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The article presents an experiment regarding the evaluation of the chemical stability of silver alloy in physiological saline and organic acids by immersion tests. The method used in the study was the immersion test wherein it dissolves the constituent elements of silver alloy. Result shows that silver alloy became more corrosive in organic acids than in physiological saline which can also dissolve constituent elements in the oral cavity.

In the 8th edition of Japan's Specifications and Standards for Food Additives, the purity test for silicone resins requires the determination of the refractive index and kinetic viscosity of the extracted silicone oil, and allows for only a limited amount of silicon dioxide. In the purity test, carbon tetrachloride is used to separate the silicone oil and silicon dioxide. To exclude carbon tetrachloride, methods were developed for separating the silicone oil and silicon dioxide from silicone resin, which use hexane and 10% n-dodecylbenzenesulfonic acid in hexane. For silicone oil, the measured refractive index and kinetic viscosity of the silicone oil obtained from the hexane extract were shown to be equivalent to those of the intact silicone oil. In regard to silicon dioxide, it was confirmed that, following the separation with 10% n-dodecylbenzenesulfonic acid in hexane, the level of silicon dioxide in silicone resin can be accurately determined. Therefore, in this study, we developed a method for testing the purity of silicone resins without the use of carbon tetrachloride, which is a harmful reagent.

Purpose: To obtain a surgical contact lens with adequate operative field in vitreous surgery of gas-filled eyes., Methods: We designed a new biconcave prism contact lens for gas-filled eyes by improving the material and the design of the lens (prism angle, radius and area of front concave of the lens). The operative field was calculated by a simulation using the ray tracing method for cases of simultaneous phaco-vitrectomy surgery, vitrectomy of pseudophakic eyes, and vitrectomy without phaco-surgery. For this study, a prototype of the newly designed lens was made and used for vitrectomy of gas-filled eyes., Results: The calculated operative field was about 47 degrees (central angle) for vitrectomy of pseudophakic eyes and vitrectomy without phaco-surgery. In cases of simultaneous phaco-vitrectomy surgery, the operative field can be varied continuously from 47 to 145 degrees (central angle) by adjusting the viscoelastic material in the anterior chamber. Appropriate visual field, good binocular vision, and visibility of the peripheral region were obtained in the vitrectomy of gas-filled eyes., Conclusion: The newlydesigned contact lens is useful for viewing the fundus during the vitrectomy of gas-filled eyes.

In 1939 the author reported the results of measured refractive indices of about a hundred crystalline drugs listed in [JP V] at the Takeda Research Laboratory using a Leitz PM polarizing microscope and newly developed immersion oils. When the author had reopened the study of crystalline drugs using a polarizing microscope at the Kobe-Gakuin University starting from 1975 one of the main purposes was to clarify the relation between crystal habits and refractive indices. It had been found that in most cases of crystal habits refractive indices were uniquely measured from a predominant pair of faces forming superior the habit, and they were called as "key refractive indices". The author and his co-workers tried to investigate the possibility of measuring the key refractive indices widely from all the obtainable crystalline drugs listed in the [JP X] or [JP XI], co-operating with the Pharmacy of Kobe University Hospital. Thus, more than 170 kinds of crystalline drugs were tested for their key refractive indices and found that they were measured from about 60-70% of tested drugs. It was also clarified that the difference of 2 key refractive indices, (n2 - n1), the birefringence of the section, was also an unique invariable number for the habit, and it played an important role not only for the graphic representation of log(n2 - n1), abscissa, against (n1, n2), ordinate, for the sake of an analytical purpose but also to measure a thickness of a section (habit) using a retardation color. Then, it had been cleared that the similarity of crystal habits in the microscopic field was based on the facts of measuring the same key refractive indices, and the author had developed a chart for measuring key refractive indices as well as producing a 3 dimensional orthographic projection of a crystal habit simultaneously applying a thickness measuring method using a birefringence. Finally 3 dimensional parameter a, b, c of a crystal habit and "habit coefficients" T: square root of ab/c and L: b/c were determined from the orthographic projection. In conclusion using the similarity in crystal habits the distributions of particle sizes and specific surface areas of all the crystals in the microscopic field had been calculated by a personal computer putting in necessary habit coefficients and obtained data of parameter b. The relation between 2 dispersions of particle sizes in log (V) and specific surface areas in log (SSA) were shown under the rectangular coordinates log (V) on the abscissa and log (SSA) on the ordinate, where the loci of log (SSA) formed simple striped pattern composed of parallel straight lines depending on habit coefficients. It would be possible to estimate the value of a specific surface area of any crystalline substance by plotting the value of log (V) on the straight line of a locus of log (SSA) having the same habit coefficients.

Crystal morphology and habit analyses necessary for a pharmaceutical technique have been studied by a polarizing microscope for tiny crystals of sulfamethizole, levodopa and phenobarbital listed in the Japanese Pharmacopoeia XII. Measurement of key refractive indices by an immersion method has been tried semiautomatically using photographs and the kit of immersion oils produced at 0.005 intervals, and a decision of an orientation of the section has been also carried by conoscope using photos. From the orthographic projections produced by the habit analysis of the colored photo as mentioned in the previous reports morphological and optical properties were clarified.

We prospectively evaluated lens changes after vitrectomy on 55 patients with vitreoretinal interface syndrome such as idiopathic epiretinal membrane, vitreomacular traction syndrome, and impending stages of idiopathic senile macular hole. Postoperative changes in crystalline lenses were assessed by fluorophotometric measurement of lens autofluorescence, measurement of refractive errors and biomicroscopic evaluation of progression of nuclear sclerosis. Examinations were repeated prior to surgery and at 1, 3, 6, and 12 months postoperatively. While autofluorescene and light transmittance of the lens were not affected by vitrectomy in patients less than 50 years old, older patients showed a significant increase of autofluorescence and decreased transmittance as early as 3 months after surgery. The refraction became myopic with time especially in the older patient group. Nuclear cataract was also found on biomicroscopic examination in the older patients as early as 1 month after surgery and progressed with time. The older the patients were, the more prominent those lens changes were.

To improve the transmittance of light-cured composite resins, the matching of the refractive indices of the matrix monomer and filler were examined. Eight fluorinated aromatic dimethacrylates and diacrylates with a low refractive index were synthesized. Three of these monomers had a poor solubility to TEGDMA. The depths of cure and the other physical properties of eight experimental composites prepared from one of five fluorinated monomers, TEGDMA and UDMA were determined compared with those of the control composites prepared from Bis-GMA or Bis-MEPP/ and TEGDMA in the same ratio. These composites contained 70 wt% of silanized silica filler. The depths of cure of the experimental composites except for one were significantly greater than those of the control composites. The mechanical properties of the experimental composites were comparable to those of the control composites with a few exceptions, but the difference in the mechanical properties between these exceptional composites and the control was small. The water sorption of the experimental composites was markedly lower than that of the composite containing Bis-GMA and comparable to that of the composite containing Bis-MEPP. These five fluorinated monomers are considered useful as the matrix monomer of light-cured composite resins.

A translucent aluminous porcelain was developed for dentistry. The effects of refractive indexes and sintering behaviors on transparency and strength of the aluminous porcelains consisting of high refractive germanate-glass (Na2O-TiO2-GeO2) and alumina crystal powders were examined. The various germanate-glass specimens with a high refractive index were made by fusion at about 1,300 degrees C. The refractive indexes of fused Na2O-TiO2-GeO2 glass specimens were 1.64-1.76, heightened with an increasing TiO2 content. The sintered aluminous porcelains were made from the mixed compacts consisting of 80 wt% germanate-glass and 20 wt% alumina at the densification temperature of 580-820 degrees C. Sintered aluminous porcelains prepared with high refractive germante-glass had a high transparency compared with the other aluminous porcelains, with almost the same transparency as a commercial feldspathic porcelain (body). Aluminous porcelains had lower transparency with different refractive index due to generation of crystals following the crystallization of glass matrix than that without crystallizing property. Bending strength value was 120 MPa, which is similar to that for the glass-alumina ceramics with the same content of alumina volume as germanate-glass aluminous porcelains. Non-crystallized aluminous porcelain had a higher strength compared with the crystallized one.

Radiopaque monomers were synthesized to examine their properties and the physical properties of their bulk polymers, to obtain basic data for new radiopaque filling composite resin. Octachlorocyclotetraphosphazene (P4N4Cl8) was used as material to be synthesized, and 2,4,6-tribromophenol, (Br3C6H2OH) and 2,4-dibromophenol (Br2C6H3OH) were selected as organic compounds having radiopacity. As a polymerizing functional group, 2-hydroxyethylmethacrylate (HEMA) was used. Radipaque monomers were synthesized as follows: 1 Cl of P4N4Cl8 was replaced by 1 mol of 2,4,6-tribromophenol, or 2 Cls by 2 mols of 2,4-dibromophenol, and the remaining 7 or Cls were replaced by HEMA, polymerizing functional group, to obtain 2 kinds of radiopaque monomers; 4 PN-(Br3Ph)1-(EMA)7 and 4 PN-(Br2Ph)2-(EMA)6. The specific gravity of these monomers was 1.4629 and 1.4978, refractive index 1.5315 and 1.5423 and viscosity, 70 and 80 poise respectively. Radiopacity was measured by an X-ray apparatus. Al equivalent, of specimen, 10 phi x 3 mm, 4 PN-(Br3Ph)1-(EMA)7 was 5.8 mm and 4 PN-(Br2Ph)2-(EMA)6 7.0 mm. 4 PN-(Br3Ph)1-(EMA)7 and 4 PN-(Br2Ph)2-(EMA)6, both wet specimens, had compressive strength of 83.7 and 81.3 MPa, in transverse strength of 45.5 and 53.0 MPa and knop hardness of 25.8 and 22.6 respectively. After 7 days, 4 PN-(Br3Ph)1-(EMA)7 had water sorption of 1.46 wt%, and 4 PN-(Br2Ph)2-(EMA)6, 0.84 wt%, and solubility of 0.15 and 0.14 wt%, respectively.

The relationship between the refractive index and specific gravity of urine was studied with specimens from 165 Sprague-Dawley rats, by graphic analysis of the plot of the refractometrically determined index against the specific gravity which was measured with a pycnometer. 1. A linear regression was demonstrated between the refractive index and specific gravity. 2. The nomogram fitted the data of even those samples with high refractive index and specific gravity, irrespective of changes in food or water intake and protein or glucose contents in the urine. 3. The nomogram was in good agreement, in respect of linearity, with the regression line derived from the conversion table of TS meter by the American Optical Corporation and also with the nomogram of the Japanese Society of Clinical Pathology. It approximated more closely to the former than to the latter.