Mitsuhiro Tamamoto

Evaluation of denture cleansers with and without enzymes against Candida albicans

The fungicidal effect on Candida albicans was evaluated for denture cleansers with and without enzymes (alkaline peroxide type). Three cleansers with proteolytic enzymes showed little yeast lytic ability, while one cleanser with yeast lytic and proteolytic enzymes and one cleanser without enzymes showed slight yeast lytic ability. The results suggested that the activity depended on alkaline peroxide rather than on enzymes. Five denture cleansers showed strong effects.

Ability of enzymes to remove Candida.

Infection by C. albicans is a significant cause of denture stomatitis. Therefore, the results of this study, which demonstrated that yeast lytic enzymes and proteolytic enzymes removed C. albicans from acrylic resin surfaces, suggest that these compounds are potentially useful denture cleansers.

The fungicidal effect of ultraviolet light on impression materials

The effects of ultraviolet (UV) light on fungi and impression materials were tested. UV light (250 microW/cm2) killed most Candida organisms (10(3) cells/ml) within 5 minutes. UV light (8000 microW/cm2) killed most C. albicans (10(7) cells/ml) within 2 minutes of exposure. The effect of UV light on dimensional change and surface roughness of impression materials (irreversible hydrocolloid, agar, and silicone rubber) was tested. The results showed that neither dimensional change nor surface roughness of the impression materials were affected. The results of this study indicate that UV light disinfects impression materials that are contaminated with Candida organisms.

Experimental and clinical studies on dose reduction effects of spacers in interstitial brachytherapy for carcinoma of the mobile tongue

The difference of radiation dose reduction effect with spacers of different materials, a heat-curing denture base resin and a silicon impression material, was examined experimentally and clinically. Radium needles and iridium hairpins were used as radioactive sources. In both studies, it was revealed that a dose reduction effect of silicon impression material was greater than that of denture base resin. Silicon impression material was thought to be a better material for spacers because of its larger radiation dose reduction effect and the time saving to produce the spacer.

In vitro study on the effects of trial denture cleansers with berberine hydrochloride

The antifungal activity of trial denture cleansers prepared with berberine hydrochloride was examined against Candida albicans, C. tropicalis, and C. glabrata. A commercial denture cleanser and a trial denture cleanser that exhibited strong antifungal activity were tested for their effects on Candida spp., the color stability of the dental material, and the surface roughness of acrylic resin plates. The results of these tests revealed that the trial denture cleanser removed 64% to 89% of adhered cells from acrylic resin surfaces and had little effect on the other physical properties tested.

Dose-reducing effect of lipowitz metal-embedded spacers in interstitial brachytherapy for carcinoma of the mobile tongue

Dose-reducing effects of spacers with and without a Lipowitz metal plate for the purpose of decreasing osteoradionecrosis after interstitial brachytherapy for tongue cancers were examined experimentally and clinically. The thicker the sample or spacer and the thicker the metal plate, the greater was the dose reduction achieved. A more marked dose reduction was achieved with iridium than with radium because of lower gamma ray energy of iridium. Iridium has been used widely as a radioactive source for interstitial brachytherapy. It was concluded therefore that a metal plate should be used as a shield into the spacer in interstitial brachytherapy both to reduce the radiation dose to surrounding normal tissues and to help prevent osteoradionecrosis.

Computer-Aided Technique for the Design and Manufacturing of Auricular Prostheses

Custom-made esthetic auricular prostheses, which are used for rehabilitation of patients with missing or impaired auricles, have been fabricated manually. However, such fabrication is time-consuming and requires manual skill. This paper proposes a computer-aided technique for fabricating auricular prostheses to save time and allow fabrications that do not require considerable manual skill. In this technique, the shape of a patient’s healthy auricle, which is contralateral to the impaired auricle, is first scanned using a laser scanner to make a 3D model of the healthy auricle. Because the 3D model obtained by laser scanning has the surface abnormalities and gaps, we apply morphing technology to make the 3D model complete. The morphing technology is originally for changing (or morphing) one image to another through a seamless transition. In this study, the morphing technology is used to change the 3D model of standard auricle by referring to the 3D model obtained by laser scanning, and consequently we obtain a 3D model that resembles a patient’s healthy auricle. An auricular prosthesis for the patient is designed by mirroring the 3D model obtained by morphing. Based on the 3D model, a mold is designed, using the 3D modeling tools and computer-aided design system. The resulting mold is then fabricated using a 3D printer. An auricular prosthesis is fabricated by pouring silicone resin into the mold. An auricular prosthesis for a volunteer was experimentally fabricated according to the proposed technique.

Evaluation of Denture Cleansers against Candida albicans, Part II.

Candida albicans is known to cause denture stomatitis. In this study, the effects of four kinds of commercial denture cleansers (DC A, B, C and D) on C. albicans were evaluated under the various conditions. Yeast-lytic enzymes were contained only in DC A. Proteases were contained in DC A, B and C, and alkaline-oxidants were contained in DC B, C and D.Candida-lytic activity was demonstrated only in DC A from the results of the reduction of optical density of yeast suspension, the microscopical observation and the degradation of β-1, 3-glucan.Strong fungicidal effects were found in DC B and C. The fungicidal effect in DC D was slightly lower than that in DC B and C, and the effect in DC A, which contained no oxidants, was the lowest. However, it was found that a small amount of Candida cells was alive, even in the solution of DC B, C and A when the residual cleansers were removed and then inoculated on the culture plate.Resin plates adhering Candida cells were soaked in the cleansers, and then the remaining cells were counted under the microscope. The removal of the adhering cells by DC A, B and C were significantly greater than that by the control. But DC D did not show any significant differences from the control and the other cleansers.DC A exhibited the highest protease activity at pH 7. At the own pH of cleansers, however, DC C exhibited higher activity than DC A. The protease activity in DC B was lower than that in DC A and C. DC D exhibited no protease activity, but it generated the largest quantity of hydrogen peroxide. No hydrogen peroxide was generated from DC A.