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Koji OYAMA, Akimasa TSUJIMOTO, Eiichiro OTSUKA, Yusuke SHIMIZU, Koji S ...
2012 Volume 31 Issue 1 Pages
26-31
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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We compared the surface free energies and enamel bond strengths of single-step self-etch adhesives with and without an oxygen-inhibited layer. The adhesives were applied to the enamel surfaces of bovine incisors, light irradiated, and the oxygen-inhibited layer was either retained or removed with ethanol. The surface free energies and their components (γ
SLW, γ
S+, and γ
S−) were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths of specimens with and without the oxygen-inhibited layer were measured. For all surfaces, the value of the estimated surface tension component γ
SLW was relatively constant. The value of the γ
S+ component increased slightly when the oxygen-inhibited layer was removed, whereas that of the γ
S− component decreased significantly. The enamel bond strengths of the self-etch adhesives were significantly lower in the specimens without an oxygen-inhibited layer. The oxygen-inhibited layer therefore appeared to promote higher enamel bond strength.
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Phumisak LOUWAKUL, Veera LERTCHIRAKARN
2012 Volume 31 Issue 1 Pages
32-39
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aims of this study were to investigate the release of fluocinolone acetonide from an experimental pulp capping material containing fluocinolone acetonide (PCFA) and compare some physical and mechanical properties with Dycal
®. The PCFA is a hard-setting calcium hydroxide cement composed of 50 mmol/L fluocinolone acetonide. Conditioned media from the setting material was collected for determination of fluocinolone acetonide release by high performance liquid chromatography and pH measurement by pH meter. The setting time, compressive strength, disintegration, and acid soluble arsenic content were measured according to ISO 3107:2004. Dycal
® was used as control. Fluocinolone acetonide could release at a range of suitable concentrations from PCFA. The pH, setting time, and acid soluble arsenic content of PCFA were significantly higher than those of Dycal
®. The compressive strength and disintegration of PCFA were comparable to control. PCFA may be considered as an alternative in pulp capping of inflamed dental pulp tissue.
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Masanao INOKOSHI, Manabu KANAZAWA, Shunsuke MINAKUCHI
2012 Volume 31 Issue 1 Pages
40-46
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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A new trial method for complete dentures using rapid prototyping (RP) was compared with the conventional method. Wax dentures were fabricated for 10 edentulous patients. Cone-beam CT was used to scan the wax dentures. Using 3D computer-aided design software, seven 3D denture images with different artificial teeth arrangements were made and seven trial dentures per patient were fabricated accordingly. Two prosthodontists performed a denture try-in for one patient using both conventional and RP methods. The prosthodontists and patients rated satisfaction for both methods using a visual analogue scale. Satisfaction ratings with both conventional and RP methods were compared using the Wilcoxon signed-rank test. Regarding prosthodontist’s ratings, esthetics and stability were rated significantly higher with the conventional method than with the RP method, whereas chair time was rated significantly longer with the RP method than with the conventional method. Although further improvements are needed, the trial method applying RP seems promising.
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Walter DUKIC, Barbara DELIJA, Doria DEROSSI, Ivana DADIC
2012 Volume 31 Issue 1 Pages
47-53
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aim of this study was to evaluate the radiopacity of 32 current dental composite materials with digital technique. Digital radiographs with CCD sensor along with an aluminum step wedge, 1-mm-thick tooth slice and 1mm thick composite specimen were taken in five different combinations of exposition/voltage. The radiopacity in pixels was determined using Digora 2.6. software. The equivalent in thickness of aluminum for each material was then calculated from the calibration curve. 74.9% of all tested materials in all exposure combinations had radiopacity between 2 mm and 4 mm aluminum equivalent. The radiopacity of composites ranged from 0.61 mm Al (Gradia Direct Anterior) to 4.78 mm Al (Te-Econom). The average radiopacity for enamel and dentine was 2.05 and 1.11 mm Al. The use of digital technique for radiopacity is an easy, reliable, fast and precise way to analyze different dental materials. Most of the tested composite materials fulfill the requested criteria for radiopacity with a few exceptions.
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Hideo SHIGEISHI, Masaaki TAKECHI, Masahiro NISHIMURA, Megumi TAKAMOTO, ...
2012 Volume 31 Issue 1 Pages
54-60
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aim of this study was to evaluate the clinical behavior and the histological aspects of interconnected porous hydroxyapatite ceramics (IP-CHA) in maxillary sinus floor augmentation procedures. A 59-year-old female patient received one-stage implant integration with right maxillary sinus floor augmentation with mixture grafts from the cortical bone and IP-CHA. Implant stability of each fixture increased at 9 months after fixture installation compared with the first operation and adequate fixation of each fixture could be obtained. Histological analysis revealed there was new bone formation in the majority of pores of IP-CHA. Moreover, on a panoramic radiograph taken at 33 months the mixture grafts were distinctly observed as a radiopacity in the right sinus cavity, and marked absorption of mixture grafts was not found. Our results suggest that IP-CHA has the potential to provide a major scaffold for osteoprogenitor cells and is a useful grafting material for maxillary sinus augmentation.
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Kiyoshi KAKUTA, Amornrat WONGLAMSAM, Shin-ichi GOTO, Hideo OGURA
2012 Volume 31 Issue 1 Pages
61-67
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The purpose of this study was to investigate the relation between the texture of worn surfaces of composite resins and the maximum wear depth. Three types of composite resins were investigated: a hybrid composite resin consisting of irregular-shaped inorganic filler particles (APX); a composite resin which contained small, irregular-shaped, inorganic filler particles and large organic composite filler particles (SRE); and another which contained spherical inorganic filler particles and large organic composite filler (SDX). Surface profile measurement and elemental analysis were carried out on the worn surfaces of these three composite resins using an electron probe microanalyzer (EPMA). For the composite resin which exhibited the largest maximum wear depth, its surface texture was slightly rough with fine pores and grooves. For the composite resin with lowest maximum wear depth, it had a smooth worn surface due to the large organic composite filler being abraded during the combined wear test.
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Gürel PEKKAN, Mutlu ÖZCAN
2012 Volume 31 Issue 1 Pages
68-75
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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This study evaluated the radiopacity of different resin-based luting materials and compared the results to human and bovine dental hard tissues. Disc specimens (
N=130,
n=10 per group) (diameter: 6 mm, thickness: 1 mm) were prepared from 10 resin-based and 3 conventional luting cements. Human canine dentin (
n=10), bovine enamel (
n=10), bovine dentin (
n=10) and Aluminium (Al) step wedge were used as references. The optical density values of each material were measured from radiographic images using a transmission densitometer. Al step wedge thickness and optical density values were plotted and equivalent Al thickness values were determined for radiopacity measurements of each material. The radiopacity values of conventional cements and two resin luting materials (Rely X Unicem and Variolink II), were significantly higher than that of bovine enamel that could be preferred for restorations cemented on enamel. Since all examined resin-based luting materials showed radiopacity values equivalent to or greater than that of human and bovine dentin, they could be considered suitable for the restorations cemented on dentin.
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Bo-Tao GAO, Hong LIN, Gang ZHENG, Yong-Xiang XU, Jin-Liang YANG
2012 Volume 31 Issue 1 Pages
76-85
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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A silorane-based composite was compared against methacrylate-based composites in terms of shrinkage characteristics, thermal properties, gel point, and vitrification point. Shrinkage strain was measured using a laser triangulation method. Shrinkage stress was measured using a stress analyzer. Heat flow during photopolymerization was measured using photo-DSC. Statistical analysis was performed using one-way ANOVA and Tukey’s test (
p=0.05). Silorane exhibited significantly lower shrinkage strain than the methacrylate-based composites. It also presented the lowest stress values during light exposure, but the highest maximum stress rate after light exposure. It showed the highest heat flow rate, and it took the longest time to reach gel and vitrification points. Silorane demonstrated improved performance over the methacrylate-based composites with delayed gel and vitrification points as well as reduced shrinkage strain and stress. However, a high quantity of heat was liberated during the curing process, causing silorane to show significantly higher stress rate (
p<0.05) than the methacrylate-based composites after light exposure.
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Ai KUMADA, Yoshizo MATSUKA, Atsushi MINE, Mitsuaki ONO, Junji UEHARA, ...
2012 Volume 31 Issue 1 Pages
86-91
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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Resin coating materials have been used for composite resin or provisional restoration in order to prevent plaque accumulation on their surfaces. However, it is not clear whether the coating materials influence attachment of periodontal bacteria. Therefore, we investigated the effect of resin coating materials on the attachment of
Porphyromonas gingivalis (Pg). The polymerized auto cure resin plates were coated with two resin coating materials. To estimate the Pg attachment, each plate was immersed in brain heart infusion medium containing Pg. The quantity of bacteria attached on each plate was evaluated by crystal violet quantification. Morphological change of Pg was recorded using scanning electron microscopy. Both coating groups presented significantly lower Pg attachment compared to the control. The Pg shapes on the plates with resin coating materials were similar to the non-treated control plates. The resin coating materials clearly prevent Pg attachment on the polymerized auto cure resin plate.
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Hidehiro OGATA, Makoto HAYASHI, Hiromasa TSUDA, Naoto SUZUKI, Masao MA ...
2012 Volume 31 Issue 1 Pages
92-97
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aim of this study was to investigate mineralizing ability of a premixed calcium phosphate cement (premixed-CPC) compared to mineral trioxide aggregate (MTA) and zinc oxide eugenol cement (SuperEBA) in ROS17/2.8 cells. The measurements of cell proliferation, alkaline phosphatase (ALPase) activity and mineralized nodule formation in the presence or absence (control) of the test materials were performed using a cell culture insert method with the test materials placed on a porous membrane of culture plate insert. Mineralized nodules were detected by staining with alizarin red, and the calcium content of the mineralized nodules was determined quantitatively using a calcium assay kit. Premixed-CPC and MTA indicated significantly higher cell proliferation, ALPase activity, mineralized nodule formation, and calcium content in nodules than those of SuperEBA (
p<0.05). The present results suggest that premixed-CPC has the same mineralizing ability as MTA.
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Min-Kyung KANG, Sang-Bae LEE, Seung-Kyun MOON, Kwang-Mahn KIM, Kyoung- ...
2012 Volume 31 Issue 1 Pages
98-105
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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Dental implant failure often occurs due to oral bacterial infection. The aim of this study was to demonstrate that antibiotic efficacy could be enhanced with modified titanium. First, the titanium was modified by anodization and heat-treatment. Then, a biomimetic coating process was completed in two steps. Surface characterization was performed with scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Release of antibiotic was evaluated by UV/VIS spectrometry, and the antibacterial effect was evaluated on
Streptococcus mutans. After the second coating step, we observed a thick homogeneous apatite layer that contained the antibiotic, cefalotin. The titanium formed a rutile phase after the heat treatment, and a carbonated apatite phase appeared after biomimetic coating. We found that the modified titanium increased the loading of cefalotin onto the hydroxyapatite coated surface. The results suggested that modified titanium coated with a cefalotin using biomimetic coating method might be useful for preventing local post-surgical implant infections.
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Takashi NAKAMURA, Hirofumi USAMI, Hiroshi OHNISHI, Hisataka NISHIDA, X ...
2012 Volume 31 Issue 1 Pages
106-112
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aim of this study was to determine the machinability of new silica-doped Y-TZP by CAD/CAM and the resistance to low temperature degradation of the milled sample by comparing with a commercial HIP type Y-TZP material. The copings could be milled from silica-doped Y-TZP blocks without chipping, and there was no significant difference between the two types of Y-TZP materials in either the marginal or the inner gap between the abutment and the coping. After aging, the monoclinic content in the commercial Y-TZP copings increased from 25% before testing to 65%, while that of silica-doped Y-TZP copings slightly increased from 23% to 30%. The silica-doped Y-TZP copings did not have any significant difference in fracture load in a comparison between the control group and the aging group, while the commercial Y-TZP copings had a significantly lower fracture load for the aging group than for the control group.
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Naosuke KUMAGAE, Wataru KOMADA, Yuji FUKUI, Daizo OKADA, Hidekazu TAKA ...
2012 Volume 31 Issue 1 Pages
113-119
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The purpose of this study was to evaluate the influence of flexural modulus of non-metal posts on the fracture strength and failure mode of composite resin cores. Thirty-two human premolars were divided into four groups: prefabricated glass fiber post with 1.0 mm diameter and composite resin core (Group PE1.0), that with 1.5 mm diameter and composite resin core (Group PE1.5), experimental post (flexural modulus; 4.25GPa) and composite resin core (Group EX), and preparation for abutment teeth only (Group NT). After a static loading test, the fracture strength and failure mode were recorded. Group NT (1670.81 N) showed higher fracture strength than Groups PE1.0 (866.44 N), PE1.5 (825.19 N) and EX (1075.63 N) (
p<0.05). This study showed that the fracture strength of endodontically treated teeth restored with composite resin cores is not influenced by the flexural modulus of non-metal posts.
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Kenzo ASAOKA, Ji-Young BAE, Hae-Hyoung LEE
2012 Volume 31 Issue 1 Pages
120-124
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The porosity of gypsum-bonded investments for set and heated compacts was measured and theoretically computed quantitatively, because porosity is an effective factor for determining the strength, setting/heating expansion, and permeability of compacts at casting. A helium gas pycnometer was used to measure the solid volume of fine powders, powder-water mixtures, and porous compacts. The compositions of the conventional cristobalite investment and rapid-heating type investment were estimated from the measured solid densities of the as-received powders and the set investments. The porosity and water content of the set investments were determined from the experimental data. Excess water content in the set investment was calculated in relation to the elapsed time from the start of mixing with water. The experimental porosities of the set and heated investments were about 40% for dry set >compacts and about 50% for fired compacts, which well agreed with the numerically computed estimations, respectively.
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Naruporn MONMATURAPOJ, Wiwaporn SOODSAWANG, Siriporn TANODEKAEW
2012 Volume 31 Issue 1 Pages
125-130
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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In this paper, we report on the enhanced strength of glass ionomer cement (GIC) by using the process of pre acid-base reaction and spray drying in glass preparation. The pre acid-base reaction was induced by prior mixing of the glass powder with poly(alkenoic acid). The weight ratios of glass powder to poly(alkenoic acid) were varied to investigate the extent of the pre acid-base reaction of the glass. The effect of the spray drying process which produced spherical glass particles on cement strength was also studied and discussed. The results show that adding 2%-wt of poly(alkenoic acid) liquid in the pre-reacted step improved cement strength. GICs prepared using a mixture of pre-reacted glass with both spherical and irregular powders at 60:40 by weight exhibited the highest compressive strength at 138.64±7.73 MPa. It was concluded that glass ionomer cements containing pre-reacted glass with mixed glass morphology using both spherical and irregular forms are promising as restorative dental materials with improved mechanical properties and handling characteristics.
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Hiroe TAKEFU, Shinji SHIMOJI, Tsutomu SUGAYA, Masamitsu KAWANAMI
2012 Volume 31 Issue 1 Pages
131-138
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The purpose of this study was to evaluate the influence of blood contamination before or after surface treatment on adhesion of 4-META/MMA-TBB resin. After bovine root dentin surfaces were contaminated with blood before or after dentin surface treatment with 10-3 solution, the contaminated surface was rinsed with water, air-dried, or re-treated with 10-3 solution. Dye leakage and microtensile bond strength (MTBS) of 4-META/MMA-TBB resin to dentin were measured after storage in water for 24 h. When blood contamination occurred before surface treatment, there was no significant difference in the leakage value and MTBS as compared with that of the uncontaminated group. When blood contamination occurred after surface treatment, the leakage value increased and MTBS significantly decreased (
p<0.05) even if the blood was washed away. However, when the surface was re-treated with 10-3 solution after rinsing with water, the leakage value and MTBS were restored to those of the uncontaminated group.
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Guang HONG, Hiroki TSUKA, Takeshi MAEDA, Yasumasa AKAGAWA, Keiichi SAS ...
2012 Volume 31 Issue 1 Pages
139-149
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The purpose of this study was to investigate the use of different plasticizers in soft acrylic resin materials to reduce leaching of the plasticizer and thus increase the durability of tissue conditioners. Samples were prepared containing different combinations of three types of polymer/copolymer powder and four types of plasticizer liquid (DEHM, DIBA, DAA and DINA). The dynamic viscoelasticity of each sample was measured after water immersion using a dynamic mechanical analyzer. Water absorption, solubility and weight change were also measured. A significant difference was found among the materials regarding dynamic viscoelasticity, water absorption and solubility. The samples containing P-n-BMA had the most stable
G’ and
G’’ scores throughout the immersion. P-n-BMA is the most suitable powder together with DEHM as the most suitable liquid component for a tissue conditioner. These results suggest that it is possible to improve the durability of tissue conditioners by combining different polymers and plasticizers.
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Sai MA, Naomi IZUTANI, Satoshi IMAZATO, Ji-hua CHEN, Wakako KIBA, Rann ...
2012 Volume 31 Issue 1 Pages
150-156
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached
Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached
Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives.
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Hae-Hyoung LEE, Chung-Jae LEE, Kenzo ASAOKA
2012 Volume 31 Issue 1 Pages
157-164
Published: 2012
Released on J-STAGE: February 03, 2012
Advance online publication: January 21, 2012
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The aim of the present study was to measure various mechanical properties of acrylic denture base resins, including flexural modulus, flexural strength, fracture toughness, Barcol and Vickers hardness and their related properties, and to investigate correlations between different mechanical properties. Resin specimens were prepared according to manufacturers’ recommended instructions. The mechanical properties were measured under specified standards. Data from the mechanical tests were examined using correlation tests. In general, the mean results for mechanical properties of each specimen group were differently ranked depending on the tested mechanical property. The flexural modulus value showed strong or reasonable positive correlation with those of proportional limit, flexural strength, and surface hardness. In contrast, fracture toughness revealed strong negative correlations with the flexural parameters and hardness values. Results of correlation tests for the different parameters can be used for estimation of mechanical performance of acrylic denture bases in clinical situation and for quality control purposes.
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