Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
Current issue
Showing 1-29 articles out of 29 articles from the selected issue
Review
  • Marion LABUSSIERE, Zahi BADRAN, Gildas RETHORE, Christian VERNER, Asse ...
    Type: review-article
    2021 Volume 40 Issue 4 Pages 839-852
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: June 12, 2021
    JOURNALS FREE ACCESS

    The aim of the systematic review was to analyze the use of combination of bone substitutes and vectors in periodontology and implantology among animals models and humans. Electronic databases were searched, and additional hand search was performed. The research strategy was achieved according to the PRISMA guidelines. The including criteria were: combination of bone substitutes and vectors, in vivo studies, a precise number of specimens, histological and radiographic analysis, written in English. The risk of bias was evaluated for individual studies. Thirty-two articles were selected and investigated in this systematic review. The results do not show a superiority of the use of composite biomaterial in comparison with simple biomaterial but suggest the efficacity of their utilization as a carrier of bioactive agents. Future studies need to identify the suitable association of bone substitutes and vectors and explore interest in their use such as the support of growth factors.

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Original Paper
  • Le REN, Nuonuo CONG, Hao HAN, Zhe ZHANG, Chunni DENG, Nan ZHANG, Daxu ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 853-862
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: June 30, 2021
    JOURNALS FREE ACCESS

    The benefits of different silicic concentrations on chondrogenesis of mesenchymal stem cell (MSC) are unclear. Here an in vitro scaffoldless model was used to determine the impact of different silicic concentrations on the three-dimensional chondrogenesis of MSCs. Sodium metasilicate solutions were used as the source of silica, and were added in the chondrogenic medium and replenished every 3 days. The thickness and area of cartilage; the expression of collagen II, aggrecan, and the collagen type II/I ratio; the glycosaminoglycan and cell contents; and the tangent modulus of the constructs were all significantly higher in 100 and 200 ng/mL groups compared with those in 0 and 10 ng/mL groups. All the above parameters, as well as several mechanical parameters of cartilage constructs were highest in 200 ng/mL group. Thus, 200 ng/mL sodium metasilicate could promote the chondrogenic differentiation of MSCs and the mechanical and biochemical properties of the cartilage constructs.

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  • Yumiyo HAYASHI, Harumi KAWAKI, Masaharu HORI, Kohei SHINTANI, Tomoya H ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 863-869
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: February 27, 2021
    JOURNALS FREE ACCESS

    Mineral trioxide aggregate (MTA) cement is widely used in the field of endodontic treatment. We herein synthesized calcium silicates from calcium carbonate and silicon dioxide, with the aim of reducing the cost associated with the MTA. Additionally, we prepared gypsum-containing calcium silicate cement to reduce the setting time while enhancing the mechanical strength. We evaluated the physical properties of this cement and investigated the response of human dental pulp stem cells (hDPSCs) grown in culture media containing cement eluate. Our results revealed that calcium silicates could be easily synthesized in lab-scale. Furthermore, we demonstrate that gypsum addition helps shorten the setting time while increasing the compressive strength of dental cements. The synthesized gypsum-containing calcium silicate cement showed minimal cytotoxicity and did not inhibit the proliferation of hDPSCs. These results suggested that the newly developed calcium silicate material could be a promising pulp capping material.

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  • Kouta KODAMA, Alireza VALANEZHAD, Mohammad KHODAEI, Sirus SAFAEE, Shiv ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 870-876
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 09, 2021
    JOURNALS FREE ACCESS

    Yttria doped ZrO2 was deposited using an acidic zinc phosphatizing solution and the hydrothermal treatment. The coating was analyzed using a field emission-scanning electron microscope (FE-SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). A piston on three balls (ISO 6872) was used for the measurement of biaxial flexural strength. MC3T3-E1 cells attachment was evaluated by SEM, and cell proliferation were assessed using MTS assay™. SEM images confirmed that the zinc phosphate coating layer was successfully prepared and fully covered the surface. The measured adhesive strength of the coating was 79.11 MPa. In vitro cell study indicated that the coated sample had better cell morphology and proliferation. XRD and EDS analysis revealed that the crystalline coating structure indexed as zinc phosphate (hopeite) and the substrate was assigned as zirconia. The flexural strength test showed that the strength of zirconia before and after hydrothermal treatment was not affected.

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  • Mayu HASEGAWA, Antonin TICHY, Keiichi HOSAKA, Yusuke KUNO, Masaomi IKE ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 877-884
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 06, 2021
    JOURNALS FREE ACCESS

    The influence of sulfinate agents applied as a dentin pretreatment or a mixture with multi-mode one-step self-etch adhesives (1-SEAs) on the degree of conversion (DC) and micro-tensile bond strength (μTBS) of light-cured 1-SEAs was investigated. 1-SEAs Clearfil Universal Bond Quick (UBQ) or Scotchbond Universal Adhesive (SBU) were applied to dentin in etch&rinse or self-etch mode using various application strategies: 1) no pretreatment, 2) pretreatment with 90 wt% ethanol, 3) pretreatment with a sulfinate agent Clearfil DC Activator (UDC) or Scotchbond Universal DCA (SDC), or 4) a mixture of UBQ+UDC or SBU+SDC. μTBS was measured after 24 h. Additionally, DC was measured using attenuated total reflectance Fourier-transform infrared spectroscopy. Pretreatment with sulfinate agents resulted in the highest μTBS and DC, significantly improving them especially in etch&rinse mode. The mixture of sulfinate agents with 1-SEAs was less effective. Pretreatment with ethanol significantly improved μTBS in etch&rinse mode but compromised μTBS in self-etch mode.

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  • Noriko IIJIMA, Shinya HOMMA, Ryotaro NAKANO, Shota HAYASHI, Tomoki HIR ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 885-893
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 09, 2021
    JOURNALS FREE ACCESS

    The objective of this study was to clarify the fatigue behavior of hollow yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) specimens assuming its use for two-piece implants. The fatigue properties of a solid specimen (which simulated a one-piece implant) and 3 types of hollow specimens (which simulated two-piece implants) were evaluated. Specimens were either solid with a diameter of 4.0 mm (S) or hollow with an inner diameter of 3.0 mm and outer diameters of 4.0 mm (H0.5), 4.5 mm (H0.75), or 5.0 mm (H1.0). For each group, 25 specimens were prepared followed by blast and acid etch treatment. Static fracture and cyclic fatigue tests were conducted by modifying the methods provided in ISO6872. Fracture modes were determined by observing the surfaces under a scanning electron microscope. As a result, the cyclic fatigue load of S and H1.0 were similar, and hollow specimens with outer diameters greater than 0.75 mm displayed the ability to withstand molar occlusal forces.

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  • Peer SCHRADER, Stefan KOLLING, Maximiliane Amelie SCHLENZ, Bernd WÖSTM ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 894-902
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    Material characteristics can change significantly with increasing chewing velocity. As these in-vitro examinations are very time-consuming and cost-intensive, the application of finite element analysis (FEA) offers a suitable alternative for predicting the material behavior of complex specimen geometries under clinically relevant loads. Although FEA is applied within numerous dental investigations, there are only few studies available in which a nonlinear FEA is validated with real experiments. Therefore, the aim of the present study was to predict the mechanical behavior of a clinically close three-unit temporary bridge composed of polymethyl methacrylate (PMMA) in the left upper jaw with nonlinear FEA and to verify the prediction through validation experiments. In conclusion, simplifying assumptions of linear elastic material properties for polymeric materials should be avoided in FEA studies, because rate dependencies, stress relaxation and plastic flow are not considered. Additionally, precise preliminary investigations for material characterization are necessary.

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  • Martina VICHEVA, Takaaki SATO, Tomohiro TAKAGAKI, Yuuta BABA, Masaomi ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 903-910
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 27, 2021
    JOURNALS FREE ACCESS

    The purpose of this study was to investigate the influence of phosphoric acid etching, metal primer or silane coupling agent application on dentin bonding performance of a 2-step self-etch adhesive system. Human dentin surfaces were prepared and divided into four groups depending on the pre-treatment method: no pretreatment (Clearfil SE Bond 2, CONTROL); 40% phosphoric acid (K-Etchant GEL, K); metal primer (Alloy Primer, AP); or silane coupling agent (Porcelain Bond Activator, PB). The specimens were sectioned into beams, separated into 2 subgroups (n=20): no thermocyling or thermocycled (TC), and subjected to a µTBS test and an acid-base challenge for SEM observation. Statistically lower results were observed between K and AP groups, PB and CONTROL, and PB with/without TC (p<0.05). SEM images at the dentin-adhesive interface revealed that all groups produced an acid-base resistant zone (ABRZ), with a funnel-shaped erosion under the ABRZ for the K group.

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  • Motoi TAKAHASHI, Khairul MATIN, Naoko MATSUI, Miyuki SHIMIZU, Yuka TSU ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 911-917
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 18, 2021
    JOURNALS FREE ACCESS

    Effects of silver diamine fluoride preparations (SDFs) on cariogenic biofilm formation on root dentin (RD) were investigated. Streptococcus mutans (S. mutans) biofilms were formed on bovine RD blocks coated with one of three the SDFs (38%-SDF, 3.8%-SDF and 35%-SDF+potassium-iodide; SDF+KI) and a non-coated Control which were quantified (spectrometric-measurement) and thickness measured (optical coherence tomography) after 20 h. Bacterial viability test (BacLight) and biofilm-morphometry (SEM) of 2 h biofilms were also performed. The amounts of biofilms (bacteria and water insoluble glucan) and the thickness of biofilm were minimum on 38%-SDF specimen; 3.8%-SDF and SDF+KI had significantly more than that, but had significantly less than Control (p<0.05). Most S. mutans cells found dead and morphology damaged by 38%-SDF. Some dead bacteria and remarkably damaged biofilms were observed in case of 3.8%-SDF and SDF+KI. Inhibition potential of 3.8%-SDF and SDF+KI on S. mutans biofilm formation is almost similar, although not equivalent to 38%-SDF.

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  • Tomoyasu MORI, Kazuma TAKASE, Kazuhiro YOSHIDA, Hitomi OKAZAKI, Hirosh ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 918-927
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 03, 2021
    JOURNALS FREE ACCESS

    We evaluated the influence of monomer type, plasticizer content, and powder/liquid (P/L) ratio on the setting characteristics of light-cured acrylic permanent soft denture liners based on poly(ethyl methacrylate/butyl methacrylate). Two monomers, iso-butyl methacrylate (i-BMA) and 2-ethylhexyl methacrylate (2-EHMA), that contained various concentrations of the plasticizer acetyl tributyl citrate (ATBC) and trace amounts of the photo initiator and reducing agent were used. The P/L ratio was 1.0 or 1.2. The gelation time was measured using a controlled stress rheometer. Materials with i-BMA had shorter gelation times than those for materials with 2-EHMA. The gelation time increased exponentially with increasing plasticizer content. A higher P/L ratio led to a shorter gelation time. The effects of monomer type and plasticizer content were larger than that for the P/L ratio. These results show that 2-EHMA is a suitable monomer for soft denture liners and that the setting characteristics can be controlled via ATBC content.

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  • Azusa YAMANAKA, Atsushi MINE, Mariko MATSUMOTO, Ryosuke HAGINO, Masahi ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 928-933
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 27, 2021
    JOURNALS FREE ACCESS

    This study evaluated the bonding effectiveness of a newly developed two-step hydrophobic bonding material. Three groups using different bonding systems were compared: BZF group, using the new bonding system (BZF-29; GC, Tokyo, Japan); GPB group, using a one-step bonding system (G-Premio Bond; GC); and SE2 group, using a two-step bonding system (CLEARFIL SE Bond 2; Kuraray Noritake Dental, Tokyo, Japan). Microtensile bond strength (µTBS) was measured after storage in water for 24 h, 3 months and 6 months (n=25/group). Fracture surfaces were observed under scanning electron microscopy. The BZF group showed significantly higher µTBS than the other groups (p<0.001). Dominant failure patterns were cohesive failure for the BZF group (48–84%), mixed failure for the SE2 group (48–60%) and interface failure between adhesive and resin composite for the GPB group (48–52%). The hydrophobicity of the BZF-29 bonding system improves the long-term bonding effectiveness between adhesive and resin composite.

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  • Paponsun SIWAKUL, Lertrit SIRINNAPHAKORN, Jintamai SUWANPRATEEP, Tohru ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 934-941
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 03, 2021
    JOURNALS FREE ACCESS

    Effects of histatin-derived peptides immobilization by tresyl chloride-activation technique for MC3T3-E1 cellular responses on titanium (Ti) were evaluated. MC3T3-E1 were cultured on sandblasted and acid-etched Ti disks immobilized with histatin-derived peptides, including histatin-1, JH8194, and mixed histatin-1 with JH8194. Surface topography and cellular morphology were examined using a scanning electron microscope. Elemental composition and conformational peptides on Ti surface were examined using energy dispersive X-ray and fourier transform infrared spectroscopy, respectively. Cellular adhesion, proliferation, osteogenesis-related genes, and alkaline phosphatase activity were evaluated. The results showed that peptides were successfully immobilized on Ti surface. Cell attachments on histatin-1 and mixed peptides coated groups are higher than control. Histatin-1 achieved the significantly highest cellular proliferation. Histatin-derived peptides improved the osteogenesis related-gene expression and alkaline phosphatase activity (p<0.05). This study suggested that histatin-1 immobilization by tresyl chloride-activation technique enhanced cellular responses and might be able to promote cellular activities around the dental implants.

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  • Yadanar Su PHYO, Kentaro HASHIMOTO, Nobuyuki KAWASHIMA, Masashi KURAMO ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 942-948
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 13, 2021
    JOURNALS FREE ACCESS

    This study compared the cytocompatibilities of three methacrylate resin-based root canal sealers [MetaSEAL Soft (MSS), Hybrid Root SEAL (HRS), and Superbond Sealer (SBS)] in either freshly mixed or set conditions using the Kusa A1 osteoblastic cell line. The three sealers and an epoxy resin-based sealer (AH Plus; AHP) were extracted in culture medium; cell growth and osteogenic properties were analyzed. Cell adhesion on set sealers was analyzed with scanning electron microscopy. The respective extents of cell growth were as follows in freshly mixed and set sealer extracts: SBS>MSS>AHP>HRS and SBS=AHP>MSS>HRS. Light irradiation of MSS and HRS increased the cell growth of set sealer extracts. Set SBS, MSS, and AHP did not alter expression of osteogenic genes or formation of mineralized nodules. Attached cells were observed only on SBS. In conclusion, the four sealers exhibited varying degrees of compatibility to osteoblasts; SBS and HRS were the most and least compatible, respectively.

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  • Sirus SAFAEE, Alireza VALANEZHAD, Mahdis NESABI, Shiva JAFARNIA, Hidea ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 949-956
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 13, 2021
    JOURNALS FREE ACCESS

    This study aimed to assess the mechanical and biological properties of bioactive glass (BG) coating on titanium (Ti). Bioinert Ti substrates were coated by BG to induce bioactivity to the surface. The sol-gel derived BG 58S sol was successfully prepared and coated on the abraded and blasted Ti surface using the sol-dip method. The characterization and cell study for all substrates’ surface was carried out. Adhesion test confirmed that a firmly adhered BG coating layer was formed on the abraded and blasted Ti. The measured bonding strength between the coating and the blasted Ti substrate was the highest among all samples, which was 41.03±2.31 MPa. In-vitro cell viability and alkaline phosphatase activity (ALP) tests results also showed that BG coating on the Ti substrate improved the biological properties of the surface. The BG sol-dip coating method could be used to fabricate Ti substrate with a bioactive surface.

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  • Yoshinosuke HAMADA, Susumu TANAKA, Yohei FUJISHITA, Jung-soo CHO, Taka ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 957-963
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 13, 2021
    JOURNALS FREE ACCESS

    In the present study, we investigated the possible involvement of the TGF-β/Smad signaling pathway in the osteopontin-derived SVVYGLR (SV) peptide-mediated migratory activities of myogenic cells and evaluated the facilitative effects of the SV peptide on the differentiation of myogenic cells in vitro. The SV peptide-induced migration in both human-derived satellite cells and myoblasts was substantially suppressed by the TGF-β1 receptor inhibitor SB431542 or SB505124. Besides, the expression level of the Smad3 phosphorylation was further enhanced by the addition of the SV peptide in comparison with control groups. Furthermore, an increase in the expression of myogenin-positive nuclei and a higher number of nascent myotubes with myosin heavy chain expression was confirmed in cultured myoblasts supplemented with the SV peptide. These results suggest that the involvement of the TGF-β/Smad signaling pathway in the SV peptide-mediated migration and the facilitative effect of the SV peptide on the differentiation of myogenic cells into myotubes.

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  • Fangshuo WANG, Hidemi NAKATA, Xiaolong SUN, Wai Myo MAUNG, Masashi SAT ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 964-971
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    Hydroxyapatite (HA) [Ca10 (PO4)6 (OH)2] has a high degree of chemical similarity with the mineral composition of animal bone. Hydroxyapatite fiber scaffold (HAF) is a biological material with a highly interconnected porous structure. We aimed to study the physical and biological characteristics of HAF and compare the osteogenic effects of HAF, natural osteogenic materials (NOM), and carbonate apatite (CO3Ap-DP) in the parietal defects of a rabbit’s skull. X-ray analysis and histological assessment showed that HAF followed a trend of early initial osteogenesis and bone trabecular structure formation, especially at the cortical bone portion.Compared to the other two materials, HAF was more absorptive. Results indicated that HAF had the same osteoconductive and new bone formation properties as NOM and CO3Ap-DP. These findings will provide options for future material development and novel protocols for use in surgeries, ultimately leading to better patient outcomes.

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  • Mohammed M. GAD, Reem ABUALSAUD, Firas K. ALQARAWI, Abdel-Naser M. EMA ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 972-978
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 22, 2021
    JOURNALS FREE ACCESS

    The aim of this study was to assess the translucency of denture base acrylic resin reinforced with zirconium dioxide (ZrO2NPs), silicon dioxide (SiO2NPs), and diamond (DNPs) nanoparticles. A total of 130 heat-polymerized acrylic discs (15×2.5 mm) were fabricated conventionally and divided into control and experimental groups according to nanoparticle type and concentration (0.5, 1, 1.5, and 2.5 wt%). Unmodified acrylic resin specimens served as control. All specimens were thermocycled (5,000 cycles). Translucency was measured using a spectrophotometer. ANOVA and post-hoc Turkeys’ test were used for data analysis at α=0.05. The translucency of modified PMMA was significantly lower than control (p<0.05) except 0.5% ZrO2NPs and SiO2NPs (p>0.05) which exhibited the highest translucency values among modified groups. As the NPs concentration increased, the translucency decreased and the lowest value was seen with 2.5% DNPs (1.18±0.10). The addition of ZrO2NPs, SiO2NPs, and DNPs into denture base resin decreased the translucency.

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  • Hajime OOUCHI, Toshiki TAKAMIZAWA, Tomohiko TAMURA, Ryo ISHII, Akimasa ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 979-985
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    This study investigates the flexural properties, Knoop hardness number (KHN), and wear behavior of computer-aided design and computer-aided manufacturing (CAD/CAM) resin blocks and compares these values with those of conventional resin composites for direct restoration (RCDs). Four CAD/CAM resin blocks and two RCDs are compared. Ten specimens per material are used to obtain the flexural properties according to ISO 6872 specifications, and five specimens per material are used for KHN measurement. For sliding impact wear testing, twelve specimens are prepared. Confocal laser scanning microscopy (LSM) is used to determine maximum facet depth and volume loss. Polished material surfaces and worn surfaces after wear testing are observed using scanning electron microscopy and LSM. While measured flexural properties and KHN are found to be material-dependent, CAD/CAM resin blocks exhibit higher wear resistance than RCDs. CAD/CAM resin blocks polymerized at high-pressure and high-temperature are found to exhibit wear behaviors far superior to those of RCDs.

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  • Yanhong YAN, Peng ZHOU, Haibing LU, Yun GUAN, Ming MA, Juan WANG, Guan ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 986-993
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 22, 2021
    JOURNALS FREE ACCESS

    Microorganisms may persist in the root canal system after root canal therapy (RCT). The purpose of this study was to explore the metronidazole (MTR)- and chlorhexidine (CHX)-loaded hydrogels as the potential application in intracanal medicaments for root canal disinfection. Ultraviolet cross-linked hydrogels (gGels) were synthesized by GelMA solution and photoinitiator, which were loaded with MTR (MTR@gGels) and CHX (CHX@gGels). gGels, MTR@gGels and CHX@gGels were characterized by scanning electron microscopy. The antimicrobial activity against E. faecalis, S. mutans and P. intermedia was assessed. Meanwhile, the biocompatibility of human dental pulp stem cells (hDPSCs) was evaluated. DCT, CCK-8, CFU and live/dead-stained biofilm results showed that the viability of E. faecalis, S. mutans and P. intermedia was significantly reduced in MTR@gGels and CHX@gGels in vitro. CCK-8 results showed considerable biocompatibility with hDPSCs. The filling and clearance of gGels in root canals were demonstrated in vivo. Therefore, MTR- and CHX-loaded hydrogels may be a potential application in intracanal medicaments for root canal disinfection.

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  • Chie TOKITA, Masahiko MAENO, Yoichiro NARA
    Type: research-article
    2021 Volume 40 Issue 4 Pages 994-1006
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 07, 2021
    JOURNALS FREE ACCESS

    The effects of space setting values and restorative materials on the bonding of metal-free CAD/CAM onlay restoration were examined quantitatively and qualitatively. Seventy-two standardized MODB onlay cavities, prepared using human molars were restored under nine conditions, based on three space setting values, Increased (IC), Standard (SC, control), Decreased (DC), and three restorative block materials, resin-composites (RC), lithium disilicate glass-ceramics (LD), Feldspar ceramics (FC, control). All the restored specimens were subjected to cyclic loading and thereafter the microtensile bond strength (µ-TBS) was measured and analyzed statistically. The effect of space setting value on the µ-TBS varied with the restorative material. The bonding reliability of RC and the bonding durability of LD were significantly superior to FC. The bonding characteristics of RC under IC and DC were similar to those under SC. LD under DC and FC under IC were effective in obtaining an excellent bonding reliability relative to their SC.

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  • Gabriella KAKONYI, Steven MULLIGAN, Andrew W. FAIRBURN, Keyvan MOHARAM ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1007-1013
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: May 21, 2021
    JOURNALS FREE ACCESS

    As resin-based composites (RBC) replace dental amalgam for environmental reasons, there is a requirement to understand the environmental impact of this alternative dental restorative material. In this study we standardize the simultaneous detection of five monomeric components associated with RBCs using high performance liquid chromatography (HPLC) coupled with solid-phase microextraction (SPME). Factors affecting method performance (detection wavelength, calibration conditions, method sensitivity/accuracy/precision, extraction time/efficiency) are evaluated using standard solutions containing the mixture of TEGDMA, UDMA, Bis-GMA, BPA and HEMA. Detection sensitivity and analytical efficiency of the method is optimized for these compounds using 200 nm detection wavelength, PDMS/DVB fiber and extraction time of 90 min. Analytical accuracy of the HPLC is >95% for all monomers, with precision of 2.3–5.1%. Detection limits under the conditions described are 25 µg/L for HEMA, BPA, UDMA, Bis-GMA, and 100 µg/L for TEGDMA. The extraction time is governed by the largest molecular weight compounds.

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  • Mitsunori UNO, Harumi KAWAKI, Hajime ISHIGAMI, Yoshiyuki YOKOGAWA, Yut ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1014-1019
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 07, 2021
    JOURNALS FREE ACCESS

    Radiofrequency magnetron sputtering of silicon was applied onto zirconia surfaces by use of a non-doped Si wafer at 2%, 5%, 8%, and 10% oxygen volumes. Immediately after sputtering, the contact angle was practically 0 for all oxygen volume specimens. In terms of sustainability of the hydrophilicity, however, 5% oxygen volume was found to be optimal. Scanning electron microscopy and energy dispersive X-ray spectroscopy clearly suggested the presence of silica layer on zirconia surfaces. The shear bond strength of the pre-treated zirconia and resin was 35.03±4.97 MPa, which was approximately 3.5 times higher than that of zirconia without any sputtering treatment (9.26±1.21 MPa). The failure mode of the pre-treated zirconia specimen was cohesive failure, whereas that of the control specimen was observed to be interface failure.

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  • Toshiyuki SUGE, Kunio ISHIKAWA, Takashi MATSUO, Shigeyuki EBISU
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1020-1026
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 07, 2021
    JOURNALS FREE ACCESS

    The aim of the present study was to assess the duration of dentin tubule occlusion by the calcium phosphate precipitation (CPP) method in the vital teeth of beagle dogs. Vital teeth were treated using the CPP method, potassium oxalate, or a bonding agent (Liner bond II) after cavity preparation and acid etching. The dentin tubules of all groups, except for the bonding agent, opened more widely with time in the absence of plaque control. Dentin tubules treated with the CPP method were open and no precipitate remained in the absence of plaque control. Differences were observed in dentin tubule occlusion when plaque control was achieved by daily tooth brushing. The majority of dentin tubules were occluded with an apatitic precipitate seven days after the CPP method with plaque control. The present results demonstrated that the CPP method is useful with proper plaque control.

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  • Takashi OGIHARA, Kiyoshi TOMIYAMA, Junko IIZUKA, Masato ISHIZAWA, Toru ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1027-1032
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 07, 2021
    JOURNALS FREE ACCESS

    We investigated the remineralization effects of Nanoseal (NS) dentin desensitizer on demineralized root dentin. Baseline lesion specimens prepared from bovine root dentin were immersed in artificial saliva (AS) or deionized water (DW) after treatment with NS or fluoride-free Nanoseal (NS(−)). Treatment and control groups comprised: 1, AS; 2, NS/AS; 3, NS(−)/AS; 4,NS/DW; 5, NS(−)/DW; and 6, baseline demineralization. Integrated mineral loss (IML) and lesion depth (LD) were determined by transverse microradiography. Fluoride concentrations in the immersion solutions were measured. AS, NS/AS and NS(−)/AS showed higher mineral volume % at the surface and lesion body than did other groups. NS/AS showed significantly lower IML than did AS. There was no significant difference in IML between NS/AS and NS(−)/AS. The highest concentration of fluoride was in the NS/AS immersion solution. The findings suggest Nanoseal facilitated remineralization of demineralized root dentin, and fluoride and other ions included may have contributed to this effect.

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  • Shun KOBAYASHI, Masatoshi NAKAJIMA, Kiyoka FURUSAWA, Antonin TICHY, Ke ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1033-1040
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    This study evaluated the effect of the structural color phenomenon in resin composites (RCs) on the color adjustment of restorations by investgating their color reproduction performance in human incisors of various shade. Cervical cavities were filled with a single-shade RC with 260 nm spherical fillers (Omnichroma (OMN)), conventional A2-shade RCs (Estelite Σ Quick or Clearfil AP-X), or experimental RCs with 5–50 nm fumed silica fillers (R1) and 100 nm spherical fillers (R2). Color parameters (L*C*h*) were measured using a CIE XYZ camera along the centerline of the restorations, and the color difference (∆E00) between corresponding areas of intact and restored teeth was calculated. Additionally, the reflectance spectra of OMN, R1, and R2 were investigated. OMN exhibited significantly lower ∆E00 than other tested RCs (p<0.05) and its reflection spectrum ranged from blue to red, while a blue peak was observed with R1 and R2, indicating a higher color adjustment potential of OMN.

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  • Miyuki SHIMIZU, Naoko MATSUI, Mahmoud SAYED, Hidenori HAMBA, Sho OBAYA ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1041-1048
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: March 27, 2021
    JOURNALS FREE ACCESS

    This study evaluated the ability of different types of silver diammine fluoride (SDF) to inhibit dentin demineralization using micro-focused X-ray computed-tomography (µCT). Dentin specimens were divided into five groups (n=10); no-treatment (control), 3.8% SDF (RC), 38% SDF, 38% SDF with potassium iodide (SDF/KI), and potassium fluoride (KF). The treated-dentin surfaces were subjected to demineralization for 7-days and assessed using µCT to determine mineral loss (ML) values. Specimens were also analyzed with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The ML values of the SDF and KF groups were significantly lower than those of the RC and SDF/KI groups. EDS detected fluoride ions in the SDF and KF groups but not in the RC and SDF/KI groups. It was concluded that 38% SDF demonstrated a high ability to inhibit dentin demineralization while additional application of KI may diminish the inhibitory effect of SDF. The amount of dentin demineralization with SDF treatments was material dependent.

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  • Masateru ANZAI, Tomonari KUMASAKA, Erika INOUE, Kazuhide SEIMIYA, Nori ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1049-1054
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    Titanium are often used as dental materials, pure titanium present low strength and titanium alloy is reported poor biocompatibility, respectively. To overcome the problem, we fabricated high-strength multi-directional forged (MDF) titanium with improved mechanical properties without changing the chemical composition and evaluated its applicability in prosthetic crowns. Cutting tests: the average absolute value of the difference before and after cutting was calculated as the uncut amount. Surface evaluations: MDF titanium, pure titanium, and the Ti-6Al-4V alloy were the surface properties (the surface roughness, the contact angles, glossiness) of the samples were evaluated. The fitness test used digital data. These demonstrated that the good workability of high-strength MDF titanium. The surface-roughness and contact-angle properties of MDF titanium and pure titanium were similar. The fitness test showed no significant differences between MDF titanium and pure titanium crowns. These results suggest that MDF titanium is promising for fabricating prosthetic crowns in dental applications.

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  • Simone Gomes Dias de OLIVEIRA, Josué MARTOS, Rodrigo Varella de CARVAL ...
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1055-1062
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 22, 2021
    JOURNALS FREE ACCESS

    The effect of the addition of nystatin and an alternative antifungal derived from pyrazoles in different commercial denture adhesives on their retentive efficacy, cytotoxicity and antimicrobial activity against Candida albicans was evaluated. Commercial denture adhesives were prepared with the inclusion of nystatin and 3,5-diaryl-4,5-dihydro-1H-pyrazole-1-carboximidamide (pyrazole) in three concentrations: 23.78 %w/w, 3.02 %w/w, and 0.31 %w/w (0.015 g, 0.0015 g, and 0.00015 g, respectively). The retentive efficacy was tested observing the influence of the medium, type of commercial denture type and the test condition (dipping). The antifungal action through disk diffusion and direct contact tests at 1, 4, 8 and 12 h and cytotoxic activity was evaluated in mouse fibroblasts (NIH/3T3) by the MTT reduction colorimetric assay. The addition of pyrazole and nystatin in commercial denture adhesives did not affect retentive efficacy rates and enhanced antifungal actions against Candida albicans. Results show a possibility of using denture adhesives as a delivery system for commercial antifungals (Nystatin) or pyrazole, with the second concentration (1,560 µg–3.02 %w/w) as the most efficient.

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  • Mitsunobu KAWASHIMA, Atsushi MINE, Satoshi YAMAGUCHI, Satoshi IMAZATO
    Type: research-article
    2021 Volume 40 Issue 4 Pages 1063-1067
    Published: July 25, 2021
    Released: July 31, 2021
    [Advance publication] Released: April 20, 2021
    JOURNALS FREE ACCESS

    The aim of this study was to develop a new method to evaluate the consistency of resin cements by modeling the operation of setting a crown. First, the weight of the resin cements and the inner surface area of the crown were measured to configure the conditions for consistency evaluation using a model abutment tooth and a model crown. As the evaluation method, a 200 mm2 contact surface area of a glass plate was placed on top of 30.0 mg of resin cement paste, and a pressure of 10.0 N was applied to the glass plate. When the paste was spread over the entire bottom surface of the glass plate, it was designated a “Pass”. A “Pass” result was obtained for all resin cements tested and a “Fail” result for all resin composites, indicating the usefulness of the new method for assessing cement flowability when setting a crown.

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