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Ibrahim DAMLAR, Erhan OZCAN, Erkan YULA, Muhammet YALCIN, Salih CELİK
2014 Volume 33 Issue 4 Pages
453-457
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: March 04, 2014
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The purpose of this study was to evaluate,
in vitro, the antimicrobial effect of iRoot BP, iRoot BP Plus, and mineral trioxide aggregate (MTA) against
Entercoccus faecalis and
Candida albicans by using direct contact test. The materials were tested immediately after application to the microtiter wells and after setting for 1-day and for 7-days. Ten microliters of microbial suspension was added to each well for direct contact with each material for 1 h at 37°C and 100% humidity. Then fresh media was added and, survival of bacteria and fungi was determined by using 10-fold serial dilution and inoculated onto agar plates. In fresh and 1-day samples all of tested materials showed statistically significant antimicrobial effects compared to control groups (
p<0.05). In 7-day samples, there were no significantly differences compared to control groups. MTA, iRoot BP and iRoot BP Plus had similar antimicrobial efficacy against
E. faecalis and
C. albicans.
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Ali Abdullah Al-MAQTARI, Abdul Aziz Abdul RAZAK, Mohd HAMDI
2014 Volume 33 Issue 4 Pages
458-465
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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This study aimed at investigating and establishing stress distributions in graded multilayered zirconia/alumina ceramic cores and at veneer-core-cement-dentin interfaces, using finite element analysis (FEA), to facilitate the structural design of ceramic cores through computer modeling. An intact maxillary premolar was digitized using CT scanning. An imaging software, Mimics, was used to reconstruct 3D models based on computed tomography (CT) data saved in DICOM format. Eight different 3D models were created for FEA, where each 3D model was meshed and its bottom boundaries constrained. A static load was applied in the oblique direction. The materials were assumed to be isotropic and homogeneous. Highest von Mises stress values were found in areas directly below the load application point, and stress gradually decreased in occlusal loading direction from the external surface toward the dentin. Stress levels occurring at veneer-ceramic core-cement-dentin interfaces were shown to be lower in multilayered ceramic cores than in single-layer models.
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Juliane Maria GUERREIRO TANOMARU, Inara STORTO, Guilherme Ferreira DA ...
2014 Volume 33 Issue 4 Pages
466-470
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: April 29, 2014
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The aim of this study was to evaluate some properties of the calcium silicate materials Mineral Trioxide Aggregate (MTA) and Portland cement (PC) with microparticulated (micro) and nanoparticulated (nano) zirconium oxide (ZrO
2) or niobium oxide (Nb
2O
5). The experimental materials: White PC (PC), MTA-Angelus
® (MTA), PC+ZrO
2micro, PC+ZrO
2nano, PC+Nb
2O
5micro and PC+Nb
2O
5nano were submitted to radiopacity and pH evaluations. Furthermore, the antimicrobial activity against different microorganisms was assessed by agar diffusion test. MTA presented higher radiopacity than other materials. However, all materials except PC presented higher radiopacity than recommended by ISO/ADA. MTA promoted higher pH values in all analyzed periods (
p≤0.05). At the initial periods, PC and PC+ZrO
2micro showed pH similar to MTA. All materials showed antimicrobial activity against the evaluated microorganisms. In conclusion, ZrO
2 and Nb
2O
5 could be alternative radiopacifiers to be added to calcium silicate materials.
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Bichen LIN, Yuming ZHAO, Jie YANG, Wenjun WANG, Li-hong GE
2014 Volume 33 Issue 4 Pages
471-475
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 11, 2014
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The purpose of this study was to compare the effects of zinc oxide-eugenol (ZOE) and calcium hydroxide/iodoform paste (Vitapex), as root canal filling materials in pulpectomy, on delaying the root resorption of primary molars without permanent successors. Animal models without permanent successors were surgically established in beagle dogs. Root resorption was observed
via periapical radiographs. The onset of root resorption of primary mandibular molars without successors occurred later (
p<0.05) than physiologic resorption. ZOE pulpectomy clearly delayed the root resorption of primary molars without permanent successors (
p<0.05), whereas resorption of primary molars with Vitapex pulpectomy started at almost the same time as physiologic resorption. Compared with Vitapex, ZOE was a more effective root canal filling material in delaying the root resorption of primary molars.
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Yukihiko TAKEMURA, Koji HANAOKA, Ryota KAWAMATA, Takashi SAKURAI, Tosh ...
2014 Volume 33 Issue 4 Pages
476-483
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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The polymerization shrinkage of flowable resin composites was evaluated using air bubbles as traceable markers. Three different surface treatments
i.e. an adhesive silane coupling agent, a separating silane coupling agent, and a combination of both, were applied to standard cavities. Before and after polymerization, X-ray micro-computed tomography images were recorded. Their superimposition and comparison allowed position changes of the markers to be visualized as vectors. The movement of the markers in the resin composite was, therefore, quantitatively evaluated from the tomographic images. Adhesion was found to significantly influence shrinkage patterns. The method used here could be employed to visualize shrinkage vectors and shrinkage volume.
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Shoko MIURA, Ryoichi INAGAKI, Shin KASAHARA, Masanobu YODA
2014 Volume 33 Issue 4 Pages
484-489
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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The purpose of this study is to investigate the fit of zirconia cores and all-ceramic crowns prepared with different cervical margin designs. The radius of curvature between the axial wall and the occlusal surface was set to 1 mm in an abutment using the cervical shoulder marginal design (S) and to 0.2 and 0.5 mm in abutments with round shoulders (0.2RS and 0.5RS, respectively). The internal gaps of the cores were 45–138 μm (S), 41–141 μm (0.2RS), and 43–133 μm (0.5RS). The internal gaps of the all-ceramic crowns were 40–115 μm (S), 45–113 μm (0.2RS), and 42–126 μm (0.5RS). There were no significant differences in one-way ANOVA for any region in any marginal design before and after firing the porcelain. The marginal gaps between the all-ceramic crowns and dies were 27±25 (S), 30±29 (0.2RS), and 24±27 μm (0.5RS), again with no significant differences in one-way ANOVA.
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Miao YU, Hisashi DOI, Yusuke TSUTSUMI, Peng CHEN, Maki ASHIDA, Shohei ...
2014 Volume 33 Issue 4 Pages
490-498
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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This study aimed to develop a novel abutment material with good esthetic and mechanical properties by producing a white oxide layer on a zirconium-14 mass% niobium (Zr-14Nb) alloy substrate using a thermal oxidation process. Oxidation temperatures ranged 700–1000°C and oxidation time ranged 30–180 min. The color of the oxide layer varied depending on temperature and time. A white oxide layer was obtained under appropriate conditions. The oxide layer thickness increased with increased temperature and time, as revealed by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Moreover, X-ray diffraction and X-ray photoelectron spectroscopy revealed that the oxide layer was predominantly monoclinic ZrO
2, tetragonal ZrO
2, and Nb
2O
5. The oxide layer revealed good abrasion resistance and high adhesion to the substrate. This novel process for producing white materials with good mechanical properties will be useful for abutments and prostheses in dental implant treatment.
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Takako YOSHIKAWA, Makoto MORIGAMI, Alireza SADR, Junji TAGAMI
2014 Volume 33 Issue 4 Pages
499-503
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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This study aimed to evaluate the effects of the light curing method and resin composite composition on marginal sealing and resin composite adaptation to the cavity wall. Cylindrical cavities were prepared on the buccal or lingual cervical regions. The teeth were restored using Clearfil Liner Bond 2V adhesive system and filled with Clearfil Photo Bright or Palfique Estelite resin composite. The resins were cured using the conventional or slow-start light curing method. After thermal cycling, the specimens were subjected to a dye penetration test. The slow-start curing method showed better resin composite adaptation to the cavity wall for both composites. Furthermore, the slow-start curing method resulted in significantly improved dentin marginal sealing compared with the conventional method for Clearfil Photo Bright. The light-cured resin composite, which exhibited increased contrast ratios duringpolymerization, seems to suggest high compensation for polymerization contraction stress when using the slow-start curing method.
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Ki-Baek KIM, Jae-Hong KIM, Woong-Chul KIM, Ji-Hwan KIM
2014 Volume 33 Issue 4 Pages
504-509
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The purpose of this study was to investigate, by measuring the gap, the possible clinical use of three-unit fixed dental prostheses (FDPs) manufactured using stereolithography. A total of 20 epoxy models were built with a same case (abutment teeth 14, 16). The 40 specimens were produced using the stereolithography (SLA) and wax-up (LW). The 960 gaps of the 40 specimens produced were measured by a silicone replica. The Wilcoxon rank sum test was then used to compare and analyze the data obtained from the two groups (α=0.05). The total gap, as measured from the SLA and LW groups, was 98.6 and 66.6 µm, respectively. The results indicate that the gap in the SLA group is statistically significantly greater than that in the LW group (
p<0.05). Further assessment and improvement of the SLA method for the fabrication of FDPs is evidently still required.
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Takashi KAMEDA, Kazuo OHKUMA, Natsuki SANO, Kazuto TERADA
2014 Volume 33 Issue 4 Pages
510-521
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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Multi-bracket systems are popular orthodontic appliances and are commonly bonded directly to enamel surfaces by resin adhesives. In light-cured bonding, the tip of the curing unit must be kept at a distance from the adhesive on the tooth, which can lead to low polymerization and insufficient bond strength. The curing lights also generate low-frequency electromagnetic fields, which can be harmful to patient health. Furthermore, bacterial contamination of the light-curing tips during use presents an infection risk for patients. In this study, we describe the development of optical guiding forceps (OGFs) for polymerizing light-cured resin as a solution to these problems. With OGFs, polymerization of adhesives was deeper than with lower magnetic fields and the bonds had the same shear strength as those formed by conventional procedures. These results suggest that OGFs may have practical use in the direct bonding of orthodontic appliances as well as in provisional bonding.
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Yoshikazu OKUYAMA, Takanobu SHIRAISHI, Kazuhiro YOSHIDA, Tadafumi KURO ...
2014 Volume 33 Issue 4 Pages
522-529
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 02, 2014
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We evaluated the influence of composition and powder/liquid (P/L) ratio on the setting characteristics and mechanical properties of autopolymerized hard direct denture reline resins composed of methyl methacrylate (MMA, monomethacrylate) and ethylene glycol dimethacrylate [EGDMA, dimethacrylate (cross-linking agent)], with poly (ethyl methacrylate) used as the powder, and a mixture of MMA and EGDMA containing p-tolyldiethanolamine as the monomer. Setting times were determined using an oscillating rheometer and mechanical properties were based on ISO specifications. Setting time increased exponentially with an increase in the ratio of EGDMA to MMA and decrease in P/L ratio. Materials with a liquid component of approximately 75–85 wt% EGDMA and a higher P/L ratio showed higher ultimate flexural strength and flexural modulus. Our results suggest that setting characteristics are more influenced by the ratio of monomethacrylate and cross-linking agent, whereas mechanical properties are more influenced by P/L ratio.
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Sera SIMSEK DERELIOGLU, Yucel YILMAZ, Pelin CELIK, Burak CARIKCIOGLU, ...
2014 Volume 33 Issue 4 Pages
530-538
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The aim of this study was to compare the shear bond strengths (SBS), failure modes (adhesive, cohesive, or mixed), and marginal microleakage occurrence of conventional resin (CR)-based, glass ionomer (GI)-based, and self-adhesive resin (SAR)-based fissure sealants with or without prior phosphoric acid (PA) etching. Fifty extracted premolars were randomly and equally assigned into five groups —G1:PA+CR, G2:PA+GI, G3:GI, G4:PA+SAR, and G5:SAR. Prior PA etching significantly (
p<0.05) increased the SBSs of sealants. Adhesive failure mainly occurred in teeth treated with SAR- or GI-based fissure sealants, and cohesive failure mainly occurred in PA-etched teeth. Microleakage occurrence differed significantly (
p<0.05) among the five groups of treated teeth. We concluded that conditioning of a tooth’s enamel surface is crucial to creating strong bonds and leak-free sealing between tooth and fissure sealant.
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Jindan PIAO, Kana MIYARA, Arata EBIHARA, Naoyuki NOMURA, Takao HANAWA, ...
2014 Volume 33 Issue 4 Pages
539-544
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The effects of cyclic fatigue on bending properties of NiTi endodontic instruments were investigated. Sixteen Profiles
® were divided into two groups (A, and B). The sequence of cantilever bending test and cyclic fatigue test was alternated repeatedly until file separation occurred. In the cyclic fatigue test, the instrument curvature was 19° in group A and 38° in group B. Fractographic examination was performed to determine fracture patterns. In group A, there were significant differences between the bending load values measured before the cyclic fatigue test and the last cantilever bending test before instrument fracture at each deflection (
p<0.05). Fractographic examination showed the specific patterns of cyclic fatigue fracture. The stress required to induce martensitic transformation might be reduced due to the softening behavior caused by the cyclic fatigue under the relaxation condition of the superelasticity range (group A). The SEM images were able to display specific patterns indicating cyclic fatigue fracture.
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Kisaki SHIMAZU, Hiroyuki KARIBE, Kiyokazu OGATA
2014 Volume 33 Issue 4 Pages
545-550
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The purpose of this study was to evaluate the effects of artificial saliva contamination on three restorative materials, namely, a glass ionomer cement (GIC), a resin-modified GIC (RMGIC), and a composite resin (CR), for which two different etching adhesive systems were used. Thus, three surface conditions were created on bovine teeth using artificial saliva: control, mild saliva contamination, and severe saliva contamination. The dentin bond strength for CR was significantly lower after artificial saliva contamination. There were, however, no significant differences among the three surface conditions in terms of the dentin and enamel bond strengths of GIC and RMGIC. Moreover, CR exhibited significantly greater microleakage after artificial saliva contamination, whereas no significant differences were found in GIC and RMGIC. The results showed that artificial saliva contamination did not affect the shear bond strengths of GIC and RMGIC or their degrees of microleakage.
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Ruman Uddin CHOWDHURY, Hiroshi CHUREI, Hidekazu TAKAHASHI, Takahiro WA ...
2014 Volume 33 Issue 4 Pages
551-556
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 05, 2014
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The aims of the present study were to investigate the shock absorption capability and force dispersion effect of mouthguard (MG) materials using load cell and film sensors. Two kinds of MG materials, ethylene vinyl acetate and polyolefin, were chosen for this study. When impact forces of approximately 5,000 N were applied on the MG materials using a round flat-nosed rod and a bluntly pointed rod, peak intensities were measured using the load cell sensor while peak stresses and impressed stress distribution areas were measured using the film sensor. Combined analysis using both load cell and film sensors clearly showed the shock absorption properties and force dispersion effects of different MG materials with different impact object shapes. Therefore, impact analysis involving a combined use of these sensor systems was useful and reliable in assessing the shock absorption capability and force dispersion effect of MG materials.
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Yuya ASAKAWA, Hidekazu TAKAHASHI, Naohiko IWASAKI, Masahiro KOBAYASHI
2014 Volume 33 Issue 4 Pages
557-564
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The aim of this study was to evaluate the effects of ultraviolet light (UV) irradiation and sandblasting treatment on the shear bond strength between polyamide and chemical-cured resin. Three types of commercial polyamides were treated using UV irradiation, sandblasting treatment, and a combining sandblasting and UV irradiation. The shear bond strength was measured and analyzed using the Kruskal-Wallis test (
α=0.05). Comparing shear bond strengths without surface treatment, from 4.1 to 5.7 MPa, the UV irradiation significantly increased the shear bond strengths except for Valplast, whose shear bond strengths ranged from 5.2 to 9.3 MPa. The sandblasting treatment also significantly increased the shear bond strengths (8.0 to 11.4 MPa). The combining sandblasting and UV irradiation significantly increased the shear bond strengths (15.2 to 18.3 MPa) comparing without surface treatment. This combined treatment was considered the most effective at improving the shear bond strength between polyamide and chemical-cured resin.
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Seiji BAN, Masahiro NAWA, Fumio SUGATA, Jiro TSURUKI, Hiroshi KONO, Ta ...
2014 Volume 33 Issue 4 Pages
565-569
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
Advance online publication: July 05, 2014
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The surface of a ceria-stabilized tetragonal zirconia polycrystal (Ce-TZP/Al
2O
3) nanocomposite was sandblasted by alumina particles and veneered with feldspathic porcelain
via a conventional condensation method. The part of each specimen containing the interface layer was sliced to ultrathin sections with an argon ion slicer, and these sliced sections were observed using high-resolution transmission electron microscopy (HRTEM). For both interfaces, Ce-TZP/porcelain and Al
2O
3/porcelain, no transition layers due to abrupt changes in atomic distributions were observed. Besides, the porcelain layers of both interfaces consisted of homogeneous amorphous phases. These results suggested that both Ce-TZP and Al
2O
3 could be directly bonded to porcelain by Van der Waals forces arising from the close contact between them.
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Emel Olga ONAY, Christos GOGOS, Mete UNGOR, Nikolaos ECONOMIDES, Vasi ...
2014 Volume 33 Issue 4 Pages
570-575
Published: July 31, 2014
Released on J-STAGE: August 01, 2014
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The aim of this research was to evaluate the apical sealing abilities of 60 root-end cavities filled with mineral trioxide aggregate (MTA) and iRoot BP cements after treated with either 17% EDTA solution or Er,Cr:YSGG laser irradiation. After the filling procedure, apical leakage quantity was measured at 4 weeks using a fluid filtration method. One root from each group was processed for scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. Both EDTA/MTA and laser irradiation/MTA combinations showed significantly lower microleakage than EDTA/iRoot BP and laser irradiation/iRoot BP combinations (
p<0.05). Between groups of the same filling material, there were no significant differences among specimens treated with EDTA or laser (
p>0.05). Both MTA and iRoot-BP demonstrated tag-like structures within the dentinal tubules when used in conjunction with EDTA.
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