The vibration damping implant (VDI) is an endosseous implant system,which is designed to absorb input dynamic force by using the intrinsic function of internal friction of TiNi alloy. The intermetallic compound TiNi alloy shows a thermoelastic type of martensite phase (M-phase) transformation from a regularly atomic arranged crystal structure (P-phase:a body-centered crystal structure for TiNi alloy) at a specified temperature, and the transformation temperature and the internal friction property substantially depends on its constitution of titan (Ti) and nickel (Ni). Thus it is important to know the material properties of the actual TiNi alloy that is clinically used.
In this study, material properties of internal friction and elastic moduli (i.e.,Young's modulus and Poisson's ratio) are presented for the following three materials:
1) 56(weight)% Ni-44% Ti alloy (M-phase): the objective specimen,
2) 54.8% Ni-44% Ti-1.2% Co alloy (P-phase): the comparative specimen,
3) pure Ti: the comparative specimen.
Here a P-phase alloy (the second one) is used as a comparative specimen in order to confirm that the vibration damping performance of the NiTi alloy is intrinsically changed across the transformation temperature. A bending vibration method was used, and the testing equipment was the ”MS Fyne” manufactured by Nippon Mechatron Co.
Accurate diagnosis and exact treatment planning are very important for successful implant treatment. Especially, pretreatment examination and simulation utilizing computed tomography (CT) can be very effective information sources, and diagnosis by CT image before treatment substantially enhances determination of the treatment plan and safety. It is useful to achieve the above for SIM/Plant (Columbia Scientific, USA), which uses the actual CT scan and reformated CT images combined with computer graphics for measurement and simulation. The purpose of this study was to evaluate the accuracy of measurement tools within the CT images in SIM/Plant. Human mandible shaped master model, which had a hollow structure (outer wall: 3.00 mm thick) simulating cortical and sponge bone, was composed of aluminum. The master model was CT scanned by Legato DUO (GE, USA) in 1.0 mm thickness. The CT data was reformated and transfered to the hard disk of a personal computer for SIM/Plant simulation. Ten dentists measured an external and internal diameter of height (top-bottom) and width (bucco-lingually) on the master model's selected cross sectional images in the personal computer using a SIM/Plant distance measurement tool.
ANOVA showed that the SIM/Plant distance measumement tool demonstrated significant difference (p＜0.05) from the actual size of the master model.
Analytical effects of an extended bridge length in Branemark implant system and biting force applied to the bridge length on a magnitude of vertical stress and the stress distibution in the cross sections of an abutment tooth and a gold screw placed at three different positions I-1 (near front site in the mandible), Ｉ-2 (middle site), I-3 (back site) were investigated in statics by the three-dimensional elastic finite element method (FEM) on a clinical size model. The average equivalent stress, vertical stress distributiton, and the stress gradient of the abutment tooth and screw increase as it chfanges from I-1 to I-2 and to I-3 positions, and the average vertical stress on the abutment tooth gives a small tensile, a large tensile and a large compressive stresses in that order.These stress values increase with increment in both the applied biting force and the extended bridge length. FEM solutions and their variations were found to be approximately true by static experiments performed on a 1.4-fold long stainless steel model. About one year after oral surgery, a clinical example showed that gold screws at I-1 and I-2 positions failed earlier than the one at I-3 position, which were contrary to FEM solutions in statics. A new dynamic biting machine was designed and manufactured to clarify the discrepancy between the solutions in statics and the failures in the clinical example. Dynamic biting tests repeated to about 2×10 cycles at max. were performed both on an abutment replica model at 20℃±1℃ in air. It was found that mechanical effects not only in statics but also in dynamics affect fracture behavior and loosening of gold screws at different positions, which are mainly controlled by the average vertical stress, the magnitude of vertical stress and its stress gradient in the cross section of a gold screw in statics and also by the number of repeated cycles in biting, the biting velocity, the stress amplide, the average stress in repeated biting in dynamics. Finally, the SEM fractography of failed gold screws in the clinical example and in the abutment tooth replica model tested by the biting machine were examined and differences in failure behavior in gold screws at I-1, I-2, I-3 positions were mechanically analyzed and discussed in both statics and dynamics.
It has been demonstrated that pulsing electromagnetic fields (PEMFs) have osteogenic action in vitro and in vivo. It has also been shown that PEMFs stimulated mRNA expression of bone morphogenetic protein (BMP)-2 and -4 in chick embryonic calvaria. However, the effects of PEMFs on the gene expression of other BMPs are still unclear. The current study was undertaken to examine the effects of PEMFs on the gene expression of BMPs (BMP-1 to -7) in SV 40 large T antigen immortalized human osteoblastic cells (SV-HFO cells) by reverse transcription-polymerase chain reaction(RT-PCR). When the cells were 75% confluent, the cells were continuously exposed by the PEMFs for l and 6 hr, respectively. PEMFs reproducibly and markedly increased the mRNA for BMP -2, -4, and -5 in SV-HFO cells after 6 hr. These results indicate that the osteogenic effect of PEMFs may be, in part, mediated by up-regulation of bone morphogenetic protein -2, -4, and -5 in human osteoblastic cells in vitro.
Purpose: Shortening the period required for initial fixation of oral implants can hasten early recovery of the patient's occlusion. To assess the feasibility of employing capacitively coupled electrical field (CCEF), we studied the response to CCEF of osseous tissue around implants in experimental animals.
Method: A POI implant was placed in the femur of Japanese white rabbits.The CCEF (experimental) group was stimulated 4 hours and 8 hours per day with CCEF. The effect was evaluated by basic fuchsin-methylene blue double stain, triple fluorescent labeling technique, CMR, and computer image analysis.
Results: Promotion of new bone formation around the implant by CCEF, suggests the possibility of using CCEF in oral implantology.
To know the service life of IMZ drills, repeated drilling tests were done for spiral and cannon drills using pig thighbone under 450 gf static load,
As a result, the following conclusion were obtained.
1. On the spiral drill, drilling time was extended after every drilling and drilling became impractical after the twenty seventh time drilling.
2. And the edge of the spiral drill was worn out after twenty seven times' repeated drilling.
3. Difference in drilling time with cannon drill was not recognized up to fifty times' repeated drilling.
4. And the edge of cannon drill did not wear out.
Purpose: For pre-operative planning of implant installation to the posterior mandible, radiographic diagnosis using both mesio-distal images by panoramic radiograph and the bucco-lingual images by cross section tomograph is very useful to under stand the position of the mandibular canal and the shape of the mandible. Therefore, informations of precise magnification on each position of a radiograph are required to decide the length of fixtures during planning. The purpose of this study is to evaluate the accuracy of magnification on both images by means of Scanora® multimodal radiography system.
Materials and methods: Ninety seven ITI Bonefit solid screw implant fixtures that were installed in the posterior edentulous mandible of fifty patients who underwent measured the length of their fixtures on panoramic radiographs and crosssection tomographs immediately after surgery and caluculated its' magnificationo. Measurement points were the first premolar (PM1), second premolar (PM2), first molar (M1), and second molar (M2) parts of the mandible. The PM2 located at the center of the mental foramen was determined as the standard point, PM1 was at distances of 7 mm anterior to its center, M l and M2 were at distances of 8 mm and 16 mm posterior to its center.
Results: In panoramic radiograph magnification (1.3 standard magnification), each magnification of PM1, PM2, M1 and M2 indicated 1.30±0.02,1.30±0.03,1.29±0.02 and 1.29±0.02, and the whole magnification of the posterior edentulous mandible indicated 1.29±0.02. In cross section magnification (1.7 standard magnification), each magnification of PM1, PM2, M1 and M2 indicated 1.70±0.04,1.70±0.03,1.70±0.03 and 1.70±0.02, and the whole magnification of the posterior edentulous mandible indicated 1.70±0.03.Correlation analysis of the magnification between panoramic radiograph and cross section tomograph by means of Spearman's correlation coefficient by rank best indicated that at M1(p=0.0006), magnification of panoramic radiograph and cross-section radiograph correlated, but at PM1 (p=0.546), PM2 (p=0.605) and M2 (0.676), it did not correlated.
Conclusion: Radiographic diagnosis using both panoramic radiograph and cross section tomograph is fairly precise and clillically useful when perforlning implant surgery,because both ilnages have very small standard deeiation.
A panoramic X-ray machine with a function of linear tomography is frequently used in imaging diagnosis of dental implant treatment. However, the angles of the linear tomographic objective planes are automatically determined and can not be adjusted for individual patients.
A direct laser positioning system (DLP system) by which the angles can be manually set in accordance with an optimal tomographic plane for individual patients was developed.
The DLP system consists of three parts, computer software, laser beam units, and accessory tools. The laser beams,which cross each other at right angles, indicated the location and angle of the tomographic objective planes. The accessory tools were fabricated to obtain high reproducibility of accurate positioning during examination.
In this report, the DLP system was introduced and its accuracy in dental implant treatment was evaluated. The accuracy of the DLP system was sufficient for clinical use. Therefore, it was thought that the DLP system promises high quality diagnosis for dental implant treatment.
The status of plaque control after placing of endosseous dental implant was investigated.
Seven patients in whom the IMZ implant was placed into the posterior region were selected as the experimental subjects. These patients were instructed on toothbrushing until the O'Leary plaque score became 25% less before implant operation. The plaque score was recorded on day 1, day 3 and day 7 after implant operation.
Plaque score was 31.0% before operation and 45.4% on day 1, 39.5% on day 3 and 28.6% on day 7 after operation. However, the plaque score after operation was not statistically higher than before operation.
The result suggested that the implant operation did not disturb the plaque control in the patients with missing posterior teeth.
The reason that “ the best implant system” in dental practice has not been determined is due to kind of raw material, shape and structure of the implants, and various procedures in surgical operation.
As the JIAD KOM implant system has been popularized gradually in the clinical field, the histopathological reaction between host and implanted piece was investisated. According to KOM system, 9 implant pieces composed of grade 2 titanium were embedded into mandibular bone of 3 dogs, 3 pieces in each. The dogs were sacrificed under anesthesia at 6,8, and 12 weeks after surgical operation. The host bones with implanted pieces, which were fixed with 4% paraformaldehyde before sampling, embedded in paraffin, sectioned and stained with H.E. and Movat's stain, and made SEM preparations according to routine procedures, were examined using a light microscope and EPMA (Electron Probe X-ray Microanalizer).
All implants were appreciable in every term after implantation. Microscopically, stabile sustained osseointegration was shown in the surface of host bones in all implants in every term. At 6 weeks after implantation, immature bony matrix was formed on the surface bordering the implant piece. Bony tissue hardened at 8 weeks. The osseointegration and ossification were stable 12 weeks after implantation. The mucosa and submucosa of gingiva wounded by a drill showed a normal healing process of second intention with flattened epithelial papillae and fibrosis with newly-formed blood vessels in the submucosa. No inflammatory reaction was suggested by abscess formation or round cell accumulation. The EPMA findings coincided with those of histomorphologic observations. Dissolution and dispersion of raw materials (Titanium) in the newly-formed bone tissue were not detected.
The Periotest® values (PTVs) of 11 single free standing implants for a long period were measured.
In the 4 cases (A, B, C, D) of Brånemark system® , the PTVs of 2 cases (A, B) were about zero after a long period. The other PTVs of 2 cases (C, D) rapidly tended upwards for a half year, and since then tended downwards slowly. In the 4 cases (E, F, G, H) of ITI bonefit® , the PTVs of 2 cases (E, F) tended downwards for a long period and were about zero after g yrs. The PTV of case (G) was 1.0 immediately after the setting of the superstructure and -2.0 after 5 yrs.10 mos., but 6.4 after 9 yrs. 2 mos. because the screw loosing of the abutment and the implant body. The PTV was -2.8 after tightening the screw. The PTV of case (H) increased from 7.2 to 11.6 for l mo., and since then tended downwards gradually. In the 3 cases (I, J, K) of ITI Ftype, the PTV of case (I) tended upwards on the way, and was 3.4 after 12 yrs.11 mos. The PTVs of case (J) tended downwards slowly since starting of PTV measurement. The PTVs of case (K) were over 13.6 for 7 yrs. 2 mos. without unusual xray finding.
As mentioned above, the PTVs of single free standing implant changed variously for a long period. The prognoses of implants ought to be decided synthotically with PTV, intra-oral and x-ray examination.
ITISLA implants are said to allow early loading (i.e., the mounting of the framework) within 6 weeks. In this study, 33 implants impacted in a total of 18 mandibles were assessed based on the clinical manifestations, X-ray findings,and findings from the Periotest. Thirty-four other conventional ITITPS implants impacted in 18 mandibles, in which the healing period was 12 weeks, and surgical procedure and implant morphology were the same, but surface features were different, were used as the controls.
There were significant differences neither in the X-ray findings, nor in the Periotest levels between the two groups.
There were no clinically abnormal findings in the ITISLA implant group. These findings indicated that ITISLA implants allow early loading within 6 weeks in the mandigbular molars of Japanese people. However, further studies are required to monifor ITISLA implants.
This 3-year retrospective follow-up study was conducted to evaluate longitudinal changes in periimplant sulcus depth (PISD) and findings of the Periocheck diagnostic (PCD) tests. A total of 61 people participated in the latest of this series of trials. They were comprised of 16 males (mean age: 65.1±9.3 years) and 45 females (mean age 58.2±9.0 years). The number of subjects who revisited three times consecutively was 59. All the subjects underwent oral implant surgery 4 to 24 years ago.
The results of the tests performed on the 3rd year trial revealed that as high as 86.9% of the subjects had PISDa, but did not show any significant change in the PCDo and PCDb evaluations associated with PISD variations. From the relationships between PCD evaluation and PISD measurement,even the subjects with PISDa were found to have PCDo and PCDb. There were no significant differences in values between 4 major factors. However, significant differences in mean PISD values were observed between sub-factors. Changes during the period of three years were diverse in males, “unchanged type,”“recovery type,”“unstable type,”and “deteriorating type.”While in 55.9% of the females,“unchanged type”was observed. Changes in mean values and occurrence rates during the period were insignigicant.
The findings suggested that both tests like the peri-implant sulcus depth and the Periocheck as well as instruction on oral hygiene and daily life guidance should be introduced as clinical routine in order to obtain better clinically stability results.
In the case of edentulous jaw with very thin or deformed alveolar crest, alveoplasty with bone graft should be required for dental implants. The graft should usually be fixed using a metal plate,screw, or circumferential wiring, which might obstruct the implantation of the dental implants when not removed. The materials were considered, and it was decided to make nails from the graft, autogenous cortical bone of the iliac crest. Fixing of grafted bone by this method has been performed on 5 cases at our clinic. As a result, autogenous bone nail for alveoplasty showed sufficient strength to fix the graft obtaining excellent results, and the nail did not need to be removed afterward, unlike an artificial material. Within a few weeks after grafting, dental implantation was performed successfully. This paper reports the method and how to make and utilize autogenous bone nails to fix grafted bone, will be reported in the future.
It is usual that a clinical follow-up examination of osseointegrated dental implants is mainly done radiographically with dental X-rays. Hence a conventional dental X-ray reveals only two dimensional information,and we could miss early sign of implant failure. In this study we evaluated the condition of peri-implant mucosa to use periodontal parameters such as plaque index (PLI), bleeding on probing (BOP), probing pocket depth (PPD), probing attachment level (PAL) and Periotest® scores as well as a radiographic parameter for over 7-year controlled follow-up study.
The subjects of this study were 32 non-submerged ITI Bonefit® solid screw type implants, all placed in the mandible, in 12 patients with a good oral hygiene. All patients were regularly recalled at 6-month intervals. The overall implant success rate was 100%. On the whole, these implants showed good signs of inflammation, radiographic bone resorption and detectable mobility during the follow-up period.One of the implants caused periimplantitis after 2 years of placement, but it was healed with irrigation. The position of implant shoulder to surrounding mucosa related to periodontal parameters, especially BOP scores.
This study indicated that these results might be slightly different from natural teeth, however, the methods used to evaluate the natural dentition could be effectively employed to assess clinical status of dental implants objectively.
The circulation responses of systolic blood pressure, diastolic blood pressure, and pulse rate during implant placement under local anesthesia were analyzed. The subjects were 30 normal healthy patients (ASA-PS-1).
The operational steps were the beginning of local anesthesia, five minutes after the anesthesia, surgical flap procedures, drilling, implant placement, suture, and completion of the surgery. The data of each step were identified based on the Video Overlay Monitoring System (VOLMS) images and printed output from Automated Surgery Recording System (ASURS).
The controls for fluctuation were the preoperative values obtained from the Preoperative Values Searching Program of VOLMS. Every possible effort was made not to give stress to the patient with the help of the advisory marks from VOLMS that indicated fluctuations. As a result, any of the fluctuations was transitory and none of them were serious. At the beginning of local anesthesia and five minutes after that, as well as at the time of drilling, the circulation responses rose significantly in the statistical viewpoint. At the end of the surgery, however, all of the three parameters became almost equal to their respective preoperative values.
A case of 10-year follow-up after treatment with osseointegrated implants following reconstructive surgery with iliac bone graft was reported.
The patient was 23-year-old male who was referred to our clinic due to swelling in the left lower molar region. Extraoral findings showed painless and diffuse hard swelling from the left chin to the mandibular ramus angle.Intraoral findings showed the swelling at the mucogingival junction from 4 to 8.
Radiographic findings showed multilocular radioluent area from 4 to the mandibular ramus.
A biopsy was performed,and examination of the biopsy specimen indicated ameloblastoma.
The patient underwent left hemimandiblectomy and mandibular reconstruction using iliac bone graft simultaneously on Oct. 27, 1988. The plates and screws were removed,and free gingival graft was performed in 3-6 region on Nov. 7, 1988. Implantation using ITI Bonefit® was performed in 3-6 region on Dec. 16, 1989. Superstructures were fixed removably (screw retaining type) to the implants in Mar.,1990. The patient has been observed for 10 years after implantation. There are no problems at present.
Absorption of the grafted iliac bone was 24.8% for 9 years after the reconstructive surgery by radiograph. Especially, it was 4.9% for 8 years after the implantation.
PAL (Probing Attachment Level) showed slight attachment loss,and PERIOTEST® (SIEMENS Product) showed a decrease of the score. PPD (Probing Pocket Depth) did not show appressed change. DENTAL PRESCALE® (FUJIFILM Product) score showed 888.7 N. The result was a high score, and so it was suggested that the implants resisted the occlusal force.
This study showed a case of occlusal and esthetic reconstruction using techniques of sagittal split ramus osteotomy (SSRO), sinus lifting procedure, periodontal treatment and implant restoration for a patient suffering from mandibular protrusion, missing molar teeth, and periodontal disease.
The patient was a 47-year-old female. Her chief complaint was disturbance of masticating. She had mandibular protrusion with asymmetry. She had periodontal disease and her molar teeth were missing. Panorama X-ray showed insufficient alveolar bone height of the maxilla for implant placement.
First of all, SSRO and sinus lifting procedure on the right side were performed under general anesthesia on Nov.17, 1995.
Mandibular bone was used as augmentation material in the sinus lifting procedure,and implants were placed in 64 region simultaneously. Seven months after the first surgery, the sinus lifting procedure using iliac bone was performed on the left side and implants were placed in 67 and 65 region. Final restoration was performed 6 months after the second surgery.
This case has been followed up for 2 years 9 months. Functionally and esthetically, the patient has been satisfied with the restoration, and periodontal parameters for implants have been stable.
Although it is recommended that the connection between the bone-binding implant and the natural tooth should be avoided as much as possible, occasionally the connection there of cannot be completely avoided in routine clinical settings. In this study, cases were clinically assessed, in which the bone-binding implant was connected to the natural tooth,and in which 5 years or more had passed since the framework was mounted on the base components.
1) The subjects were 56 patients seen from 1986 to 1994, in whom the bone-binding implant was impacted and the framework was mounted on both the natural tooth and the implant. The materials consisted of 70 impacted implant fixtures, 96 natural teeth, and 62 mounted frameworks.
2) Complications consisted of fracture of the tooth root (n=4), secondary caries (n=1), submerged natural tooth (n=2), bone absorption of the implant neck (n=4), and fracture of the implant body (n=1).
3) Complications were encountered in 12 of the 56 patients (21%). One of the submerged natural teeth was preserved, and the fractured implant body was removed.
The above findings suggested that complications associated with the connection between the implant body and the natural tooth may occur more frequently in the natural tooth than in the implant body, and sometimes lead to complications such as tooth extraction.
In the present study, patients hospitalized due to secondary accidental events and poor prognosis after primary implant therapy were reported. On the basis of clinical evaluation, some data was added to the knowledge about implant therapy complications.
1. Twenty-one patients with 36 implants were examined in this study. The patients were aged 40 to 70 years, sex was not taken into consideration.
2. At admission, for almost all of the patients, the chief complaints were a combination of complications of peri-implant gingival hyperplasia, drainage, and orther abnormalities.
3. As for implant locations, in most cases the implants were inserted into molar or premolar positions of both maxilla and mandible.
4. In the majority of patients (20 of the 21 patients), the removed implants were of the osseointegrated type, and many patients had implants coated with hydroxyapatite (HA).
5. At the time of implant removal, clinical findings revealed abnormalities in the following order of occurrence:jaw ostitis was detected in the largest number of cases (8 of the 21 cases), other cases demonstrated maxillary sinusitis, paresthesia and jaw osteomyelitis.
6. The shortest period from implant insertion to implant removal was 1 month, and the longest, 14 years 3 months.
7. In 19 of the 21 patients, implant removal was used as a treatment method. The remaining 2 patients, whose implants were not removed, complained of paresthesia in the course of clinical observation.