Dental Materials Journal

Original papers

Biomechanical analysis of combined treatment of high calcium and bisphosphonate in tibia of steroid-treated growing-phase rats

Yusuke YOKOTE, Emi KIMURA, Mitsutaka KIMURA, Yoshio KOZONO

2008 Volume 27 Issue 5 Pages 647-653
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.647

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Childhood systemic diseases are commonly treated with steroids. Consequently, steroid-induced osteoporosis is often observed as a side effect of steroid therapy. However, osteoporosis of tibia resulting from steroid therapy has not been reported yet. Herein we constructed a steroid-induced osteoporosis in tibia of the growing phase rats to examine internal structural changes of the bone and tried to find out the effect of bisphosphonates as a new and early treatment method. Biomechanical analysis was performed using two-dimensional microdensitometry and three-dimensional pQCT method. In addition, the following evaluations were carried out: noninvasive bone strength measurements in steroid-induced osteoporotic rat tibiae; comparing the effectiveness of single high-calcium diet versus combined treatment of high calcium and bisphosphonate for osteoporosis; and quantitative measurement of four elements (Ca, P, Mg, Zn) in bone matrix. Our data suggested that a combined treatment of high calcium and bisphosphonate was an effective new method to improve and treat steroid-induced osteoporosis in childhood.

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Influence of environmental conditions on orthodontic bracket bonding of self-etching systems

Akitomo RIKUTA, Takeshi YOSHIDA, Keishi TSUBOTA, Hiroaki TSUCHIYA, Aki ...

2008 Volume 27 Issue 5 Pages 654-659
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.654

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The influence of temperature and relative humidity (RH) on the bond strength of orthodontic adhesives was investigated. Two self-etching/composite type, one acid-etching/composite type, and one acid-etching/PMMA type of adhesives were examined under different temperature and RH conditions. Orthodontic brackets were bonded to bovine enamel, and shear bond strength test was performed at a crosshead speed of 1.0 mm/min after 24-hour storage in 37°C water. Data were analyzed by Tukey's HSD test. Each specimen was assigned an ARI score. All the materials tested exhibited their highest bond strength under room conditions at a range of 10.4–17.0 MPa. Conversely, when under a lower RH condition, bond strength for all the systems ranked the lowest within a range of 6.8–12.0 MPa, with bond failure at the bracket—adhesive interface. These results demonstrated that care should be exercised when using orthodontic adhesive systems in the oral environment.

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Effect of light intensity for adhesives on shear bond strength to dentin

Koichi SHINKAI, Shiro SUZUKI, Yoshiroh KATOH

2008 Volume 27 Issue 5 Pages 660-665
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.660

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This study evaluated the effect of light intensity on the shear bond strength (SBS) of two self-etch adhesive systems: SI-R20401 (an experimental two-step) and Fluoro Bond Shake One^® (a commercial one-step bonding system). The adhesive systems were applied to the flat dentin surfaces of extracted human teeth according to manufacturers's instructions. Light intensities used for the adhesive systems were 100, 300, and 500 mW/cm². A resin composite paste was placed and polymerized for 40 seconds with 600 mW/cm² of light intensity after each bonding procedure. Specimens were subjected to SBS test with a 1.0 mm/minute crosshead speed. Data were statistically analyzed using ANOVA, followed by Bonferroni post hoc test. Two-way ANOVA showed no significant differences in the effects of the adhesive system, light intensity for applied adhesive, and the interaction between them. Based on the results and limitations of this study, it was concluded that light intensity showed no significant effects on the SBS of the two self-etch adhesive systems.

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Hydroxyapatite coating by electrophoretic deposition at dynamic voltage

Xianwei MENG, Tae-Yub KWON, Kyo-Han KIM

2008 Volume 27 Issue 5 Pages 666-671
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.666

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The aim of this study was to evaluate hydroxyapatite (HA) coatings produced by dynamic voltage during electrophoretic deposition (EPD). Dynamic voltages from 0 to 200 V were incrementally applied in three interims. The as-deposited coating was sintered at 800°C and its properties evaluated. Structure and phase analyses of both as-deposited and sintered coatings were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The HA coatings obtained by dynamic voltage consisted of two layers. While the inner layer was dense and firmly attached to the substrate and contained fine HA particles, the outer layer was porous and contained bigger particles. Repeated deposition was applied to increase the thickness of the coatings. SEM analysis showed that these coatings were free of cracks. In addition, decomposition of HA coatings was not observed until 800°C.

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Effects of liquid phase on basic properties of α-tricalcium phosphate-based apatite cement

Makoto ODA, Akari TAKEUCHI, Xin LIN, Shigeki MATSUYA, Kunio ISHIKAWA

2008 Volume 27 Issue 5 Pages 672-677
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.672

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Effects of liquid phase on the basic properties of α-tricalcuim phosphate (α-TCP)-based cement, BIOPEX^®, were investigated by employing three liquid phases: distilled water, neutral sodium hydrogen phosphate solution, and succinic acid disodium salt solution containing sodium salt of chondroitin sulfate. When mixed with neutral sodium hydrogen phosphate or succinic acid disodium salt solution, the initial setting times of the cement were 19.4±0.55 and 11.8±0.45 minutes respectively. These setting times were much shorter than that of distilled water, 88.4±0.55 minutes. Formation of needle-like crystals typical of apatite was much faster when neutral sodium hydrogen phosphate solution was used, as compared to distilled water or succinic acid disodium salt solution. Moreover, at 24 hours after mixing, the largest amount of apatite was formed when neutral sodium hydrogen phosphate solution was used, whereas use of succinic acid resulted in the least. On the final mechanical strength of the cement, that yielded with neutral sodium hydrogen phosphate solution was the highest. In contrast, lower mechanical strength was observed—especially at the initial stage—when succinic acid sodium salt was used. It was thus concluded thatα-TCP-based cement allowed accelerated transformation to apatite, and that higher mechanical strength since the initial stage was achieved when neutral sodium hydrogen phosphate solution was used as the liquid phase.

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Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4-META adhesive cement to these alloys

Shin-ichi GOTO, Pornkiat CHURNJITAPIROM, Yukio MIYAGAWA, Hideo OGURA

2008 Volume 27 Issue 5 Pages 678-686
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.678

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The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40%Pd, and 10%, 15% or 20%Cu, 20%Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.

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Fatigue resistance and structural integrity of different types of fiber posts

Simone GRANDINI, Nicoletta CHIEFFI, Maria Crysanti CAGIDIACO, Cecilia ...

2008 Volume 27 Issue 5 Pages 687-694
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.687

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The study aimed at assessing and estimating the fatigue resistance of different fiber posts and to observe their ultrastructures through SEM.
Six types of fiber posts were used: GC Fiber Post (Group 1), ParaPost Fiber White (Group 2), FibreKor (Group 3), DT Light-Post radiopaque (Group 4), FRC Postec (Group 5), and Luscent Anchors (Group 6). Ten out of 15 posts within each group were used for the fatigue test, and the other five were processed for SEM evaluation.
The fatigue test revealed that Groups 1, 4, and 5 performed better than all the other groups, and that their performance differed significantly from the other tested groups from a statistical standpoint. For SEM analysis, Groups 1, 4, and 5 also obtained better results.
Through correlation analysis, an absence of correlation between fatigue resistance and structural characteristics suggested that the latter reflected more of the divergence inherent in the manufacturing process of fiber posts.

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Bond strengths of two conventional glass-ionomer cements to irradiated and non-irradiated dentin

Cemal YESILYURT, Bilinç BULUCU, Orhan SEZEN, Günes BULUT, ...

2008 Volume 27 Issue 5 Pages 695-701
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.695

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This study evaluated the influence of irradiation on the dentin shear bond strength of two conventional glass ionomer cements (GICs). Thirty extracted molars were bisected in the mesio-distal direction. One-half of 20 teeth were irradiated with 60 Gy (5 days/week) for 6 weeks, and then GIC was placed on the irradiated dentin surface (Groups A1, B1). For the other halves of these tooth specimens, the GICs were first placed on their dentin surfaces and then the specimens irradiated (Groups A2, B2). The remaining 10 teeth were bisected and used as non-irradiated controls (Groups C1, C2). The GIC-dentin shear bond strengths were examined. Groups A2 and B2 had significantly lower bond strengths than groups A1, B1, C1, and C2 (p<0.05). No significant differences were found among groups A1, B1, C1, and C2 (p>0.05). In conclusion, irradiation may have an adverse effect on the bond strength of GICs depending on the application sequence.

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Sorption and solubility of luting cements in different solutions

Ayse MESE, Michael F. BURROW, Martin J. TYAS

2008 Volume 27 Issue 5 Pages 702-709
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.702

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This study examined the solubility, sorption, and dimensional change of eight luting cements in two different solutions: 50% ethanol:water and distilled water. Ten disk specimens were prepared of each material following the manufacturers' instructions, and then ground with silicone carbide paper. Sorption and solubility were calculated by weighing the specimens before and after immersion and desiccation. Data were analyzed by two-way ANOVA, Tukey's HSD and Fisher's PLSD tests. GC Fuji Plus and RelyX Luting2 showed the highest values of sorption and solubility both in water and ethanol:water. The percentage changes in volume for Maxcem, Nexus 2, Panavia F, RelyX Veneer, and VariolinkII were considerably smaller than for GC Fuji Plus, RelyX Luting2, and seT in both water and ethanol:water and after desiccation. Stability occurred within 2 weeks for all the eight materials when in water, while GC Fuji Plus, Maxcem, Panavia F and seT took 3 to 4 weeks to stabilize in ethanol:water.

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Fabrication of B-type carbonate apatite blocks by the phosphorization of free-molding gypsum-calcite composite

Chowdury Tanira ZAMAN, Akari TAKEUCHI, Shigeki MATSUYA, Q.H.M. Shawket ...

2008 Volume 27 Issue 5 Pages 710-715
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.710

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B-type carbonate apatite (CO₃Ap) block may be an ideal artificial bone substitute because it is closer in chemical composition to bone mineral. In the present study, the feasibility to fabricate CO₃Ap blocks was investigated using compositional transformation, which was based on the dissolution-precipitation reaction of a gypsum-calcite composite with free-molding behavior. For the compositional change, or phosphorization, gypsum-calcite composites of varying CaCO₃ contents were immersed in 1 mol/L (NH₄)₃PO₄ aqueous solution at 100°C for 24 hours. No macroscopic changes were found after the treatment, whereas microscopic change was observed at SEM level. X-ray diffraction, Fourier transform infrared spectroscopy and CHN analysis indicated that the composites were B-type CO₃Ap containing approximately 6–7 wt% of CO₃, a value similar to that of biological bone apatite. Diametral tensile strength of the CO₃Ap block was approximately 1–3 MPa. Based on the results obtained, it was therefore concluded that gypsum-calcite was a good candidate for the fabrication of CO₃Ap blocks, coupled with the advantage that the composite can be molded to any shape by virtue of the setting property of gypsum.

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Effects of abrasive and fiber components in medium on wear of composite resins

Kiyoshi KAKUTA, Hideo OGURA

2008 Volume 27 Issue 5 Pages 716-722
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.716

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Effects of abrasive and fiber components in a medium on the wear behavior of composite resins were evaluated. Calcium diphosphate and methyl cellulose were included in the medium as abrasive and fiber components respectively. A range of 0, 4, or 8% abrasive- or fiber-containing media were applied on a composite resin specimen during a simulated occlusal wear test. Four composite resins, Clearfil AP-X, Z100 Restorative, SOLARE P, and SOLIDEX F, were tested to evaluate the effects of these components in the medium.
Presence of abrasive material in the medium increased the wear of composite resins significantly, but its effect differed among the composite resins. Presence of fiber material in the medium significantly decreased the wear of two composite resins, whereas the other two composites showed no significant differences. Nonetheless, presence of fiber in the medium generally tended to prevent the wear of composite resins.

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Effect of commercially available bonding agents impregnated with fibers on bending strength of hybrid resin

Sumio TSUSHIMA, Harunori GOMI, Akikazu SHINYA, Daiichirou YOKOYAMA, Pe ...

2008 Volume 27 Issue 5 Pages 723-729
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.723

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To clarify the mechanical properties of fiber-reinforced hybrid resin bridges, this study evaluated the influence of various bonding agents ((Modeling Liquid (ML), DE Resin (DE), Bell Bond (BE), Mega Bond (MG), Durafil Bond (DU), Fluoro Bond (FB), Mac-Bond (MC), EG Bond (EG), Unifill Bond (UN), Single Bond (SN)) impregnated with fibers on bending strength. FB attained the highest bending strength of 570 MPa, whereas SN exhibited the lowest value of 224 MPa, which meant that the bending strength of FB was 2.5 times higher than that of SN. Results of this study suggested that the bending strength of fiber-reinforced hybrid resin was significantly affected by bonding agents impregnated with fibers. Therefore, selection of bonding agent for hybrid resin restoration requires careful consideration of product composition to ensure an optimal bonding agent-fiber combination, thereby imparting improved mechanical properties to the resultant dental restoration.

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Setting properties and sealing ability of hydraulic temporary sealing materials

Yoko OGURA, Ichiroh KATSUUMI

2008 Volume 27 Issue 5 Pages 730-735
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.730

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This study sought to investigate the setting progress and sealing ability of hydraulic temporary sealing materials used in endodontic treatment: Lumicon, Caviton, and HY-Seal. To evaluate setting progress, the materials were filled into glass tubes with one end sealed and immersed in water. After immersion, a measurement apparatus was inserted from the non-immersed end and the set area was determined by subtracting the unset area from the sample thickness. To evaluate sealing ability, materials were filled into glass tubes and divided into four groups based on different immersion times. Thermal cycling and dye penetration were performed. At 7 days, the setting depths of HY-Seal and Caviton were almost equivalent to full sample thickness, while that of Lumicon was only half of full sample thickness (p<0.01). On sealing ability, Lumicon ranked the highest followed by Caviton, whereas HY-Seal was unstable (p<0.01). These results suggested that there was no correlation between setting progress and sealing ability.

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Effect of fiber-reinforced composite at the interface on bonding of resin core system to dentin

Isil CEKIC-NAGAS, Gulfem ERGUN, Arzu TEZVERGIL, Pekka K. VALLITTU, Lip ...

2008 Volume 27 Issue 5 Pages 736-743
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.736

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The aim of this study was to evaluate the effect of fiber-reinforced composite (FRC) at the interface on bonding of resin core systems to bovine dentin using different adhesive systems. To this end, the labial surfaces of 60 bovine incisors were ground to obtain flat dentin surfaces and then divided into two groups according to the adhesive system used: total-etching (Solobond Plus) versus self-etching (Clearfil SE Bond). Resin core systems were bonded to tooth structure either without or with a FRC layer (everStick Net, StickTech). For groups with FRC layer, a silicon forming aid was used to adapt the latter on the dentin surfaces. After resin core was polymerized with Optilux 501 for 40 seconds, the specimens were tested in a universal testing machine. ANOVA revealed that presence of FRC at the interface had a significantly positive effect on bond strength (p<0.001). However, differences between groups were not significant for either adhesive system (p=0.076) or with the use of silicon forming aid (p=0.348).

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Gene expression monitoring in osteoblasts on titanium coated with fibronectin-derived peptide

Nobuyuki YAMAMICHI, Kamolparn PUGDEE, Wei-Jen CHANG, Sheng-Yang LEE, M ...

2008 Volume 27 Issue 5 Pages 744-750
Published: 2008
Released on J-STAGE: April 30, 2009

DOIhttps://doi.org/10.4012/dmj.27.744

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Enhanced adhesion and migration of osteoblastic cells on titanium (Ti) surface is believed to increase the success rate of implant therapy. A GRGDSP peptide derived from fibronectin was coated on Ti surfaces using a tresyl chloride activation technique, and then MC3T3-E1 osteoblastic cells were cultured on the Ti surfaces. After 15 days, total RNA was isolated from the cells and gene expression level were analyzed by Affymetrix GeneChip system. The expression levels of many genes in MC3T3-E1 cells cultured on GRGDSP-coated Ti surface were altered when compared to uncoated Ti. In particular, the elevated mRNA levels of bone sialoprotein (BSP) and osteocalcin (OC) were successfully confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR. In light of the results obtained, GRGDSP-coated Ti presented the potential of evolving into a useful biomaterial for successful implant therapy.

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