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Kanitsak BOONANANTANASARN, Kajohnkiart JANEBODIN, Prapan SUPPAKPATANA, ...
2014 Volume 33 Issue 2 Pages
157-165
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
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This present study investigated the potential of
Morinda citrifolia leaf aqueous extract to induce osteogenic differentiation and matrix mineralization of human periodontal ligament (hPDL) cells. Human periodontal ligament cells were cultured in complete medium, ascorbic acid with β-glycerophosphate, or
Morinda citrifolia leaf aqueous extract.
Morinda citrifolia leaf aqueous extract significantly increased alkaline phosphatase activity compared to culturing in complete medium or ascorbic acid with β-glycerophosphate. Matrixcontaining mineralized nodules were formed only when the cells were cultured in the presence of
Morinda citrifolia leaf aqueous extract. These nodules showed positive alizarin red S staining and were rich in calcium and phosphorus according to energy dispersive X-ray analysis. In conclusion,
Morinda citrifolia leaf extract promoted osteogenic differentiation and matrix mineralization in human periodontal ligament cells, a clear indication of the therapeutic potential of
Morinda citrifolia leaves in bone and periodontal tissue regeneration.
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Shunsuke NOMURA, Kanji TSURU, Michito MARUTA, Shigeki MATSUYA, Ichiro ...
2014 Volume 33 Issue 2 Pages
166-172
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 08, 2014
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Carbonate apatite (CO
3Ap), fabricated by dissolution-precipitation reaction based on an appropriate precursor, is expected to be replaced by bone according to bone remodeling cycle. One of the precursor candidates is gypsum because it shows self-setting ability, which then enables it to be shaped and molded. The aim of this study, therefore, was to fabricate CO
3Ap blocks from set gypsum. Set gypsum was immersed in a mixed solution of 0.4 mol/L disodium hydrogen phosphate (Na
2HPO
4) and 0.4 mol/L sodium hydrogen carbonate (NaHCO
3) at 80–200°C for 6–48 h. Powder X-ray diffraction patterns and Fourier transform infrared spectra showed that CO
3Ap block was fabricated by dissolution-precipitation reaction in Na
2HPO
4-NaHCO
3 solution using set gypsum in 48 h when the temperature was 100°C or higher. Conversion rate to CO
3Ap increased with treatment temperature. CO
3Ap block containing a larger amount of carbonate was obtained when treated at lower temperature.
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Chang CUI, Jian SUN
2014 Volume 33 Issue 2 Pages
173-178
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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Due to elastic modulus mismatch between the different layers in all-ceramic dental restorations, high tensile stress concentrates at the interface between the ceramic core and cement. In natural tooth structure, stress concentration is reduced by the functionally graded structure of dentin-enamel junction (DEJ) which interconnects enamel and dentin. Inspired by DEJ, the aim of this study was to explore the optimum design of a bio-inspired functionally graded material (FGM) layer in all-ceramic dental restorations to achieve excellent stress reduction and distribution. Three-dimensional finite element model of a multi-layer structure was developed, which comprised bilayered ceramic, bio-inspired FGM layer, cement, and dentin. Finite element method and first-order optimization technique were used to realize the optimal bio-inspired FGM layer design. The bio-inspired FGM layer significantly reduced stress concentration at the interface between the crown and cement, and stresses were evenly distributed in FGM layer. With the optimal design, an elastic modulus distribution similar to that in DEJ occurred in the FGM layer.
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Kazuya DOI, Takayasu KUBO, Ryou TAKESHITA, Shiho KAJIHARA, Shinichi KA ...
2014 Volume 33 Issue 2 Pages
179-186
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: February 06, 2014
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Inorganic polyphosphate (poly(P)) is recognized as a therapeutic agent that promotes fibroblast growth factor and enhances osteogenic differentiation, and
in vivo, when adsorbed onto interconnected porous calcium hydroxyapatite (IP-CHA) enhances bone regeneration. The present study focused on the effect of poly(P) adsorbed onto IP-CHA granules (Poly(P)/IP-CHA) in guided bone regeneration (GBR). Dental implants were placed into the edentulous mandibular areas of five Beagle-Labrador hybrid dogs with screw expose on the buccal side, and then bone defects were filled Poly(P)/IP-CHA (test) or IP-CHA (control). After 12 weeks, histological evaluation and histomorphometrical analysis were performed. Newly-bone formation around exposed implant screw was clearly detected in the test-group. The ratio for regenerated bone height in the test group
versus the control-group was 85.6±20.2 and 62.6±23.8, respectively, with no significant difference, while, that for bone implant contact was significantly higher (67.9±11.8 and 48.8±14.1, respectively). These findings indicate that Poly(P)/IP-CHA enhances bone regeneration in GBR.
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Takashi KAMEDA, Hirotake ODA, Kazuo OHKUMA, Natsuki SANO, Nomintsetseg ...
2014 Volume 33 Issue 2 Pages
187-195
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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Biocorrosion (microbiologically influenced corrosion; MIC) occur in aquatic habitats varying in nutrient content, temperature, stress and pH. The oral environment of organisms, including humans, should be one of the most hospitable for MIC. Corrosion of metallic appliances in the oral region is one cause of metal allergy in patients. In this study, an inductively coupled plasma-optical emission spectrometer revealed elution of Fe, Cr and Ni from stainless steel (SUS) appliances incubated with oral bacteria. Three-dimensional laser confocal microscopy also revealed that oral bacterial culture promoted increased surface roughness and corrosion pits in SUS appliances. The pH of the supernatant was lowered after co-culture of appliances and oral bacteria in any combinations, but not reached at the level of depassivation pH of their metallic materials. This study showed that
Streptococcus mutans and
Streptococcus sanguinis which easily created biofilm on the surfaces of teeth and appliances, did corrode orthodontic SUS appliances.
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Susumu NAKAGAKI, Masahiro IIJIMA, Keisuke HANDA, Toshiyuki KOIKE, Yosh ...
2014 Volume 33 Issue 2 Pages
196-202
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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This study investigated the effect of immediate force on bone adaptations surrounding miniscrew implants. Ten miniscrew implants were placed on the mandibles in three beagle dogs. Five pairs of miniscrew implants were immediately loaded with 150 g of continuous force using nickel-titanium coil springs for 8 weeks. The values of bone mineral density (BMD), bone mineral content (BMC), and bone volume (BV) of cortical and trabecular bone for compression loading and tension loading were obtained by µCT analysis. The percentages of bone-to-implant contact (BIC) in the compression and tension regions for cortical and trabecular bone were obtained by histologic analysis. The BMD values for the compression region of cortical bone were significantly higher compared to the tension region. The BIC values in cortical and trabecular bone at tension and compression regions were similar. In conclusion, immediate loading does not inhibit osseointegration of miniscrew implants but may stimulate bone mineralization.
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Koichi OKADA, Takehiro KAMEYA, Hiroshige ISHINO, Tohru HAYAKAWA
2014 Volume 33 Issue 2 Pages
203-209
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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The authors have developed a new technique for preparing dental CAD/CAM composite resin blocks (CRBs): the filler press and monomer infiltration (FPMI) method. In this method, surface-treated filler is molded into a green body in which the filler particles are compressed to form an agglomeration. The green body is then infiltrated with a monomer mixture before being polymerized. It is possible to produce CRBs using this method through which densely packed nanofiller is uniformly dispersed. The greater the pressure of the filler molding, the more filler in the CRB, resulting at high pressure in a very dense CRB. A CRB obtained by applying 170 MPa of pressure contained up to 70 wt% of nano-silica filler and had a flexural strength of 200 MPa, as well. It is anticipated that CRBs obtained using the FPMI method will be useful as a dental CAD/CAM material for the fabrication of permanent crown restorations.
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Jian-min HAN, Guang HONG, Hiroyuki MATSUI, Yoshinaka SHIMIZU, Gang ZHE ...
2014 Volume 33 Issue 2 Pages
210-219
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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The purpose of this study was to evaluate the surface characterization and bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) in comparison to yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi). Three-dimension surface morphology, surface wettability, bovine serum albumin adsorption rate, cell morphology, cell proliferation and ALP activity of three tested materials were measured. There were no significant differences in surface roughness, contact angle among the three materials. The ALP expression of NANOZR was higher than CpTi and 3Y-TZP at 14 and 21 days although bovine serum albumin adsorption rate, cell morphology; and cell proliferation was not different among the three materials. These results suggest that the three test materials basically had similar surface characterization and bioactivity. Within the limitations of this study, our results show that the three test materials were biologically similar bio-inert materials.
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Takashi NAKAMURA, Tsuyoshi SUGANO, Hirofumi USAMI, Kazumichi WAKABAYAS ...
2014 Volume 33 Issue 2 Pages
220-225
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 08, 2014
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In this study, two types of porous zirconia and dense zirconia were used. The flexural strength of non-layered zirconia specimens and those of the layered zirconia specimens with veneering porcelain were examined. Furthermore, the shear bond strength of veneering porcelain to zirconia was examined. The flexural strength of the non-layered specimens was 1,220 MPa for dense zirconia and 220 to 306 MPa for porous zirconia. The flexural strength of the layered specimens was 360 MPa for dense zirconia and 132 to 156 MPa for porous zirconia, when a load was applied to the porcelain side. The shear bond strength of porcelain veneered to dense zirconia was 27.4 MPa and that of porcelain veneered to porous zirconia was 33.6 to 35.1 MPa. This suggests that the veneering porcelain bonded strongly to porous zirconia although porous zirconia has a lower flexural strength than dense zirconia.
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Yusuke OBA, Hiroyasu KOIZUMI, Daisuke NAKAYAMA, Takaya ISHII, Nobutaka ...
2014 Volume 33 Issue 2 Pages
226-232
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 04, 2014
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The purpose of this study was to evaluate the effects of primers on the bond strength and durability of an acrylic resin luting agent bonded to zirconia. Disk specimens were fabricated from zirconia partially stabilized with yttrium oxide. The disks were primed with one of the following materials: Alloy Primer (AP), Ceramic Primer (CP), Liquid A of the Porcelain Liner M (PLM-A), Liquid B of Porcelain Liner M (PLM-B), Porcelain Liner M (PLM-A+PLM-B), Monobond Plus (MP), and mixture of AP and PLM-B. The specimens were bonded with a tri-
n-butylborane (TBB)-initiated luting agent. The shear bond strengths were determined both before and after thermocycling. The results were statistically analyzed with a non-parametric procedure. The highest post-thermocycling bond strength was generated from the groups primed with MP, CP, and AP. It can be concluded that the application of three phosphate primers is recommended for bonding the zirconia with the TBB-initiated luting agent.
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Takuma SUZUKI, Tohru HAYAKAWA, Tadafumi KAWAMOTO, Kazuhiro GOMI
2014 Volume 33 Issue 2 Pages
233-241
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 01, 2014
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The present study aimed to immobilize TGF-β2 onto titanium implants by using a tresyl chloride-activation technique and to evaluate the bone response of TGF-β2 immobilized titanium (TGF-β2/Ti) implants in a rat femur defect model. XPS and FT-IR measurements identified the presence of TGF-β2 on titanium. Atomic force microscopy showed globular images of immobilized TGF-β2. The contact angle of TGF-β2/Ti against water significantly decreased compared with untreated titanium (Ti). There was no change of surface roughness after immobilization of TGF-β2. Ti and TGF-β2/Ti implants were inserted into rat femur defects. TGF-β2/Ti showed more bone formation by calcein labeling and histological observation. The measurements of bone to implant contact (BIC) and bone mass (BM) around the implants revealed that BIC and BM of TGF-β2/Ti implants were significantly higher than those of Ti at 4 weeks after the implantation. In conclusion, TGF-β2/Ti implant effectively enhances bone regeneration around implants.
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Ryuhei NISHIKAWA, Takahisa ANADA, Risa ISHIKO-UZUKA, Osamu SUZUKI
2014 Volume 33 Issue 2 Pages
242-251
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 04, 2014
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The present study investigated the role of mitogen-activated protein kinase (MAPK) signaling in osteoblastic differentiation of stromal ST-2 cells induced by synthetic octacalcium phosphate (OCP) incubation. Since our previous studies revealed that OCP consumes calcium ions in media during conversion to hydroxyapatite, the effect of the ions on ST-2 cell differentiation with or without OCP crystals was analyzed. The effect of presence or absence of MAPK inhibitors was also analyzed. OCP increased alkaline phosphatase (ALP) activity and the mRNA expression of differentiation markers
via the p38 signaling pathway. The PD98059 MAPK inhibitor increased ALP activity and differentiation marker genes in cells cultured in OCP-coated wells. Reduction of calcium ions in the medium by EGTA increased the ALP activity without OCP in the presence of phosphate ion concentrations up to 7.5 mM. OCP may enhance osteoblastic differentiation through the p38 signaling pathway
via the reduction of calcium ions induced by its physicochemical property.
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Masahiro KOYASU, Toshikazu SHIBA, Yumi KAWAZOE, Atsufumi MANABE, Takas ...
2014 Volume 33 Issue 2 Pages
252-260
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 04, 2014
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Polyphosphate is a phosphate polymer which is effective for stain removal and prevention of stain deposition. Ultraphosphate belongs to the polyphosphate group and has a highly branched mesh-like structure. To evaluate stain control ability of ultraphosphate, we used HAP powder, glass-ionomer cement and detached human teeth for models of
in vitro stain control experiments. When using HAP powder, the stain removal ability of ultraphosphate was the highest among common chelating agents. In addition, ultraphosphate efficiently removed stain and prevented stain deposition on glass-ionomer cement at 20°C and 37°C. Finally, ultraphosphate removed coffee stain from human teeth surface efficiently and the color difference (Δ
E*
ab) before and after ultraphosphate treatment was changed dramatically from 59.4 to 8.3. Similarly, the Δ
E*
ab value of human teeth treated with ultraphosphate before coffee treatment was only 9.9, while the value without ultraphosphate pre-treatment was 21.2. These results indicate that ultraphosphate is a potent agent for stain control.
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Masato HOTTA, Takashi MORIKAWA, Daisuke TAMURA, Shusuke KUSAKABE
2014 Volume 33 Issue 2 Pages
261-267
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 08, 2014
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This
in vitro study performed elemental analysis of the ions absorbed into the salivary coat covering the surfaces of S-PRG resin blocks and assessed the adherence of
Streptococcus sanguinis and
Streptococcus mutans to these saliva-coated S-PRG resin blocks. Elemental analysis of ions absorbed into the salivary coat of resin blocks exposed to the saliva was performed using an inductive coupled plasma atomic emission spectrometer and the fluoride electrode method. Quantitative adherence of radio-labeled test bacteria to the resin blocks was determined. As the results, the saliva-coated S-PRG resin showed significantly greater amounts of absorbed B, Al, Si, Sr, and F than the saliva-coated unfilled resin. It was of particular significance that the salivary coating of the S-PRG resin reduced the adherence of
S. mutans to this resin. However, in the case of
S. sanguinis, no significant difference in adherence could be recognized between saliva-coated S-PRG resin and saliva-coated unfilled resin.
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Yusuke MORITA, Susumu IMAI, Ai HANYUDA, Khairul MATIN, Nobuhiro HANADA ...
2014 Volume 33 Issue 2 Pages
268-274
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
Advance online publication: March 08, 2014
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Titanium and stainless steel wires used for retainers in orthodontic procedures were coated with Ag ions and the effects of the coating on common oral pathogens and their pathogenicity were investigated. Two species of cariogenic and three species of periodontopathic bacteria were assessed. Biofilms of
Streptococcus sobrinus and two VSC gases produced by
P. gingivalis were also examined. Ag ioncoated wires showed marked antibacterial activities compared with uncoated wires; in most cases, the differences were statistically significant (
p<0.05). All Ag ion-coated wires (Ti+ and SS+ wires) displayed more than 2-mm diameter bacteria growth-resistant zones around them in radial diffusion tests. Ag ion release was 0.043±0.005 ppm in 24 h that didn’t show cytotoxicity. Thus, these results suggest that a simple Ag ion coating on pure titanium and stainless steel wires can restrict growth and pathogenic activities of oral pathogenic bacteria, even in the early stages of culture.
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Mari SAITO, Takeo KARAKIDA, Ryuji YAMAMOTO, Takatoshi NAGANO, Yasuo YA ...
2014 Volume 33 Issue 2 Pages
275-283
Published: March 26, 2014
Released on J-STAGE: March 28, 2014
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We examined the adaptability of zirconia as a fixture for implants. A mouse myoblast cell line (C2C12) was seeded on Ce-TZP and titanium disks, and on poly-L-lysine-coated glass slides. Proliferation potency was determined by cell counting and mineral induction by BMP2 was studied. The osteoblastic differentiation potency was determined by alkaline phosphatase (ALP) and alizarin red (ARS) staining. ALP activity and calcium concentrations were colorimetrically measured. The number of cells on all materials was approximately equal. ALP and ARS staining showed densely-stained images, demonstrating the induction of C2C12 cells to express the osteoblastic phenotype. RT-PCR showed that mRNA expressions of
type I collagen,
osteocalcin,
osterix and ALP were up-regulated. With regard to ALP activity and calcium concentration of C2C12 cells, no significant differences were observed between Ce-TZP and titanium disks. We conclude that Ce-TZP has the biological activity comparable to titanium and has the utility as fixture of dental implants.
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