (III) and 1.3 mm in postforaminal region (IV)). On the other hand, the most advanced atrophy occurred near blade implants (1.7 mm in region III and 3.3 mm in region IV). Twelve out of 331 implants were lost (3.6%)--seven during the healing process and five after placement of suprastructures (all cylindrical), contributing to successful implantoprosthetic therapy in 96.4% of cases. One out of twelve implants was lost in the mandible and eleven in the maxilla indicating that the mandible is more suitable for implantation. On the basis of this prospective study it can be concluded that further progress in implantoprosthetics, a relatively new branch of dentistry, will open new possibilities for prosthetic therapy.