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Biomedical subjects

Y Tsuchitani

Publications and source records attributed to Y Tsuchitani.

At least 19 recordsLinked to original sources
PubMed2000

Effects of resin composite components on glucosyltransferase of cariogenic bacterium.

The aim of our study was to investigate the effect of resin composite components on glucan synthesis by glucosyltransferase (GTase) derived from a cariogenic bacterium, Streptococcus sobrinus B13. The eluates from cured composites stored in 0.05 mol/L potassium phosphate buffer (KPB) (pH 6.8) for 2 weeks at 37 degrees C stimulated the formation of water-insoluble glucan, whereas those from amalgam inhibited it. This finding suggests that the eluates from the resin composites enhance GTase activity and contribute to plaque formation. In the individual resin components, a diglycidyl methacrylate and triethylene glycol dimethacrylate significantly enhanced GTase activity. However, most polymerization inhibitors and accelerators were potent inhibitors of enzyme activity. Thus, GTase stimulation by eluates from resin composites is hypothesized to be heavily dependent on the effect of the eluated resin monomers, even though the other eluting components had inhibitory effects on GTase.

Composite Resins↗
PubMed1995

Marginal adaptability and fit of ceramic milled inlays.

The authors investigated the marginal adaptation and internal fit of ceramic inlay made by a ceramic milling system. The study's results indicated that the mean marginal and internal gap size of the ceramic inlay restorations was less than 100 microns, making the fit clinically acceptable.

Computer-Aided Design↗
PubMed1995

Relationship between the degree of conversion and internal discoloration of light-activated composite.

In order to elucidate the relationship between the degree of conversion and internal discoloration of light-activated composite, four experimental composites which contained different amounts of Bis-GMA and TEGDMA were prepared, and the degree of conversion and discoloration of each composite, with or without annealing, were determined. The degree of conversion was measured by Fourier transformation infrared spectroscopy and the color change was determined after 1, 2, 3 and 4 weeks of immersion in water at 60 degrees C. The non-annealed composites demonstrated a greater degree of conversion and less discoloration as the amount of TEGDMA was increased. Annealed composites showed a significantly greater degree of conversion and less discoloration compared with the non-annealed composites. The results indicate that the greater the degree of conversion, the less the discoloration of composite, and the correlation between the two factors was significant for light-activated composite.

Amines↗
PubMed1995

Relationship between particle size of barium glass filler and water sorption of light-cured composite resin.

The reaction of barium glass filler with water was determined by investigation of the effects of the particle size of barium glass filler on the water sorption rate and the mechanical properties of composite resin. Barium glass and quartz were milled to obtain powders with different average particle sizes. These powders were silanized and used as inorganic filler in composite resin. Photoactivated base monomer was loaded at 65% (w/w) with these fillers to prepare the composite resin paste. The water sorption of barium glass filled resin was always more than that of quartz filled resin. The amount of sorbed water obtained by barium glass filled resin increased as the particle size decreased. The particle size of the quartz filler did not affect the water sorption. The flexural strength of barium filled resin decreased after water immersion more than that of the quartz filled resin as the particle size decreased. These results suggest that the water durability of barium glass is low and the surface of barium glass filler is damaged by water. Water would be retained in the interface between the barium glass filler and the matrix resin.

Absorption↗
PubMed1995

Effect of particle variation on wear rates of posterior composites.

PURPOSE: To evaluate the relationship between filler size, shape, mechanical properties and wear resistance of posterior resin composite was evaluated. MATERIALS AND METHODS: Six UDMA/TEGDMA-based experimental resin composites consisting of different types of filler particles were investigated. These included four sized spherical fillers, (9.88 microns, 2.01 microns, 0.62 micron, 0.20 micron) and two irregular, (9.46 microns, 1.97 microns). Property measurements consisted of hardness and compressive strength. Wear resistance was evaluated by a three-bodied in vitro wear test. RESULTS: The composites containing the smallest sized spherical particle exhibited maximum mechanical strength and maximum wear resistance. The composites containing the largest spherical particle exhibited minimum wear resistance. There were no significant differences amongst those containing similar sized fillers regardless of particle shape. However, differences between the 0.20 microns spherical filled composite and other composites were statistically significant. SEM analysis showed that only the larger sized filler exhibited some exfoliation after wear testing. The smaller size spherical filler exhibited better mechanical strength and substantially higher wear resistance.

Analysis of Variance↗
PubMed1995

Antibacterial effect of composite incorporating Triclosan against Streptococcus mutans.

It has been shown that composite incorporating the antibacterial agent Triclosan (Irgasan DP 300, which is sparingly soluble in water, inhibited in vitro plaque formation by Streptococcus mutans, although the release of the agent was much less than the minimum inhibitory concentration for the bacterium. In this study, the inhibitory effect of the composite incorporating 1% Triclosan against growth and adherence of S. mutans was investigated. S. mutans was inoculated on the surface of a specimen made of control or Triclosan-incorporated composite and the number of bacteria was compared after 3, 6, 12 and 24 hr of incubation. The adherence of S. mutans to the control and experimental composite, with or without saliva treatment, was also examined by scanning electron microscopy. The composite incorporating Triclosan demonstrated significant inhibition of growth of S. mutans after 6, 12 and 24 hr of incubation. Adherence of S. mutans to the Triclosan-incorporated composite was less compared with control for both non-treated and saliva-treated specimens. It is concluded that the antiplaque effect of composite incorporating Triclosan depends upon its ability to inhibit bacterial growth and adherence, and Triclosan-incorporated composite is able to exhibit the antibacterial activity even after being treated with saliva.

Anti-Infective Agents, Local↗
PubMed1994

Incorporation of bacterial inhibitor into resin composite.

Attempts to produce resin composite with antibacterial properties by incorporation of an antibacterial agent such as chlorhexidine have been reported, but problems can arise due to release of the inhibitory agent from the composite. Such problems may include toxic effects, influence on mechanical properties, and loss of effectiveness. A new monomer, methacryloyloxydodecylpyridinium bromide (MDPB), was synthesized by combining an antibacterial agent and methacryloyl group. The monomer was incorporated into resin composite to develop a non-releasing antibacterial composite. The ability of composite incorporating MDPB to inhibit growth and plaque accumulation by Streptococcus mutans in vitro was assayed, elution of antibacterial components from the material was investigated, and the influence of incorporation of MDPB on the mechanical properties of composite was studied. Uncured MDPB revealed antibacterial activity against S. mutans and six other species of oral streptococci, with the minimum inhibitory concentration for S. mutans being comparable with that of triclosan. After composite incorporating MDPB was cured, no elution of the antibacterial components was observed from the material, even after 90 days' immersion in water or other solvents. Growth of S. mutans on agar under specimens of MDPB-containing composite was inhibited compared with controls. In a bacterial accumulation study, S. mutans accumulated to a lesser degree on the surface of composite incorporating MDPB (p < 0.05) than on control. Incorporation of MDPB had no significant influence on the mechanical properties of the composite.

Analysis of Variance↗
PubMed1994

Comparison of two methods for measuring generalized wear of dental materials.

The object of this study was to analyze two measuring methods for determining the amount of generalized wear of dental materials. Using a recently developed three-body wear testing machine, generalized wear defect was produced on the surface of various dental materials. Although the generalized wear was defined as the depth of the enamel exposed at the cavity margin for both methods, this depth was measured with two different devices. One is an image-analyzer and the other was a profilometer. From the results of this study, it was confirmed that measurement by means of profilometer gave almost the same wear values with those by image-analyzer. In addition, the measurement by profilometer seemed to be more precise and not very much sophisticated.

Composite Resins↗
PubMed1994

In vitro quantitative assessment of generalized wear of dental composites.

The purpose of this paper was to compare generalized wear resistance of eleven proprietary posterior dental composites and one amalgam using a recently developed in vitro wear testing apparatus. Upon completion of the in vitro wear testing process the wear area of occlusal surface was replicated and the depth of enamel exposed at the cavity margin was measured by a traveling microscope. Based upon the results of this study it was demonstrated that there were significant differences amongst materials included in this study. Also this wear test not only reproduced the microstructure of worn oclusal surface, but also predicted wear rates which correlated somewhat well with clinical performances.

Analysis of Variance↗
PubMed1994

Localized three-body wear of resin composites.

Localized wear tests have been performed on six resin composites using a recently developed three-body wear testing machine. After repeated loading to the composites, the worn surface was replicated. Then the wear values of the respective resin composites were determined from the surface area of the worn defect using an image-analyzer. In addition, the microstructure of the worn area was analyzed with a scanning electron microscope (SEM). This study revealed that a fine particle hybrid composite exhibited the greatest localized wear resistance of all resin composites investigated in this study. SEM of the microfilled resin composites showed some degradation between filler and matrix.

Acrylic Resins↗
PubMed1994

Shear bond strength of amalgam adhesives to dentin.

This study compared the bond strength of resinous adhesives used to bond amalgam to dentin. The adhesives were: All-Bond 2 (AB), Liner-F (LF), SuperBond C&B (SB), Amalgambond (AM), Photo Bond (PB), and Panavia (PA). Occlusal surfaces of non-carious molars were ground wet to 600 grit finish, exposing dentin. The dentin surfaces were conditioned and the adhesives were applied according to manufacturers' instructions. Dispersalloy amalgam (D) was condensed onto the adhesive immediately. For comparison, resin composite, Photo Posterior (PO) and Bis-Fil (BIS) were used. After 24 hours of storage in 100% humidity at room temperature, shear bond strengths were determined with a shear testing jig in an Instron testing machine at a crosshead speed of 0.5 mm/minute. The data were compared using ANOVA, P < 0.01. AB, LF, D had significantly higher bond strengths than other amalgam adhesives. There was no significant difference between SB, D and PB, PO. Bond strength of PB, PA, D was significantly higher than PA, D. Thus, there were significant differences among adhesives for bonding amalgams. Amalgam to dentin and composite to dentin bond strength were comparable except for the All-Bond groups. Fracture patterns at the dentin/restoration interfaces were examined by scanning electron microscopy (SEM).

Analysis of Variance↗
PubMed1993

Appearance of neuropeptide Y-like immunoreactive cells in the rat trigeminal ganglion following dental injuries.

The effects of these injuries on the presence and distribution of neuropeptide Y (NPY)-immunoreactive (-IR) neurones were examined immunohistochemically. In the normal trigeminal ganglion: some perivascular nerves displayed NPY-IR but there were no NPY-IR ganglionic cells. Fourteen days after extraction or pulp exposure of the upper first molar, NPY-IR cells appeared in the maxillary region of the trigeminal ganglion. About 90% of the injury-evoked NPY-IR cells had medium to large diameters (more than 300 microns2 in cross-sectional area). Shallow cavity preparation, however, did not induce the appearance of NPY-IR cells in the trigeminal ganglion. These results indicate the dental injuries alter the primary sensory neurones in the trigeminal ganglion.

Animals↗
PubMed1993

[The evaluation of interval period to prepare the left ventricle for Jatene operation for simple transposition of the great arteries].

Laboratory studies indicate that it can be as short as one week after a first-stage operation to prepare the left ventricle for a subsequent second-stage arterial switch (Jatene operation) for simple transposition of the great arteries (TGA). In order to ascertain it, we evaluated the left ventricular (LV) function immediately after the first-stage procedure and late postoperatively by echocardiography and catheterization. There were 6 cases with simple TGA. The age at palliation was 6.6 +/- 4.5 (mean +/- SD) months, and the interval between the first-stage and Jatene operation was 16 days-16 months (6.7 +/- 6.4 months). All patients survived after arterial switch. In 2 early infant cases, arterial switch operation was performed with ventilatory support due to cardiac and respiratory failures 16 and 21 days after the first-stage operation respectively. LV end-diastolic dimension increased by 1 week and showed no change after 1 week (n = 4). LV ejection fraction was depressed from 0.84 +/- 0.03 preoperatively to 0.61 +/- 0.08 at 1-4 days after the first-stage operation but improved to 0.83 +/- 0.06 by 7-9 days after that (n = 4). LV end-diastolic posterior wall thickness increased to more than 4 mm in 3 infant cases, more than 3 mm in 2 early infant cases by 7 days. The results of catheterization after the first-stage operation were as follows (n = 5); left ventricular right ventricular peak systolic pressure ratio increased from 0.53 +/- 0.16 to 0.94 +/- 0.04 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1991

False aneurysm formation of the great arteries after arterial switch operation.

An infant with simple transposition of the great arteries underwent a two-staged arterial switch operation, after which mediastinal infection occurred. Continuous irrigation with povidone-iodine solution was performed for 10 days. After that, the patient experienced life-threatening hemorrhage three times. At the time of the second hemorrhage, greater omental transfer was performed. On postoperative day 109, false aneurysm was recognized, having developed from both great arteries. Successful repair was performed on postoperative day 110.

Aneurysm↗
PubMed1991

Echocardiographic comparison of postoperative left ventricular contractile state between one- and two-stage arterial switch operation for simple transposition of the great arteries.

Left ventricular contractile function was compared between primary and two-stage arterial switch operation (ASO) in neonates and infants with simple transposition of the great arteries (TGA). Eight patients (group 1) underwent primary ASO at 13-42 (23 +/- 10 [mean +/- SD]) days of age, and five patients (group 2) underwent two-stage ASO after pulmonary artery banding and Blalock-Taussig shunting at 11-26 (15 +/- 3) months of age. Postoperative echocardiographic studies were undertaken at 6-48 (22 +/- 16) months of age in group 1 and 25-45 (32 +/- 7) months of age in group 2. The results were compared with those obtained from nine age-matched normal children (group N). To compare left ventricular contractile state among the patients, the deviations from the mean normal values in relations of end-systolic wall stress to fractional shortening and to rate-adjusted mean velocity of circumferential shortening (the stress-shortening index and stress-velocity index, respectively) were obtained for each patient. The stress-shortening index was significantly lower in group 2 (-3.1 +/- 3.1) than in group 1 (1.3 +/- 1.7, p less than 0.05); the stress-velocity index was significantly lower in group 2 (-3.3 +/- 1.8) than in group 1 (1.5 +/- 1.6, p less than 0.01) or in group N (-0.4 +/- 0.5, p less than 0.05). These results suggest that postoperative left ventricular contractility can be well preserved in patients after primary ASO for simple TGA in neonates, but there is a possibility of depressed contractility in patients after two-stage ASO.

Cardiac Surgical Procedures↗
PubMed1990

Factors affecting the amount of fluoride ion release from fluoride releasing resin.

The purpose of this study was to gain a deeper understanding of factors affecting fluoride-ion release from a newly developed fluoride releasing resin (F-resin) under various conditions. Both higher temperature and longer immersion times resulted in a greater amount of fluoride ion released from this material, whereas thermal cycling did not accelerate the fluoride release. It was also found that the amount of released fluoride ion increased with increase in pH. The experiments performed also demonstrated that the fluoride release rate was reduced by polishing or heating the test disc of F-resin. Although the amount of released fluoride ion varied with each experimental conditions employed, a fluoride ion release was always observed under all experimental conditions.

Fluorides↗
PubMed1990

Bonding ability of light cured composite resin to enamel and dentin promoted by various bonding systems--microleakage and bond strength studies.

The purpose of this study was to estimate bond strength between light cured composite resin and enamel or dentin, and marginal sealing ability of composite resin promoted by five commercial bonding systems. At first, tensile bond strength between light cured composite resin and enamel or dentin promoted by these bonding systems were measured. Next, class V cavities were prepared at cementoenamel junction of extracted human molars and filled with light cured composite resin, using the same bonding systems. Microleakage around the restoration was estimated by dye penetration test. All bonding systems presented high bond strength and good marginal sealing between composite resin and enamel. The bonding systems which presented high bond strength between composite resin and enamel or dentin inhibited microleakage around restoration effectively. However, no bonding system could inhibit microleakage completely at the cementum/dentin-composite resin interface.

Bisphenol A-Glycidyl Methacrylate↗