Biomedical subjects

T Nokubi

Publications and source records attributed to T Nokubi.

At least 19 recordsLinked to original sources

PubMed1998

Ontogeny of NADPH-diaphorase in rat forebrain and midbrain.

This study characterizes the developmental expression of NADPH-diaphorase from embryo to adulthood in the forebrain, midbrain and cerebellum of rat brain via histochemical staining. On embryonic day 12 no neurons stained. Labeling was observed in certain nuclei from E15 through the postnatal period to adulthood. Labeling in neurons increased or maintained a constant level with increased age. The embryo demonstrated substantial labeling in neurons of the caudate putamen, bed nucleus of the stria terminalis, preoptic area, lateral hypothalamic area, paraventricular thalamic nucleus, ventromedial hypothalamic nucleus, magnocellular nucleus posterior commissure, and periaqueductal central gray. Additional neuronal labeling was observed postnatally in the olfactory bulb, cerebral cortex, amygdala, various nuclei of the thalamus, interpeduncular nucleus, linear nucleus of the raphe, pretectal area and superior colliculus. In the cerebellum, labeling appeared only after P14 in cells of the molecular cell layer and granular cell layer. The sizes of labeled neurons developed significantly from P4 to P14 in several nuclei. The distinctive temporal and spatial expression pattern of NADPH-diaphorase implies that the NO/cGMP system may play an important role in physiological and developmental functions.

Age Factors↗

PubMed1997

Clinical observations of noncoping overdenture abutments protected by tannin-fluoride preparation.

STATEMENT OF PROBLEM: The exposed dentin of overdenture abutments can lead to caries. Therefore chemical protection is needed to prevent caries. Considering that dentin contains both organic and inorganic components, reinforcement of both components should give reasonable results. Tannin-fluoride preparation strengthens both the organic and inorganic components of teeth. PURPOSE: This study examined whether the tannin-fluoride preparation protects noncoping abutments. MATERIAL AND METHODS: Thirty-one subjects aged 36 to 86 years participated in the clinical trial. A trial autopolymerizing resin containing the preparation or a conventional autopolymerizing resin was applied to the inner surface of the denture base, which was in contact with the abutments. When there were autopolymerizing resin group abutments, there was also at least one preparation group abutment under the overdenture. RESULTS: The incidence of caries in the preparation and autopolymerizing resin groups were 0% and 0%, respectively, for the first 2 years, 4.5% and 0%, respectively, during the 3- to 4-year period, 13.8% and 75%, respectively, during the 5- to 8-year period, and 10% and 15%, respectively, in total. Gingival crevicular fluid demonstrated a tendency to decrease in both groups over time. CONCLUSION: The trial autopolymerizing resin containing the preparation has a long-term caries prevention effect, and helps to maintain gingival health. Without adding clinical steps, abutments can be protected by the tannin-fluoride preparation.

Adult↗

PubMed1995

Inhibitory effect of sympathetic stimulation on activities of masseter muscle spindles and the jaw jerk reflex in rats.

1. To evaluate sympathetic effects on jaw muscles, the discharges of masseter muscle spindle afferents, jaw muscle electromyographic (EMG) activities and blood flow changes were compared in anaesthetized decerebrate rats before and during electrical stimulation of the cervical sympathetic trunk. 2. To eliminate the possibility of efferent control from the trigeminal motoneurones, muscle spindle activity was recorded from the cut peripheral end of the masseter nerve. The absence of a sympathetic component in the masseter nerve was confirmed by the horseradish peroxidase method. 3. Electrical stimulation of the sympathetic nerve at frequencies within the physiological range reduced muscle spindle afferent discharges evoked by passive jaw opening. 4. Sympathetic stimulation also reduced the EMG activity evoked by the jaw jerk reflex, which may reflect a sympathetic effect on spindle afferents. After cessation of stimulation, a transient increase in EMG activity was observed, which may be due to efferent supply from the trigeminal motoneurones. During rhythmical jaw movements, no sympathetic effect on EMG activity was detected. 5. The above sympathetic effect on muscle spindle afferents and EMG activity was independent of blood flow changes.

Action Potentials↗

PubMed1995

Hardness of denture reline materials polymerized with different techniques.

Two kinds of hard type self-cured denture reline materials were polymerized using three different techniques: (1) on a surface of glass plate, (2) under water, (3) under water with some hardening agent. Hardness of specimens were measured longitudinally during three weeks periods of storage in water at 37 degrees C. Results of our study indicated that the specimen cured with the special hardening agent showed the higher hardness than those cured only in water. Most of the hardness changes took place during first three days of the experiment period.

Acrylic Resins↗

PubMed1994

A multimedia system for infection control education.

We developed a computer system for infection control education utilizing multimedia including video presentation. To evaluate the efficiency of the system, trial sessions were held among dental students attending final year of clinical courses. According to our results of comparison between pre and post assessment tests among these students, we concluded that this system has a great potential and advantages for achieving certain level of knowledge of infection control in limited amount of time.

Computer-Assisted Instruction↗

PubMed1994

Clasping system with rotational path of insertion Part 3. Clinical application.

This study investigated the retentive forces of rotational path clasping systems. Twelve rotational path removable partial dentures were applied in the clinical field and the retentive forces of the dentures were measured. The following results were obtained; 1. Retentive forces of the 12 dentures were varied from 187g to 1,380g. 2. As distances between abutment teeth increased from 10.9 mm to 27.7 mm, the retentive forces decreased accordingly (r = -0.56; p < 0.05). 3. As the inclination of the proximal surfaces was increased from 0 degrees to 50 degrees, the retentive forces showed a tendency to increase (r = +0.47). 4. Longer distances between abutment teeth as well as smaller inclination of proximal surface were present in three patients who answered that their dentures showed movement while eating. From these results, it became clear that the distance between abutment teeth and the inclination of the proximal surfaces greatly influenced the retention of the rotational path clasping system in the clinical field.

Dental Abutments↗

PubMed1994

Root surface caries of denture wearers in middle-aged and elderly people.

With an increasing number of elderly people retaining natural dentition, the number of exposed root surfaces and root surface caries is increasing. A total of 100 people, aged from 38 to 86, were examined for exposed root surfaces and root surface caries. Denture wearers and non-denture wearers were examined. The following results were obtained; 1. The percentages of exposed root surfaces were significantly higher (P < 0.05) in the 60's and 70's age groups. Root surface caries showed a tendency to increase until people were in their 60's. 2. Denture wearers had more exposed root surfaces (P < 0.05) and were more likely to have root surface caries than non-denture wearers. Denture wearers showed a tendency to have more severe grades of root surface caries than non-denture wearers. 3. Concerning denture wearers, there were not significant differences in the percentages of exposed root surfaces of buccal and proximal surfaces facing edentulous space. However, proximal surfaces facing edentulous space were more prone to root surface caries than buccal surfaces (P < 0.05).

Adult↗

PubMed1993

A new sectional partial denture utilizing lock mechanism for an upper removable partial denture.

A new sectional partial denture utilizing lock mechanism (lock denture) has been developed. Utilizing the lock mechanism, two parts of sectional partial denture are locked together easily and tightly. A lock denture has been constructed for an upper removable partial denture, has been worn for over three months and has clinically been proven to obtain good function and esthetics.

Ameloblastoma↗

PubMed1993

Clinical studies on marginal gingiva around abutment tooth (Part 3). Effect of tannin-fluoride preparation on gingival health.

It was examined whether the tannin-fluoride preparation (HY preparation), which might have a caries-reductive, plaque inhibiting and astringent action, could reduce the incidence of gingival inflammation around abutment teeth. Zinc oxide eugenol cement mixed with the HY preparation was packed in the cavity prepared in the resin base facing the abutment tooth. Gingival crevicular fluid (Periotron units:GCF), gingival index (GI), plaque index (PlI) and probing depth around the abutment teeth were measured over a 3 month period. The following results were obtained: 1. GCF decreased at month 1 and showed low values at months 2 and 3. 2. GI showed a decreasing tendency. 3. PlI and probing depth did not show obvious changes. These results indicate that the tannin-fluoride preparation reduces gingival inflammation around abutment teeth.

Adolescent↗

PubMed1993

Biomechanical study of temporomandibular joint on its form and function. Part I: Condyle morphology in frontal section.

In this study the mechanisms controlling the biomechanical relationship between form and function in the temporomanidbular joints were investigated using two-dimensional finite element analysis and optimization theory. Factors investigated included morphology and occlusion, the latter being an important attribute of this system. Results indicate that change in frontal condyle head morphology was closely related to the occlusion condition.

Biomechanical Phenomena↗

PubMed1993

Bending rigidity of composite resin coating clasps.

The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps.

Chromium Alloys↗

PubMed1992

Clinical application of a newly developed surveying system for designing and fabricating removable partial dentures.

In this paper, some problems in commercially available surveying systems were discussed, and a clinical technique for designing and fabricating clasps by using an improved 'Digital Surveyor' and a computer system were presented. This system has the advantages as follows: (1) morphological factors on abutment teeth could be measured and evaluated using the improved 'Digital Surveyor' and its accessories set, (2) clasps providing with proper mechanical properties according to various conditions in the mouth could be designed and fabricated precisely and easily. It became clear that conventional surveying methods involved empirical rules should be re-examined and replaced by the more rational surveying method like this system.

Computer-Aided Design↗

PubMed1992

Three dimensional shape measurement system for residual ridges.

It is very important for design and construction of complete dentures to evaluate the condition of residual ridges of edentulous patients objectively and precisely. The authors have been developing a shape measurement system for residual ridges. In this study, the outline of the system is described and the accuracy of the system is evaluated. The system consists of a high precision laser displacement meter, a working table and its controller, and a personal computer. The working table, on which a plaster model is placed, can move until the end of the moving range at a speed of 0.7 mm/sec. The height of the plaster model was measured intermittently with a frequency of 7 points/sec. To determine the accuracy of this system, experimental plaster models, which simulated the simplified shape of residual ridge, were measured and analyzed. The measurement error was 2.5%, which seemed to be highly accurate. The accuracy of the measurement decreased with the darkness of the color of the plaster model.

Alveolar Bone Loss↗

PubMed1992

Effects of heat treatment on mechanical properties of base metal wrought wire clasps.

The purpose of this study is to determine the effects of heat treatment and soldering on the change of shape and mechanical properties of cobalt-chromium-nickel alloy wrought wire clasps. The change of distance between the tips of the clasp arm was measured and mechanical properties were examined using the bending test. The following results were obtained. 1) By heat treatment at 500-700 degrees C for 10 minutes, bending rigidity and deflection at the proportional limit of the clasp arm increased significantly (p < 0.01), while permanent deformation after the bending test decreased considerably (p < 0.01). Concerning the deformation of clasp arms by heating, the distance between clasp tips increased remarkably above 500 degrees C (p < 0.01). 2) These mechanical properties of clasp arms were improved both by electric resistance soldering with silver solder and by heat treatment at 500 degrees C for 10 minutes after soldering. From these results, it was concluded that electric resistance soldering and adequate heat treatment were very effective to improve the mechanical properties of the clasp arm, especially to increase the deflection at the proportional limit and reduce the permanent deformation.

Chemical Phenomena↗

PubMed1992

Influence of dimensional factors and heat treatment on permanent deformation of wrought wire clasps.

The purpose of this study is to examine the fatigue profiles of wrought wire clasps during the clinical use. Cobalt-chromium-nickel alloy wires were bent into circular beams, which dimensions and fabrication methods were similar to the clinical cases. Deflections of 0.5 mm in a normal direction were applied 10,000 times to the tips of clasp arm and permanent deformations were measured. The following results were obtained. 1) The clasp arms with larger cross sectional diameter, shorter length and smaller radius of curvature showed larger amounts of permanent deformation. 2) The amounts of permanent deformation of the clasp arm remarkably decreased by electric resistance soldering and decreased further more by heat treatment at 500 degrees C for 10 minutes after soldering regardless of the number of deflection. From the results of this study, it was concluded that dimensional factors and heat treatment influenced the permanent deformation of the wrought wire clasps remarkably. Therefore, considering these factors, wrought wire clasps could be designed to reduce permanent deformation.

Chemical Phenomena↗

PubMed1990

[Teeth arrangement of anterior artificial teeth. 1. Age and teeth exposure].

In selecting and arranging anterior artificial teeth for edentulous patients, it is necessary to consider their sex, personality, age and other factors. The relation of upper and lower lip lines to incisal edge has been one of the standards for the selection and the arrangement of anterior artificial teeth. The purpose of this report was to establish and to evaluate decision bases for the selection and arrangement. We recorded and measured the exposure rate of anterior natural teeth (48 men, 46 women) during function, such as smile, pronunciation, by means of the image analysis. Following results were obtained. 1. As the age of patients increased, upper anterior teeth appeared less than lower's. 2. Differences in exposure ratio between upper and lower teeth were found more remarkable in smiling rather than in pronunciation.

Adult↗

PubMed1990

[Clinical studies on crevicular fluid of abutment tooth. 3. Effect of tannin-fluoride preparation on gingival health].

It was examined, in this study, whether the tannin-fluoride preparation (HY preparation), which might have a caries reductive, plaque inhibiting and astringent action, could reduce the incidence of gingival inflammation around abutment teeth for removable partial dentures. Zinc oxide eugenol cement mixed with HY preparation filled in the cavity prepared in the resin base facing the abutment tooth. Crevicular fluid (Periotron unit: GCF), gingival index (GI), plaque index (PII), probing depth and caries activity around the abutment tooth were measured during 12 months. The following results were obtained: 1. GCF decreased at 1 month later and showed low values at 2, 3, 6 and 12 months. 2. The percentage of low GI value showed an increasing tendency during the experimental period. 3. There was slight variation in PII and probing depth during the experimental period. 4. Caries activity showed a decreasing tendency. These results indicate that the tannin-fluoride preparation reduces not only caries activity but also gingival inflammation around abutment tooth.

Dental Abutments↗

PubMed1990

Clinical application of electric resistance welding and soldering methods to removable partial dentures.

The joining procedure for uniting metal structures is very important in the construction of removable partial dentures. However, it has several restricted problems in joining wrought wire clasps to rests or major connectors. For example, the base metal wires made of chromium-cobalt alloy are subject to changes in their mechanical properties caused by heating, and damage to acrylic resin materials (denture base and artificial teeth) occurs in the repair of removable partial dentures by using the torch soldering method. In this paper, in order to resolve these problems, an electric resistance welding machine was applied to attach wrought wire components to a removable partial denture framework. This welding machine was used to attach metal structures temporarily to each other, and to solder the welded joint with hard solder. Consequently, some problems of the conventional torch soldering method were improved by using the electric resistance welding and soldering methods. It was suggested that the clinical application of the electric welding and soldering methods was very useful in the construction of removable partial dentures.

Aged↗