Pore size must be large enough to help cell ingrowth of bone marrow cells and new bone ingrowth. However, increasing the pore size results in a decrease of compressive strength of the porous structure. Therefore, the pore size should be controlled so as to obtain higher mechanical strength than that of cortical bone. Ti60-Zr40 porous blocks of pore size 95 ～172 μm had higher mechanical strengths than that of cortical bone. In this in vitro study, Ti60-Zr40 porous blocks with mean pore sizes of 95 μm, 120 μm, 149 μm and 172 μm were used to investigate cell ingrowth of bone formative group cells (BFGCs) derived from beagle's femur. Clear-cut evidence of pore size dependency on cell ingrowth was found. No cell ingrowth of BFGCs into the porous block was observed for pore sizes of less than 95 μm. For large pore sizes of more than 149 μm active cell ingrowth was demonstrated. This in vitro study clarified that Ti60-Zr40 porous implant with 149 μm pore size may be effective for early fixation of dental implant by tissue engiveering using host bone marrow cells.
Rickets rat, the bone metabolic disease model, reveals calcification defects. The aim of this study was to observe the bone of the rickets rat using micro-computed tomography (micro-CT) and to examine the bone contact ratio around the sand blasted and anodic oxidation implants. Micro-CT revealed that the femur of the rickets was composed of thin, compact and spongy bones having few trabeculae in comparison with that of the control. At 1 week after the implantation, the bone contact ratio of both implants in the rickets rat was much lower than that of the control. The bone contact ratio of the sand blasted implants (rickets, 9.8±4.4%;control, 76.5±16.5%) was higher than that of the anodic oxidation implants (rickets, 5.2±9.2%;control, 47.2±5.7%) in both the rickets rats and control. Analysis of variance demonstrated a significant difference in all, except for between the sand blasted implants and the anodic oxidation implants of the rickets rats. In conclusion, it was considered that the sand blasted implant could develop more osseointegration than the anodic oxidation implant at 1 week after implantation.
Although the fabrication of passively fitting superstructures of dental implants is generally considered difficult, most clinicians agree that the impressions should be highly accurate. Numerous impression techniques have been reported to date. In this study, we evaluate the impression accuracy of low-elasticity additional silicone impression material using the ITI and Brånemark implant systems.
A master cast that replicated the human edentulous region was constructed from a stainless steel block. Three implant analogues for each system were placed at intervals of 12 mm. Master frameworks that accurately fitted the analogues of each master cast were fabricated. Impressions were made in five groups using the following impression copings and techniques: (1) ITI screw-retained impression copings (Group Ⅰ); (2) ITI screw-retained impression copings splinted with acrylic resin (Group Ⅱ); (3) ITI snap-on plastic impression copings and positional cylinders (Group Ⅲ); (4) Brånemark squared impression copings (Group Ⅳ); and (5) Brånemark squared impression copings splinted with acrylic resin (Group Ⅴ). The impressions were made using Examixfine Regular Type and Examixfine Regular Hard Type in each group. Stone replicas were fabricated after impression. Misfits between the master frameworks and stone replicas were evaluated using the one-screw test.
The results show that: (1) the low-elasticity impression material improves impression accuracy for non-splinted Brånemark and ITI plastic copings, which were the most difficult cases in this study; (2) the splinting technique helps to improve impression accuracy; (3) impression accuracy is strongly influenced by the component configuration.
Facial reconstruction by epithesis using osseointegrated implants as an anchorage has been performed since 1990 in Nagoya University Hospital. In this report,clinical evaluation of implants and psychological examinations with questionnaires pre- and post-treatment were carried out for 6 patients over 5 years after implant-supported epithesis therapy.
Twenty-four fixtures had been installed for the reconstruction of eye, nose, and ear. Survival rate of the implants was 100% (average observation period: 7 years).
The Cornell Medical Index-Health Questionnaire (CMI) proved that there were no patients with emotional disturbance. In addition, our original questionnaire revealed that wearing of the facial epithesis had reduced the psychological burden and the feeling of uneasiness toward personal relationships.
We performed dental implant treatment following autogenous bone graft from the iliac bone to the sinus floor for a 68-year-old male patient with severe atrophy of the posterior maxilla. After bone grafting, the sinus floor was lifted up 10 mm to 15 mm. On the 14th day after the operation, fracture of the iliac crest occurred accidentally. An avulsion fracture of the anterior superior iliac spin at the lower part of the donor site was diagnosed. We treated the fracture conservatively, and after four weeks, the patient recovered to be able to go up and down the stairs. Four months later, four implants were inserted in the bone grafted area.
For patients with severe atrophy of the posterior maxilla, sinus elevation with iliac bone harvesting is considered to be an effective method. However, there are possible complications associated with iliac bone grafting, such as in this case. Therefore, careful management after such an operation is necessary.