All issues
Volume 21 (2002)
- Issue 4 Pages 285-
- Issue 3 Pages 225-
- Issue 2 Pages 73-
- Issue 1 Pages 1-
Volume 21, Issue 1
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Takahito KANIE, Hiroyuki ARIKAWA, Koichi FUJII2002 Volume 21 Issue 1 Pages 1-8
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThis study examined the reinforcing effect of woven glass fibers on the relaxation modulus by three-point loading of denture base resin. Three sandwich-type flexure test specimens polymerized by heating were used, all 3mm thick: glass fibers in compression (U type); glass fibers in the center (C type); and glass fibers in tension (L type). Unreinforced specimens (ACR) were produced as a control. The relaxation modulus after 8sec from the start of stress |Er(8)| was calculated from stress relaxation curves. In the glassy state, the Er(8)s of the U and L types were greater than those of the ACR and C types. In the rubbery state (plateau region), the Er(8)s of the U and L types were greater than those of the ACR and C types. The woven glass fibers added to the U and L type specimens increased the relaxation modulus of PMMA near the oral temperature; moreover, they inhibited stress relaxation when the temperature increased.View full abstractDownload PDF (879K) -
Linlin HAN, Cruz EDWARD, Akira OKAMOTO, Masaaki IWAKU2002 Volume 21 Issue 1 Pages 9-19
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSOne of the most important and exciting properties of recently introduced dental restorative materials is their ability to release fluoride ions, as this has several advantageous effects on tooth structures. They have been extensively used as fluoride-releasing filling and luting materials. Recently, fluoride-releasing adhesive resins and fluoride-releasing adhesive resin cement have been developed and introduced for clinical use. The purpose of this study was to evaluate the fluoride release from these adhesive resins and the fluoride uptake by both enamel and dentin, as well as the acid-resistance of these tooth structures. Based on our results, we conclude that fluoride-releasing adhesive resins and luting cements are useful for the prevention of initial or secondary caries, especially along the margins of restorations.View full abstractDownload PDF (962K) -
Observation of Hard Tooth Structures by Laser Scanning Microscope and Examination of the Time necessary to Remove CariesYoshimi SHIGETANI, Akira OKAMOTO, Neamat ABU-BAKR, Masaaki IWAKU2002 Volume 21 Issue 1 Pages 20-21
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe purpose of this study was to observe and measure the morphological changes that occur in the hard tissue after the application of Er: YAG laser. Another objective was to evaluate and compare the duration of application of both the laser apparatus and a conventional cutting device. In this study, sound and newly extracted carious tissues were used. The morphological changes in hard tooth structures produced by Er: YAG laser irradiation were examined by using a laser scanning microscope. Results showed that appropriate laser irradiation was 100 mJ/pulse for dentin, and 200mJ/pulse for enamel. Also, the laser scanning microscope images were less damaged than the SEM images due to pretreatment of the specimens. The time taken to remove carious enamel by laser irradiation was slightly longer than the compared rotary cutting device; however, no differences between the two methods were observed in case of carious dentin removal.View full abstractDownload PDF (2783K) -
Toshiko INOUE, Hidekazu TAKAHASHI, Fumio NISHIMURA2002 Volume 21 Issue 1 Pages 32-43
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe purpose of this study was to investigate the effects of the location and orientation of dentinal tubules in the tooth on tensile strengths of the dentin. Dumbbell-shaped specimens of 12 groups from various locations and dentinal tubule orientations were prepared. The tensile test was performed in distilled water at a temperature of 37°C. The tensile strengths of the parallel to the orientation were significantly greater than those of the perpendicular to the orientation; the tensile strengths of the radicular dentin were significantly greater than those of the coronal dentin. Nevertheless, in the radicular dentin, the tensile strengths of the perpendicular to dentinal tubules differ with respect to tensile forces. These results suggest that tensile strength of the dentin varies according to the location and orientation of dentinal tubules in the tooth.View full abstractDownload PDF (2429K) -
Carlos Martins AGRA, Glauco Fioranelli VIEIRA2002 Volume 21 Issue 1 Pages 44-52
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThis investigation compared, by quantitative analysis, the surface roughness of dental porcelain submitted to three different treatments (glaze, trimming and polishing), utilizing a surface profiling instrument. The parameters Ra (median roughness), Rz (median of the maximum profile heights of five sample lengths), Rpm (median of the maximum profile heights related to the median line of five sample lengths), Pc (peak count per centimeter) and Rpm/Rz (proportional parameter) were evaluated. In addition, the correlation between Ra and the other parameters was analyzed. Based on the results obtained, it was seen that the Ra parameter did not present any correlation with the other parameters in some of the situations evaluated. This demonstrates that complementation of the measurement with other parameters is always necessary, providing a better evaluation of the functional properties of a surface.View full abstractDownload PDF (1267K) -
Hiroshi MURAKAMI, Miho MIZUGUCHI, Masami HATTORI, Yutaka ITO, Tatsushi ...2002 Volume 21 Issue 1 Pages 53-60
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSWe examined the bactericidal and virucidal effectiveness of a denture cleaner that uses ozone (ozone concentration, 10ppm) against methicillin-resistant Staphylococcus aureus (MRSA) and T1 phage, respectively- In the bactericidal activity test, with the ozone supply turned on, the number of bacteria was 3.1×103CFU/mL at the beginning of the experiment, fell to 1.0×100 CFU/mL 10min later, and was 1.0×100CFU/mL or less afterwards. In contrast, when the ozone supply was cut off (air bubble only), the number of bacteria was 3.4×103CFU/mL at the beginning of the experiment, and had fallen to 3.0×103CFU/mL 60min later (no statistically significant difference). In the virucidal activity test, the number of phages was 1.2×106PFU/mL before ozone treatment, fell to about 1/10 of that number 10min later, and was 6.1×100 PFU/mL 40min later.
These results indicate that the use of ozone in this denture cleaner is effective against MRSA and viruses.View full abstractDownload PDF (346K) -
Kazumi WATANABE, Eiji OHNISHI, Takushi KANESHIMA, Atsushi MINE, Hirofu ...2002 Volume 21 Issue 1 Pages 61-68
Published: 2002
Released on J-STAGE: May 25, 2009
JOURNAL FREE ACCESSThe resin bond strength of plasma-arc curing in restorative dentistry was investigated in comparison to halogen-light curing with respect to two kinds of thickness, shade and opacity of porcelain laminate veneers. The bond strength of the light-cured resin was evaluated by shear tests and SEM observations of the fracture surfaces, and the results were interpreted in terms of the degree of resin polymerization. It was found that plasma-arc curing for 6s was sufficient to obtain bond strengths similar to those of specimens polymerized with halogen light for 40s, whereas the plasma-arc curing time needed to be doubled to 12s in order to achieve similar failure patterns for a darker-shade porcelain of 2mm thickness. The bond strength achieved by plasma-arc curing was found to be relatively unaffected by the shade or opacity of porcelain.View full abstractDownload PDF (941K)
- |<
- <
- 1
- >
- >|