Dental Materials Journal
Online ISSN : 1881-1361
Print ISSN : 0287-4547
ISSN-L : 0287-4547
Volume 41, Issue 6
Displaying 1-18 of 18 articles from this issue
Review
  • Gaetano PAOLONE, Francesca PAVAN, Paolo Chiara GUGLIELMI, Nicola SCOTT ...
    Article type: review-article
    2022 Volume 41 Issue 6 Pages 791-799
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: September 06, 2022
    JOURNAL FREE ACCESS

    The objective of this study was to review the experimental in vitro procedures employed to assess the color stability of resin-based composites exposed to smoke. A literature search was performed on four databases (Pubmed, Scopus, Embase, and Web of Science). The quality of the included papers was assessed with the Cochrane risk-of-bias tool (RoB 2). In total, 25 studies were selected for full-text reading, from which 12 were included in the review. The assessed variables were: dimensions, shape, time before exposure, finishing, smoke-type, exposure time, brushing simulation, color, measuring system, repolishing. A disk-shaped specimen was used in most studies (n=10) with a 2 mm thickness (n=7) in custom made devices equipped with vacuum pumps or in Vitrocell systems. Spectrophotometers were the most used devices (n=11). Color differences were quantified with ΔE (n=12), ΔE00 (n=1). The large variety of staining procedures suggests the need for standardization.

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Original Paper
  • Hyun-Jin OH, Chang-Ha LEE, In-Bog LEE
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 800-807
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: July 20, 2022
    JOURNAL FREE ACCESS

    This study investigated transmittance changes during photo-polymerization of composites in real-time. The transmittance changes of one conventional micro-hybrid, three conventional nano-hybrid, and four bulk-fill composites were measured before, during, and after photo-polymerization, and the maximum rate of transmittance change was compared with that of polymerization shrinkage. A significant difference in transmittance of composite between before and after photo-polymerization was observed. The transmittance of composites except for one bulk-fill composite increased during photo-polymerization. There was a correlation between the maximum rate of transmittance change and the maximum rate of polymerization shrinkage. The transmittance analysis of composites gives very important information to know for the final aesthetic restoration and allows to evaluate polymerization kinetics.

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  • Hiroaki KAKINUMA, Kuniyuki IZUMITA, Nobuhiro YODA, Hiroshi EGUSA, Keii ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 808-815
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: July 06, 2022
    JOURNAL FREE ACCESS

    This study aimed to compare the dimensional accuracies of three-dimensional (3D)-printed and milled resin-composite crowns, and to determine acceptable abutment-tooth shapes for printing. Four first-molar abutment models were prepared: the master model form and three models with sharp occluso-axial line angles. Crowns were designed on each abutment using computer-aided design software. The drill-offset value was set at 0.0 or 0.5 mm to evaluate the effect on the dimensional accuracy of milling. A digital light processing-based 3D printer was used to fabricate 3D-printed crowns. Milled crowns were fabricated by wet-milling. The trueness was evaluated by superimposing the design data. Regardless of the abutment form, 3D-printed crowns showed higher accuracy with fewer marginal discrepancies than milled crowns. Milled crowns showed significant dimensional deviations, especially at cusps. Moreover, offset correction resulted in grooves on the internal surface of milled crowns with negative deviations, which were especially evident in crowns for the sharp models.

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  • Fang GUO, Shuo HUANG, Ning LIU, Min HU, Changquan SHI, Dichen LI, Chan ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 816-823
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: July 20, 2022
    JOURNAL FREE ACCESS

    Compared with CAD/CAM, fused deposition modeling (FDM) 3D printing technology is simple and safe to operate and has a low cost and high material utilization rate; thus, it is widely used. The present investigation aimed to evaluate the mechanical properties and fit of polyetheretherketone (PEEK) removable partial dentures (RPDs) constructed by FDM. We analyzed mechanical properties of PEEK samples prepared by FDM, milling, or injection molding. RPDs were designed and finite element analysis models was constructed to evaluate maximum stress and strain in the RPDs, cortical bone and mucosa. Geomagic Qualify software was used to analyze gaps between the model and the tissue surface of the framework. The results showed that the compressive strength of the 3D-printed PRDs was greater than that of the injection-molded samples. Finite element analysis demonstrated that the maximum stress on the PRDs was less than the yield strength of the material. Overall, the mechanical properties and fit of the PEEK RPD fabricated by FDM technology essentially fulfilled clinical requirements.

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  • Hiro MATSUMOTO, Takatsugu YAMAMOTO, Tohru HAYAKAWA
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 824-832
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: July 06, 2022
    JOURNAL FREE ACCESS

    The present study examined color changes in the tooth-colored restorative materials, zirconia (3Y-TZP), resin composite, and porcelain. The colors (CIELab) of these materials were measured using a spectrophotometer. Specimens were immersed in black tea or curry for 1 and 7 days, after which colors were re-assessed. Color differences (∆E*ab) before and after immersion were calculated. Specimens after the 7-day immersion were ultrasonically cleaned, and colors were measured again to assess the color recovery rate. The surface free energy, roughness, and water sorption/solubility of each material were also evaluated. Specimens were observed under a scanning electron microscope. The ∆E*ab of 3Y-TZP was the smallest with both immersions. Resin composite had the smallest recovery rate. The surface free energy and roughness of 3Y-TZP were smaller than those of porcelain. 3Y-TZP and porcelain showed almost no sorption during the 7-day period. The present results revealed that 3Y-TZP exhibited the strongest resistance to discoloration.

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  • Wei ZHOU, Zi-Xuan LIAO, Ji-Hua CHEN, Bi-Ying QIU, Yang ZHANG, Ling ZHA ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 833-842
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 05, 2022
    JOURNAL FREE ACCESS

    This study aimed to comprehensively evaluate the effect of dual-cured resin luting agents with different initiator systems on the color stability of glass ceramic restorations by simulating various clinical glass ceramic restorations. Three commonly used shades from each of the two dual-cured resin luting agents with an amine-initiation system or without it were studied. The individual specimens had different translucency and thickness and were artificially aged using a xenon light aging machine. The color was measured before and after aging using a digital spectrophotometer with the difference calculated and analyzed statistically. As results, the amine-free dual-cured resin luting agents were more color stable than those using amine-initiation systems for both uncovered and bonding groups. The translucency and thickness of the ceramic, and shade and type of the resin luting agent significantly affected the color stability of glass ceramic restorations.

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  • Jared MASON, Timothy KIRKPATRICK, Howard W. ROBERTS
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 843-849
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 05, 2022
    JOURNAL FREE ACCESS

    This study evaluated the dislodgement push-out resistance of five bioceramic materials. One hundred single-rooted teeth with one canal had the apical 3 mm and crown resected to create a 14 mm standardized length. The canals were instrumented to an apical size 80 with a 3 mm root-end preparation made with ultrasonic diamonds. The prepared roots were randomly divided into 5 root-end restorative groups (n=20). ProRoot MTA, Biodentine, EndoSequence Root Repair Material, EndoSequence Fast Set Putty, and EndoSequence BC Sealer with each material placed following manufacturer’s instructions and stored at 100% humidity for 2 weeks. An apical-to-coronal static testing load with the identified dislodgement force converted into MPa with mean results analyzed with Kruskal-Wallis and Dunn’s post hoc tests (α=0.05). ProRoot MTA and Biodentine displayed similar push-out stress resistance and exhibited significantly greater stress resistance than the similar Endosequence materials. However, all materials failed cohesively and were not dislodged from the root canal surface.

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  • Qiuying GAO, Yuli SHANG, Weiwei ZHOU, Shu DENG, Cheng PENG
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 850-859
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 05, 2022
    JOURNAL FREE ACCESS

    The purpose of this study was to analyze the therapeutic effects of marine collagen peptides (MCPs) from tilapia skin on oral mucosal ulcers in a rat model. CCK-8 and wound healing assays were performed in vitro to evaluate proliferation and migration of L929 cells after treatment with MCPs. The effects of MCPs on the healing of oral mucosal ulcers in a rat model were macroscopically and microscopically analyzed in vivo. Results showed that MCPs promoted proliferation and migration of L929 cells. Moreover, 75%MCPs enhanced the ulcer healing process, suppressed inflammatory response and up-regulated the expression levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF). MCPs are potentially used as a new therapeutic strategy for oral mucosal ulceration.

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  • Taro IWASAKI, Shunsuke NAGATA, Takahiro ISHIKAWA, Yasuhiro TANIMOTO
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 860-867
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 05, 2022
    JOURNAL FREE ACCESS

    The objective of this study is to investigate the mechanical properties, such as the dynamic hardness and indentation elastic modulus, of commercially available aesthetic orthodontic brackets, such as ceramic and plastic brackets, by the dynamic micro-indentation method. Five ceramic brackets, which were made of alumina (both monocrystalline and polycrystalline forms) or zirconia, and two plastic brackets, which were made of glass fiber-reinforced polycarbonate or polyamide, were tested. There were significant differences in the mechanical properties of the monocrystalline and polycrystalline alumina brackets. The mechanical properties of the glass fiber-reinforced plastic bracket were significantly superior to these of the non-glass-fiber-reinforced plastic bracket. The differences in the crystal structures of the ceramic brackets surface affected the dynamic hardness and indentation elastic modulus. Furthermore, the short glass fibers contained in the plastic bracket might contribute to the improvement of the mechanical properties.

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  • Jiao ZHANG, Qing YU
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 868-873
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 23, 2022
    JOURNAL FREE ACCESS

    The objective of this study was to analyze the effect of the type of ceramics and resin cements on the fluorescence of ceramic veneers under the 405 nm UV-light by digital imaging. One hundred and ninety-two veneers were fabricated using three types of ceramics (IPS e.max CAD, IPS Empress CAD, and Zenostar). Eight pieces of substrates were made of resin-nano-ceramic (Lava Ultimate). The level of fluorescence for each sample cemented with the substrate using three kinds of resin cements (RelyX U200, Variolink N, and Choice 2) was analyzed by using histogram data of luminosity from Adobe Photoshop software. Furthermore, the fluorescence values were evaluated by two-way ANOVA and Tukey’s test. The highest fluorescence values were observed for the IPS e.max CAD cemented with Choice 2 cement, followed by IPS Empress CAD, and Zenostar the lowest. The final fluorescence intensity of ceramic veneer is affected by ceramic materials and resin cements.

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  • Ana Cláudia DALMOLIN, Luisa Fernanda Alegria ACEVEDO, Letícia Antonel ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 874-881
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 05, 2022
    JOURNAL FREE ACCESS

    Bioactive glasses have been recommended for the occlusion of dentinal tubules in treating cervical dentin hypersensitivity. This study evaluates an in vivo model of dentin exposure, and tests the efficacy of bioglass treatments. Thirty male Wistar rats received gingival recession surgery on the upper left first molar. The treatments were applied over the surface of the exposed dentin every 4 days for 28 days. The groups were as follows: Naive; Gingival recession; Cavity varnish; Biosilicate®; Strontium bioglass; and Potassium bioglass. Changes in the dentin-pulp complex, and the presence of substance P, were evaluated through hematoxylin-eosin and immunohistochemical staining. The groups had similar results. Teeth with exposed dentinal tubules in rats showed a typical pattern in the dentin-pulp complex and immunotracing for substance P. The materials did not cause pulp damage. The effects of gingival recession and open dentinal tubules on pulp tissue require further clarification.

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  • Hikaru TAKEYAMA, Michito MARUTA, Taira SATO, Noboru KAJIMOTO, Eiji FUJ ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 882-888
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 23, 2022
    JOURNAL FREE ACCESS

    We prepared hydroxyapatite (HAp) bone grafts by the setting reaction of calcium phosphate cement, and investigated the effects of the porosity and crystallinity on the osteoconductivity and bioresorbability. We examined the effect of the water-mixing ratio, pressure, and post-heat treatment temperature during preparation on the crystallite size and porosity of the HAp blocks. The quantity of protein adsorption increased with increasing porosity and specific surface area (SSA) of the HAp blocks, whereas the initial cell attachment was similar despite the different porosities and crystallinities. In in vitro dissolution tests with a pH 5.5 buffer, which mimics an osteoclast-created Howship’s lacuna, both the porosity and SSA of the HAp blocks affected the solubility; most likely due to the increased contact area with the buffer. Thus, HAp blocks prepared by the setting reaction of calcium phosphate cement could be applicable for bioresorbable HAp bone grafts because of the high porosity and SSA.

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  • Shota OKAZAKI, Yuichi MINE, Yuko IWAMOTO, Shiho URABE, Chieko MITSUHAT ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 889-895
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: August 23, 2022
    JOURNAL FREE ACCESS

    The aim of the feasibility study was to construct deep learning models for the classification of multiple dental anomalies in panoramic radiographs. Panoramic radiographs with single supernumerary teeth and/or odontomas were considered the “case” group; panoramic radiographs with no dental anomalies were considered the “control” group. The dataset comprised 150 panoramic radiographs: 50 each of no dental anomalies, single supernumerary teeth, and odontomas. To classify the panoramic radiographs into case and control categories, we employed AlexNet, which is a convolutional neural network model. AlexNet was able to classify whole panoramic radiographs into two or three classes, according to the presence or absence of supernumerary teeth or odontomas. The performance metrics of the three-class classification were 70%, 70.8%, 70%, and 69.7% for accuracy, precision, sensitivity, and F1 score, respectively, in the macro average. These results support the feasibility of using deep learning to detect multiple dental anomalies in panoramic radiographs.

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  • Xin-Yi YE, Ming-Yue LIU, Jing LI, Xiao-Qiang LIU, Yu LIAO, Ling-Lu ZHA ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 896-904
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: October 14, 2022
    JOURNAL FREE ACCESS

    This study aims to evaluate the effects of cold atmospheric plasma (CAP) treatment on the bonding of resin cement to high-translucency zirconia. Zirconia specimens were subjected to different treatments: no treatment (ZrT), 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primer (ZrT-M), alumina particle air-abrasion with/without MDP-containing primer (ZrT-AM/ZrT-A), CAP with/without MDP-containing primer (ZrT-PM/ZrT-P). The surface topography, wettability, and chemical composition were evaluated. The shear bond strength (SBS) was tested before and after thermocycling. CAP did not alter the morphology, increased the wettability, and decreased the carbon/oxygen ratio of zirconia surface. The SBSs of ZrT-PM and ZrT-P were significantly higher than the other groups. After thermocycling, ZrT-A, ZrT-M, ZrT-AM, and ZrT-P showed comparable SBSs, all of which were lower than ZrT-PM. It was concluded that CAP improved the bonding performance of high-translucency zirconia without damaging its surface. The combination of CAP with MDP further enhanced the bond strength and may enable durable bonding.

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  • Qian CHENG, Ran LU, Xin WANG, Su CHEN
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 905-915
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: October 14, 2022
    JOURNAL FREE ACCESS

    The initialization of the gingival crevicular barrier epithelium facing the exposed implant surface is reported to take 1–2 weeks, and peri-implant inflammation mediated by bacterial infection has been an increasing concern. In this study, we developed a novel composite coating containing graphene oxide (GO) and the antimicrobial peptide (AMP) Nal-P-113 on smooth titanium surface, and then investigated the antibacterial properties and cytocompatibility of the coating. The results showed that Nal-P-113 exhibited a slow and continuous drug release in vitro from the composite coating. The Nal-P-113-loaded GO coating demonstrated excellent antibacterial properties against both Gram-positive Streptococcus mutans (S. mutans) and Gram-negative Porphyromonas gingivalis (P. gingivalis), without no obvious cytotoxicity to human gingival fibroblast (HGF) cells. The Nal-P-113-loaded GO coating need further optimization for anti-infective and wound healing promoting purpose of peri-implant tissues.

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  • Mona GIBREEL, Leila PEREA-LOWERY, Pekka K. VALLITTU, Sufyan GAROUSHI, ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 916-922
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: October 27, 2022
    JOURNAL FREE ACCESS

    The aim of this in vitro study was to evaluate the wear and surface hardness of nine materials for conventional manufacturing, subtractive milling, and 3D printing of occlusal splints, as well as to evaluate the differences in wear and surface hardness between rigid and flexible 3D-printed occlusal splint materials. Two-body wear and Vickers hardness tests were performed. The vertical wear depth and Vickers hardness values were statistically analyzed. Vertical wear depth and surface hardness values were statistically significant among the investigated materials (p<0.05). The lowest vertical wear depth was observed for the heat-cured resin (27.5±2.4 μm), PMMA-based milled material (30.5±2.8 μm), and autopolymerizing resin (36.7±6.3 μm), with no statistical difference (p<0.05). Flexible 3D-printed and CAD-CAM milled polycarbonate-based splint materials displayed lower surface hardness and higher wear than the PMMA-based materials. PMMA-based splint materials displayed the most consistent surface hardness and wear resistance regardless of the manufacturing technology.

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  • Chang-Ha LEE, In-Bog LEE
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 923-929
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: October 27, 2022
    JOURNAL FREE ACCESS

    In this study, a novel method for simulating human teeth was developed, with which the effect of radiant emittance of an LED curing light on the cuspal deflection was investigated. A mesio-occluso-distal (MOD) cavity was replicated using a heat-pressed ceramic and lost wax technique, and the cuspal compliance and cuspal deflection of the replicated ceramic teeth and extracted human teeth were evaluated. The replicated ceramic teeth were restored using a nano bulk-fill composite and photopolymerized using three different protocols. Data were analyzed with t-test and one-way ANOVA (α=0.05). The cuspal compliance and cuspal deflection of the replicated ceramic teeth and extracted human teeth were similar. Cuspal deflections did not differ significantly among the tested photopolymerization protocols. Thus, the replicated ceramic teeth were an effective simulation of human teeth. During bulk-fill composite restoration of the MOD cavity, cuspal deflection was not affected by changing the radiant emittance of the LED light.

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  • Aida SEYIDALIYEVA, Stefan RUES, Zinonas EVAGOROU, Alexander Jochen HAS ...
    Article type: research-article
    2022 Volume 41 Issue 6 Pages 930-936
    Published: November 25, 2022
    Released on J-STAGE: November 30, 2022
    Advance online publication: November 17, 2022
    JOURNAL FREE ACCESS

    To investigate the predictability and the outcome of surface modification techniques, including anodization. Four surface modification techniques were evaluated in this in-vitro study: sandblasting (S), polishing+anodizing (PA), sandblasting+anodizing (SA), polishing+etching+ anodizing (PEA). Color coordinates L*, a* and b* were collected using a spectroradiometer. Color differences between all groups were quantified by use of ΔE00. A possible influence of group membership was evaluated using 1-way ANOVA. Pair-wise inter-group comparisons were performed using post-hoc Tukey tests. PA specimens were the brightest and showed a pronounced yellowish and reddish hue. S and SA groups were significantly darker and predictability of outcome was higher compared to another groups. The most predictable surface treatment method is sandblasting. Anodizing techniques come along with the brightest and most chromatic color impression of the titanium.

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