Biomedical subjects

Shuichi Sato

Publications and source records attributed to Shuichi Sato.

48 records · Page 3Linked to original sources

PubMed2004

The comparative effect of ultrasonic scalers on titanium surfaces: an in vitro study.

BACKGROUND: Professional maintenance is as important for patients with dental implants as it is for patients with natural teeth. However, no proper maintenance instruments have been available for implant patients. The purpose of this in vitro study was to compare the effects of a new ultrasonic scaler (VR), a conventional ultrasonic scaler (SP), and a plastic scaler (PS) on titanium surfaces. METHODS: To simulate subgingival conditions, the implant healing abutments were connected to acrylic resin blocks with artificial gingiva using silicon impression material. The abutments were painted with ink as an artificial form of debris. The ink was removed with the VR, SP, or PS scaler for 60 seconds under standardized conditions, and the removal rate was calculated. The roughness of the abutment surface was measured with a profilometer and observed by scanning electron microscopy (SEM). RESULTS: The removal rate using the VR and SP scalers was higher than that using the PS scaler. No significant differences in the surface roughness or SEM observations were found among the VR, SP, or PS scalers. CONCLUSIONS: In this preliminary study, the new ultrasonic scaler and conventional ultrasonic scaler were shown to be useful for removing artificial debris and produced no significant damage to titanium surfaces compared to plastic scalers. We concluded that new and conventional ultrasonic scalers with a non-metal tip would be suitable for implant maintenance.

Acrylic Resins↗

PubMed2004

Comparison of the effects of various periodontal rotary instruments on surface characteristics of root surface.

The efficacy of scaling and root planing using various periodontal rotary instruments was examined. Eighty extracted human teeth with a history of periodontal disease were divided into four groups of 20 and subjected to one of the following procedures: Use of 1) a Root Burnisher, 2) a Perio Planing Bur (both rotating instruments for contra angle handpieces), 3) a Tooth Planing Bur (rotating instrument for use with an air turbine), or 4) a Gracey Scaler. In each case, the time required for cleaning was measured. Twenty healthy extracted human teeth were used as untreated controls. After treatment, the surface roughness of 10 specimens out of each group were measured using a profilometer and observed by scanning electron microscopy (SEM). Half of the samples were then incubated in dishes with a suspension of fibroblasts. After counting the number of attached cells, the attachment of fibroblasts was observed by SEM. The root surfaces treated with the rotary instruments appeared smooth and there were no significant differences between groups. From the SEM observations, smooth root surfaces with different surface textures were evident and a tight attachment of fibroblasts was observed. The results of this study suggest that use of rotary instruments is superior for periodontal scaling and root planing.

Cell Adhesion↗

PubMed2004

Relationship between Porphyromonas gingivalis, Epstein-Barr virus infection and reactivation in periodontitis.

The aim of this study was to assess the relationship-between Porphyromonas gingivalis, Epstein-Barr virus (EBV) infection and reactivation in periodontitis using real-time PCR. The mean proportion of P. gingivalis cells to total bacterial cells in the saliva from EBV-positive periodontitis patients was significantly higher than that in saliva from EBV-negative patients. An EBV-positive B-cell line was used to determine whether P. gingivalis sonicate induced reactivation of EBV, using real-time PCR to measure the virus genome in the culture medium. A significant increase in EBV numbers was observed after the stimulation with P. gingivalis sonicate. These findings suggest that the interaction between EBV and P. gingivalis is bi-directional, with EBV reactivation suppressing host defenses and permitting overgrowth of P. gingivalis, and P. gingivalis having the potential to induce EBV reactivation.

Adult↗

PubMed2003

Famotidine does not induce long QT syndrome: experimental evidence from in vitro and in vivo test systems.

The effects of famotidine on the cardiac repolarization process were assessed using four different levels of test systems described in the draft stage guideline ICH S7B. A supratherapeutic concentration of famotidine (10(-5) M), which is >8 times higher than C(max) obtained after its therapeutic dose, neither inhibited human ether-a-go-go-related gene (HERG) K(+) current expressed in human embryonic kidney 293 (HEK293) cells nor affected any of the action potential parameters of guinea pig papillary muscles. Therapeutic (0.3 mg/kg, i.v.) to supratherapeutic doses (3-10 mg/kg, i.v.) of famotidine did not affect the repolarization process of the halothane-anesthetized canine model, while only supratherapeutic doses exerted the positive chronotropic, inotropic and dromotropic effects without affecting the mean blood pressure. Moreover, supratherapeutic doses of famotidine (1-10 mg/kg, i.v.) neither induced torsades de pointes nor prolonged QT interval in the canine chronic atrioventricular conduction block model. These results suggest that famotidine possesses no cardiovascular effects at a therapeutic dose, while it may exert cardiostimulatory actions after drug overdoses that might potentiate the proarrhythmic potential of co-administered cardiotonic agents by increasing the intracellular Ca(2+) concentration.

Action Potentials↗

PubMed2003

Natural course of disc displacement with reduction of the temporomandibular joint: changes in clinical signs and symptoms.

PURPOSE: The goal of this study was to examine the natural course of disc displacement with reduction in the temporomandibular joint (TMJ). PATIENTS AND METHODS: This retrospective study involved 24 patients who had been diagnosed with disc displacement with reduction of the TMJ, but who had not undergone any treatment. The extent of maximal mouth opening, protrusion, lateral excursions, noise of the TMJ, pain of the TMJ, and tenderness of masticatory muscles were recorded monthly for a mean of 25.8 months. RESULTS: Maximal mouth opening, protrusion, and lateral excursions remained unchanged during follow-up. TMJ pain decreased by 15.7% (P >.05). Clicking decreased by 20.8% (P <.05), and tenderness of masticatory muscles decreased by 33.3% (P <.05). Reciprocal clicking remained unchanged in 19 patients (79.2%) and disappeared in 5 patients (23.8%). Four patients (16.7%) in whom clicking disappeared had a normal mouth opening, but locking developed in 1 patient (4.2%). CONCLUSIONS: In patients with disc displacement with reduction who do not undergo treatment, range of movement remains unchanged over time. Tenderness of masticatory muscles tended lessen, but reciprocal clicking and TMJ pain tended to remain. Clicking did not progress to locking in most patients.

Adolescent↗

PubMed2002

Evaluation of the performance of polished mirror surfaces for the TAMA gravitational wave detector by use of a wave-front tracing simulation.

We evaluated the performance of polished mirror surfaces for the TAMA interferometric gravitational wave detector by comparing the experimental results with a wave-front tracing simulation. The TAMA mirror surfaces were polished to a roughness of a few nanometer rms. We confirmed that these polished mirrors do not limit the present TAMA sensitivity and that the target shot-noise sensitivity will be achieved with these mirrors, even if a power-recycling technique is introduced in the next stage of the TAMA.

Journal Article↗

PubMed2002

The function of the psoas major muscle: passive kinetics and morphological studies using donated cadavers.

This study was carried out to analyze the phasic heterogeneity in the function of the psoas major muscle (PMM) depending on the flexion angle at the hip joint. The study design was a passive kinetic experiment using 25 osteoligamentous specimens with the PMM tendon. We measured the flexion angle of the hip joint where the PMM tendon loses contact with the femoral head and pelvic surface. Ten osteoligamentous specimens were used for additional measurements of the tensile force and pressure exerted on the PMM and/or at the bone-tendon interface when the PMM tendon was gently pulled in line with the PMM origin in the supine position. The tension loading the PMM tendon was measured at seven different angled positions of hip joint flexion (0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, and 90 degrees ), using a load cell attached to a traction appliance. The pressure was measured at each of eight sites along the long axis of the PMM, using a pressure sensor. The PMM tendon lost contact with the femoral head at angled positions of 14 degrees (average) hip flexion, and lost contact with the iliopectineal eminence at positions of 54 degrees (average). The tension was stronger at angled positions of 0 degrees -30 degrees at the hip joint. The pressure on the femoral head and pelvic surface were stronger at positions of 0 degrees -30 degrees at the hip joint. The pressure on the femoral head was strongest at a hip flexion of 0 degrees. The tensile force markedly decreased at 45 degrees -60 degrees flexion at the hip joint, while the pressure on the femoral head gradually reduced to zero in the same phases. We concluded that the PMM works phasically: (1) as an erector of the lumbar vertebral column, as well as a stabilizer of the femoral head in the acetabulum at 0 degrees -15 degrees flexion at the hip joint; (2) less as a stabilizer, in contrast to maintaining its erector action, at 15 degrees -45 degrees; and (3) as an effective flexor of the lower extremity, at 45 degrees -60 degrees.

Aged↗

PubMed2002

Natural course of nonreducing disc displacement of the temporomandibular joint: changes in chewing movement and masticatory efficiency.

PURPOSE: The purpose of this study was to examine changes of chewing movement and masticatory efficiency during the natural course of nonreducing disc displacement of the temporomandibular joint (TMJ). PATIENTS AND METHODS: The subjects were 15 patients who had been diagnosed with nonreducing disc displacement of the TMJ but had received no treatment. Chewing movement and masticatory efficiency were examined at the initial visit and at a mean follow-up of 21.7 months, using mandibular kinesiography and adenosine triphosphate ebteric-coated granules. As a control, 23 persons who had no current or previous TMJ symptoms were studied. RESULTS: The patients' clinical signs and symptoms tended to be alleviated during the follow-up period. In normal controls, chewing movement showed lateral excursion to the chewing side on both the right and left sides. In patients, chewing movement at the initial visit showed lateral excursion to the chewing side during chewing on the TMJ affected side, but no such deviation was noted during chewing on the TMJ unaffected side in the horizontal plane. However, chewing movement at follow-up became similar to that of controls. In patients, masticatory efficiency became better during the natural course, although that at follow-up did not always reach the control's level. CONCLUSION: In untreated patients with nonreducing disc displacement of the TMJ, chewing movement and masticatory efficiency tend to improve spontaneously.

Adenosine Triphosphate↗

PubMed2002

Changes of the collagen fibre arrangement of the rabbit temporomandibular joint following discectomy.

PURPOSE: The purpose of the present study is to examine changes in arrangement of collagen fibres of the temporomandibular joint (TMJ) following discectomy. MATERIAL AND METHODS: Twelve male Japanese white rabbits were used. The right TMJs of six rabbits were surgically exposed, and the disc removed with a scalpel. Three untreated and three sham-operated rabbits were used as controls. The TMJs were removed in three rabbits 1 month and in three other rabbits, 3 months after discectomy and processed for demonstration of collagen fibres. RESULTS: One month after discectomy, collagen fibres in the fibrous layers of condyle and articular eminence were of various sizes and were running in various directions. Collagen fibres in the cartilaginous layers were sparser in the study TMJs than in the control TMJs. Three months after discectomy, the direction of collagen fibres in the fibrous layers of the condyle and articular eminence became organized and were similar to that in the control TMJs. However, collagen fibres in the cartilaginous layers of the condyle remained sparser 3 months after discectomy than in the control TMJs. CONCLUSION: Experimental discectomy in the rabbit alters the distribution and density of collagen fibres in the TMJ. Thorough postoperative follow-up seems to be necessary after discectomy.

Animals↗

PubMed2002

Effects of ipriflavone on bone augmentation within a titanium cap in rabbit calvaria.

Ipriflavone (7-isopropoxyisoflavone, IP), a drug used in the treatment of osteoporosis, may promote bone formation during bone remodeling. IP has been shown to accelerate both the activity of, and formation of mineralized nodules by a human osteosarcoma cell line at an early stage. However, the direct effects of IP on bone augmentation have not been investigated. The purpose of this study was to determine whether IP induces bone augmentation within a titanium cap in rabbit calvaria at an early stage. Five adult male Japanese white rabbits were used. One cap (test site) was packed with IP in a collagen gel, and the other (control site) was packed with the collagen gel alone. After the one- and three-month healing periods, we measured the newly generated tissue and bone within the titanium caps. The amount of newly generated tissue within the titanium caps of the control sites was higher than the tests sites after one month and three months. However, the percentage of newly generated bone/bone marrow in the newly generated tissue at the test sites was higher than for the control sites after one month and three months. These results suggest that IP affects the quality of bone augmentation at an early stage.

Animals↗

PubMed2001

Pumping injection of sodium hyaluronate for patients with non-reducing disc displacement of the temporomandibular joint: two year follow-up.

Objectives: The purpose of the present study was to examine the long-term effect of pumping injection of sodium hyaluronate into the TMJ in patients with non-reducing disc displacement. Patients: Sixty patients with non-reducing disc displacement underwent pumping injection of sodium hyaluronate (pumping group). Seventy-six patients with non-reducing disc displacements were observed without any active treatment (observation group). Study design: In both patient groups clinical signs and symptoms were observed periodically for 2 years. Variables such as age, range of maximum mouth opening, angle of posterior slope of the articular eminence and degenerative bony changes of the condyle at the initial visit were also examined. Cox hazards analysis was applied to examine the clinical outcome for such variables in addition to the results of pumping injection of sodium hyaluronate. Results: Pumping injection of sodium hyaluronate seemed to have a favourable effect when compared with the control group (untreated) (p=0.0002). However, the four background variables mentioned could not be explained as predictors of outcome. Conclusion: Pumping injection of sodium hyaluronate seems to be effective for non-reducing disc displacement of the temporomandibular joint. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗

PubMedDate not supplied

Clinical application of a new cone-beam computerized tomography system to assess multiple two-dimensional images for the preoperative treatment planning of maxillary implants: case reports.

Accurate assessment of the location of the maxillary sinuses, incisive canal, and nasal cavity, as well as the height, width, and angulation of bone is essential for implant treatment planning. The purpose of this study was to introduce the clinical application of a cone-beam computerized tomography system (Ortho-CT) to assess multiple two-dimensional (2D) images for the preoperative treatment planning of maxillary implants. To evaluate the multiple 2D images scanned using the Ortho-CT system the maxillary region placed with radiopaque template in the maxilla. Ortho-CT images provided useful information for evaluating the morphology of the maxilla, for locating the incisive canal, maxillary sinuses, nasal cavity, and for showing the relationship of the template to the bone. It is concluded that the Ortho-CT system is a useful aid for diagnosis and treatment planning for maxillary implant treatment.

Adult↗