The enhancement of adhesion and migration of osteoblastic cells on titanium surfaces is an important process for successful implant therapy. In this study, osteoblastic cells, MC3T3E1, were cultured on GRGDSP peptide coated titanium surfaces. After 15 days of cell culture, total RNA was isolated from cells, and gene expression levels were analyzed by the Gene Chip system. Many gene expression levels were found to be altered in MC3T3E including a baculoviral inhibitor of apoptosis repeat-containing gene 6 (Birc6). The enhancement of Birc6 mRNA levels was successfully confirmed by reverse transcription polymerase chain reaction (RTPCR) and real-time PCR. Since it has been reported that titanium stimulates apoptosis in osteoblasts, these findings suggest that GRGDSP coated titanium may promote cell proliferation of osteoblasts through Birc6 expression.
The purpose of this study was to compare and examine implant mobility which had been obtained from a different viewpoint.
Implant mobilities were recorded for 36 implants in total by two devices: a periotest device and an automatic mobility diagnostic system. The relation among the periotest value obtained from the periotest device, the value of viscosity, and the value of elasticity obtained from the automatic mobility diagnostic system were calculated.
The periotest values were distributed between -5 and ＋5, and the overall average and standard deviation were -0.78±3.38, respectively. The overall average and standard deviation in the three dynamic parameters of viscosity c1 , viscosity c2 and elasticity k were 58.26±13.79, 687.08±151.71, and 549,119.88±237,058.91, respectively. A negative correlation was found between the periotest value and viscosity c1 (r=0.714), viscosity c2 (r=0.689) and elasticity k (r=0.774).
It was possible to compare, evaluate and analyze the degree of osseointegration from a large amount of quantitative data for the periotest value,elasticity and viscosity.
The purpose of this study was to clarify the correlation between the bone mineral density of cancellous bone in the jawbone and the grading of the bone quality by operative findings in implant patients. The jawbones of 53 implant patients (15 males and 38 females), 150 sites (maxilla: 50 sites, mandible: 100 sites) were analyzed by the preoperative Quantitative Computed Tomography (QCT) examination. The oral surgeons categorized the bone quality in four grades based on the operative findings (tactile sense). Statistical analyses were performed and the bone mineral densities of cancellous bone were compared with the grades of the bone qualities.
The results were as follows:
1. The bone mineral density of cancellous bone of males was significantly higher than that of females (p＜0.05). The bone quality of females was significantly poorer than that of males (p＜0.05).
2. The bone mineral density of cancellous bone of the maxillae tended to be lower than that of the mandibles. The bone quality of the maxillae was significantly poorer than that of the mandibles (p＜0.05).
3. There was a significant correlation between the bone mineral density of cancellous bone and the bone quality in the implant patients (p＜0.05, r=-0.60).
These results demonstrated that the measurement of the bone mineral density of cancellous bone in the implant patients from the preoperative Quantitative Computed Tomography examination had the potential to diagnose the bone quality of the implant sites.
In this study, bone defects were repaired by filling different sizes of β-tricalcium phosphate(β-TCP) granules, and observed by scanning electron microscope(SEM), light microscope (LM), and micro-CT.
We extracted bilateral mandibular molars of 8 crab-eating monkeys,and used β-TCP granules in two granular sizes, large (type L) and small (type S). Three months after extraction, bone defects had formed in the sites of the extracted molars, and type L or type S granules were then filled into those sites. The animals were euthanized at 2, 4, 8, and 12 weeks after operation. Bone specimens and histological slides of 4 monkeys were prepared, which were observed by SEM and LM, respectively. Those of the remaining 4 monkeys were fixed with 10% formalin for micro-CT examinations with three-dimensional image processing software. Based on the results of image analysis, the volume ratio of opaque images was obtained.
SEM, LM and micro-CT findings revealed that the bone defects were filled with trabecular bone from 4 to 8 weeks after operation in the type L group. Granules were seen in some superficial areas at those time points, however, none were observed at 12 weeks. In the type S group, the repair process was not as extensive at 4 weeks and the presence of granules was confirmed. However, after 8 weeks, the findings in the type S group were the same as those in the type L group. The opaque images in micro-CT contained trabecular bone and β-TCP granules. Image analysis results showed that the volume ratio of the opaque images reached the maximum at 4 weeks and then declined from 8 to 12 weeks in the type L group, while in the type S group, the ratio gradually declined from 2 to 12 weeks.
In conclusion, bone repair progressed at a faster rate in the type L group than in the type S group at 4 weeks. However, both experimental groups had nearly the same level of osteogenesis after 12 weeks. Further, granule size did not influence the bone defect repair. In addition, it was suggested that micro-CT can be used in clinical treatment.
The purpose of this study was to evaluate the clinical application of endosseous implants placed into bone-grafted alveolar clefts. Seventy-nine implants inserted at cleft sites of 46 cleft lip and palate patients were studied. In 34 patients, implants were placed into the cleft sites without bone augmentation because the bone volume of osseous bridging was sufficient for implantation.However, it was necessary to regraft the alveolar cleft region in 13 patients to provide adequate bone volume for implant placement. The interval between initial bone grafting in alveolar clefts and implant placement was 17.4 months (range, 4-72 mo). Thirty-six hydroxyapatite-coated cylindrical implants were placed in 20 patients, 15 titanium screw implants with a machined surface were placed in 12 patients, and 28 titanium screw implants with a rough surface were placed in 14 patients. The length of the placed implants was mainly 13 mm or 15 mm. Soft tissue management around the implants was performed in 26 patients, and most of the management was vestibular extension, although 3 implants failed to establish osseointegration before the fitting of superstructures, and the remainder were stable. Thus, the overall survival rate was 96.2% at the end of the observation period. The results of this study suggest that endosseous implants can be successfully placed in bone-grafted alveolar clefts as into the non-cleft maxilla.
Conventional osseointegrated-type implants are considered to require a 3-5 month nonweight-bearing period after implantation. There are few reports regarding mechanical observations of the osseointegration processes of implants, although recently there have been some reports on attempts to reduce the nonweight-bearing period as a result of issues such as esthetics, occlusion, and manducation. Here, we report the results of measurements of initial tooth movement after implantation, and clinical observations of mechanical changes.
The subjects consisted of 63 CAMLOG implants which were grafted at our department from January 2004 to December 2006, and were measured once every week after implantation using a Periotest device. Gingivaformers with 6 mm gingival heights were screwed into the implants, PT values were measured three times at a height of 5 mm using a PT handset, and the average values were calculated.
The average PT value was -3.83 at the time of implant. This value increased to -3.14 after two weeks, then decreased over time to a value of -4.14 after 6 weeks.
Our results show that the PT values of osseointegration implants demonstrate an overall downward tendency. However, there is a period during which PT values temporarily increase and mechanical instability occurs. As PT values are slightly affected by sex, age, and site specificity, it was inferred that it is desirable to reduce nonweight-bearing periods by taking into consideration stability measurements obtained using mechanical test devices such as the Periotest.
Bone grafts and GBR (Guided Bone Regeneration) have been common treatment options for vertical bone mass enhancement. However, they have problems, especially when a large volume of osteogenesis is required, with occasions for bone harvesting, such as: the limited bone mass of the donor site, difficulties in treating soft tissues and the predictability of osteogenesis. Therefore, vertical distraction osteogenesis to improve the deficiency involving both bone and soft tissue has now been adopted and many good results have been reported. However, we have experienced some accidents in cases of implant restoration using vertical distraction osteogenesis of the maxillary anterior region that yielded inadequate results. Here, a summary and review of the case are reported.
A male patient lost 5 maxillary anterior teeth in a traffic accident. Vertical distraction osteogenesis was conducted with a destructor (TRACK 1.0 mm-System), followed by GBR to augment alveolar bone horizontally and then implants were placed. Accidents included: 1) Palatally directed distraction; 2) Asymmetric quantity of distraction due to contact between the transport segment and the underlying bone; 3) Relatively large bone defect remaining in the regeneration chamber; and 4) The mucoperiosteal flap dehisced during the horizontal bone augmentation by GBR.
In actual clinical practice, potential accidents of all kinds should be taken into consideration when planning the treatment, and a review of accidents and countermeasure preparations are important to increase predictability.
Purpose: It has been reported that the displacement of implants by applied force is markedly small in vivo. This suggests that in contrast to fixed prostheses of natural teeth, fixed implant prostheses need greater accuracy to avoid failure due to the inadequate force on components such as fixtures. In this study, we focused on impression manipulation that affects the fitting accuracy of superstructures. The influence of differences in the handling of impression copings on the positional relationship of implants on casts was evaluated.
Methods: For a case of right mandibular free-end edentulism from the 2nd premolar, 3 Brånemark-system implant fixtures were inserted at intervals of approximately 10 mm on an acrylic model, and abutments were connected to the fixtures. From this intra-oral assumption model, casts in which abutment replicas were jointed, were produced using custom trays and silicone rubber impression materials. Impressions were taken by the open tray method. Regarding the handling of impression coping screws, two methods were performed by 10 clinicians respectively, which were the hand-fastening method according to the manufacturerʼs instruction and the torque-control method in which screws were fastened at 15 N using a torque wrench. Regarding impression accuracy, dimensional changes were evaluated by measuring the distance between the center of fixtures on the intra-oral assumption model and that on the final casts.
Results: No significant differences in dimensional changes were found between the model and final casts produced by the two methods.
Conclusions: There are no differences of impression accuracy between the hand-fastening and torque-control methods.