Biomedical subjects

Masanori Hashimoto

Publications and source records attributed to Masanori Hashimoto.

At least 19 recordsLinked to original sources

PubMed2006

Diffusion-induced water movement within resin-dentin bonds during bonding.

It is thought that water-filled channels and nanovoids in resin-dentin bonds represent potential sites for degradation of bonds or hydrolysis of collagen or both. How water gains access to bonded interfaces is not clear. This study evaluated the diffusion-induced water uptake through resin-dentin interfaces during bonding. Two light-cured total-etch adhesive systems (Excite and One-Step Plus) and a chemical-cured adhesive (Amalgambond Plus) were used in this study. Dentin disks were placed in a split-chamber device, and the fluid movement across dentin was measured, with and without a physiological pressure, during bonding procedures and 24 h after bonding. For light-cured adhesives in the experimental groups, a 6 min interval of dark storage was conducted prior to light-curing, to evaluate the diffusion of water through the uncured resin monomers, and to test the effect of prolonged infiltration time of adhesives on water permeability of bonds. Prolonged adhesive infiltration reduced the water permeability of resin-dentin bonds for light-cured adhesives. Water gradients produced by bonding systems contribute to water movement across the dentin-adhesive interfaces during bonding procedures. Differences in chemical formulations for adhesive systems may lead to differences in the extent of diffusion-induced water movement and the amount of water within the resin-dentin bonds.

Dentin↗

PubMed2006

Relationship between survival rates and numbers of natural teeth in an elderly Japanese population.

OBJECTIVES: The objective of this study was to assess whether elderly people with 20 or more natural teeth were more likely to live longer than a cohort with less than 20 teeth. MATERIALS AND METHODS: Groups of elderly people over 80 years of age (24 males and 35 females) with 20 or more teeth (>or=20 group) were compared with elderly people (24 males and 35 females) with less than 20 teeth (<20 group). Follow-up studies were conducted at regular intervals for 10 years from July 1992 to July 2002. The cumulative survival rate of the >or=20 group (average +/- SE tooth number of teeth - males, 23.9 +/- 0.6; females, 23.8 +/- 0.4) was compared with the <20 group (average number of teeth - males, 3.8 +/- 1.1; females, 2.6 +/- 0.8). The multivariate Cox proportional hazard models with the number of teeth in a group (>or=20 group or <20 group). Smoking status and alcohol intake as covariates were used to adjust the cumulative survival rate. RESULTS: The male participants in the >or=20 group had a significantly higher cumulative survival rates (p < 0.05) than the <20 group at 18 and 21 months from baseline. There were no significant differences in survival rates between the female groups. Adjusted cumulative survival rate was significantly different at 72, 75 and 78 months between the >or=20 group and <20 group for males but not for females. CONCLUSION: Having 20 or more natural teeth was associated with increased survival rate in elderly males, but not among the elderly females.

Age Distribution↗

PubMed2006

Oral condition and health status of elderly 8020 achievers in Aichi Prefecture.

The purpose of this study was to investigate differences in oral condition and health status between persons with 20 or more teeth at the age of 80 (8020 elderly) and persons of the same age with less than 20 teeth (non-8020 elderly). This study was conducted by a team belonging to the Aichi Dental Association. Number of remaining teeth, Community Periodontal Index of Treatment Needs (CPITN), salivary blood test, masticatory ability, bone mineral density (BMD), grip strength, balance test (length of time one can stand on one leg with eyes open), height, weight and body mass index (BMI) were all examined. The percentages of CPITN code 0, 1 and 2 were 68% in the 8020 male elderly and 72% in the 8020 female elderly. The positive percentage in the salivary blood test in the 8020 elderly was lower than that in the non-8020 elderly. Masticatory ability was 1.55 g in the 8020 male elderly, and 1.53 g in the 8020 female elderly. Relative masticatory ability in the 8020 female elderly was 20% higher than that in the non-8020 female elderly. BMD in the 8020 female elderly was significantly higher than that in the non-8020 female elderly. Grip strength in the 8020 elderly was also significantly higher than that in the non-8020 elderly. The duration of balance test in the 8020 male elderly was 2.2 times longer than that in the non-8020 male elderly. The 8020 elderly showed good oral condition and health status was found to be better in the 8020 elderly than in the non-8020 elderly.

Aged, 80 and over↗

PubMed2005

The effects of common errors on sealing ability of total-etch adhesives.

OBJECTIVES: This study evaluated the effect of errors commonly made in using total-etch adhesives, on the resulting bond strength, fluid movement and nanoleakage of resin dentin bonds. METHODS: Two total-etch adhesives were used for bonding to dentin according to the manufacturers' recommendations, with meticulous solvent evaporation (control), or with the introduction of common bonding errors-wet bonding without solvent evaporation (no evaporation), and dry bonding. RESULTS: The 24-hour bond strength of the control was significantly higher than the other groups (p <0.05). For all groups, the higher initial permeability declined significantly after 24 h. The fluid movement across bonded dentin was similar in the control and dry bonding for both adhesives, whereas significantly higher permeability (p<0.05) was recorded for the no evaporation groups even after 24 h. Extensive silver impregnation within hybrid layers was seen by TEM in the no evaporation and dry bonding specimens after 24 h. Dry bonding caused collapse of the collagen matrix and interfered with resin infiltration. In contrast, inadequate solvent evaporation and/or residual water during dentin bonding results in dilution or incomplete polymerization of the resin, leading to severe nanoleakage formation. SIGNIFICANCE: Increased permeability associated with incomplete solvent evaporation in total-etch adhesives may lead to poor bond strength.

Acid Etching, Dental↗

PubMed2005

Permeability of adhesive resin films.

The purpose of this study was to quantify the permeability of adhesive resin films to water by measuring convective flow across thin films. Cured resin films were prepared with the use of five commercially available adhesive resins and an experimental resin. Two types of resin films were prepared from solvated comonomer blends within each product; resin films made before or after evaporation of solvent (10 s of drying with air-syringe). The permeability of the resin films was measured 30 min or 24 h after polymerization by placing the films in a split-chamber device. Fluid filtration rate through the resin films was measured with the use of 20 cm of water pressure. Osmotically induced water movement was measured by applying hypertonic aqueous solutions of CaCl2 or HEMA to the resin films. The results showed that evaporation of solvent before polymerization reduced the permeability of adhesive resin films, compared to permeabilities obtained without solvent evaporation. The cured adhesive resin films were all permeable to water, but to varying degrees.

Adhesives↗

PubMed2005

Effects of resin hydrophilicity on water sorption and changes in modulus of elasticity.

UNLABELLED: As acidic monomers of self-etching adhesives are incorporated into dental adhesives at high concentrations, the adhesive becomes more hydrophilic. Water sorption by polymers causes plasticization and lowers mechanical properties. The purpose of this study was to compare the water sorption and modulus of elasticity (E) of five experimental neat resins (EX) of increasing hydrophilicity, as ranked by their Hoy's solubility parameters and five commercial resins. METHODS: After measuring the initial modulus of all resin disks by biaxial flexure, half the specimens were stored in hexadecane and the rest were stored in water. Repeated measurements of stiffness were made for 3 days. Water sorption and solubility measurements were made in a parallel experiment. RESULTS: None of the specimens stored in oil showed any significant decrease in modulus. All resins stored in water exhibited a time-dependent decrease in modulus that was proportional to their degree of water sorption. Water sorption of EX was proportional to Hoy's solubility parameter for polar forces (delta(p)) with increasing polarity resulting in higher sorption. The least hydrophilic resin absorbed 0.55 wt% water and showed a 15% decrease in modulus after 3 days. The most hydrophilic experimental resin absorbed 12.8 wt% water and showed a 73% modulus decrease during the same period. The commercial resins absorbed between 5% and 12% water that was associated with a 19-42% reduction in modulus over 3 days.

Absorption↗

PubMed2005

Technique-sensitivity of contemporary adhesives.

Besides micro-mechanical interlocking through hybrid-layer formation, self-etch adhesives may benefit from additional chemical interaction between the functional monomer and residual hydroxyapatite. One-step adhesives are commonly associated with lower bonding effectiveness, which must be attributed in part to the dissolution of hydrophilic and hydrophobic monomers in a relatively highly concentrated solvent. In this 'difficult' mixture, also water is essential as ionization medium to enable self-etching activity. Due to the high hydrophilicity, one-step self-etch adhesives have been reported to behave as semi-permeable membranes, allowing fluids to pass through and seriously jeopardizing bond durability. Recent research has also revealed that HEMA-free one-step adhesives are prone to phase-separation, which may also account for their lower bonding effectiveness. Employing an appropriate air-drying technique may, however, improve the bonding effectiveness of such phase-separating adhesives by getting rid of substantially more interfacial water than HEMA-containing adhesives, of which water might be more difficult to remove from.

Acid Etching, Dental↗

PubMed2005

[Prolonged cerebral salt wasting following craniopharyngioma surgery and posterior reversible encephalopathy syndrome: a case report].

A 9-year-old boy was admitted to our hospital with daytime urinary incontinence for the past one year. MRI showed craniopharyngioma occupying the third ventricle. The tumor was excised by interhemispheric approach. Because hyponatremia and polyuria with high renal loss of sodium were observed on postoperative day 3, hydrocortisone and DDAVP were replaced. On postoperative day 24, successive general convulsions and hyponatremia recurred, and MRI FLAIR imaging showed marked brain edema in the bilateral parieto-occipital lobes. This finding disappeared late in the course of treatment, and the case was diagnosed as posterior reversible encephalopathy syndrome. The pathophysiology of cerebral salt wasting and posterior reversible encephalopathy syndrome in a craniopharyngioma patient are also discussed in the article.

Brain↗

PubMed2005

Conversion of one-step to two-step self-etch adhesives for improved efficacy and extended application.

PURPOSE: One-step self-etch adhesives have restricted use due to their acid-base incompatibility with autocured composites and their behavior as permeable membranes after polymerization. This study examined the feasibility of their conversion to two-step self-etch adhesives via the adjunctive use of a non-solvented, relatively hydrophobic resin coating. METHODS: iBond, Xeno III and Adper Prompt were used either in multiple coats, or in a single coat followed by the use of a layer of Scotchbond Multi-Purpose Plus bond resin for coupling to light- and auto-cured composites. Four types of experiments were performed. Bonded specimens were examined with TEM after immersion in an ammoniacal silver nitrate tracer. Fluid flow measurements of iBond were conducted using the two application protocols to compare the permeability of the bonded dentin with the original smear layer. Permeability of vital dentin bonded with both application protocols were compared for the transudation of dentin fluid across the bonded dentin. Microtensile bond strengths of dentin bonded with the two protocols were examined for their compatibility with an auto-cured composite. RESULTS: The results of the four experiments were complementary. iBond and Xeno III exhibited "apparent incompatibility" to auto-cured composites that resulted from their inherent permeability. This was confirmed by the presence of dentin fluid transudate on the adhesive surfaces when they were bonded to vital dentin. Conversely, Adper Prompt exhibited "true incompatibility" to auto-cured composites that was caused by adverse acid-base interaction, masking the inherent permeability of this adhesive. "True" and "apparent" incompatibility issues were eliminated upon their conversion to two-step self-etch adhesives.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2005

Effects of multiple coatings of two all-in-one adhesives on dentin bonding.

PURPOSE: Simple changes to bonding technique can improve resin-dentin bond strengths. The objective of this study was to evaluate the effects of multiple coatings of two all-in-one adhesive resins on both microtensile bond strength (microTBS) and nanoleakage. MATERIALS AND METHODS: The mid-coronal occlusal dentin of extracted human molars was used. Two all-in-one adhesives--iBond (Heraeus Kulzer) and Xeno III (Caulk Dentsply)--were applied to 320-grit abraded dentin surfaces. In groups 1 and 3 during bonding, monomer application and solvent evaporation were done 1, 2, 3, 4 or 5 times on the dentin surface before light curing. In groups 2 and 4 after light curing the first layer, the adhesive was re-applied, the solvent evaporated, and the layer light cured. This was repeated from 2 to 5 times, followed by creation of composite buildups. After 24 h storage in 37 degrees C water, the teeth were sectioned perpendicular to the adhesive interface to produce multiple beams of composite-bonded dentin, approximately 0.9 mm2 in area. These were tested to failure in tension. Data were evaluated by three-way ANOVA (material vs coatings vs light curing) followed by multiple comparisons at alpha = 0.05. Additionally, nanoleakage of silver uptake and adhesive layer thickness were evaluated using transmission electron microscopy (TEM). RESULTS: The results indicated that bond strengths increased with the number of coatings (p < 0.0001) with both adhesives, up to 3 layers, especially if each layer was light cured. Nanoleakage of silver tended to decrease with each coat in both adhesive systems. CONCLUSION: By simply applying more coats of adhesive, the strength and quality of dentin adhesion can be improved.

Composite Resins↗

PubMed2005

Expression of human telomerase reverse transcriptase gene and protein, and of estrogen and progesterone receptors, in breast tumors: preliminary data from neo-adjuvant chemotherapy.

Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase, is very closely associated with telomerase activity. Telomerase has been implicated in cellular immortalization and carcinogenesis. In situ detection of hTERT will aid in determining the localization of telomerase-positive cells. The aim of this study was to detect expression of hTERT mRNA, hTERT protein, estrogen receptor (ER) and progesterone receptor (PR) in paraffin-embedded breast tissue samples and to investigate the relationship between hTERT expression and various clinicopathological parameters in breast tumorigenesis. We used in situ hybridization (ISH) to examine hTERT gene expression, and immunohistochemistry (IHC) to examine expression of hTERT protein, ER and PR, in breast tissues including 64 adenocarcinomas, 2 phyllode tumors and their adjacent normal breast tissues. hTERT gene expression was detected by ISH in 56 (88%) carcinomas, but in neither of the 2 phyllode tumors. hTERT protein expression was detected by IHC in 52 (81%) carcinomas, but in neither of the 2 phyllode tumors. Moreover, ER and PR were expressed in 42 (66%) and 42 (66%) carcinomas, respectively, and in neither of the 2 phyllode tumors. In 4 cases of breast carcinoma that strongly expressed hTERT gene and protein before treatment, neo-adjuvant chemotherapy led to disappearance of gene and protein expression in all cases. There was a strong correlation between detection of hTERT gene expression by ISH and of hTERT protein by ICH in tissue specimens from breast tumors. These results suggest that detection of hTERT protein by ICH can be used to distinguish breast cancers as a potential diagnostic and therapeutic marker.

Adenocarcinoma↗

PubMed2004

A case of abdominal CSF pseudocyst associated with silicone allergy.

CASE REPORT: The authors present a case of a patient with an abdominal CSF pseudocyst that resulted from an allergic reaction to silicone. The patient underwent repair surgery of the meningomyelocele associated with the Chiari II malformation, and the V-P shunt was instituted at 6 months of age. A formation of the abdominal CSF pseudocyst and the consequent shunt malfunction were observed 40 days after the V-P shunt. An increase in the number of the peripheral eosinophils and serum immunoglobulin E (IgE), and an infiltration of eosinophils in the specimen harvested from the pseudocyst wall suggested an allergic reaction as the cause of the pseudocyst. A sixth operation to revise the V-P shunt was performed using the shunt system made of "extracted silicone", which was produced extracting the allergic substances. OUTCOME: The serum IgE was normalized after surgery and the abdominal CSF pseudocyst has not recurred for 22 months.

Abdomen↗

PubMed2004

Deproteinizing effects on resin-tooth bond structures.

This study investigated the effects of NaOCl on resin-tooth bonds to simulate the situations of long-term durability and caries invasion. Resin-tooth bonded specimens were produced with the use of two resin adhesives (Excite and One-Bond). Resin-tooth bonded beams (adhesive area; 0.9 mm2) were serially sectioned and the specimens were immersed in 10% NaOCl medium for 0 (control), 2, 4, and 6 h after being stored in water for 24 h. After immersion, microtensile bond tests were performed. SEM fractography was conducted to calculate each failure mode by image analysis. In addition, the adhesive interface was examined with the use of TEM. In the control specimens, enamel bond strengths had no difference between Excite (45.6 +/- 15.0) and One-Bond (56.9 +/- 12.9). On the other hand, dentin bond strengths had significant difference between Excite (80.6 +/- 21.2) and One-Bond (50.7 +/- 11.2). The bond strengths decreased with increased storage time for both systems with enamel and dentin bonds. The deteriorated mineralized dentin of beams resulted in bond-strength reduction for resin-enamel bonds. For dentin bonding, the adhesive interface was gradually dissolved from the outer to the center portion of the beam. The depletion of collagen fibrils within the demineralized dentin or hybrid layer deformation was found under SEM and TEM examinations. These morphological changes are responsible for bond strength reduction of resin-dentin bonds.

Dental Materials↗

PubMed2004

Optical and surface morphological properties of polarizing films fabricated from a chromonic dye by the photoalignment technique.

The inherent chromonic lyotropic liquid crystalline properties of a dye have been manipulated to fabricate multi-axial micropolarizing thin films by means of the photoalignment technique. The dye aqueous solution is deposited on a photopatterned polymer film to result in the macroscopic alignment of the dye molecules, followed by drying at ambient temperature. The solid polarizing dye layers thus produced exhibit very a high contrast ratio and degree of polarization in the region of visible light. Addition of a small amount of surfactant to the dye solution is a prerequisite for the generation of a nematic chromonic phase and for the formation of homogeneous thin dye layers on the polymer film. The correlation between the optical and surface morphological properties of the dye layers is discussed.

Coloring Agents↗

PubMed2004

Forty-three cases of obturator hernia.

BACKGROUND: Obturator hernia is a relatively rare pelvic hernia and usually occurs in elderly, thin, multiparous women. Because symptoms are nonspecific, the diagnosis is often delayed until laparotomy is performed form to treat bowel obstruction. METHODS: Forty-three patients with obturator hernia undergoing surgery at Tokyo Metropolitan Geriatric Hospital were divided retrospectively into two groups (group A = 23 patients from 1968 to 1986 before computed axial tomography [CAT] was developed; group B = 20 patients from 1987 to 1999 after CAT). Preoperative diagnosis, operative procedures, and postoperative course were reviewed and compared between the 2 groups. RESULTS: Preoperative diagnostic accuracy was significantly higher in group B at 80.0% (16 of 20 patients) than in group A at 43.5% (10 of 23 patients) (P = 0.0146). Rate of gut resection and mortality were significantly lower in group B at 25.0% (4 of 20) and 5.0% (1 of 20) than in group A at 52.2% (12 and 23) and 30.4% (7 of 23) (P = 0.0295 and P = 0.0385, respectively). CONCLUSIONS: The use of pelvic CAT in cases of suspected obturator hernia significantly enhances preoperative diagnostic accuracy and helps to decrease both intestinal resection rate and surgical mortality.

Aged↗

PubMed2004

Accuracy of linear-array EUS for preoperative staging of gastric cardia cancer.

BACKGROUND: The feasibility of a less invasive operation for early stage cancer of the gastric cardia with a low frequency of lymph node involvement has been previously demonstrated by us. Precise discrimination among mucosal, submucosal, and advanced cancers, as well as accurate evaluation of the proximal tumor margin are prerequisites for such stage-specific treatment. EUS is considered the most reliable staging modality. However, there is no EUS study specifically of cardia cancer. METHODS: Forty-five patients with gastric cardia cancer who underwent gastrectomy with at least first-tier lymphadenectomy were retrospectively analyzed. The results of preoperative linear-array echoendoscopy (7.5 MHz) with respect to cancer depth, lymph node involvement, and esophageal invasion were compared with postoperative histopathologic findings. RESULTS: Overall diagnostic accuracy for depth of invasion was 71%. Sensitivity for T1, T2, and T3 lesions was 100%, 31% and 75%, respectively. Overstaging of T2 cancers was the main diagnostic error. Mucosal (pT1-m) and submucosal (pT1-sm) cancers were correctly discriminated in 81% of patients. Diagnostic accuracy for lymph node involvement was 80%. EUS had positive and negative predictive values of 90% and 80%, respectively, for esophageal invasion. CONCLUSIONS: For gastric cardia cancer, the linear-array echoendoscope yielded satisfactory results with respect to depth of invasion, lymph node involvement, and esophageal invasion evaluation. The information obtained is useful to the performance of stage-specific treatment.

Adult↗

PubMed2004

New mechanical retention method for resin and gold alloy bonding.

OBJECTIVE: The purpose of this study was to improve adhesion between dental adhesive resins and 14K gold alloy by creating a sponge-like structure on the alloy surface which enhanced mechanical bonding. METHODS: The internal oxidation particles of Cu oxides precipitated on a 14K gold alloy surface after high-temperature oxidation at 800 degrees C in air were removed by pickling with an acid solution to create a sponge-like structure on the alloy surface. A PMMA resin containing 4-META as an adhesive monomer and a self-cured resin without 4-META were used to examine the effects of mechanical and chemical factors on bond strength. A thiophosphate-type metal primer (M-Primer II) was used in combination with 4-META resin to strengthen the chemical bonding of 4-META resin to the porous alloy surface. The surfaces of the alloy specimen treated by oxidation, pickling, and bonding with 4-META resin were analyzed using an electron probe X-ray micro-analyzer. RESULTS: SEM observation showed many resin tags on the resin side of the bond structure after removal of the gold alloy matrix with aqua regia. The bond strength of 4-META resin to the porous alloy surface was 38+/-3 (mean+/-SD) MPa whereas that to a flat alloy surface with the same composition was 19+/-1 MPa. The bond strength of a self-cured resin without 4-META to the porous alloy surface was 24+/-2 MPa. SIGNIFICANCE: A high bond strength was obtained when 4-META resin was bonded to the porous 14K gold alloy surface treated with M-Primer II.

Acrylic Resins↗

PubMed2004

Surgical treatment of endolymphatic sac tumor with adjunctive stereotactic radiation therapy--case report.

A 44-year-old man presented with an endolymphatic sac tumor (ELST) associated with von Hippel-Lindau disease, which required four surgical procedures within 10 years. The earlier two surgeries resulted in only partial removal of the tumor because of vigorous intraoperative bleeding. Stereotactic radiation therapy was performed twice. The intraoperative bleeding was easy to control in the third operation, and ultimately the tumor was totally extirpated in the fourth operation. Histological examination of the tumor specimen harvested in the final surgery showed that the tumor cells had clearly decreased in number, and the interstitial tissue had become fibrous with organization of the tumor vessels, compared with the tumor specimen from the first surgery. Preoperative radiotherapy may be effective to reduce the devastating intraoperative bleeding of ELST.

Adult↗