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Yukari OGURA, Yusuke SHIMIZU, Koji SHIRATSUCHI, Akimasa TSUJIMOTO, Tos ...
2012 年 31 巻 4 号 p.
507-513
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The effect of warm air-drying on the dentin bond strengths of the single-step self-etch adhesives was determined. The adhesives were applied to bovine dentin followed by drying in a stream of warm air for 5, 10, and 15 s at 37°C. Resin composites were condensed into a mold and polymerized. Specimens were stored in distilled water at 37°C for 24 h, then shear tested. The surface free-energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The dentin bond strengths varied according to the air-drying time. The value of the acid component increased slightly when drying was performed with a stream of warm air, whereas that of the base component decreased signifi cantly. These data suggested that warm air-drying was essential to obtain adequate bond strengths, although increasing the drying time did not significantly influence the bond strength.
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Mutlu ÖZCAN, Marijn BREUKLANDER, Esra SALIHOGLU-YENER
2012 年 31 巻 4 号 p.
514-522
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
This study evaluated the effect of a) pontic materials and b) occlusal morphologies on the fracture resistance of fi ber-reinforced composite (FRC) inlay-retained fixed dental prostheses (FDP). Inlay-retained FRC FPDs (
N=45,
n=9) were constructed using a) resin composite (deep anatomy), b) natural tooth, c) acrylic denture tooth, d) porcelain denture tooth and e) resin composite (shallow anatomy), as pontic materials. In addition resin composite beams were fabricated (
N=30,
n=10): i) ‘circular', ii) ‘elliptic I', and iii) ‘elliptic II'. There was no significant difference between the fracture resistance of Groups a, b, c, and d (598, 543, 539, 509 N, respectively) (
p>0.05) (One-way ANOVA). Fracture resistance of Group e (1,186 N) was significantly higher than those of other groups (
p<0.05) (Tukey's test). No significant difference was found between Group i (1,750 N) and Group ii (1,790 N). Not the pontic material but the occlusal morphology affects the fracture resistance of FRC FDPs.
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Haitham ELBISHARI, Nick SILIKAS, Julian SATTERTHWAITE
2012 年 31 巻 4 号 p.
523-527
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The objective of this study was to investigate the correlation between filler size, fracture toughness and voids. Seven model resin composites and one commercial have been used in the study. A single edge notch mould was used to prepare samples (
n=8). A selected area of 1mm below and above the notch was scanned with micro CT and then the percentage of voids calculated. A universal testing machine was used to measure fracture toughness. Percentage of voids and fracture toughness data were analysed using ANOVA and post hoc methods were performed to check any significant differences between materials tested (
p<0.05). Conclusion: Filler size is strongly correlated to % voids but has no effect on fracture toughness.
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Burak SAĞSEN, Yakup ÜSTÜN, Kanşad PALA, Sezer DEMİRBUĞA
2012 年 31 巻 4 号 p.
528-532
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The aim of this study was to compare the fracture resistance of roots filled with gutta percha (GP) and different root canal sealers.Fifty-five human maxillary central incisors were selected and randomly divided into three experimental groups (Groups 1-3) and two control groups (Groups 4 and 5). They were Group 1-15 root canals filled with an epoxy resin-based sealer (AH Plus) and GP, Group2 -15 root canals filled with a calcium silicate-based sealer (iRoot SP) and GP, Group 3: 15 root canals filled with another calcium silicate-based sealer (MTA Fillapex) and GP, Group 4: five roots were instrumented but not filled, and Group 5: five roots were neither instrumented nor filled. Compressive loading was carried out using a universal testing machine until fracture occurred. Force applied at time of fracture was recorded as fracture strength of specimen in Newtons. There were no significant differences in fracture strength among the three experimental groups (
p>0.05), whose results were significantly superior to that of Group 4 (
p<0.05). In conclusion, all the root canal sealers used in the present study increased the fracture resistance of instrumented root canals.
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Keiko NAKATA, Toru NIKAIDO, Syozi NAKASHIMA, Nobuhito NANGO, Junji TAG ...
2012 年 31 巻 4 号 p.
533-540
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
To indicate the possibility of a new approach to creating mineral density profiles, and to examine longitudinal changes in ‘the rate of remineralization (RA)' and ‘the mineral density (DAs) at 4 different depths' (surface zone: SZ, lesion body: LB, middle zone: MZ, deep zone near to sound area: DZ) in enamel subsurface lesions, eight demineralized bovine enamel-dentin blocks were remineralized for 1 to 4 week and investigated using Micro-focus X-ray CT (micro-CT). After CT scanning, mineral density profiles were created.Mineral densities at each depth after demineralization were SZ≅LB<MZ<DZ. Increase in RA was the greatest in the first week of remineralization and it decreased over time. Increments of the mineral density were greater in the order of SZ≅LB>MZ>DZ. This study indicated a new approach to create a mineral density profile and suggested the greater the value of the mineral density before the remineralization, the smaller the mineral density increments.
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Toshiko INOUE, Makoto SAITO, Masato YAMAMOTO, Fumio NISHIMURA, Takashi ...
2012 年 31 巻 4 号 p.
541-548
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
In one aspect, this study examined the tensile strength of coronal dentin, as a function of the location of incremental lines, in two types of teeth: human molar
versus bovine incisor. In another aspect, tensile strength in coronal dentin was examined with tensile loading in two different orientations to the incremental lines: parallel
versus perpendicular. There were four experimental groups in this study: HPa, human molar dentin with tensile orientation parallel to the incremental lines; HPe, human molar dentin with tensile orientation perpendicular to the incremental lines; BPa, bovine incisor dentin with tensile orientation parallel to the incremental lines; BPe, bovine incisor dentin with tensile orientation perpendicular to the incremental lines. Tensile strengths of the parallel group (HPa and BPa) were significantly higher (
p<0.05) than those of the perpendicular group (HPe and BPe). Effect of structural anisotropy, contributed by the incremental lines, was thus confirmed in coronal dentin. However, there were no differences in anisotropy effect between the two tooth types.
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Kazuhiro SUNOUCHI, Kanji TSURU, Michito MARUTA, Giichiro KAWACHI, Shig ...
2012 年 31 巻 4 号 p.
549-557
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
Spherical carbonate apatite (CO
3Ap) microspheres approximately 1 mm in diameter were fabricated by granulation of calcium hydroxide around a core followed by carbonation and phosphatization through dissolution-precipitation reaction. CO
3Ap microsphereswith high uniformity could not be achieved without using a core. Solid CO
3Ap microspheres were obtained using a calcite core whereas hollow CO
3Ap microspheres were obtained using a NaCl core. The obtained microsphere was identified as B-type CO
3Ap by Fourier transform infrared analysis and the carbonate content was approximately 7—8 wt% regardless of the type of core used for sample preparation. The mechanical strength of both the solid and hollow CO
3Ap microspheres was sufficient for practical use as a bone substitute.
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Tomoyuki TAKAI, Keiichi HOSAKA, Keisuke KAMBARA, Suppason THITTHAWEERA ...
2012 年 31 巻 4 号 p.
558-563
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The purpose was to evaluate the effect of air-drying dentin surfaces on the microtensile bond strength (μTBS) of a solvent-free onestep adhesive (Bond 1 SF). Twelve human molars were ground with 600-grit SiC paper. Before applying bonding agent, the dentin surface was rinsed with distilled water and blot-dried with tissue paper, followed by air-drying for 0, 3, 30, and 60 s using with a dental air syringe. After applying and curing Bond 1 SF, resin composite was incrementally built up. Specimens were then stored in distilled water for 24 h and then μTBSs were measured at a cross-head speed of 1 mm/min. Higher μTBS were observed when the dentin surface was air-dried for 3 s (33.2±6.8MPa)>0 s (26.7±4.5MPa)>30 s (22.6±5.5MPa)=60 s (20.4±5.0MPa). The results suggested that prolonged air-drying of the dentin surface removed water and decreased the bond strengths of Bond 1 SF.
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Guangyan QIAO, Jiansheng SU, Meifeng HE
2012 年 31 巻 4 号 p.
564-574
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The aim of this study was to investigate the electrochemical behavior of Co-Cr alloy in artificial saliva containing (−)-epigallocatechin gallate (EGCG) and to characterize the composition and structure of the passive film formed by potentiodynamic polarization.Electrochemical measurements ranked the corrosion resistance of Co-Cr dental cast alloy as follows when exposed to artifi cial saliva containing different concentrations of EGCG: 4.0 g/L<2.0 g/L<0 g/L<0.5 g/L<1.0 g/L. This showed that the concentration of EGCG in artificial saliva affected the corrosion behavior of Co-Cr alloy. X-ray photoelectron spectroscopy (XPS) results revealed that theoutermost surface layer on Co-Cr alloy was mainly composed of Cr
2O
3 and EGCG-Cr (III) ion complex, which were formed by redoxand complex formation reactions respectively. When the redox reaction was dominant, Co-Cr alloy exhibited high corrosion resistancein EGCG-containing artificial saliva. On the contrary, when the complex formation reaction was dominant, Co-Cr alloy exhibited low corrosion resistance.
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Nilüfer Celebi BERIAT, Ahmet Atila ERTAN, Zeliha YILMAZ, Gülsah GULAY, ...
2012 年 31 巻 4 号 p.
575-582
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
This study evaluated the sealing ability and push-out bond strength of two luting cements cured with two different types of light curing units (LCU): light-emitting diode (LED)
versus quartz tungsten halogen (QTH). Forty teeth were divided into four groups(
n=10/group). Quartz fiber posts (D. T. Light-Post) were luted to coronal or apical section of root canals using two types of resin cements (Panavia F or RelyX) cured with either LED LCU (Elipar FreeLight II) or QTH LCU (Optilux 501). Highest push-out bond strength was exhibited by QTH-cured RelyX, which was not significantly different from LED-cured RelyX but was higher than QTHcured Panavia F. The push-out bond strength of Panavia F did not differ with LCU type (
p>0.05), but exhibited lower values than both QTH- and LED-cured RelyX. Fluid filtration test revealed that sealing ability was not influenced by luting cement type, but was signifi cantly influenced by LCU type in favor of QTH light source: QTH-cured specimens displayed better seal than LED-cured ones (
p<0.05).
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Juliana Maria Capelozza BOAVENTURA, Marcio José BERTOLINI, Gislaine C ...
2012 年 31 巻 4 号 p.
583-592
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The present work seeks to evaluate the biocompatibility of experimental glass ionomer cements (GIC) prepared from niobium-calcium fluoro-alumino-silicate glass powder and two commercial GICs. The GICs were implanted into the subcutaneous connective tissue of sixty rats. The rats were sacrificed during four varying time periods: 7, 15, 30, and 60 days and histopathological examinations were then performed. The Kruskal-Wallis test was performed to evaluate any significant differences between the materials. Additionally, multiple comparisons of the mean rank were also carried out using the Dunn test (
p<0.05). No significant differences were observed that one GIC was superior to the other. The tissue response for all of the GICs tested was similar in all the periods examined.
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Akihiro OTSU, Kanji TSURU, Michito MARUTA, Melvin L. MUNAR, Shigeki MA ...
2012 年 31 巻 4 号 p.
593-600
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
Effects of carbonation temperature and compacting pressure on basic properties of calcite block were studied using Ca(OH)
2 compact made with 0.2-2.0 MPa and their carbonation at 200-800ºC for 1 h. Microporous calcite was obtained only when carbonated at 600ºC using Ca(OH)
2 compact made with 0.2 MPa even though thermogravimetry analysis showed that calcite powder was stable up to920ºC under CO
2 atmosphere. CaO formed by carbonation at 700ºC and 800ºC is thought to be caused by the limited CO
2 diffusion interior to the Ca(OH)
2 compact. Also, unreacted Ca(OH)
2 was found for Ca(OH)
2 compact prepared with 0.5 MPa or higher pressure even when carbonated at 600ºC. As a result of high temperature carbonation, crystallite size of the calcite, 58.0 nm, was signifi cantly larger when compared to that of calcite prepared at room temperature, 35.5 nm. Porosity and diametral tensile strength of the microporous calcite were 39.5% and 6.4 MPa.
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Sven RINKE, Daniel FORNEFETT, Nikolaus GERSDORFF, Katharina LANGE, Mat ...
2012 年 31 巻 4 号 p.
601-609
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
This study evaluated the effect of different parameters on the marginal precision of CAD/CAM-fabricated zirconia copings. Specimens(
n=60) were fabricated with two different scanners and two milling systems. The copings were evaluated with respect to their mean and average maximum marginal gaps. A two-way analysis of variance (ANOVA) (α=0.05) was used to evaluate the effect of different parameters (scanner, milling process) on marginal accuracy. The mean (averaged maximum) marginal gaps ranged from 57.9 (112.2μm) to 71.0 (144.6 μm) in the “as machined" state. After manual adaptation, the respective values ranged from 54.6 (98.0 μm) to 59.9(107.7 μm). The system and manual adaptation variables were found both to have multiple significant effects on the marginal gap size and to have a complex interaction. Thus, synchronized/validated processing chains should be preferentially used to guarantee optimal fitting accuracy for CAD/CAM zirconia restorations.
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Pisaisit CHAIJAREENONT, Hidekazu TAKAHASHI, Norihiro NISHIYAMA, Mansua ...
2012 年 31 巻 4 号 p.
610-616
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The objective of this study was to clarify the effects of silane coupling agents and solutions of different polarity on polymethyl methacrylate (PMMA) bonding to alumina. Three silane coupling agents (3-methacryloxypropyltrimethoxysilane (MPS),3-aminopropyltriethoxysilane (APS) and N-2 (aminoethyl) 3-aminopropyltriethoxysilane) and 3 different polar solutions, 70% ethanol, isopropanol and toluene, were selected for silanization. Shear bond strengths were statistically compared with Tukey HSD(α=0.05). The alumina surfaces after silanization and shear bond test were examined with an energy dispersive spectrometer (EDS).The bond strengths of PMMA on the alumina with MPS (15.0 MPa), APS (13.8 MPa) in ethanol were greater than the others in nonthermocyclings. The bond strength decreased after thermocyclings. The ethanol groups were greater than the others. EDS revealed Si remaining on the alumina surface after the shear bond test. The results indicated that the silanization using MPS and APS with ethanol solution was effective.
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Xiaohong WANG, Jiang CHANG, Sheng HU
2012 年 31 巻 4 号 p.
617-622
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The objective of this study was to evaluate the sealing ability and antibacterial activity of Ca
3SiO
5/CaCl
2 composite cement. Fifty maxillary anterior teeth were instrumented according to step-back technique and filled with experimental and control materials. Toevaluate the sealing ability, a fluid transport model using glucose was employed for quantitative analysis of endodontic microleakage. To evaluate antibacterial activity,
E. colias (ATCC 25922) was cultivated on agar plates. Results showed that the sealing ability of Ca
3SiO
5/CaCl
2 composite cement and cortisomol paste were higher than that of zinc oxide-eugenol (ZOE) cement, and that nosignificant difference was observed between Ca
3SiO
5/CaCl
2 composite cement and cortisomol paste. On antibacterial activity, Ca
3SiO
5/CaCl
2 composite cements composed of varying amounts of CaCl
2 (0-15%) exhibited similar levels of activity against
E. coliasas calcium hydroxide cement, whereas cortisomol paste had little effect on
E. colias. All these results suggested that Ca
3SiO
5/CaCl
2 composite cement demonstrated good potential for root canal treatment applications.
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Pisaisit CHAIJAREENONT, Hidekazu TAKAHASHI, Norihiro NISHIYAMA, Mansua ...
2012 年 31 巻 4 号 p.
623-628
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
This study evaluated the different amounts of 3-methacryloxypropyltrimethoxysilane (MPS) coated alumina filler particles on flexural strength and wear resistance of alumina reinforced polymethyl methacrylate (PMMA) denture base. Ten mass% of alumina fi ller silanized with 0, 0.1, 0.2, or 0.4 mass% of MPS was blended with PMMA. PMMA without alumina particles served as control.Specimens were prepared for flexural strength and wear resistance tests (
n=10). Flexural strength was determined using a 3-point bending test and volume loss was measured by
in-vitro 2-body wear-testing. The results were analyzed by One-way ANOVA and Tamhane's test (α=0.05). Flexural strength ranged from 95.1-117.8 MPa, while volume loss ranged from 0.038-0.160 mm
3. Statistical analysis indicated the 0.1 mass% MPS silanized group had signifi cantly higher flexural strength and lower volume loss than the control group. Adding alumina filler silanized with 0.1 mass% MPS resulted in an improvement of the flexural strength and wear resistance of PMMA.
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Norimasa WASHIZAWA, Hideaki NARUSAWA, Yukimichi TAMAKI, Takashi MIYAZA ...
2012 年 31 巻 4 号 p.
629-634
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The purpose of this study was to synthesize biomaterials from daily dental waste. Since alginate impression material contains silica and calcium salts, we aimed to synthesize calcium silicate cement from alginate impression material. Gypsum-based investment material was also investigated as control. X-ray diffraction analyses revealed that although firing the set gypsum-based and modified investment materials at 1,200°C produced calcium silicates, firing the set alginate impression material did not. However, we succeeded when firing the set blend of pre-fired set alginate impression material and gypsum at 1,200°C. SEM observations of the powder revealed that the featured porous structures of diatomite as an alginate impression material component appeared useful for synthesizing calcium silicates. Experimentally fabricated calcium silicate powder was successfully mixed with phosphoric acid solution and set by depositing the brushite. Therefore, we conclude that the production of calcium silicate cement material is possible from waste alginate impression material.
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Sanjay THORAT, Niranjan PATRA, Roberta RUFFILLI, Alberto DIASPRO, Marc ...
2012 年 31 巻 4 号 p.
635-644
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
A photo-polymerizable Bisphenol-A diglycidylether methacrylate resin was characterized by Fourier transform infrared spectroscopy after its irradiation under different conditions to identify the best curing. Bonding-agent free composites with particles of ball-milled glass, silica and titania at loading of 10 and 50%wt were prepared, and their viscoelastic properties investigated by dynamic mechanical analysis, in experimental conditions close to the working environment in the mouth. All composites showed good stability at the considered conditions. The stiffest composite was the silica one, which was based on the smallest primary particles. The storage moduli close to room temperature (25°C) and mastication frequency (1 Hz) were extracted as reference bending moduli for the materials, and compared to static compressive moduli measured by nanoindentation performed by atomic force microscopy.Nanoindentation showed qualitative results in agreement with dynamic mechanical analysis as to the ranking of different materials, while resulting in approximately two-fold elastic modulus.
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Li-Hong HE, Lyndie FOSTER PAGE, David PURTON
2012 年 31 巻 4 号 p.
645-649
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The study was to evaluate the performance of different materials used in dental operative simulation and compare them with those of natural teeth. Three typical phantom teeth materials were compared with extracted permanent teeth by a nanoindentation system and evaluated by students and registered dentists on the drilling sensation of the materials. Moreover, the tool life (machinability) of new cylindrical diamond burs on cutting the sample materials was tested and the burs were observed. Although student and dentist evaluations were scattered and inconclusive, it was found that elastic modulus (
E) and hardness (
H) were not the main factors in determining the drilling sensation of the materials. The sensation of drilling is a reflection of cutting force and power consumption.An ideal material for dental simulation should be able to generate similar drilling resistance to that of natural tooth, which is the machinability of the material.
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Igor STOJANAC, Milan DROBAC, Ljubomir PETROVIC, Teodor ATANACKOVIC
2012 年 31 巻 4 号 p.
650-655
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The aim of this study was to examine the lifespan or number of cycles to failure of tapered rotary nickel-titanium (Ni-Ti) endodontic instruments. Simulated root canals with different curvatures were used to determine a relation between canal curvature and instrument lifespan. Using a novel mathematical model for the deformation of pseudoelastic Ni-Ti alloy, it was shown that maximum stress need not necessarily occur at the outer layer. On the basis of this observation, the Coffin-Manson relation was modified with parameters determined from this experiment. Results showed that the number of cycles to failure was influenced by the angle and radius of canal curvature and the size of instrument at the beginning of canal curvature. The resulting quantitative mathematical relation could be used to predict the lifespan of rotary Ni-Ti endodontic instruments under clinical conditions and thereby reduce the incidence of instrument failure
in vivo.
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Dong-Soo LEE, Tae-Sung JEONG, Shin KIM, Hyung-Il KIM, Yong Hoon KWON
2012 年 31 巻 4 号 p.
656-661
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The purpose of the present study was to evaluate the effect of dual-peak LED on the polymerization of coinitiator-containing composite resins. For this, microhardness, degree of conversion (DC), and polymerization shrinkage were evaluated. Specimens (coinitiator-containing: Aelite LS Posterior, Tetric EvoCeram, and Vit-l-escence; only camphorquinone-containng: Filtek Z350 and Grandio) were light cured using a quartz-tungsten-halogen (QTH: OP), a single-peak light-emitting diode (LED) (L. E. Demetron: DM), and a dual-peak LED (G-light: GL), respectively. All specimens light cured using GL showed the highest microhardness both on the top and bottom surfaces compared with the values obtained using the rest light-curing units (LCUs). DC had no consistent trend correspond to the LCU, but rather product specific. OP yielded the lowest polymerization shrinkage on the specimens. The coinitiatorcontaining composite resins achieved the highest microhardness by the dual-peak LED (GL). However, the influence of GL on DC and polymerization shrinkage of the specimens was not consistent.
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Miwa OZAKI, Tomoko OHSHIMA, Mio MUKUMOTO, Hirokazu KONISHI, Ayao HIRAS ...
2012 年 31 巻 4 号 p.
662-668
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The purpose of this study was to examine the biofilm removing and antimicrobial effects of microbubbled tap water and other functional water. The biofilm removal test showed that the activity of microbubbled tap water against the biofi lm of
Candida albicans and
Streptococcus mutans was significantly higher than that of ordinary tap water (
p<0.01). When the antimicrobial activities of two types of functional water were compared, the activity of electrolyzed hypochlorite water was significantly stronger than that of the ozonated water (
p<0.01). The antimicrobial effect of the electrolyzed hypochlorite water was increased in the microbubbled form, and was stronger than microbubbled tap water. The same results were obtained not only for biofilms, but also for planktonic microbes. Our results demonstrated that the microbubbled water showed strong biofilm removing effects. Moreover, the application of functional water, such as electrolyzed hypochlorite microbubbled water was effective for both removing and sterilizing biofilms.
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Kazuo KOISO, Takahiro SAITO, Isao KAWASHIMA
2012 年 31 巻 4 号 p.
669-673
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The objective of this research was to investigate the effect of mold temperature on grain interior and grain boundary reactions in a14-karat gold alloy. The alloy (Au-15%Ag-3%Pd-24 mass%Cu) was cast into an investment with different mold temperatures (22, 250,400, and 700°C) and then analyzed using SEM, X-ray diffraction, and potentiodynamic polarization tests. Lower mold temperatures(22 and 250°C) retarded a grain boundary reaction evidently present when using higher mold temperatures (400 and 700°C). Phase separation, which was manifested as a dual phase grain boundary nodular formation, was observed at a higher degree at 400°C mold temperature than at 700°C. The corrosion potentials of alloys cast at lower mold temperatures were more noble than those cast at higher mold temperatures, suggesting improved corrosion properties. Results of this study showed that the microstructure, crystalline phases present, and corrosion properties of 14-karat gold alloy were keenly influenced by the mold temperature, which controls and influences the cooling rate.
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Kenichi HARIMOTO, Yasuhiro YOSHIDA, Kumiko YOSHIHARA, Noriyuki NAGAOKA ...
2012 年 31 巻 4 号 p.
674-680
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
Titanium has an osseointegrative property, while hydroxyapatite has an osteoconductive property. It remains a matter of controversy among researchers whether hydroxyapatite has higher osteoblast compatibility than titanium. Here, we compared the activities between osteoblasts cultured on titanium and those cultured on hydroxyapatite. An osteoblast-like cell line, MC3T3-E1, was cultured on machined titanium, evaporated titanium, and hydroxyapatite disks to compare the affinity of osteoblasts to each of these materials. The adhesion and proliferation of MC3T3-E1 cells were higher on hydroxyapatite disks than on the other disks. Osteoblast differentiation was not affected by the nature of disks investigated, but calcium was more easily deposited on the hydroxyapatite disks. The amount of absorbed serum proteins detected on hydroxyapatite was greater than that on titanium. In conclusion, our results indicate hydroxyapatite is a more suitable material for osteoblast growth than titanium because of its higher absorption of serum proteins.
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Emiko SAITO, Akira SAITO, Yoshinori KUBOKI, Mariko KIMURA, Yoshiyuki H ...
2012 年 31 巻 4 号 p.
681-688
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
The aim of this study was to investigate the effect of the pore characteristics of β-tricalcium phosphate (β-TCP) on periodontal healing in class III furcation defects in dogs. Two types of β-TCP were prepared for grafting; 1) a tunnel pipe structure with an inner diameter of 300 μm, and 2) continuous pore structure with interconnected macropores. The furcations of thirty mandibular premolar teeth were implanted with each type of β-TCP or were left untreated as control. The dogs were sacrificed 8 weeks post-surgery, and healing was evaluated histologically. Downgrowth of junctional epithelium in the tunnel structure group was significantly less than that in the other two groups (
p<0.01). There was significantly more new bone formation and new cementum formation in the tunnel structure group than that in the other two groups (
p<0.01). These findings suggested that β-TCP with a tunnel pipe structure promotes periodontal healing in class III furcation defects.
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Cesar Penazzo LEPRI, Regina Guenka PALMA-DIBB
2012 年 31 巻 4 号 p.
689-696
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
This study evaluated the influence of beverages and brushing on the surface roughness(SR) and color change(∆
E) of a composite resin.For this, 120-disks(10 mm×2 mm) of composite resin(Filtek-Z250) were prepared and polished. Initials SR(Ra-μm) and color(CIELabsystem) were measured with rugosimeter and spectrophotometer; specimens were divided into four groups(red wine, soft drink, sugar cane spirit, or artificial saliva=control) and three subgroups(without brushing; brushed with Colgate or with Close-Up). Specimens were immersed in the beverage 5×/day, for 5', over 30 day, being two subgroups brushed(120 strokes/day). Color was measuredat 15th day, 30th day and after repolishment; SR at 30th day. ∆
E-values were statistically different after immersion in the beverages(
p<0.05). Red wine promoted the highest alteration, followed by soft drink=sugar cane spirit and finally saliva. At 30th day, specimens exhibited ∆
E higher than 15th day; after repolishing, ∆
E was similar to 15th day. Beverages and brushing negatively influenced the SR. Therefore, ∆
E and SR can be influenced by beverages and brushing.
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Yasuhiro YOSHIDA, Kumiko YOSHIHARA, Noriyuki NAGAOKA, Masao HANABUSA, ...
2012 年 31 巻 4 号 p.
697-702
発行日: 2012/07/30
公開日: 2012/08/03
ジャーナル
フリー
According to the ‘Adhesion-Decalcification' concept, specific functional monomers within dental adhesives can ionically interact with hydroxyapatite (HAp). Some specific functional monomers form monomer-Ca salts due to chemical interactions. The chemical stability of the monomer-Ca salts was thought to contribute to bond durability. In the present study, we analyzed the chemical interaction between an acidic three-dimensional self-reinforcing monomer (3D-SR) of Bond Force and enamel, dentin and HAp, and assessed its chemical stability by thin-fi lm X-ray diffraction (TF-XRD). 3D-SR forms a hydrolysis-resistant Ca-salt on the dentin in a clinical application time period and on enamel and HAp in a longer time period. This suggests that the functional monomer 3D-SR is able to contribute to bond durability.
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