著者

Akimasa TSUJIMOTO Wayne W. BARKMEIER Toshiki TAKAMIZAWA Mark A. LATTA Masashi MIYAZAKI

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

pp.2016-131, (Released:2017-02-01)

参考文献数

32

被引用文献数

49

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The purpose of this study was to investigate the depth of cure, flexural properties and volumetric shrinkage of low and high viscosity bulk-fill giomers and resin composites. Depth of cure and flexural properties were determined according to ISO 4049, and volumetric shrinkage was measured using a dilatometer. The depths of cure of giomers were significantly lower than those of resin composites, regardless of photo polymerization times. No difference in flexural strength and modulus was found among either high or low viscosity bulk fill materials. Volumetric shrinkage of low and high viscosity bulk-fill resin composites was significantly less than low and high viscosity giomers. Depth of cure of both low and high viscosity bulk-fill materials is time dependent. Flexural strength and modulus of high viscosity or low viscosity bulk-fill giomer or resin composite materials are not different for their respective category. Resin composites exhibited less polymerization shrinkage than giomers.

著者

Chie KANAZAWA Ryosuke MURAYAMA Tetsuya FURUICHI Arisa IMAI Shunichi SUDA Hiroyasu KUROKAWA Toshiki TAKAMIZAWA Masashi MIYAZAKI

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

pp.2016-175, (Released:2016-12-06)

参考文献数

28

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This study used an ultrasonic measurement device to monitor the setting behavior of silicone elastomeric impression materials, and the influence of temperature on setting behavior was determined. The ultrasonic device consisted of a pulser-receiver, transducers, and an oscilloscope. The two-way transit time through the mixing material was divided by two to account for the down-and-back travel path; then it was multiplied by the sonic velocity. Analysis of variance and the Tukey honest significant difference test were used. In the early stages of the setting process, most of the ultrasonic energy was absorbed by the elastomers and the second echoes were relatively weak. As the elastomers hardened, the sonic velocities increased until they plateaued. The changes in sonic velocities varied among the elastomers tested, and were affected by temperature conditions. The ultrasonic method used in this study has considerable potential for determining the setting processes of elastomeric impression materials.

著者

Akimasa TSUJIMOTO Wayne W. BARKMEIER Toshiki TAKAMIZAWA Mark A. LATTA Masashi MIYAZAKI

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

vol.35, no.3, pp.418-424, 2016-05-31 (Released:2016-06-01)

参考文献数

37

被引用文献数

1 46

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The mechanical properties, volumetric shrinkage and depth of cure of a short fiber-reinforced resin composite (SFRC) were investigated in this study and compared to both a bulk fill resin composite (BFRC) and conventional glass/ceramic-filled resin composite (CGRC). Fracture toughness, flexural properties, volumetric shrinkage and depth of cure of the SFRC, BFRC and CGRC were measured. SFRC had significantly higher fracture toughness than BFRCs and CGRCs. The flexural properties of SFRC were comparable with BFRCs and CGRCs. SFRC showed significantly lower volumetric shrinkage than the other tested resin composites. The depth of cure of the SFRC was similar to BFRCs and higher than CGRCs. The data from this laboratory investigation suggests that SFRC exhibits improvements in fracture toughness, volumetric shrinkage and depth of cure when compared with CGRC, but depth of cure of SFRC was similar to BFRC.

著者

Fumi YOSHIDA Akimasa TSUJIMOTO Ryo ISHII Kie NOJIRI Toshiki TAKAMIZAWA Masashi MIYAZAKI Mark A. LATTA

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

vol.34, no.6, pp.855-862, 2015-11-27 (Released:2015-12-01)

参考文献数

28

被引用文献数

2 37

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This study investigates the influence of surface treatment of contaminated lithium disilicate and leucite glass ceramic restorations on the bonding efficacy of universal adhesives. Lithium disilicate and leucite glass ceramics were contaminated with saliva, and then cleaned using distilled water (SC), or 37% phosphoric acid (TE), or hydrofluoric acid (CE). Specimens without contamination served as controls. The surface free energy was determined by measuring the contact angles formed when the three test liquids were placed on the specimens. Bond strengths of the universal adhesives were also measured. Saliva contamination and surface treatment of ceramic surfaces significantly influenced the surface free energy. The bond strengths of universal adhesives were also affected by surface treatment and the choice of adhesive materials. Our data suggest that saliva contamination of lithum disilicate and leucite glass ceramics significantly impaired the bonding of the universal adhesives, and reduced the surface free energy of the ceramics.

著者

Kie NOJIRI Akimasa TSUJIMOTO Takayuki SUZUKI Syo SHIBASAKI Saki MATSUYOSHI Toshiki TAKAMIZAWA Masashi MIYAZAKI

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

vol.34, no.5, pp.611-617, 2015-10-02 (Released:2015-10-05)

参考文献数

28

被引用文献数

5 8

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In this study, we investigated the influence of light intensity on the surface-free energy and dentin bond strength of single-step selfetch adhesives. The adhesives were applied to the dentin surfaces of bovine mandibular incisors and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm2. Surface-free energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. Dentin bond strengths of the specimens were also measured. Polymerization with a higher light intensity resulted in a lower surface-free energy of the cured adhesives. The greatest bond strength was achieved when a light intensity of 400 mW/cm2 or greater was used. Our data suggest that the surface-free energy and dentin bond strength of single-step self-etch adhesives are affected by light intensity of the curing unit.

著者

Hiroyasu Kurokawa Toshiki Takamizawa Akitomo Rikuta Keishi Tsubota Masashi Miyazaki

出版者

日本大学歯学部

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.57, no.2, pp.101-108, 2015 (Released:2015-06-10)

参考文献数

35

被引用文献数

3 15

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In this clinical study, we evaluated the 3-year clinical performance of a resin composite containing a surface-prereacted glass ionomer (S-PRG) filler (Beautifil II; Shofu Inc., Kyoto, Japan) placed with a single-step self-etch adhesive (BeautiBond; Shofu Inc.) in posterior restorations. Using modified US Public Health Service criteria, two experienced investigators performed clinical evaluations at the baseline, 6 months, 18 months, and 3 years. Color match, marginal adaptation, anatomical form, surface roughness, marginal discoloration, postoperative sensitivity, and secondary caries were evaluated. After 3 years, 26 patients attended the recall and 31 restorations were evaluated. No postoperative sensitivity or secondary caries was observed at any time point, and no restorations failed during the follow-up period. However, surface roughness, marginal adaptation, and marginal discoloration showed deterioration after 3 years. In conclusion, although some clinical changes were observed, resin composite containing S-PRG filler placed with self-etch adhesive exhibited acceptable clinical behavior in posterior restorations. (J Oral Sci 57, 101-108, 2015)

著者

Mayumi KOTAKU Ryosuke MURAYAMA Yutaka SHIMAMURA Fuminori TAKAHASHI Takayuki SUZUKI Hiroyasu KUROKAWA Masashi MIYAZAKI

出版者

日本歯科理工学会

雑誌

Dental Materials Journal (ISSN:02874547)

巻号頁・発行日

vol.33, no.5, pp.648-655, 2014-09-30 (Released:2014-10-01)

参考文献数

33

被引用文献数

11

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Effects of a fluoride-releasing varnish containing surface reaction-type prereacted glass ionomer (S-PRG) filler on dentin demineralization were examined using optical coherence tomography. Bovine incisors that were sliced and treated with undersaturated 0.1 M lactic acid buffer solution (DE group). A thin film of varnish-containing S-PRG filler was applied before demineralization (PRG group). Control was maintained in artificial saliva. Using optical coherence tomography of selected locations on the dentin surface, peak intensity (dB) and width (μm) at 1/e2 were obtained and integrated values calculated. Although alterations in integrated values were different in each group, there was a slight but not significant increase in those for the control group and a slight but significant increase for the De group. For the PRG group, integrated values were doubled seven days after experiment initiation, followed by a significant increase. Fluoride-releasing varnish containing S-PRG fillers prevented dentin demineralization as detected by optical coherence tomography.

著者

Masashi Miyazaki Akimasa Tsujimoto Keishi Tsubota Toshiki Takamizawa Hiroyasu Kurokawa Jeffrey A. Platt

出版者

日本大学歯学部

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.56, no.1, pp.1-9, 2014 (Released:2014-03-15)

参考文献数

90

被引用文献数

8 62

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Improvements in dentin bonding systems have influenced modern restorative dentistry. The desire for minimal invasiveness has resulted in more-conservative cavity design, which basically relies on the effectiveness of current dentin bonding systems. Interaction of adhesives with enamel and dentin is based on two systems, commonly described as etch-and-rinse and self-etch. Priming and bonding agents can be separate or combined, resulting in two- or three-step systems for etch-and-rinse adhesives and one- or two-step systems for self-etch adhesives. Self-etch systems use acidic functional monomers that simultaneously demineralize and impregnate tooth structures. Etch-and-rinse and self-etch systems have advantages and disadvantages, which are primarily related to the simplified bonding procedures required under clinical conditions. Knowledge of the composition, characteristics, and mechanisms of adhesion for each adhesive system is critical in selecting the ideal adhesive materials for clinical use. (J Oral Sci 56, 1-9, 2014)