Biomedical subjects

M Sakuda

Publications and source records attributed to M Sakuda.

At least 19 recordsLinked to original sources

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

Midline cervical cleft. A case report.

A case of incomplete midline cervical cleft of the upper neck is reported. It showed histological resemblance to a mature teratoma with three different germ-cell components, including cartilage, striated muscles, small salivary glands, and nerves.

Branchial Region↗

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

The effect of local application of 1,25-dihydroxycholecalciferol on osteoclast numbers in orthodontically treated rats.

Orthodontic tooth movement requires remodeling of periodontal tissues, especially alveolar bone. 1,25-(OH)2D3, the active form of vitamin D3, is known to be a potent stimulator of osteoclastic bone resorption. The purpose of this study was to investigate the effect of local application of 1,25-(OH)2D3 on osteoclast numbers induced by experimental tooth movement. A piece of orthodontic elastic band was inserted between the first and second upper molars of male Wistar rats weighing about 200 g each. Twenty microL of 1,25-(OH)2D3 (10(-12)-10(-7) mol/L) was injected locally into the submucosal palatal area of the root bifurcation of the right first molar. The left side was injected with phosphate-buffered saline (PBS). The number of osteoclasts was counted in a 700 x 1050 microns 2 area of the interradicular septum. The local injection of 1,25-(OH)2D3 caused a dose-dependent increase in osteoclast number. The effect of 1,25-(OH)2D3 reached a response plateau at 10(-10) mol/L when greater than a three-fold rise in osteoclast number was attained compared with the PBS-treated controls. While the insertion of a piece of elastic band for three days induced a significant increase in osteoclasts in the alveolar bone, daily injections of 20 microL of 10(-10) mol/M 1,25-(OH)2D3 for three days markedly stimulated the numbers of osteoclasts induced by the insertion of an elastic band. 1,25-(OH)2D3 was apparently synergistic with mechanical stimuli, resulting in enhancement of the numbers of osteoclasts induced by mechanical stimuli alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗

PubMed1992

Effect of a pulsing electromagnetic field on demineralized bone-matrix-induced bone formation in a bony defect in the premaxilla of rats.

A 2-mm non-healing bony defect was prepared in the premaxilla of male Wistar rats weighing about 180 g as a simulation of an alveolar cleft, for determination of whether a pulsing electromagnetic field (PEMF) could promote regeneration of bone induced by demineralized bone matrix (DBM). The defect was either treated with 7 mg DBM or was left as a non-grafted control. The rats were exposed to a PEMF with a frequency of 100 Hz, a 10-ms-wide burst with 100 microseconds-wide quasi-rectangular pulses, repeating at 15 Hz, and magnetic field strength of 1.5-1.8 G. Alkaline phosphatase activity increased significantly from day 7 in the DBM-graft-plus-PEMF group and from day 10 in the DBM-graft group, reaching a maximum on day 14. A greater-than-two-fold rise in alkaline phosphatase activity and a three-fold rise in the amount of 45Ca incorporation in the DBM-graft-plus-PEMF group were attained compared with those of the DBM-graft group. The DBM-graft-plus-PEMF group produced more bone with almost complete osseous bridging in the defect sites than did the group treated with DBM only on day 35. The findings indicate that PEMF had an enhancing effect on the bone-inductive properties of the DBM through the stimulation of osteoblast differentiation induced by DBM.

Alkaline Phosphatase↗

PubMed1992

Differential effects of 1 alpha, 25-dihydroxycholecalciferol and 24R,25-dihydroxycholecalciferol on the proliferation and the differentiated phenotype of rabbit craniofacial chondrocytes in primary culture.

The response of chondrocytes from the craniofacial complex to vitamin D3 has been investigated in vitro. Chondrocytes were isolated from nasal septal cartilage (NSC), sphenooccipital synchondrosis (SOS) and mandibular condylar cartilage (MCC) of New Zealand rabbits weighing from 250-350 g. Treatment of NSC-chondrocytes with 1,25-(OH)2D3 or 24,25-(OH)2D3 for 6 days from days 4 to 10 in medium containing charcoal-treated FBS increased DNA synthesis dose-dependently at the concentrations of 10(-9) M to 10(-8) M, or 10(-11) M to 10(-9) M, respectively. 1,25-(OH)2D3 inhibited GAG synthesis dose dependently at the concentrations of 10(-11) M to 10(-8) M. 24,25-(OH)2D3 had no effect on GAG synthesis in NSC-chondrocytes. 1,25-(OH)2D3 increased DNA synthesis in SOS-chondrocytes at a concentration of 10(-10) M and inhibited GAG synthesis. 24,25-(OH)2D3 had no significant effect on DNA and GAG syntheses of SOS-chondrocytes. 1,25-(OH)2D3 slightly increased GAG synthesis at a concentration of 10(-10) M in MCC-chondrocytes but had no effect on DNA synthesis. 24,25-(OH)2D3 had no effect on DNA and GAG synthesis in MCC-chondrocytes at concentrations of 10(-11) M to 10(-9) M. These finding suggest that vitamin D3 metabolites, 1,25-(OH)2D3 and 24,25-(OH)2D3 play an important role in the growth of craniofacial cartilage by differently stimulating proliferation and expression of the differentiated phenotype of chondrocytes from NSC, SOS and MCC.

24,25-Dihydroxyvitamin D 3↗

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↗

PubMed1992

Stimulation of alkaline phosphatase activity by ascorbic acid and suppression by 1,25-dihydroxycholecalciferol in rabbit craniofacial chondrocytes in culture.

To clarify the role of vitamins D and C in chondrocyte hypertrophy of craniofacial cartilage, we have studied cultured chondrocytes from rabbit mandibular condylar cartilage (MCC), sphenooccipital synchondrosis (SOS) and nasal septal cartilage (NSC) under conditions in which these cells mature into hypertrophic chondrocytes. In cultures of MCC- and SOS-chondrocytes, alkaline phosphatase (ALPase) activity started to increase on day 9 at confluence and the cessation of cell division, and reached a maximum on day 18. The degree of the increase of ALPase activity on day 18 was higher in MCC-chondrocytes than in SOS-chondrocytes. ALPase activity was very low level in NSC- and CGC-chondrocytes. Ascorbic acid induced a marked increase in ALPase activity in MCC-, SOS-, NSC- and CGC-chondrocytes. The ALPase activities in MCC- and SOS-chondrocytes with 50 micrograms/ml ascorbic acid were 2.5-times those in its absence. Those in NSC- and CGC-chondrocytes were 10 times and 20 times, respectively. When chondrocytes were cultured with 10% charcoal-treated serum, ALPase activity decreased less than that in cultures with 10% normal serum in MCC-, SOS-, NSC- and CGC-chondrocytes. Treatment of 1,25-(OH)2D3 for 9 days from days 4 to 13 in MCC-chondrocytes and for 14 days from days 4 to 18 in SOS-, NSC- and CGC-chondrocytes inhibited ALPase activity dose-dependently at the concentrations of 10(-12) M to 10(-8) M in MCC- chondrocytes, 10(-10) M to 10(-8) M in SOS- and CGC-chondrocytes, 10(-11) M to 10(-9) M in NSC-chondrocytes. These findings suggest that 1,25-(OH)2D3 and ascorbic acid may be involved in the control of cartilage growth and terminal differentiation.

Alkaline Phosphatase↗

PubMed1991

Frequency of the hypercalcemia-leukocytosis syndrome in oral malignancies.

There have been a number of reports over the last 15 years of patients with cancer who develop both leukocytosis and hypercalcemia, particularly in patients with cancers of the oral cavity. In this study, the authors report the frequency of hypercalcemia and leukocytosis in 225 patients with oral malignancies. Ten patients (4.4%) had hypercalcemia, 11 patients (4.9%) had leukocytosis, and five (2.2%) had both hypercalcemia and leukocytosis. The occurrence of these two distinct paraneoplastic syndromes in the same patients was greater than could have been expected from chance alone (chi-square = 45.8, P less than 0.0001). This study demonstrates that although hypercalcemia and leukocytosis are relatively uncommon in oral cancers, when they do occur they are frequently associated. To the knowledge of the authors, this is the first report in which the frequency of the association hypercalcemia and leukocytosis is studied in detail in large numbers of patients with oral cancer.

Adenocarcinoma↗

PubMed1991

Changes in facial skin temperature associated with chewing efforts in man: a thermographic evaluation.

Eleven healthy male adults chewed hard and soft chewing-gums for 5 min. A thermographic record of the face on the chewing side was made at the beginning of, during and after the effort. Facial temperature distributions during open/close cyclic unloaded jaw movements were recorded at a later date. The dimensions of the zones whose temperatures were 1.4 degrees C or more higher than the central temperature during the experiment were determined. There was a linear increase in the dimensions of these zones after the chewing. In contrast, the cyclic jaw movements did not result in significant increases. Chewing the hard gum produced significantly higher temperature rises than did the soft in the masseter area. After the chewing effort, the temperature fell gradually, but did not return to the initial state even after 30 min. The overall decreasing pattern of the temperature distribution for chewing the soft gum was similar to that for the hard gum. The facial temperature associated with chewing efforts rose in accordance with the resistance offered by the chewing-gums.

Adult↗

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

Comparison of the effects of hydrostatic compressive force on glycosaminoglycan synthesis and proliferation in rabbit chondrocytes from mandibular condylar cartilage, nasal septum, and spheno-occipital synchondrosis in vitro.

We have developed a simple in vitro model whereby precise quantities of compressive force can be applied to cultured chondrocytes from craniofacial cartilage: mandibular condylar cartilage (MCC), nasal septal cartilage (NSC), and spheno-occipital synchondrosis (SOS). Using this model, we found that hydrostatic compressive force stimulated glycosaminoglycan (GAG) synthesis, a cartilage phenotype, in MCC and SOS chondrocytes and DNA synthesis in MCC, NSC, and SOS chondrocytes. These stimulations were dependent on force magnitude and duration, reaching maximal GAG synthesis at 27 hours and maximal DNA synthesis at 20 hours after application of force. The maximal increase of GAG synthesis induced by compressive force was about 60% at 100 gm/cm2 for 5 minutes in nonstimulated MCC chondrocytes and 40% at 50 gm/cm2 for 1 minute in nonstimulated SOS chondrocytes. The maximal increase in DNA synthesis, produced by a compressive force of 50 gm/cm2 for 1 minute, was 50% in NSC chondrocytes, 50% in SOS chondrocytes, and 30% in MCC chondrocytes. There was no stimulation of GAG synthesis in NSC chondrocytes. These observations suggest that extrinsic force regulates craniofacial growth by controlling the differentiation and proliferation of chondrocytes in the craniofacial skeleton and that the difference in their responses to compressive force may reflect differences in the characteristics of these cells and their physiologic function in vivo.

Animals↗

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

Nonlinear interpolation of mandibular kinesiographic signals by applying sensitivity method to a GMDH correction model.

The purpose of the present paper was to propose an improved nonlinear interpolation method for estimating distorted kinesiographic recording of interlattice points in space, and to evaluate its correction accuracy. The group method of data handling (GMDH) correction method we have reported previously is essentially different from other geometric correction methods in the sense that the GMDH correction model can be adapted to the measurement environment in which kinesiographic signals are subject to ferromagnetic interferences. Due to its inherent structure, however, our previous GMDH correction model was restricted to kinesiographic signals representing lattice points in space. In this paper, we explored the sensitivity method for GMDH correction modeling. This provides for nonlinear interpolation of kinesiographic signals for interlattice points. Nominals, i.e., true values, of 3-D coordinates of the interlattice points were determined by means of a mandibular jaw movement simulator together with simultaneous recording of distorted kinesiographic signals which corresponded to the nominals. Distorted signals were corrected by the new method of correction modeling. A mean estimation error of 0.16 mm (SD 0.19 mm) was determined for 24 interlattice coordinates. Thus, nonlinear interpolation by the sensitivity method was confirmed to be effective.

Data Interpretation, Statistical↗

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↗

PubMed1991

Occurrence of hypercalcemia and leukocytosis with cachexia in a human squamous cell carcinoma of the maxilla in athymic nude mice: a novel experimental model of three concomitant paraneoplastic syndromes.

Hypercalcemia and leukocytosis may occur in conjunction as paraneoplastic syndromes associated with malignant disease. Here we describe a human squamous cell carcinoma of the maxilla that was associated with hypercalcemia and leukocytosis, and also cachexia. The primary tumor was surgically removed and established in permanent cell culture. When either primary tumors or cultured tumor cells were inoculated into nude mice, the nude mice developed the same paraneoplastic syndromes as those which occurred in the patient from whom the tumor was originally derived. The plasma calcium was increased two and one-half-fold and the WBC count 30-fold, and the body weight was decreased by 45% in tumor-bearing animals. Each of these paraneoplastic syndromes was alleviated by surgical excision of the tumor, indicating that the paraneoplastic syndromes were due to a factor or factors produced by the primary tumor. The development of each of these paraneoplastic syndromes in nude mice correlated positively with the other two syndromes. We examined the organs of tumor-bearing mice and found striking histopathologic abnormalities in the bones, spleen, and liver, but no infiltration with tumor cells. The bones showed marked evidence of osteoclastic bone resorption. This model of a human tumor associated with the hypercalcemia-leukocytosis paraneoplastic syndrome, together with cachexia, should make it possible to determine the mechanisms responsible for these paraneoplastic syndromes and their relationship to each other.

Animals↗