Biomedical subjects

M Yatabe

Publications and source records attributed to M Yatabe.

At least 19 recordsLinked to original sources

PubMed2001

The relation of mandibular laterotrusion with ipsilateral TMJ clicking.

The purpose of this study was to investigate the association of temporomandibular joint (TMJ) clicking with the types of canine guidance, the tracing patterns of mandibular laterotrusion and, especially, with the movements of the working side condyle. In a young subject group, the movements of left and right mandibular laterotrusion were measured at the incisal and the lateral pole point of the working side condyle. All samples were divided into one of two groups according to the mesial (M) or distal (D) canine guidance. They were also divided into protrusive laterotrusion (PL) or retrusive laterotrusion (RL) groups according to the tracing patterns. The incidence of clicking was 23.8% in all 84 TMJs. There was no significant difference between the M and the D groups. However, clicking occurrence was significantly higher in the RL than in the PL group (P<0.05). The condyles in clicking joints moved more posterior in ipsilateral laterotrusion than the condyles in non-clicking joints. The condyles in RL also moved more posterior than those in PL. It is suggested that the posterior movement of the working side condyle in RL has a strong relationship with the internal derangement of the TMJ. However, it is not related to the type of canine guidance.

Adult↗

PubMed2001

Effect of the reducing agent on the oxygen-inhibited layer of the cross-linked reline material.

The purpose of this study was to clarify the effect of the reducing agent on the oxygen-inhibited layer of the cross-linked reline material. A commercial autopolymerizing reline resin containing 1,6-hexanediol dimethacrylate as cross-linking agent and 1 wt.% sodium sulphite solution as a reducing agent was prepared. The inhibited layer was observed using an optical transmission microscope under the conditions of the application of sodium sulphite for 0, 1, 5 and 15 min after curing for 10 min in air. As a control, the reline material was cured on sealing from air. Moreover, the three-point flexural strength test was performed under the same conditions. The fracture was then observed using scanning electron microscopy (SEM). Although hardness of the inhibited layer was enhanced after the application of the reducing agent, the layer was still observed. The flexural strength of the control and the groups after application of the reducing agent was significantly higher than the group without reducing agent. SEM examination revealed many polymer beads on the group without reducing agent, whereas polymer beads could not be observed on the groups applying the reducing agent. These results indicated that the application of sodium sulphite was effective in hardening the surface unpolymerized zone.

Analysis of Variance↗

PubMed2000

The relation of canine guidance with laterotrusive movements at the incisal point and the working side condyle.

The effect of different types of canine guidance on the patterns of laterotrusive tracing at the incisal point and the relationship between the laterotrusive inclinations and the working side condylar movements were investigated in 42 young subjects. The subjects were divided into M and D groups according to their mesial and distal canine guidance, and were also divided into protrusive laterotrusion (PL) and retrusive laterotrusion (RL) groups according to their laterotrusive tracing patterns. No differences of laterotrusive inclinations and working side condylar movements were found between the M and D groups. The laterotrusive tracing pattern had no corresponding association with the type of canine guidance. In relation to the movements of the working side condyles, significant differences were found between the PL and RL groups. The condyles moved laterally and posteriorly in the RL group, but moved lateral and inferior in the PL one. The distance of condylar movement in the X direction was correlated with the horizontal and sagittal inclinations of laterotrusion. The results indicate that the movements of the working side condyle were affected functionally by the laterotrusion, but not by either the mesial or the distal type of canine guidance.

Adult↗

PubMed1999

Improvement in CNS protective treatment in non-high-risk childhood acute lymphoblastic leukemia: report from the Japanese Children's Cancer and Leukemia Study Group.

BACKGROUND: Prevention of central nervous system (CNS) leukemia by early introduction of therapy to this sanctuary site is an essential component of modern treatment strategy for acute lymphoblastic leukemia (ALL). However, the optimal form of preventive CNS therapy remains debatable. PROCEDURE: To address this issue, we evaluated the efficacy of CNS preventive therapy for 572 children with ALL who achieved complete remission in the Children's Cancer and Leukemia Study Group (CCLSG) ALL874 (1987-1990) and ALL911 (1991-1993) studies. They received risk-directed therapy based on age and leukocyte count. In the ALL 874 study, the non-high-risk (low-risk [LR] + intermediate risk [IR]) patients were randomly assigned to the conventional cranial irradiation (CRT) regimen (L874A and I874A) and the high-dose methotrexate (HDMTX) regimen without CRT (L874B and I874B). The former patients received 18-Gy CRT plus 3 doses of intrathecal (i.t.) MTX and the latter patients received 3 courses of HDMTX at 2 g/m2 plus 13 doses of ITMTX (L874B) or 4 courses of HDMTX at 4.5 g/m2 plus 1 dose of ITMTX (I874B). RESULTS: The 7-year probabilities (+/- SE) of CNS relapse-free survival were 97.3% +/- 2.6% (L874A, n = 41) vs. 90.3% +/- 5.3% (L874B, n = 39) (P = 0.25) in the LR patients, and 100% (I874A, n = 55) vs. 78.5% +/- 6.5% (I874B, n = 54) (P = 0.002) in the IR patients. The corresponding disease-free survival (DFS) rates were 79.4% +/- 6.5% vs. 74.4% +/- 7.3% (P = 0.62) in the LR group and 63.3% +/- 6.8% vs. 58.3% +/- 7.2% (P = 0.66) in the IR group. Thus, the HDMTX regimen could not provide better protection of CNS relapse as compared with the CRT regimen, although their overall efficacy was not significantly different. In the ALL 911 study, intensive systemic chemotherapy with extended i,t, injections of MTX plus cytarabine achieved a high CNS relapse-free survival (98% +/- 1.9% at 7 years) and a favorable DFS (85.5% +/- 5% at 7 years) in the IR patients. The patients in the high-risk (HR) group in both ALL874 and ALL911 studies received the 18-Gy or 24-Gy CRT with intensive systemic chemotherapy. Their 7-year probabilities of CNS relapse-free survival ranged from 88% to 95%, among which the T-ALL patients had a risk of CNS leukemia, which was 3-4 times higher compared with B-precursor ALL patients. CONCLUSIONS: These results indicate that long-term intrathecal CNS prophylaxis as well as appropriate systemic therapy for the non-high-risk patients can provide protection against CNS relapse equivalent to that provided by cranial irradiation.

Adolescent↗

PubMed1999

What types of occlusal factors play a role in temporomandibular disorders...? A literature review.

Recent studies and literature reviews of temporomandibular disorders (TMD) do not strongly support the role of occlusal etiologic factors. For this paper we collected and classified studies dealing with occlusion as a contributing factor to TMD through reviews, and discussions of these difficulties and possible solutions. Related articles from 275 papers covering nearly the past twenty years were selected from a prosthetic point of view and reviewed. The validity and reliability of occlusal examinations, however, are questionable since the epidemiological studies dealt with numerous varied subjects. Although occlusal relationships, such as overbite, non-working side interferences, and discrepancy between the intercuspal position and the retruded contact position, have often been considered as contributing factors of TMD, there is no consistency among even those studies that support such an occlusal factor. A project should be initiated to create a revised, precise and practical method to determine the occlusal contact and to categorize an occlusal contact scheme. To detect whether the patients' occlusal scheme works traumatically or not should be an important part of the occlusal examination. That is, the frequency and duration of tooth contact on the occlusal scheme should be studied.

Adolescent↗

PubMed1998

The influence of some demographic and clinical variables on psychosomatic traits of patients requesting replacement removable partial dentures.

The purpose of this study was to investigate the influence of some demographic and clinical variables on psychosomatic traits of the patients who visited the prosthodontic section of the Dental Hospital at Tokyo Medical and Dental University for replacement of their removable partial dentures (RPDs). Sixty-six patients with 50 maxillary and 44 mandibular RPDs completed the psychological measurements concerning their dentures using visual analogue scales (VAS). Female patients rated significantly lower satisfaction with the comfort of their dentures than males. Younger patients expressed less satisfaction with the aesthetics of their dentures than the older patients. The period of wearing the present denture significantly correlated with psychological measures of pain, comfort, and general satisfaction, suggesting that this clinical variable may be an important factor. There was no significant correlation between the patients' general satisfaction with dentures and the retention/stability scores assessed by the examiner.

Adult↗

PubMed1998

[Oral conditions of inhabitants in Tokashiki Island, Okinawa].

The Department of Health of Okinawa Prefecture with the cooperation of the Ministry of Health and Welfare and eight Dental Schools in Japan, is performing dental treatment and oral health care on inhabitants in areas of Okinawa where no dentists are present. We were asked to offer dental treatment and oral health care for the inhabitants of Tokashiki Island, Okinawa from June 30 to July 29, 1997. The DMF rates of school children of Tokashiki Island was much higher than the average rates in Japan. Among the treatment procedures, conservative treatment was 72.5%, most of which was composite resin filling. Most middle-aged persons had severe periodontal disease rather than severe dental caries. Patients, who suffered from severe dental caries chose extraction of their teeth rather than conservative treatment. The denture wearers of Tokashiki Island used their dentures longer than those who visited our Prosthodontic Department. They were not necessarily dissatisfied with their dentures, but their alveolar ridges were absorbed extensively. These conditions could be due to not only patients' consciousness but also the lack of dental hygiene education. It seems that primary prevention and higher dental hygiene education are needed for the inhabitants of Tokashiki Island where dental treatment must be done in a short time.

Adolescent↗

PubMed1998

[Bone marrow relapse in high-risk pediatric patients with acute lymphoblastic leukemia: a comparison of relapse times and initial clinical features of patients on different protocols. Children's Cancer and Leukemia Study group (CCLSG)].

To clarify the efficacy of modern intensive chemotherapy for ALL patients with unfavorable features, we compared the time to failure and initial clinical features of children who relapsed in the bone marrow or combined sites, as documented by early CCLSG studies (H811 and H851; 1981-1987) and later studies (H874 and H/HH911; 1987-1993) concerning high-risk ALL patients. In the later studies patients outcomes with new intensive regimens employing early intensification and reinduction therapy were apparently better than those of patients in the early studies with conventional regimens. When we compared the number of relapsed patients based on duration of first remission, we found that the improved outcomes for patients in the later studies were due to a decrease in the number who relapsed 7-36 months after the start of treatment (intermediate relapse), and that the percentage of those who relapsed within the first 6 months of therapy (early relapse) was higher. Patients with high initial WBC counts tended to relapse much earlier than those with low initial WBC counts. However, in the later studies, patients with high WBC counts often relapsed after the termination of therapy (late relapse). These results suggest that the intensive chemotherapy regimens used in the later studies can prevent the development of drug resistant leukemic clones, except in extremely high-risk patients likely to relapse within the first 6 months of therapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1997

Movements of the mandibular condyle kinematic center during jaw opening and closing.

Little is known about the detailed kinematics of the human temporomandibular condyle during jaw opening and closing. According to the rotate and swing model by Osborn (1989), the condyle is kept in close contact with the articular eminence during opening. Whether the condyle is in closer contact with the articular eminence during opening than during closing is unknown. Another consequence of the model is that the opening condylar movements are less variable than the closing movements. In this study, the hypothesis that the opening condylar path is closer to the articular eminence and also less variable than the closing condylar path is tested. Twenty subjects (10 males and 10 females with a mean age of 22) without signs or symptoms of a craniomandibular disorder performed 2 series of 4 protrusive movements and 2 series of 4 empty opening-closing movements. The movements were recorded by a six-degrees-of-freedom opto-electronic jaw movement recording system (OKAS-3D). The kinematic center of the condyle was used as a reference point for the reconstruction of condylar movement paths. Characteristics of the opening and closing paths were investigated by means of a displacement index (DI). This index is the quotient between the three-dimensional path length and the three-dimensional path distance between the start and the end point of an opening or closing movement of the kinematic center. The DI was smaller (p < 0.0001) and also less variable (p < 0.0001) during opening than during closing. The smaller DI value, in combination with the concave nature of the movement path, indicates that the opening path of the kinematic center lies above the closing path and thus closer to the articular eminence.

Adolescent↗

PubMed1995

The kinematic center: a reference for condylar movements.

The kinematic center of the temporomandibular condyle is that condylar point which follows as much as possible the same movement path during different types of mandibular movements. In this study, the location of the kinematic center with respect to the palpated lateral pole of the condyle was investigated. Also, the lengths of the condylar movement path reconstructed by means of the kinematic center and the palpated condyle were compared. Mandibular movements were recorded with 6 degrees of freedom in 20 healthy subjects. A software procedure calculated the location of the kinematic center as that mandibular point for which the protrusive and opening movement path showed a minimal difference. For each subject, its average location was calculated on the basis of 16 pairs of protrusive and opening movements. The kinematic center was located posteriorly and superiorly with respect to the palpated condylar point (p < 0.0001). The standard deviation in the anterior-posterior coordinate of the average kinematic center was smaller than that in the superior-inferior coordinate (p < 0.0001). During opening, the path length of the kinematic center is longer than that of the palpated lateral pole of the condyle (p < 0.0001). In contrast to left-right differences found in the path lengths of the lateral pole of the condyle, no left-right differences were found for the kinematic center.

Adolescent↗

PubMed1992

[Erythroleukemia in pregnancy with successful outcome of delivery].

A 37-year-old woman was admitted to our hospital because of anemia in the 33rd week of pregnancy. On admission, the hemoglobin was 7.6 g/dl, platelets 508,000/microliters and WBC 8,300/microliters with 4% blast cells. Bone marrow aspirate demonstrated 50% erythroblasts of nucleated cells, which had prominent megaloid and polynucleic changes, and 20% myeloblast cells. We diagnosed her as having erythroleukemia. Receiving packed-red-cell transfusions, she had a cesarean section, and gave birth to a female infant (BW 2,175 g) in the 34th week of pregnancy. At the same time, she had a total hysterectomy with left adnexectomy. The postoperative course was favorable. She had a combination chemotherapy of BHAC-DMP, resulting in a partial remission. After the second induction chemotherapy with subcutaneous use of G-CSF and BHAC-DMP, complete remission was obtained, which lasted for almost 17 months. The child is growing well without any hematological disorder.

Adult↗

PubMed1991

[Study on measurement of dynamic viscoelasticity of maxillary mucosa].

The purpose of this study is to investigate the viscoelastic properties of the oral mucosa. The handy apparatus which can easily show the rheological properties (i.e., G', G", tan delta) was made for the trial. The principle of this apparatus is to measure the stress and the phase difference produced when the constant sinusoidally oscillating shear deformation is loaded on the viscoelastic materials. This handy trial apparatus was found to be applicable in vivo, as evaluated by the dynamic spectrometers. The viscoelastic properties of the mucosa of the maxilla were investigated with this apparatus. The results were as follows: 1) Viscoelastic values varied in individual cases. 2) In the maxillary ridge area and the median portion, the values of modulus G and tan delta were low. In other words, the stiffness of these areas was low and the recovery from deformation was fast. 3) The values of modulus G and tan delta were high in the side region of the palate. The result showed that in this area there was a high stiffness and the recovery from deformation was slow. 4) In the incisive papilla and the area of flabby gum, the values of modulus G were low and the values of tan delta were high. The low stiffness and the slow recovery from deformation were shown in these areas.

Biomechanical Phenomena↗

PubMed1988

Comparison of intermittent or continuous methotrexate plus 6-mercaptopurine in regimens for standard-risk acute lymphoblastic leukemia in childhood (JCCLSG-S811). The Japanese Children's Cancer and Leukemia Study Group.

From 1981 to 1983, 131 previously untreated patients with acute lymphoblastic leukemia (ALL) standard-risk group were entered to the protocol JCCLSG-S811. Of 119 eligible patients, 115 (96.6%) attained complete remission by treatment with prednisone (PRD) plus vincristine (VCR) or vindesine (VDS). After preventive central nervous system (CNS) therapy including 18 Gy cranial irradiation and three doses of intrathecal methotrexate (MTX), the patients were assigned randomly to the two maintenance chemotherapies, Regimen A and Regimen B. Regimen A (intermittent regimen) consisted of PRD (120 mg/m2/day by mouth for 5 days) plus 6-mercaptopurine (6MP) (175 mg/m2/day by mouth for 5 days) plus VCR (2.0 mg/m2 intravenously) alternating biweekly with MTX (225 mg/m2 intravenously). Regimen B (continuous regimen) consisted of 6MP (50 mg/m2/day by mouth) plus MTX (20 mg/m2/week by mouth) combined with pulses of PRD and VCR (the same dosages as Regimen A) every 4 weeks. As the late intensification therapy (LIT), five courses of high-dose MTX (2000 mg/m2 per dose per week intravenously for three doses every 12 weeks) with leucovorin rescue were administered to all patients who were in continuous complete remission (CCR) for more than 2 years. Sixty and 55 patients, respectively, were registered in Regimen A and B. The CCR rates in Regimen A and B were 75.1% +/- 5.8% (mean +/- 1 SE) and 49.7% +/- 7.3% (P less than 0.01) at 4 years, and 72.1% +/- 6.3% and 49.7% +/- 7.3% (P less than 0.05) at 5 years, respectively. In Regimen B, CNS and testicular relapses increased after 3 years of CCR. In addition, the patients in Regimen B had a much higher incidence of infections than Regimen A. The LIT did not seem to have important effects on the duration of CCR. From these data we conclude that the intermittent cyclic regimen of 6MP and MTX may be more effective as compared to the continuous administration of these drugs in the maintenance chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1988