Publications by authors named "Kazuo Hayashi"

Objective: To investigate the effectiveness of pericapsular soft tissue and realignment (PSTR) exercises for patients with osteoarthritis (OA) of the hip and Harris Hip Score (HHS) below 60 points. Most previous studies of hip exercise have not been applied for patients with moderate to severe hip OA, especially those with an HHS below 60 points. Most studies of hip exercise in OA have involved muscle strength training, stretching, functional training and aerobic fitness programs, and have not included pelvic realignment exercise.

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Purpose: Temperature, concentration and time are the three factors that affect the inactivation capacity of iodine antiseptics. We investigated the effect of these factors on the microbe inactivation of Iodine-Polyvinyl Alcohol ophthalmic and eye washing solution (PA * IODO), and also investigated the preservation conditions on stability of the inactivation activity of the PA * IODO.

Methods: Test microbes were mixed with PA * IODO, varying the three factors.

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Introduction: Virtual 3-dimensional (3D) models obtained by scanning of physical casts have become an alternative to conventional dental cast analysis in orthodontic treatment. If the precision (reproducibility) of virtual 3D model analysis can be further improved, digital orthodontics could be even more widely accepted. The purpose of this study was to clarify the influence of "standardization" of the target points for dental cast analysis using virtual 3D models.

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Introduction: The primary objective of this study was to assess the accuracy and the reliability of the SureSmile OraScanner (Orametrix, Richardson, Tex) by comparing it with other desktop 3-dimensional scanners: VIVID910 (Konica Minolta, Tokyo, Japan) and R700 (3Shape, Copenhagen, Denmark). A laser-based scanner, the SLP250 Laser Probe (Laser Design, Detroit, Mich), served as the gold standard.

Methods: Five sets of dental casts were used.

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Introduction: The purposes of this study were (1) to discover a simple method for computing an average dental form, (2) to evaluate the validity of the new computing method, and (3) to build an average digital dental model based on the resulting average dental form.

Methods: Dental casts of 51 adults were scanned, and 3-dimensional virtual models were reconstructed by using specialized software. Fifty-two anatomic landmarks were plotted on each model to obtain a configuration representing that model.

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Tooth wear is an unavoidable process associated with aging. Currently, virtual three-dimensional dental models are widely used and provide an advantage for studying tooth wear. However, there are no wear assessment parameters using virtual tooth models for the quantitative analysis of wear.

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Objective: The proportions of the anterior dentition, which is important for excellent esthetics, have been extensively studied, but there have been no 3-dimensional interpretations. This study was conducted to compare real tooth sizes and perceived tooth sizes between different genders and populations and to analyze the effects of 3-dimensional tooth position and alignment.

Materials And Methods: Complete dental stone casts were prepared for a total of 139 subjects (50 males and 44 females from Korea and 46 females from Japan).

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The aim of this study was to assess morphological differences between early-modern (Edo) Japanese and contemporary Japanese using recently uncovered human female remains at the Ikenohata-Shichikencho site in the Tokyo urban area. In this study, 30 female skeletal remains that still retained the upper and lower first molars and central incisors were selected [early-modern (Edo) Japanese group]. Forty contemporary female Japanese were selected as a control.

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The purpose of this study was to establish a new statistical method for the analysis of masticatory function. The subjects were patients with anterior crossbite who had received orthognathic surgery. Chewing movement was measured by means of an opto-electronic motion-analysis system.

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Background: Hip fracture is associated with pronounced morbidity and excess mortality in elderly women with postmenopausal osteoporosis. Many drugs have been developed to treat osteoporosis and to reduce the risk of osteoporotic fractures. We investigated the effects of combined alendronate and vitamin D3 treatment on bone mass and fracture load at the femoral neck in ovariectomized (OVX) rats, and evaluated the relationship between bone mass parameters and femoral neck strength.

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Introduction: The purposes of this study were to examine the curve of Spee of the maxillary and mandibular arches by using a 3-dimensional reconstruction method and to determine the relationship between the curve of Spee and dentofacial morphology with multiple regression analysis.

Methods: Lateral cephalograms and dental models were evaluated from 18 Korean men and 31 Korean women. The depth of the curve of Spee was measured on the virtual dental models with computer software.

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Background: Osteoporosis is a potential risk factor affecting implant stability following total joint arthroplasty. Bisphosphonates are potent inhibitors of osteoblastic bone resorption, and vitamin D is an important hormone involved in the regulation of calcium metabolism. We investigated the benefit of preoperative treatment with alendronate, vitamin D (calcitriol), or a combination of these substances on fixation of hydroxyapatite-coated implants in an ovariectomized rat model of osteoporosis.

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In dentistry, large regions of dentition often are restored with minimal information about the original anatomy. The ability to predict missing anatomy from existing anatomy would aid such restorations. This study investigated the relationship between first molar mesial-distal width and arch shape using newly defined reference points and three-dimensional (3D) digital methods.

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The purpose of this study was to demonstrate the advantage of the finite helical axis (FHA) system in the biomechanical analysis of orthodontic tooth movement by comparing it with the rectangular coordinate (XYZ) system. Ten patients (6 females and 4 males, mean age 23 years 7 months) were selected. Maxillary canine retraction using light continuous forces of two different magnitudes (0.

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We observed a novel type of airflow produced by an atmospheric rf discharge between asymmetric parallel rod electrodes. The electrodes were a bare metal rod 1 mm in diameter and a glass-coated metal rod 3.2 mm in diameter.

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Introduction: The aim of this study was to establish a novel method for simulating orthognathic surgery in 3-dimensional (3D) space.

Methods: This system mainly consists of 6 procedures: (1) reconstruction of a virtual skull model (VS) from presurgical computed tomography scans; (2) reconstruction of virtual dentition models from 3D surface scanning of dental casts occluded at presurgical and postsurgical intercuspal positions (VD1 and VD2, respectively); (3) reconstruction of a preliminary fusion model of VS and VD1 by an initial intermodality registration; (4) reconstruction of another preliminary fusion model of VS, VD1, and VD2 by a second intramodality registration; (5) repositioning of bony segments by a third intramodality registration and reconstruction of final fusion models at presurgery and postsurgery; and (6) 3D analysis of the movement of bony segments. To test this system, 2 patients with severe skeletal deformities, who had undergone presurgical orthodontic treatment, were used as models.

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The purpose of this study was to provide a quantitative assessment of galvanic corrosion behavior of orthodontic archwire alloys coupled to orthodontic bracket alloys in 0.9% NaCl solution and to study the effect of surface area ratios. Two common bracket alloys, stainless steels and titanium, and four common wire alloys, nickel-titanium (NiTi) alloy, beta-titanium (beta-Ti) alloy, stainless steel, and cobalt-chromium-nickel alloy, were used.

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In orthodontics, tooth movement is typically described using the rectangular coordinate system (XYZ); however, this system has several disadvantages when performing biomechanical analyses. An alternative method is the finite helical axis (FHA) system, which describes movement as a rotation about and a translation along a single axis located in space. The purpose of this study was to examine differences between the FHA and the XYZ systems in analyzing orthodontic tooth movement.

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The description of motion using a finite helical axis (FHA) is independent of the chosen coordinate system because the values of the helical axis parameters do not change with coordinate transformations. However, an intuitive understanding of tooth movement expressed by the FHA can be slightly difficult for orthodontists who have never used it. The purpose of this study was to clarify the basic behavior of the FHA to increase our understanding of the FHA during tooth movement.

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The purpose of this study was to compare maxillary canine retraction with sliding mechanics and a Ricketts canine retraction spring, using a midpalatal orthodontic implant as a measuring reference. Eight patients (three males and five females) were examined. Because maximum posterior anchorage was required in all subjects, osseointegrated midpalatal implants were used.

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A finite helical axis (FHA) analysis can provide precise three-dimensional information on orthodontic tooth movement compared to an analysis based on a rectangular coordinate system. The FHA has already been applied in an analysis of orthodontic tooth movement. Interestingly, the position of the FHA changes dramatically in different stages of treatment; however, no previous report has provided detailed information of its basic behavior for clinicians.

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The purposes of this study were (1) to measure the nonlinear force-deflection behavior of selected orthodontic wires using a conventional tensile test, (2) to extend a mathematical model for simulating the force system produced by orthodontic wires based on the small-deflection linear theory to the large-deflection nonlinear theory, and (3) to examine the effects of the cross-section and mechanical properties of orthodontic wires on nonlinear characteristics. A method for extending a mathematical model for simulating the force system produced by orthodontic wires based on the small-deflection linear theory to the large-deflection nonlinear theory was established, and this can provide a clear view of the true nature of orthodontic wires. Furthermore, our results demonstrated that the nonlinear properties of orthodontic wires were affected more by the cross-sectional shape than by mechanical properties.

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The purpose of this study was to clarify the three-dimensional morphological characteristics of the dentition and palate in skeletal asymmetry in patients with skeletal Class III malocclusion using a newly defined palatal reference plane in a dental cast. Twenty patients (5 males and 15 females) who had skeletal Class III malocclusion with facial asymmetry were selected. Pretreatment posteroanterior cephalometric radiographs and maxillary dental casts were used.

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The purpose of this study was to establish a new method for orthodontic diagnosis that integrates the three-dimensional (3-D) shape of a dental cast and the craniofacial morphology using a newly defined palatal reference plane. We also measured the accuracy of this new palatal reference plane as a reference for measurement and its spatial relationship to the framework of the craniofacial skeleton using lateral and frontal cephalometric radiography and maxillary dental casts, which were transferred using an anatomical face-bow. Eighteen female subjects were included in this study.

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