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Biomedical subjects

G Goto

Publications and source records attributed to G Goto.

At least 37 records · Page 2Linked to original sources
PubMed1992

Resin adhesion to the ground primary enamel: influence of etching times and thermal cycling test.

The purpose of this study was to investigate the influence of etching times and thermal cycling on resin adhesion on ground primary enamel. Two hundred bovine mandibular primary incisors were used. Materials used in this study were 40% phospholic acid gel, Photo Bond and Photo Clearfil A (Kuraray Co., Kurashiki, Japan) in PCA groups and 37% phospholic acid gel, Scotch Bond and Silux (3M Co., St. Paul, MN) in the Silux groups. The etching times were 0, 10, 20, 30 and 60 seconds. Shear bond strengths were tested. After the shear bond strength test, the test surfaces of the enamel and the resin specimens were observed using the SEM. The etching times that showed the highest bond strengths were 30 seconds both in the PCA non-thermal cycled group (80.10 +/- 13.01 MPa) and the PCA thermal cycled group (78.99 +/- 10.93 MPa), 20 seconds in the Silux non-thermal cycled group (76.77 +/- 12.99 MPa) and 60 seconds in the Silux thermal cycled group (63.61 +/- 19.64 MPa). The influence of thermal cycling test to the enamel-resin adhesion is relatively slight both in the PCA group and the Silux group.

Acid Etching, Dental↗
PubMed1992

Color changes of light-cured composite resins.

The color changes of light-cured composite resins over specified periods of time were examined. Silux Plus (3M Co.) light-cured composite resin disks (shades: U,Y,DY,L,G,UO,YO) 10 mm in diameter and 1 mm in thickness were made with 2 minutes of light exposure. Five specimens of each color were prepared. The specimens were stored in 37 degrees C artificial saliva. The colorimetric values of the specimens were measured first without a background color and then against a white plate immediately after curing and then 1 day, 1 month, 3 months, 6 months and 1 year later. The color measuring was performed with the Murakami Color Research Laboratory Fast Spectrophotometer CMS-500 and Flexible Sensor FS-3. For specimens without background color, the delta E*ab values of all shade guides increased for 6 months proportionately to the time elapsed. For specimens measured against a white plate, the delta E*ab values of all shade guides increased for 6 months after curing. However, compared to the 6 month delta E*ab values, the one year delta E*ab values increased in some shades and decreased in other shades. Using the values obtained immediately after curing as the standard, the delta E*ab of the month specimens with or with-out background color were over 1.2, meanwhile most one year specimens were near or over 2.5.

Color↗
PubMed1991

Central cholinergic agents. I. Potent acetylcholinesterase inhibitors, 2-[omega-[N-alkyl-N-(omega-phenyl-alkyl)amino]alkyl]-1H-isoindole- 1,3(2H)-diones, based on a new hypothesis of the enzyme's active site.

It has been suggested that the active site of acetylcholinesterase contains a hydrophobic binding site (HBS-1), which is closely adjacent to both the anionic and the esteratic sites. In this paper, we assumed that there exists another hydrophobic binding site (HBS-2), some distance removed from the anionic site. On this assumption, a new working hypothesis was proposed for the design of acetylcholinesterase inhibitors. A series of 2-[omega-[N-alkyl-N-(omega-phenyl-alkyl)amino]alkyl]-1H- isoindole-1,3(2H)-diones was designed based on this hypothesis and tested for its inhibitory activities on acetylcholinesterase. Some in this series were revealed to be more potent than physostigmine. Optimum activity was found to be associated with a five carbon chain length separating the benzylamino group from the 1H-isoindole-1,3(2H)-dione (phthalimide) moiety. Quantitative study of substitution effect on the phthalimide moiety revealed that hydrophilic and electron-withdrawing groups enhance the activity.

Acetylcholinesterase↗
PubMed1991

Reduction of 2,3,5-trimethyl-6-(3-pyridylmethyl)-1,4-benzoquinone by PB-3c cells and biological activity of its hydroquinone.

2,3,5-Trimethyl-6-(3-pyridylmethyl)-1,4-benzoquinone (CV-6504) has inhibitory activities on both thromboxane A2 synthase and 5-lipoxygenase as well as scavenging activity against active oxygen species. The latter two activities are closely related to the quinone moiety, which is reduced to a hydroquinone in the living body. Comparison of these two activities for both the quinone and hydroquinone showed that the hydroquinone form had superior activities. Concerning the reduction mechanism by PB-3c cells we can see that superoxide dismutase (SOD) has no influence on the rate of reduction, but dicumarol almost completely inhibits the reduction at a concentration greater than 1 x 10(-6) M. Therefore, it can be concluded that CV-6504 is reduced mainly by two electron donating enzymes without the intermediary of a semiquinone radical and that the resulting hydroquinone inhibits lipid peroxidation as well as 5-lipoxygenase activity.

Animals↗
PubMed1991

[Resin adhesion on the young permanent ground enamel (Report 3)].

The purpose of this study was to investigate the influence of thermal cycling on the adhesion of the resin on the young permanent ground enamel which was etched with different etching times. Labial surfaces of 50 extracted and frozen bovine mandibular young permanent incisors were used. The etchant used in this study was 40% phospholic acid gel and the etching times were 0, 10, 20, 30 and 60 seconds. All of the specimens were washed with an air water spray after etching. The bonding agent and composite resin used in this study were Photo Bond and Photo Clearfil A (Kuraray Co.). After thermal cycling tests of 10,000 temperature cycles between 60 degrees C and 4 degrees C water baths, shear bond strengths on the ground enamel were measured. After the shear bond strength tests, all the test surfaces of the enamel and resin specimens were observed using the SEM. The results of this study were compared with the previous results which were not thermal-cycled. The following conclusions were obtained. 1) The etching time which showed the highest bond strength was 30 seconds (45.21 +/- 8.49 Mpa). 2) When the enamel was etched with all of the etching times, the bond strength were significantly higher than that of the enamel without etching. 3) In the etched groups, the bond strength with 20 seconds of etching time was significantly lower than those with 10, 30 and 60 seconds of etching times. 4) In the 10, 30 and 60 seconds etching times, the bond strengths with thermal-cycled groups were significantly higher than those without thermal-cycled groups. 5) On the enamel specimens after the shear bond strength tests, the frequency of the clear prism structures observed on the enamel was higher in the groups which showed higher bond strengths. However, the differences were not significant.

Acid Etching, Dental↗
PubMed1990

Synthesis of isoindolo[2,1-a]quinoline derivatives and their effects on N2-induced hypoxia.

A variety of isoindolo[2,1-a]quinoline derivatives as well as the following related heterocycles have been prepared: 11b,12-dihydro-5H-isoindolo[2,1-b][2]benzazepine-7,13-dione (8a), 7,8,14,14a-tetrahydroisoindolo[2,1-c][3]benzazocine-5, 13-dione (8b), 6a,7-dihydroisoquinolino[2,3-a]quinoline-5,12-dione (12), 2,3,3a-4-tetrahydropyrrolo[1,2-a]quinoline-1,5-dione (14), and pyrido[2',3':3,4]pyrrolo[1,2-a]quinoline-5,11(5H)-dione (17). The key synthetic step involves an intramolecular Friedel-Crafts reaction of acid chlorides such as isoindole-1-acetyl chlorides (4), the acids (3) of which were prepared starting with 2-arylisoindole-1,3(2H)-diones (2-arylphthalimides) (1). The protective effects of isoindolo[2,1-a]quinoline derivatives (19 and 20) against N2-induced hypoxia were examined. Among them, 6-(diethylaminomethyl)isoindolo[2,1-a]quinoline-5,11(5H)-dio ne (19b) showed the most potency.

Animals↗
PubMed1990

[Pulpal response to diammine silver fluoride. (2). Application on exposed pulps].

A histopathological study was attempted to investigate the pulpal response to diammine silver fluoride which was applied on the exposed pulps. Cavity preparation was performed on healthy permanent teeth on mongrel dogs with an air water spray in order to expose the pulp tissue on the small area of the cavity floors. In the experimental group (28 teeth), 0.01 ml 38% diammine silver fluoride solution was applied on the cavity floors and the exposed pulps for 3 minutes after cavity preparation. In the control group (27 teeth), nothing was applied on the cavity floors and the exposed pulps. All the cavities of these groups were left open to the oral environment without any restoration. The specimens were processed for histopathological evaluation at 3, 7 and 30 days. The teeth were fixed in 10% neutral buffered formalin, embedded in celloidin, serially sectioned through the pulp and stained with hematoxylin and eosin. The following observations were obtained. 1. After 3 days, both of the 2 groups showed such severe histopathological changes as necrosis, suppurative inflammation, round cell infiltration, bleeding and hyperemia of pulps with high percentages (77.8%-100%). 2. After 7 days, both of the 2 groups showed partial-necrosis, suppurative inflammation, round cell infiltration, bleeding and hyperemia of pulps with high percentages (63.6%-100%). 3. After 30 days, the percentages of suppurative inflammation and round cell infiltration decreased, though the percentages of complete-necrosis of pulps increased in both of the 2 groups. 4. After 30 days, cicatrization of pulps and apposition of dentin on the pulp chamber wall were observed in each of 2 teeth (25%) in the experimental group, and in each of 2 teeth (16.7%) in the control group. 5. In the 2 groups, all of the teeth except one 30-day specimen in the experimental group and one 7-day specimen in the control group, which were histopathologically evaluated as fairly success, were histopathologically evaluated as failure. 6. Application of 38% diammine silver fluoride solution did not show any protective efficacy to exposed dental pulps.

Animals↗
PubMed1990

[A scanning electron microscopic investigation of accessory foramina on the pulpal floor of human primary molars. 1].

The pulp chamber floor of 39 primary first and second molars of 10 mandibuiars of the Indian scull was investigated with a scanning electron microscope for the presence of accessary foramens. All of the teeth investigated were in II A stage of Hellman's dental age. The teeth were sectioned with a diamond disk with a point of 1.5 mm apical to the external furcation area, and 5 mm coronal to the cervical line. The teeth were washed with a supersonic washer and dried. The specimens were mounted with the pulpal floor facing upward on an aluminium stub, plated with gold and observed with scanning electron microscope. As a result of this investigation the following conclusions were obtained. 1) Accessary foramens were observed in 4 mandibulars out of 10 mandibulars and in 14 teeth (35.9%) out of 39 teeth. 2) The maximum 10 and minimum one accessary foramen were found with an averrage of 2.8 per tooth. 3) Accessary foramens were observed with high frequency in the central portion of the pulp chamber floor. 4) The diameter of the opening of the accessary foramens of the mandibular first molars were maximum 83 microns, minimum 8 microns and average 45.4 microns. While maximum 51 microns, minimum 15 microns and average 37.3 microns in mandibular second molars. 5) The opening shape of accessary foramens was classified into three types, round 56.4%, oval 28.2% and others 15.4%. 6) Accessary foramen tend to be present bilaterally in the same individual. 7) It seemed that there is an individual difference in the presence or absence of accessary foramen. One individual has many accessary foramens, while another individual lacks accessary foramen.

Child↗
PubMed1990

[Resin adhesion on the primary ground enamel. (Report 1). Influence of the etching times].

The purpose of this study was to investigate the influence of the etching times on the adhesion of the resion on the primary ground enamel. Fifty extracted and frozen bovine mandibular primary incisors were used. The etchant used in this study was 40% phospholic acid gel and the etching times were 0, 10, 20, 30 and 60 seconds. All of the specimens were washed with an air water spray for 30 seconds after etching. The bonding agent and composite resin used in this study were Photo Bond and Photo Clearfil A (Kuraray Co.). Shear bond strength on the ground enamel were measured. After the shear bond strength test, all the test surfaces of the enamel and resin specimens were observed using the SEM. The following conclusions were observed. 1) The etching time which showed the highest bond strength was 30 seconds (80.10 +/- 13.01 MPa). 2) When the enamel was etched with all of the etching times, the bond strengths were significantly higher than that of the enamel without etching. 3) The bond strength with 10 seconds of etching time was significantly higher than that with 20 seconds of etching time, and the bond strength with 30 seconds of etching time was significantly higher than that with 10 seconds of etching time, and the bond strength with 30 and 60 seconds of etching time was significantly higher than that with 20 seconds of etching time. 4) On the enamel specimens after the shear bond strength test, clear prism structures were observed in the group which showed a higher bond strength. 5) On the enamel specimens after the shear bond strength test, the frequency of the resin tags were fractured inside of the enamel prisms was lower in the group which showed a higher bond strengths. 6) Thirty seconds is a sufficient time for etching on the primary ground enamel using Photo Bond and Photo Clearfil A.

Acid Etching, Dental↗
PubMed1990

[Restoration of composite on etched stainless steel crowns. (1)].

Object of investigation The retention of composite resin to etched stainless steel crowns was tested as a possible method for restoring primary anterior teeth. Method employed 1) SEM observation Stainless steel crowns (Sankin Manufacture Co.) were etched with an aqua resia to create surface roughness and undercut to retain the composite resin to the crowns. Etching times were 1, 2, 3, 5, 8, 10 and 20 minutes, then washed in a 70% alcohol solution using an ultrasonic washer and dried. A total of 96 etched samples and non etched control samples were observed through the scanning electron microscope (Hitachi 520). 2) Shear bond strength test Stainless steel crowns were etched in an aqua resia from 1 to 20 minutes, then washed and dried. Composite resin (Photo Clearfil A, Kuraray Co.) with the bonding agent was placed on the crowns and the shear bond strength was tested in 56 samples using an Autograph (DCS-500, Shimazu). Results 1) SEM observation showed that the etching surface of stainless steel crowns created surface roughness and undercut. The most desirable surface was obtained in the 3 to 5 minute etching time specimens. 2) The highest bond strength was obtained in a 3 minute etching specimen. It was 42.12 MPa, although 29.26 MPa in mean value. Conclusion Etching with an aqua resia increased the adherence of composite resin to the surface of stainless steel crowns.

Composite Resins↗
PubMed1990

[Color changes of light-cured composite resins. (1)].

The purpose of this study was to investigate the color changes of light-cured composite resins over specified periods of time. Composite resin disks which were 10 mm in diameter and 1 mm in thickness, and made by the 3M Co. light-cured composite resin Silux Plus (shades: U, Y, DY, L, G, UO, YO) were made with 2 minutes of light exposure through a 1 mm thick glass plate. The specimens were stored in 37 degrees C artical saliva. Chromatical values of the specimens immediately after curing, 1 day, 1 month, 3 months, 6 months and 1 year after curing were measured without background color, backed by a white plate. Color measuring was performed with the Murakami Color Research Laboratory Fast Spectrophotometer CMS-500 and the Flexible Sensor FS-3. 1) In the cases without background color, the delta E*ab values of all shades increased for 1 year proportionately to the time elapsed. In the cases backed by a white plate, the delta E*ab values of all shades increased for 6 months after curing, however, compared to the 6 month delta E*ab values, the 1 year delta E*ab values increased in some shades and decreased in other shades. 2) Both in the cases of with and without background color, compared to the delta E*ab values of immediately after curing, the 3 month delta E*ab values of all shades were over 1.2, and the 1 year delta E*ab values of many shades were near or over 2.5 and detectable to the naked eye. 3) Both in the cases of with and without background color, the L* values of all shades decreased for 6 months after curing. However, compared to the 6 month L* values, the 1 year L* values decreased in some shades and increased in other shades. 4) In the cases without background color, the a* values of all shades increased for 1 year after curing. In the cases backed by a white plate, the a* values of all shades increased for 6 months, however, compared to the 6 month a* values, the 1 year a* values of all shades decreased.(ABSTRACT TRUNCATED AT 400 WORDS)

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

[Resin adhesion on the primary ground enamel. (2) Influence of the etched enamel].

The purpose of this study was to investigate the influence of the etching times on the adhesion of the resin on the primary ground enamel. Fifty extracted and frozen bovine mandibular primary incisors were used. The etchant used in this study was 37% phospholic acid gel and the etching times were 0, 10, 20, 30 and 60 seconds. All of the specimens were washed with an air water spray after etching. The bonding agent and composite resin used in this study were Dual Cured Scotch Bond and Silux (3M Co.). Shear bond strengths on the ground enamel were measured. After the shear bond strength test, all the test surfaces of the enamel and resin specimens were observed using the SEM. The results of this study were compared with the previous results using Photo Bond and Photo Clearifil A (Kurarey Co.). 1) The etching time which showed the highest bond strength was 20 seconds (76.77 +/- 12.99 Mpa). 2) When the enamel was etched with all of the etching times, the bond strength were significantly higher than that of the enamel without etching (p less than 0.01). 3) In the etched groups, there was no significant difference among the bond strengths with all of the etching times categories. 4) In the etched groups, the longer the etching times, the lower the standard deviations were. 5) On the enamel specimens after the shear bond strength test, the frequency of the resin tags fractured inside of the enamel prisms was higher in the group which showed a lower bond strength. 6) For the same etching times, significant difference between the bond strengths of Silux and those of Photo Clearfil A was obtained only with the 20 seconds of etching time (p less than 0.01) and the bond strength of Silux was higher.

Acid Etching, Dental↗
PubMed1990

[Color differences between light-cured composite resin made shade guides and manufactured shade guides].

The purpose of this study was to investigate color differences between shade guides and light-cured composite resins. Resin specimens were made with resins and opaque resins of Silux Plus and Silux (3 M Co.) in a shade-guide metal mold. The resin specimens and the shade guides therefore were identical in shape and size. The sample resin specimens were compared with the shade guides provided with Silux Plus and Silux light-cured composite resins. Color measuring was performed with the Murakami Color Research Laboratory Fast Spectrophotometer C M S -500 and the Flexible Sensor F S -1. Specimens were placed on a plastic disc fixed to the top of the flexible sensor, and identical areas of their incisal, central, and cervical parts were measured. Conclusions. 1) The delta E*ab values between all shade guides and resin specimens showed color differences detectable to the naked eye. 2) Color differences between shade guides and resin specimens were great for the incisal colors (I, X L) and the deep and dark colors (D G, D Y, Y B, D G O, D Y O, Y B O, D D Y O). Color differences were relatively small, however, for the general colors (U, Y, G, U O, Y O, G O). 3) The L* values of shade guides ranged more widely than those of resin specimens. For many colors, L* values of the shade guides were lower than those of the resin specimens. 4) The a* values of shade guides and resin specimens were much more limited. The a* values of all colors showed minus values. The magnitude of a* values of shade guides were lower than those of resin specimens. 5) The b* values of shade guides were higher for some colors and lower for some colors than those of resin specimens.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

Effects of cleaning, polishing pretreatments and acid etching times on unground primary enamel.

The purpose of this study was to investigate the influence of cleaning and polishing pretreatments and etching times on unground primary enamel smooth surfaces with respect to the quality of etching patterns. Labial surfaces of 117 extracted or exfoliated caries free primary anterior teeth were used. Various cleaning and polishing methods were used before etching. Etching times with 40% phosphoric acid gel were 10, 30 and 60 seconds and all specimens were washed with an air water spray for 30 seconds. The following observations were obtained using the SEM. 1. There was not a significant difference between the appearance of prism structures by etching and the pretreatment methods in the 60 and 30 seconds etching. 2. The shorter the etching time, the higher was the rate of the cases which did not show any prism structure after etching.

Acid Etching, Dental↗
PubMed1989

Pharmacologic characterization of a novel non-benzodiazepine selective anxiolytic, DN-2327.

DN-2327, 2-(7-chloro-1,8-naphthyridin-2-yl)-3-[(1,4-dioxa-8- azaspiro[4.5]dec-8-yl)carbonylmethyl]isoindolin-1-one, produced anxiolytic, taming and anti-convulsive effects when administered orally to several species of animals. DN-2327 produced few of the sedative-hypnotic and muscle-relaxant effects observed with diazepam. The durations of the anxiolytic and anti-convulsive activities of DN-2327 were much longer than those of diazepam. Tolerance to DN-2327 did not develop when it was administered daily for 14 days in an anti-conflict test (Vogel conflict test). DN-2327 showed potent displacement activity against [3H]diazepam binding. The binding affinity of DN-2327 for benzodiazepine receptors was about twenty times that of diazepam. Furthermore, the affinity of DN-2327 for benzodiazepine receptors was not enhanced by the presence of GABA. There is a wide margin between the doses of DN-2327 that cause the anxiolytic effects and its sedative-hypnotic/muscle-relaxant effects. These results suggest that DN-2327 has more marked anxioselective properties compared with the benzodiazepines.

Aggression↗
PubMed1989

[Chromatic study of composite resins. Report 1. The influence of the color measuring instruments and the background colors on the chromatic values].

The purpose of this study was to investigate the influence of the structural difference of the color measuring instruments and the background colors on the chromatical values of the composite resins. Composite resin disks which were 10 mm in diameter and 1 mm and 2 mm in thickness, and made by the light-cured composite resin Silux Plus (3M Co.) were chromatically measured. The colors of the composite resin used in this study were universal, yellow, dark-yellow and light. The color measuring instruments used in this study were the Murakami Color Research Laboratory Fast Spectrophotometer CMS-500 used with the Flexible Sensor FS-1, FS-2 and FS-3, and the Murakami Color Research Laboratory Color Difference Meter CD-270 used with the Improved Light Guide CD-270. The diameters of the head which receives the light from the object were: FS-1 (2 mm), FS-2 (3 mm), FS-3 (5 mm) and Improved Light Guide CD-270 (2 mm). The chromatical values of the resin specimens were measured without back color, backed by a white plate and backed by a black plate. The chromatical values of the composite resin disks were measured with the different color measuring instruments under the different background colors. The XYZ, L*a*b* and xy values were compared and the following results were obtained. 1) The chromatical XYZ, L*a*b* and xy values of the composite resins showed different value patterns among the color measuring instruments. 2) Different influences of the background colors on the chromatical values of the composite resins were obtained among the different colors and different thicknesses of the resins in the cases of some color measuring instruments were used. 3) The most precise color measuring instrument for chromatical measuring of the composite resins among the instruments used in this study was the Fast Spectrophotometer CMS-500 used with the FS-3. 4) Prior to the comparison of the chromatical values measured by the different color measuring instruments, the chromatical values obtained by measurement with the same specimens should be compared and the structural differences, the precision and the sensitivities of the instruments should be understood.

Color↗
PubMed1989

[Effect of acid etching on the primary enamel smooth surfaces. (3) A study of the etching times].

The purpose of this study was to investigate the influence of etching times for the effect of acid etching on the primary enamel smooth surfaces. Fifty labial surfaces of the extracted or exfoliated caries-free primary anterior teeth were used. The cleaning and polishing pretreatment used in this study was polishing with a brush cone (Howe-Neos-Dental Co.) with water at a low speed (600-6000 r.p.m.). The etchant used in this study was 40% phospholic acid gel and the etching times were 10, 30, 60, 90 and 120 seconds. All specimens were washed with an air water spray for 30 seconds after etching. The following observations were obtained using the SEM. 1. The shorter the etching time, the higher was the rate of the cases which did not show any prism structure. 2. The numbers of the cases which did not show any prism structure were: 4 (40%) out of the 10 in 10 seconds etching, 2 (20%) out of the 10 in 30 seconds etching and 1 (10%) out of the 10 in 60 seconds etching. All cases showed prism structure in 90 seconds and 120 seconds etching. 3. The most common etching patterns in all etching times were poorly structured etching patterns. 4. The longer the etching time, the higher was the rate of the cases which showed peripheral etching patterns. 5. Tooth to tooth differences in the etching effects and patterns were observed under the same etching times. Various etching effects and patterns on the same enamel surface were observed. 6. Among the etching times used in this study, 90 seconds was an adequate time for etching on the unground primary enamel smooth surfaces polished with a brush cone.

Acid Etching, Dental↗