Biomedical subjects

K Tanne

Publications and source records attributed to K Tanne.

At least 109 records · Page 6Linked to original sources

PubMed1994

Frictional forces and surface topography of a new ceramic bracket.

The present study was designed to measure the frictional forces between orthodontic wires and a new ceramic bracket and to investigate the differences in the frictional forces with the new and two previously available ceramic brackets. Frictional forces were measured during the sliding of 0.016 x 0.022-inch and 0.017 x 0.022-inch cobalt-chromium alloy wire through three brackets bonded to a simulated tooth. The wires were not ligated into the brackets, so as to eliminate the influences of ligation on the bracket-wire friction. Further, slot surfaces of the three brackets were examined by scanning electron microscope (SEM). The magnitude of frictional forces produced by the new ceramic bracket was significantly less for both the wires than that produced by the two ceramic brackets at 1% level of confidence. The frictional forces with all the brackets exhibited a slight increase as the wire size became larger. The magnitude of frictional forces decreased substantially as the retraction point shifted more cervically. Slot surfaces of the new ceramic bracket were substantially smoother than those surfaces of the two other ceramic brackets. It is shown that refinements of slot surfaces of the ceramic bracket may be effective to reduce friction, although the bracket-wire frictions in this in vitro study were somewhat underestimated because of the lack of ligation of the wire into the bracket.

Aluminum Oxide↗

PubMed1994

Orthodontic forces exerted by activators with varying construction bite heights.

The present study was conducted to investigate the nature of forces induced with activators by measuring strains, electromyogram (EMG) and electroencephalogram (EEG) during a 2-hour sleep period. Fifteen adolescent patients with Class II and Class III malocclusions, (30 subjects) were used. Four types of activators were made for each patient with construction bites taken at incisal edge clearances of 2, 4, 6, and 8 mm vertically. The magnitude of forces generated by passive tension of soft tissues increased significantly (p < 0.01) from approximately 80 to 160 gf in the Class II group and from approximately 130 to 200 gf in the Class III group with varying construction bite heights from 2 to 8 mm. Higher construction bites also significantly changed (p < 0.01) the direction of forces by passive tension from vertical to posterior and from vertical to anterior in relation to the reference plane in the Class II and Class III groups, respectively. Duration of forces generated by passive tension was most significantly longer than that of active contraction of the jaw closing muscles, irrespective of the construction bite heights. It is concluded that passive tension, derived from viscoelasticity of soft tissues, plays a more important role in inducing changes that phasic stretch reflex during jaw orthopedic therapy with activators.

Activator Appliances↗

PubMed1994

Finite element analysis for stresses in the craniofacial sutures produced by maxillary protraction forces applied at the upper canines.

The purpose of this study was to investigate the nature of stress distributions in the craniofacial sutures produced by orthopaedic maxillary protraction forces applied to the upper canines. A three-dimensional finite element model of the craniofacial complex was developed for finite element analysis. An anteriorly directed force of 1.0 kg was applied to the upper canines in three different directions, i.e. parallel, 30 degrees upwards and downwards to the functional occlusal plane. Normal stresses acting on the sutural systems were greatest when force was applied in the 30 degrees upward direction. Furthermore, relatively large compressive stresses were induced in the frontonasal and frontomaxillary sutures, indicating that forward and upward rotation of the nasomaxillary complex was produced with substantial distortion of the complex, by the forces applied in both parallel and 30 degrees upward directions. A 30 degrees downward force produced almost uniform tensile stresses in the zygomaticotemporal and zygomaticomaxillary sutures, with least compressive stresses in the frontonasal and frontomaxillary sutures located in the superior region of the complex. This would indicate a uniform stretch of the nasomaxillary complex in both anterior and inferior directions, with negligible distortion of the complex and would be appropriate for accelerating natural growth of the nasomaxillary complex.

Biomechanical Phenomena↗

PubMed1993

[A FEM study for the biomechanical comparison of labial and palatal force application on the upper incisors. Finite element method].

The present study was designed to compare the biomechanical response of upper incisors to labial and lingual force applications. A three-dimensional finite element model was developed to analyze tooth displacement and stress distribution in the periodontal ligament. Lingually and apically directed forces of 1 N were applied at one point on the labial and at three points on the lingual surface of the crown. Tooth displacement and stress distribution resulting from lingual force applications were compared with those from the labial side. The following results were obtained: 1. Lingual horizontal forces produced similar patterns of tooth displacement and stress distribution, irrespective of the point of application (labial--lingual). 2. Apically directed vertical forces applied at the lingual points produced more uniform tooth displacements and stress distributions, although the force applied on the lingual side close to the CEJ, which happened to be most distant from the tooth's long axis, generated a pattern of movement somewhat different from the remaining two lingual force applications. The present results suggest the crucial role of the positional relation between the long axis of the tooth, respectively the center of resistance, and the point of force application. It can be deduced that lingual force application may produce more optimal tooth movement in terms of intrusion and subsequent stress distributions in the periodontal ligament.

Biomechanical Phenomena↗

PubMed1993

Stress distributions in the maxillary complex from orthopedic headgear forces.

The present study was conducted to investigate stress distributions in the maxillary complex from headgear forces by means of three-dimensional finite element analysis. A posteriorly-directed force of 1.0 Kgf was applied to the maxillary first molars in the directions parallel and 30 degrees inferior to the occlusal plane. In the lower regions resisting posterior displacement of the complex, large normal and shear stresses were observed. Meanwhile, the regions resisting upward displacement experienced larger than normal stresses. A downward force produced slightly larger stresses than a parallel force and varied the nature of stresses from compressive to tensile or vice versa in the temporozygomatic suture. Thus, the stress distributions in the sutures varied according to their anatomic locations relative to force directions. The maxillary complex exhibits postero-inferior displacement with clockwise rotation from the horizontal headgear force. This becomes more prominent as the direction of force becomes more inferior.

Adolescent↗

PubMed1993

Craniofacial morphology of adolescent mandibular prognathism.

Morphological features of the craniofacial complex during orthopedic chin cup therapy were investigated in growing patients with mandibular prognathism. Lateral cephalograms of 30 subjects (15 boys and 15 girls, mean age: 9.04 +/- 1.29 years), taken at four different stages during treatment, were analyzed for 14 measurements. These measured values were standardized by use of Japanese controls and then evaluated to investigate longitudinal changes in the craniofacial morphology at the four different stages. Further, factor analysis was used to compare factors describing the craniofacial morphology for the initial and final stages. Dimensional changes of the mandible were not easily produced even if orthopedic treatment was conducted, whereas the maxilla exhibited a tendency to approach the normal range of the controls. Positional changes of the complex, the backward and downward repositioning of the mandible in particular, played an important role in altering a profile from prognathic before treatment to orthognathic at the end of treatment. Craniofacial morphology was similar pretreatment and posttreatment, although the orthognathic factor became more prominent when associated with positional changes of the mandible at the end of treatment.

Adolescent↗

PubMed1993

Biomechanical changes of the mandible from orthopaedic chin cup force studied in a three-dimensional finite element model.

Biomechanical changes of the mandible from orthopaedic chin cup forces were investigated by means of finite element analysis. A three-dimensional model of the mandible including the temporomandibular joint was developed for stress analysis in the mandible. A chin cup force of 400 gf was applied at pogonion on the mandible in the direction toward the condyle. From the stress analyses, it was revealed that (1) uniform tensile stresses were produced at the outer borders of the mandible, (2) compressive stresses were induced in the centre of the mandible, (3) compressive stresses were generated widely on the surface of the condyle, and (4) stresses on the condyle were smaller in magnitude than those in the mandibular corpus. These results coincide with morphological changes of the mandible revealed in previous studies and, thus, indicate an association of stresses with remodelling of the mandible from chin cup therapy applied to adolescent patients with mandibular prognathism.

Adolescent↗

PubMed1993

Association between malocclusion and temporomandibular disorders in orthodontic patients before treatment.

The association between malocclusion and the prevalence of temporomandibular disorders (TMD) was studied in an orthodontic patient population before orthodontic treatment was started. A total of 305 patients, 232 with general malocclusion and 73 who also had cleft lip or palate, were given a questionnaire about the subjective symptoms of TMD. Clinical examinations for type of malocclusion and TMD signs were also conducted. No significant differences in the prevalence of TMD were observed between the sexes or between the two patient groups. Temporomandibular joint sounds and difficulty of jaw movement were the most common of the TMD signs and symptoms. Open bite, posterior crossbite, and deep bite were the most prevalent types of malocclusion in both groups. Thus, some specific types of malocclusion were significantly associated with the occurrence of TMD.

Adolescent↗

PubMed1992

An analytic method for evaluating condylar position in the TMJ and its application to orthodontic patients with painful clicking.

The purpose of this study was to develop a new method for evaluating the three-dimensional position of the mandibular condyle relative to the glenoid fossa and further to investigate its clinical application to orthodontic patients with temporomandibular disorders (TMD). A three-dimensional configuration of the temporomandibular joint was constructed by 108 triangles for the condyle and 180 triangles for the glenoid fossa. The shortest distance between the condyle and glenoid fossa (CGFD) was calculated in the model along a line perpendicular to the center of gravity of a triangle on the condyle. The CGFD was determined in the anterior, posterior, middle, lateral, and medial areas on the condyle. Preliminary investigation revealed that the present technique is accurate, regardless of condylar rotation and/or inclination to the tomographic table. The technique was applied to the diagnosis of orthodontic patients with painful clicking and TMD. It is shown that the present approach provides a method for evaluating the positional relationship between the mandibular condyle and glenoid fossa in patients with TMD.

Adolescent↗

PubMed1992

Integrated information-processing system in clinical orthodontics: an approach with use of a computer network system.

A computer network system has been developed in the Orthodontic Clinic, Osaka University Dental Hospital, to improve treatment efficiency and patient service. The system consists of a 32-bit host computer, its peripheral units, and personal computers connected to the host computer by data-transmission circuits, making up a local area network (LAN). It is possible in this system to integrate various types of data, such as the patient's basic information, treatment records, image data, and diagnostic analysis results to construct a relational database. It has been shown that the computer system developed in the orthodontic clinic has various clinical advantages.

Databases, Factual↗

PubMed1992

Distribution of calcitonin gene-related peptide and substance P-immunoreactive nerve fibers and their correlation in the periodontal ligament of the mouse incisor.

The distribution of calcitonin gene-related peptide (CGRP)- and substance P (SP)-immunoreactive (IR) nerve fibers and their correlation in the periodontal ligament of mouse incisors were examined by indirect immunofluorescence. Both CGRP-IR and SP-IR thin nerve fibers were abundant in the apical and middle third of the periodontal ligament. In the lingual portion of the incisal periodontal ligament, these nerve fibers were localized in the alveolar half of the periodontal ligament and were observed as free nerve endings. No CGRP-IR and SP-IR specialized nerve endings, such as Ruffini-like corpuscles, were observed. In the labial periodontal ligament, CGRP-IR and SP-IR nerve fibers ran along the incisal axis. The distribution of CGRP-IR nerve fibers was very similar to that of SP-IR nerve fibers.

Animals↗

PubMed1992

Biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions.

The present study was designed to investigate biomechanical responses of tooth to orthodontic forces applied at the lingual bracket positions. A three-dimensional finite element model of the upper central incisor was developed to analyze tooth displacements and stress distributions in the periodontal ligament. Lingual horizontal and apical vertical forces of 100 gf were applied at a point on the labial surface of the crown and at three different points on the lingual surface of the crown. Tooth displacements and stress distributions from the forces applied at the lingual points were compared with those from the labial force loading. The following results were obtained. 1. Lingual horizontal force produced almost similar patterns of tooth displacements and stress distributions, irrespective of labial and lingual application points of the orthodontic forces. 2. Apical vertical force applied at the lingual points produced more uniform tooth displacements and stress distributions than labial application of the force, although the force applied at the lingual point close to the cervix generated different patterns from those with the remaining lingual force loadings. The present results suggest an important role of the positional relation of force application points to the center of resistance. It is shown that lingual force application may produce more optimal tooth movement in terms of more uniform patterns of tooth displacements and subsequent stress distributions in the PDL.

Biomechanical Phenomena↗

PubMed1991

Patterns of initial tooth displacements associated with various root lengths and alveolar bone heights.

The present study was designed to investigate the nature of initial tooth displacements associated with varying root lengths and alveolar bone heights. A three-dimensional model of the upper central incisor was developed for the finite element analysis. Tooth displacements were determined at various levels of the tooth and the apicogingival levels of the center of resistance and centers of rotation were calculated. The results showed that moment-to-force values at the bracket level for translation of a tooth decreased with shorter root length and increased with lower alveolar bone height. In addition, apicogingival levels of the center of resistance shifted more gingivally to the cervix, or the alveolar crest with a shorter root. Alveolar bone loss also shifted the center of resistance toward the alveolar crest, whereas its position was more apical relative to the alveolar bone heights exhibited very slight changes in both cases. The centers of rotation from a single force varied substantially with a short root and alveolar bone loss. However, the relative distances of the centers of rotation from the alveolar crest in comparison with the alveolar bone heights were constant at 0.4 mm, with variations in the root length and alveolar bone height. Because this study showed that root length and alveolar bone height affect the patterns of initial tooth displacements both in the center of resistance and the centers of rotation and also in the amount of displacement, forces applied during orthodontic treatment should take into consideration the anatomic variations in the root length and alveolar bone height so as to produce optimal and desired tooth movement.

Alveolar Process↗

PubMed1991

Biomechanical and clinical changes of the craniofacial complex from orthopedic maxillary protraction.

The present study was designed to investigate biomechanical and clinical changes in the craniofacial complex resulting from orthopedic maxillary protraction by means of finite element and cephalometric analyses, respectively. An analytical model developed from a young human dry skull was used for finite element analysis. Three principal stresses were determined in the complex and its sutures. For evaluating morphological changes of patients, lateral cephalograms taken before and after maxillary protraction therapy were analyzed. Tensile stresses were produced in the maxillary and zygomatic bones in an anterior direction with corresponding compressive stresses in a perpendicular direction. In the sutural systems, compressive stresses were induced by counter-clockwise rotation of the complex. Cephalometric investigation demonstrated that significant improvement of the maxillo-mandibular relationship was obtained by maxillary protraction, however, maxillary growth and repositioning were not as great when compared to mean growth in the control group.

Adolescent↗

PubMed1991

Wire friction from ceramic brackets during simulated canine retraction.

The present study was designed to investigate the nature of friction between orthodontic wire and various ceramic brackets. The amount of tooth movement with metal and ceramic brackets was measured, and the wire surfaces were examined microscopically immediately after artificial tooth movement. The amount of tooth movement produced by the ceramic brackets was significantly less than that produced by metal bracket. The wire surfaces were scratched more obviously by ceramic brackets than by metal bracket. Slot surfaces and edges of the ceramic brackets were substantially more porous and rougher than those surfaces of the metal bracket. These material differences between metal and ceramic brackets significantly affect the efficiency of orthodontic tooth movement.

Aluminum Oxide↗

PubMed1991

The elastic modulus of the temporomandibular joint disc from adult dogs.

The present study was designed to measure the elastic properties of temporomandibular joint (TMJ) discs from six adult dogs. Each disc was divided mediolaterally into medial, middle, and lateral parts. Under tension, the articular disc exhibited a non-linear stress-strain relationship, which could be represented as two lines (two moduli of elasticity) connected at a point of stress around 1.5 MPa. These two elastic moduli of the disc were approximately 44 MPa and 92 MPa in the lower- and higher-stress regions, respectively. Elastic moduli of the articular disc in the middle area were significantly different from that in the lateral area of the disc. The reaction to external force appeared to be different in the medial, middle, and lateral regions of the disc.

Animals↗

PubMed1990

Association between mechanical stress and bone remodeling.

Stress patterns and levels were analyzed by use of the three-dimensional finite element method. Three-dimensional models were constructed for the human upper central incisor (1205 nodes and 920 elements) and the sheep metacarpus (240 nodes and 128 elements). Orthodontic and orthopedic forces were applied to the tooth and the bone, simulating orthodontic tooth movement and experimental loading test for the bone. Three principal stresses were determined in the alveolar bone and the sheep long bone. The following results were obtained. 1. Stress distributions in the lateral alveolar bone were similar to those with bone deformation from cantilever bending mode. On the medial surface of the alveolar bone, a bending stress was observed, however, remaining stresses exhibited changes corresponding to those in the PDL produced by tipping displacement of the tooth. 2. In the sheep long bone, tensile and compressive stresses were induced on the dorsal and volar sides, respectively. The magnitude of stresses was greatest at the mid-diaphyseal region. Compressive and tensile stresses were related with bone resorption and apposition. The magnitude of principal stresses was almost proportional to dimensional changes of the bone at the mid-diaphyseal region. Bone remodeling in the long bone is related with mechanical stress, principal stress in particular, indicating that remodeling of the alveolar bone may be induced by application of orthodontic force in addition to conventional change of the bone adjacent to the PDL. Thus, it is shown that mechanical stress in living structures may be a trigger to induce biological remodeling of bones.

Alveolar Process↗

PubMed1990

[An evaluation of 3-dimensional position of mandibular condyle to glenoid fossa using tomogram: an analytical technique and its clinical application].

In recent years, temporomandibular disorder (TMD) is occasionally found among orthodontic patients and has become a great concern in orthodontics. From this point of view, a certain technique has been hopefully anticipated for diagnosis and treatment planning. The purpose of this study was to develop a new method for evaluating three-dimensional position of the mandibular condyle relative to the glenoid fossa and also to investigate its clinical application. Seven-layered tomograms were taken and contours of the condyle and glenoid fossa were traced on an acetate paper. These contours were entered into a personal computer by use of a digitizer and were equally divided into 9 parts for the condyle and 15 parts for the glenoid fossa, consisting of 10 and 16 points on the contours of condyle and glenoid fossa. Three-dimensional configuration of the TMJ was thus constructed by 108 triangles for the condyle and 180 triangles for the glenoid fossa. The shortest distance between the condyle and the glenoid fossa (CGFD) was then calculated along a perpendicular line to center of gravity of a triangle on the condyle. For evaluating the position of the condyle to the glenoid fossa easily in a three dimensional space, surface of the condyle was divided into five areas, i.e. anterior, posterior, middle, lateral and medial areas. In order to investigate whether or not the CGFD is accurate enough to identify the distance between surface of the condyle and glenoid fossa, a model of hemi-spherical solid shell was made, of which the thickness is 3.0 mm. Tomograms of the model were taken to analyze the thickness. Direct measurement of the same area was also made by calipers. Two means were approximately 3.0 mm, which is the thickness itself and no significant differences were indicated at 5% level of confidence. The present technique was applied to diagnosis of an orthodontic patient with painful clicking as TMD. The analyzed CGFDs were coincident with clinical symptom. It is shown that the present approach provides an availability and a possibility to evaluate positional relationship between the mandibular condyle and the glenoid fossa of patients with TMDs.

Humans↗