Platon implant (Platon Japan) is surface-treated with blasting techniques so that the properties of pure titanium are not damaged.
Moreover, it has several morphological devices to increase the strength of its neck and the connection of its head and fixtures.
In this study, 2 points, (1) the strength of the implant neck and (2) the tightening and returning torque of the junction were examined.
The universal tester for test of the strength of the implant neck and torque tester for testing the tightening and returning torque of the junction were used. Implants of the same shape performing plasma-spraying techniques were compared with Platon implant.
1) The maximum load at which a crack occurred in the implant was 130.30±7.34 MPa (N=5), the maximum point strain was 45.99±4.90%, the maximum point stress was 73.86±4.16 MPa, and the maximum point elongation was 1.49±0.16 mm.
The corresponding figures for the control implant were 115.06±8.73 MPa (N=3), 26.52±3.53%, 68.08±0.35 MPa, and 0.86±0.11 mm. By examining the parameters with the umpaired t-test at the probability level of 5%, significant differences were shown in the maximum load, the maximum point strain, and the maximum point elongation.
2) In the implant head fixed at the implant body,the returning torque was 2.97±0.18, 3.47±0.40, 4.37±0.58, and 4.68±0.57 kg/cm when the tightening torque was 2.0, 2.5, 3.0, and 3.5 kg/cm, respectively. Therefore, the returning torque was greater than each of the specified tightening torque. By examining the combinations with the unpaired test at the probability test of 5%, significant differences for all of these figures. were shown. These results indicate that the Platon implant may have high strength and provide favorable clinical results.
In order to make it easy to observe the changes of the patient's vital signs during implant placement and analyze it after surgery, an Automated Surgery Recording System (ASURS), which uses a personal computer to process the output from a commercially available monitor and print the results by a general printer, was developed.
This system depicts the values of blood pressures (SBP, MBP, and DBP), pulse rate(PR), and rate pressure product (RPP) in a form of analog histogram on a real-time basis. It also accepts optional symbols input. In addition, the system can evaluate the changes of each parameter compared to the preoperative one in percentage and print the figures. By setting an alarm level for each parameter, the vital signs can be analyzed in detail when an alarm is given. The data recorded by the ASURS with such functions of processing the biological information are useful in studying the changes of the patient's vital signs during implant placement and preparing for unforeseen medical accidents.
In recent years, the application of the sinus lift procedure has increased, in which apexes of dental implants are protruded into the bone cavity, the maxillary sinus. A prompt method to prove the efficacy of the sinus lift procedure has been established. In particular, histopathological reaction has not been fully studied. To develop a model of the sinus lift procedure experimentally, the ideal experimental animal would be primates with large maxillary sinuses. Primates are, however, difficult to obtain and breed. Other species such as rabbits have too small maxillary sinuses to install dental implants clinically.
Therefore, dogs with relatively large frontal sinuses were used in this study. The purpose of this study was to evaluate the reaction of bone tissue surrounding dental implants placed in sinuses without original bone. At 1, 2, 4, and 13 weeks after implantation, histopathological specimens were obtained.
As a result, from 2 weeks after implantation, bone formation was observed, and at 13 weeks, most tissues were replaced with trabecular bone which was rich in fat tissue. The frontal sinuses in dogs showed normal healing process without infection after the surgical invasion such as opening the sinus, resection of the mucous membranes and placement of dental implants.
These results suggested that the application of dental implants to the frontal sinuses in dogs can be an effective experimental model for the sinus lift procedure.
Few studies on the structural changes of the mandibular canal due to tooth loss have been demonstrated, although the morphology there of has been well investigated.
The purpose of this study was to elucidate the difference in position and morphology of the mandibular canals and the surrounding trabecular bone between dentulous and edentulous mandibles. A total of 66 sides of 44 mandibles from Japanese cadavers were examined. For morphometrical analysis, the mandibles were embedded in resin and sectioned 500 um in thickness, and then photographs of soft X-ray were taken. For observation of the inner wall of the canal, using scanning electron micrographs, coarse structures were found on the upper wall at the molar region and mental foramen in a dentulous mandible, whereas fine structures were evident on those in an edentulous one. The fine structures were detected on the lower wall in the molar region and mental foramen in both dentulous and edentulous mandibles. The trabecular structures in an edentulous mandible were finer and more numerous than those in a dentulous one. These results suggested that the morphological changes following tooth loss may be caused by a protective action for nerves and vessels in the mandible.
The purpose of this study was to investigate the effect of periodontal ligament in alveolar socket upon autotransplantation in Japanese monkeys (Macaca fuscata). Mandibular central incisors and maxillary lateral incisors were extracted with forceps and a rotating movement. Immediately after extraction, all the teeth were put in saline solution for storage.
Group 1: Incisors were replanted.(control)
Group 2: Before right incisors were transplanted to left socket, periodontal ligament in left socket was curetted with hand instrument.
Group 3: Left incisors were transplanted to the right socket with periodontal ligament.
In each group, splinting after transplntation and replantation were done with suture thread only, and the animals were kept on a standard solid diet with fruit. At postoperative intervals of 1, 2, 4, 8 and 16 weeks, the monkeys were sacrificed. The transplantation teeth and the tissue around transplanted teeth were evaluated histlogically.
At one week, the separation line in periodontal ligament was recognizable and generally positioned at the midpoint of the periodontal ligament. After 4 weeks, periodontal fibers extending from the cemental surface to the alveolar surface were generally seen and fiber bundles were oriented to support the tooth.
Group 2 (curettage of periodontal ligament in alveolar socket)
At one week, the cemental area in the periodontal space had periodontal fibers and the alveolar area had numerous fibroblasts. After 16 weeks, periodontal fibers extending from the cemental surface to the alveolar surface were generally seen and fiber bundles were oriented to support the tooth.
Group 3 (no treated periodontal ligament in alveolar socket)
At one week, the separation line of the periodontal ligament was recognizable and generally positioned at the midpoint of the periodontal ligameat. In this area, numerous fibroblasts were seen. After 4 weeks, periodontal fibers extending from the cemental surface to the alveolar surface were generally seen and fiber bundles were oriented to support the tooth. The healing process of this group was similar to that of replantation, Group 1.
In all periods, the width of the periodontal space in Group 3 was wider than that in Group 2, and the number of epithelial rest of Malassez in Group 2 was significantly lower than in Group 3. These results suggested that epithelial rest Malassez in periodontal membrane plays a role in maintaining the width of the periodontal space.
It was concluded that periodontal ligament in alveolar socket improved periodontal healing after transplantation.
The pitting corrosion behavior and the surface oxide layer for Ni-Ti alloy have been investigated by electrochemical techniques. According to potentiodynamic polarization measurement on physiological saline solution, the critical pitting potentials for Ni-dissolution are ＋0.9 V vs. Ag/AgCl for pure Ni, whereas the Ni-corrosion reaction for Ni-Ti is shifted more anodically at about ＋1.4 V. Thus it is suggested that the presence of Ti may significantly improve the corrosion resistance of the alloy. The pitting corrosion behavior was also examined by AC impedance measurement, ICP-atomic emission spectroscopy (AES) and scanning electron microscopy (SEM). The oxide layer on alloy surface was studied in strong basic media. At the Ni-Ti alloy electrode, the redox waves caused by Ni(Ⅲ)/Ni(Ⅱ) were observed near ＋0.5 and 0.45 V vs. Ag/AgCl, which is very similar to that observed on the pure Ni electrode. However, from the results of time dependence in voltammetric measurements, the interconversion of oxide phase from α-Ni(OH)2 to β-Ni(OH)2 was confirmed to be difficult, occurring on the Ni-Ti electrode surface compared with the Ni electrode. Therefore, it was suggested that the presence of Ti in alloy stabilized the microstructure of the passivation oxide layer and consequently improved its corrosion resistance.
The split crest technique is used in implant. Where the alveolar bone is thin, a partitioning method is used according to the buccolingual diameter, which preserves the height of the alveolar bone, makes forming of the implant easy and produces an esthetic prosthesis. In addition to alveolar bone partitioning, this paper explains the bone expander, which alone can eliminate the discomfort of hammering. It is for this reason that the Bone ExpanderTM (Patent Pending No.117749) was developed.
There are three wings at the end of this tool, the expander, of which bilateral wings are 2.0 mm and center wing is 2.5 mm wide. Operating this expander makes it easy for the alveolar bone to be expanded to the correct width to match the purpose. This paper explains the construction and clinical application of the new tool.
The purpose of this clinical investigation was to study the applicability of GBR technique to the large alveolar bone defects.
There were 30 subjects: Group Ⅰ;extraction socket of the mandibular retention third molar (12 cases), Group Ⅱ;extraction socket of retention tooth in the maxillary anterior tooth region (6 cases), and Group Ⅲ;bone defect after removal of radicular cyst (12 cases). The GBR technique using e-PTFE membrane (GORE-TEX Augmentation Material, oval-6®;GTAM) was applied to these alveolar bone defects. Clinical and radiological investigation, and histological study of the removed GTAM were performed. The mean implantation period of GTAM was 3 to 6 months.However, if early removal of exposed GTAM was performed, it was estimated at that time.
As a result, GTAM exposure with inflammatory reaction due to local infection occurred in 11 of 12 cases of Group Ⅰ, in 2 of 6 cases of Group Ⅱ, in 5 of 12 cases of Group Ⅲ. All GTAM exposure was found in the cervical region of adjacent teeth. Histological study demonstrated infiltration of bacteria into the porus structure of exposed GTAM. Incomplete bone regeneration was confirmed in 2 cases by means of dental X-ray examination at 22, or 26 weeks after application of GBR. On the other hand, bony healing was not found in any other cases, whose implantation period of GTAM was less than 18 weeks.
In conclusion, the large alveolar bone defects such as extraction sockets of the retention teeth or radicular cysts in the adjacent cervical region of neighboring teeth should be excluded from the indication of GBR. Moreover, a 3 to 6-month healing period was insufficient for the GBR of large alveolar bone defects.
HAP implants bond directly with bone, the load and distribution of occlusal force differs from that of natural teeth, which have physiological motility. More specifically, we considered the occlusal force is a key measure of the restoration of chewing ability. We performed a clinical investigation of the restoration of chewing ability and changes over time in peripheral gingiva in patients that had received HAP-coated dental implants (SUMICIKON®)
The results and implications can be summarized as follows:
1) After implantation the occlusal force tends to rise on both the implants side and the non-implant side after the first year, and adaptation to the implant contributes to the restoration of chewing ability from the standpoint of occlusal force.
2) Restoration of chewing ability was good (39/40 patients), fair (1/40 patients) and poor (0/40 patients), indicating that restoration of chewing ability, including QOL, was achieved.
3) No obvious inflammation was observed in the peri-implant gingiva surrounding after 6 months, and the gingiva remained stable.
A case of neurosensory palsy caused by submersion of implants following an 11-year period of placement there of is reported.
The patient was a 44-year-old female. The chief complaint was neurosensory palsy of the right lower lip and mentum region. The patient underwent blade endosseous implant operation on the 76|67 region of the mandible at another dental office 11 years ago.
11 years after the operation, she experienced palsy of the right lower lip and mentum region.
The X-ray images of the orthopantomography were checked. It seemed that both bilateral blade endosseous implants were near the inferior alveolar canal. It was found that the right implant body was pressed into the mandibular canal on the X-ray images of the cross-sectional tomography.
After removal of the right implant body, the patient's symptom was ameliorated.
It was suggested that it is important to determine the three-dimensional shape of the jaw bones with X-ray CT scanning or the X-ray cross-sectional tomography, not only before an implant operation but after it.
This study was a clinicostatistical analysis of 16 patients treated for elevation of 22 maxillary floors with autogenous iliac bone grafts, and in whom placement of 33 implants was performed in the posterior maxilla. The longest follow-up period was 59 months. Patients requiring maxillary sinus floor lift were hospitalized, and the procedures were performed using an anterior approach under general anesthesia. All reconstructions were done by autogenous iliac bone. None of the patients that had in volvement of the iliac site complained of severe postoperative pain or difficulty in walking. There were 3 cases of immediate implant placewent, 5 cases of placement after 6 months, and 1 case of placement after a year. Seven cases are awaiting placement of implants. The average quantity of needed autogenous bone was 6.2 ml.