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Biomedical subjects

E Nagaoka

Publications and source records attributed to E Nagaoka.

At least 19 recordsLinked to original sources
PubMed2006

Influence of lip support on the soft-tissue profile of complete denture wearers.

Complete dentures change the soft-tissue profile, although the exact relationship remains unclear. This study examined the relationship between the presence and degree of lip support provided by dentures and the lateral views of the facial appearance of edentulous patients. The subjects were five edentulous patients (three men and two women). Their facial appearances with experimental record blocks, with and without their complete dentures, were measured using a three-dimensional laser measuring system. The experimental record block for each subject had different conditions in the anteroposterior direction anteriorly but the same vertical dimensions posteriorly. The lateral digital facial images were displayed on a computer monitor, and the linear and angular measurements were analysed using image analysis software. The nasolabial angle was smaller and the labial points projected more with excessive lip support versus with deficient support. Moreover, the counter of the nose was affected by the labial flange of the record base, particularly in the facial appearance of one subject with highly atrophic residual ridges. The lip support affected the lower facial soft-tissue profile, including the lower part of the nose; the nasolabial angle and positional relationship between the lips and Ricketts's esthetic plane (E plane) are useful indexes for examining lip support.

Aged↗
PubMed2002

Effects of oestrogen deficiency on osteoclastogenesis in the rat periodontium.

This study was designed to investigate quantitative changes in osteoclast generation in rat periodontium following ovariectomy. Wistar rats, aged 9 weeks, were subjected to either ovariectomy (OVX) or sham surgery. Osmotic pumps were implanted in 24 rats and either 17beta-oestradiol or vehicle solution were infused continuously. The rats were assigned to one of the following groups: (1) OVX+vehicle; (2) sham+vehicle; or (3) OVX+ 17beta-oestradiol. On the days 7 and 14 after surgery, four rats in each group were killed. Mandibles were demineralized and embedded in paraffin. Frontal sections of alveolar bone in the region of the first molar were cut for enzyme histochemistry and immunohistochemistry. On day 7, there was no significant difference in the number of tartrate-resistant acid phosphatase (TRAP)-positive cells located on bone surfaces in either group. However, the number of TRAP-positive mononuclear cells that were separated from the bone surface was significantly higher in group 1 than in groups 2 and 3. On the day 14, the number of TRAP-positive cells in group 1, which were attached to the bone surface, was significantly higher than had been apparent on day 7. There were also significant increases in the number of nuclei of TRAP-positive cells attached to the bone in group 1 compared with groups 2 and 3 on day 14. These findings demonstrate that oestrogen deficiency induces of osteoclastogenesis in the rat periodontium and that quantitative changes in osteoclastogenesis could be prevented by E2 infusion.

Acid Phosphatase↗
PubMed2002

Immunolocalization of osteoclast differentiation factor in rat periodontium.

The aim here was to observe the immunohistochemical localization of osteoclast differentiation factor (ODF)/receptor activator of NF kappa B ligand (RANKL) in the rat periodontium. Rat mandibles were demineralized and embedded in paraffin, and horizontal and frontal sections were prepared for immunohistochemical analysis. In horizontal sections, immunolocalization of RANKL was marked in the distal area of the periodontium of molars in which osteoclasts appeared, due to physiological tooth drift. In frontal sections, RANKL immunoreactivity was localized on spindle-shaped mesenchymal cells around blood vessels near the bone surface in the periodontium. In addition, immunoreaction for RANKL was detected on structures that appeared to be elongated cell processes near blood vessels in frontal sections. Immunohistochemical examination for the general antigen of nerve-specific protein suggested a similarity between these structures and nerve fibres.

Acid Phosphatase↗
PubMed2002

Dynamic viscoelastic properties of commercial glass-fibre reinforced resin used for crowns and bridges.

In order to investigate the thermal stability, the physical and mechanical, and dynamic viscoelastic properties of glass-fibre reinforced composite materials were measured. The G' of the seven materials examined was within 5;20 +/- 14; 55 and 4;50-14; 35 GPa for dry and wet specimens in air at 37 degrees C, respectively, and decreased with increasing temperature. The G' values of dry specimens decreased by 7;74-15;4% when heated to 60 degrees C. The value of tan delta ranged from 0;0102 to 0;0295 and from 0.0181 to 0.0406 for dry and wet specimens in air at 37 degrees C, respectively. The coefficient of linear thermal expansion between 30 and 60 degrees C ranged from 0;557 to 3; 95 x 10-5/ degrees C. Moreover, the filler content ranged from 56; 36 to 88; 87 wt%. These results showed that the magnitudes of G', tan delta, and the coefficient of linear thermal expansion and water absorption depend on the inorganic filler or glass-fibre content; i.e. the amount of resin matrix. Moreover, for all the materials examined, the G' values were thermostable in the temperature range encountered in the oral cavity.

Absorption↗
PubMed2000

Impression pressures against teeth in a partially edentulous model with a mobile tooth: influence of impression tray design.

The purpose of the present study was to examine the effect of custom tray designs on local pressures against teeth during the impression procedure. In a previous study, a partially edentulous simulation model with a mobile tooth was used, and the effect of custom tray designs on the displacement of the mobile tooth was examined during the impression procedure. Based on that study's results, we have assumed that the differences in impression pressures between the labial and the lingual sides of a mobile tooth could either cause or affect displacement. The present study was undertaken to determine the local impression pressures against each side of three anterior teeth, including one mobile tooth, using the same simulation model and the same custom trays as in the previous study. It was found that the local pressures exerted against teeth during the impression procedure were affected by the custom tray designs and varied according to the coronal shape, axis inclination and location of the teeth.

Analysis of Variance↗
PubMed2000

The effect of oestrogen deficiency on the alveolar bone resorption caused by traumatic occlusion.

This study, using 132 female rats, was designed to investigate whether oestrogen loss facilitates alveolar bone alterations induced by traumatic occlusion. Rats were ovariectomized (OVX) or underwent sham-operation (Sham). Seven days after surgery, half of the rats in each group were subjected to experimental traumatic occlusion (trauma), and the other half were left untreated. Thus, there were four groups: OVX+trauma, Sham+trauma, OVX, and Sham. Rats in each group were killed 1, 3, 5, 7, or 10 days after the introduction of occlusal trauma. The resected mandibles were processed without decalcification, and histomorphometric measurements were performed in the alveolar bone adjacent to the periodontal ligament of the first molar. The statistical assessment of the time- and group-specific differences by analysis of variance revealed significant differences between the OVX+trauma and Sham+trauma groups in the resorption parameters, but not in the formation parameters. The results show that the alveolar bone dynamics induced by traumatic occlusion are enhanced by oestrogen deficiency.

Alveolar Bone Loss↗
PubMed1999

Malposition of the epiglottis after tracheal intubation via the intubating laryngeal mask.

The intubating laryngeal mask has been reported to be a successful method of tracheal intubation although advancement of the tracheal tube via the laryngeal inlet into the trachea cannot be seen. Damage to the larynx or other tissues may occur during blind passage of a tracheal tube. We report a case in which the tracheal tube, advanced blindly, tucked the epiglottis into the laryngeal inlet, resulting in oedema of the epiglottis. This case illustrates the potential for airway obstruction after extubation when using the intubating laryngeal mask as a blind intubation guide.

Epiglottis↗
PubMed1998

Analysis of residual ridges and ridge relationship by three-dimensional reconstruction method.

The purpose of this study was to develop a diagnostic system with which to determine the adequate area for artificial tooth arrangement on the posterior residual ridge. Edentulous plaster models and occlusion rims were measured by a non-contact type shape measurement system. Three trigonal pyramids and their impressions on the occlusion rims were used as landmarks for the analysis and superimposition of the analysis results for the upper and lower ridges. The data points were obtained at intervals of 0.5 mm in the lateral direction and of 0.25 mm in the anteroposterior direction, and were interpolated by cubic spline curves in the lateral direction. When the ridge contour of the reconstructed image came in contact with the tangent line inclined at 30 degrees to the tentative plane of occlusion at the buccal and lingual sides in the frontal section, the area between their points of contact on both sides was comparatively flat and was regarded as adequate for the artificial posterior tooth arrangement in this study. This diagnostic system seems to be useful in determining the adequate area for the artificial tooth arrangement on the posterior residual ridges of edentulous plaster models and in displaying their horizontal relationship.

Alveolar Process↗
PubMed1998

Displacement of a mobile tooth during impression procedure: effect of impression tray design.

When fabricating prostheses in a partially edentulous arch with some mobile teeth, it is important to minimize tooth displacement during the impression procedure. The present study examined the effect of custom tray designs on the displacement of a mobile central incisor in a mandibular simulation model with six anterior teeth. Twelve custom trays were designed according to the different spaces and perforated holes in the region of the remaining teeth. As a result, the degree of displacement of the mobile tooth could be reduced according to the size of spaces and the location of perforated holes in the custom tray.

Analysis of Variance↗
PubMed1998

A visual method for analysing bucco-lingual position of artificial posterior teeth. Part 1: use of the ridge crest.

We have developed a visual analysis method to examine the spatial relationship between the edentulous ridges and the bucco-lingual position of the artificial posterior teeth in complete denture fabrication. In this system, a non-contact type shape measurement system is used. We applied this system to the plaster models and the wax dentures of an edentulous patient. Using the measurement data on the upper and lower plaster models, we reconstructed their shape three-dimensionally and determined the points regarded as the ridge crests and the inter-alveolar crest lines in the frontal sections. To generate the upper and lower ridge crest lines which consisted of the points of the ridge crests, interpolation by B-spline curves was applied. Furthermore, the loft surfaces that we regarded as the consecutive inter-alveolar crest lines, were generated between the upper and lower ridge crest lines. The surface models of the plaster models and artificial teeth were displayed on the cathode-ray tube display unit, and the ridge crest lines and the consecutive inter-alveolar crest lines were superimposed on the surface models. This method could be utilized to visualize and examine the bucco-lingual position of the artificial posterior teeth in reference to the inter-alveolar crest lines.

Computer Graphics↗
PubMed1997

Trial of duplication procedure for complete dentures by CAD/CAM.

The purpose of this study was to duplicate the shapes of complete dentures by using a computer-aided design/manufacturing (CAD/CAM) system. The shapes of the complete dentures of an edentulous patient were measured using a non-contact type shape measurement system and morphological data at the interval of 0.25 mm were obtained in the X-axis and Y-axis directions. Measurement was performed from the occlusal surface and mucosal surface sides. Based on the three-dimensional morphological data, cutter paths for cutting were generated. For cutting, the three-step method consisting of rough cutting, finish cutting, and partial finish cutting was used and for duplicating the dentures the modelling wax was cut using a computerized numerical control (CNC) processor and ball-end mills with diameters of 6 mm and 1 mm. The method for the controlling of three axes (X, Y, and Z) of CNC machine was used, and cutting was performed only from two directions. Although further improvements are needed in the measurement and cutting in acute slope areas, the duplication of complete dentures appears to be possible using the CAD/CAM system.

Analog-Digital Conversion↗
PubMed1997

Application of a three-dimensional reconstruction method to analysis of the residual ridge.

The purpose of this study was to develop a new method of analysing the shape of the residual ridge. The line of the residual ridge crest was regarded as the reference for artificial tooth arrangement and a method of determining it was evaluated. The shape of a plaster model was measured with a contact-type shape measurement system. The measurement data in each frontal section were interpolated by cubic splines. The points corresponding to the residual ridge crest were calculated and superimposed onto the image of the plaster model on a monitor screen of an image processor. Using these points and the image of the plaster model, the line of the residual ridge crest was marked on the plaster model. It was concluded that this method could be used to determine the line of the residual ridge crest on a plaster model.

Algorithms↗
PubMed1990

[A consideration of determining the removal or retention of teeth in the patient with a few remained teeth].

The alveolar bone of edentulous ridge is resorbed after the teeth extraction and the subsequent denture insertion. For the periodontal structure, the stress transmitted along the longitudinal axis is favorable, but the horizontal stress is destructive. Under the overdenture application which the retained teeth have the reduced clinical crown, it is possible to prevent the alveolar bone resorption and to improve the involved teeth. However it is difficult for the inclined teeth to get the successful results. In a case, having a few remained teeth contained the embedded root stump and the overdenture being applicated, we obtained the suggestion as follows. 1. Also the embedded root stump is useful to prevent the alveolar bone resorption. 2. The top and direction of longitudinal axes of the inclined abutment teeth can be determined by means of surveying the least teeth movement when the stress was applied to the teeth by the fingers with dental pincette. 3. Also to the inclined abutment teeth, it is possible to transmit the stress along the longitudinal axes, when the overdenture has the contact with the short dome coping at the top and in the inferior area to the longitudinal axes inclined, and is relieved in the superior area to its axes.

Alveolar Bone Loss↗