Asian Pacific Journal of Dentistry
Online ISSN : 2185-3487
Print ISSN : 2185-3479
Volume 19, Issue 2
Displaying 1-5 of 5 articles from this issue
  • Atsushi Kameyama, Akiko Haruyama, Yuichi Nakazawa, Masahiro Furusawa, ...
    Article type: Articles
    2019 Volume 19 Issue 2 Pages 51-57
    Published: 2019
    Released on J-STAGE: October 27, 2021
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    Purpose: This study compared the ability of three methyl methacrylate (MMA)-p-styrene sulfonic acid copolymer (MS polymer)-based desensitizers (Pain-Free Gel Dentin Desensitizer; PF-Gel, No-Mix Pain-Free Desensitizer; PF, No-Mix Pain-Free F Desensitizer; PF-F) to occlude dentinal tubules. Materials and Methods: Dentin disc specimens were prepared from bovine incisors and the desensitizers were applied. After dehydration for 24 h or immersion for 1 week in artificial saliva, the surfaces were observed by scanning electron microscope (SEM). PF-Gel specimens also underwent SEM/energy dispersive X-ray spectroscopy (EDS). Results: Application of the desensitizers produced complete occlusion of the dentinal tubules. Most dentinal tubules re-opened after immersion for 1 week in artificial saliva (PF and PF-F samples), but in PF-Gel samples, the dentinal tubules remained occluded. SEM/EDS analysis demonstrated that the granular crystals adhering to the dentin surface contained oxygen, carbon, and calcium, and the plugs occluding the dentinal tubules contained calcium and phosphorus. Conclusion: The findings in this study confirm the sustainable effect of PF-Gel on the occlusion of dentinal tubules.

  • Takako Yoshikawa, Alireza Sadr, Junji Tagami
    Article type: Articles
    2019 Volume 19 Issue 2 Pages 59-64
    Published: 2019
    Released on J-STAGE: October 27, 2021
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    Purpose: This study evaluated the effects of the light curing methods and thermal cycling on adaptation to the cavity wall of different type of resin composite using a dye penetration test.Materials and Methods: Cylindrical cavities with one-half enamel and one-half dentin margins were prepared on the labial cervical region of bovine incisors. Cavities were restored using Clearfil tri-S Bond ND Quick and filled with Clearfil AP-X or Clearfil Photo Bright composite. The resin composites were cured using the conventional or the slow-start curing method. Half of specimens were thermocycled.Results: Clearfil AP-X showed significantly greater cavity-wall gap formation than that of Clearfil Photo Bright with both the conventional curing method and slow-start curing method with thermal cycling at 500 cycles (p < 0.05). The slow-start curing method showed significantly improved resin composite adaptation to the cavity wall compared with the conventional curing method for thermocycled Clearfil Photo Bright specimens (p < 0.05). Thermal cycling at 500 cycles significantly decreased cavity-wall gap formation compared with 0 cycle for Clearfil Photo Bright resin composites (p < 0.05). Clearfil Photo Bright using the slow-start curing method with thermal cycling at 500 cycles showed least cavity-wall gap formation.Conclusion: Light-cured composite, increased contrast ratio during polymerization with thermal cycling at 500 cycles, improved adaptation to the cavity wall using the slow-start curing method. The slow-start curing method facilitated the high reduction for residual stress of composite that had increased contrast ratio.

  • Hidemasa Shimpo, Chikahiro Ohkubo
    Article type: Articles
    2019 Volume 19 Issue 2 Pages 65-69
    Published: 2019
    Released on J-STAGE: October 27, 2021
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    Purpose: Auto-polymerized poly(methyl methacrylate) (PMMA) resin cannot be bonded to polyamide thermoplastic resin. This study evaluated the bonding strengths of auto-polymerized PMMA resin to nylon denture bases using adhesive agents.Materials and Methods: The surfaces of polyamide thermoplastic resin plates were polished using abrasive paper and blasted with 50 μm alumina particles. An adhesive agent, 4-META/MMA-TBB resin (Super-Bond) was used on the surfaces under the following conditions: monomer + catalyst (4:1, Group 1), monomer + catalyst (8:1, Group 2), monomer + catalyst (4:1) + polymer (Group 3), monomer + catalyst (8:1) + polymer (Group 4), treatment with dichloromethane (Group 5), alumina-blasted (Group 6), without treatment (Group 7), and PMMA resin (Group 8). Auto-polymerized PMMA resin was poured into a Teflon ring and polymerized according to the manufacturer’s instructions. After polymerization, the specimens were stored in 37˚C distilled water for 24 hours. The specimens for each condition were thermo-cycled for 5,000 cycles. The tensile bond strengths were measured on an autograph at a crosshead speed of 2.0 mm/min. The data obtained (n = 13) were analyzed using a two-way ANOVA and Tukey’s multiple comparisons test (α = 0.05).Results: The bonding strengths of Groups 1 to 4 were significantly higher than for Groups 5 to 7. No significant differences were found among Groups 1-4, although Group 3 had the highest bonding strengths.Conclusion: Auto-polymerized PMMA resin will adhere to polyamide thermoplastic resin using 4-META/ MMA-TBB after alumina-blasting.

  • Chiharu Shin, Daizo Okada, Reiko Ogura, Ling Huang, Kunihiko Mizusawa, ...
    Article type: Articles
    2019 Volume 19 Issue 2 Pages 71-76
    Published: 2019
    Released on J-STAGE: October 27, 2021
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    Purpose: To evaluate stress distribution around the marginal area of three full veneer crown restorations with different thicknesses.Materials and Methods: Two types of premolar finite element model (normal and half thickness of crown; NC, HC) were made on the personal computer and three types of crown material (polyetheretherketone, PEEK, PK; hybrid composite resin, HR; and Ag-Pd-Cu-Au alloy, PD) were assumed. Then the magnitude of stress at the marginal area of crown was calculated.Results: The magnitude of stress for PD-NC, HR-NC, PK-NC, PD-HC, HR-HC, PK-HC was 26.4, 21.3, 14.2, 50.6, 26.1, and 13.3 MPa respectively. The crown fabricated by PEEK prevented the stress concentration at the marginal area.Conclusion: Crowns fabricated by PEEK prevent the concentration of stress at the crown margin, and there is a possibility that these crowns require less tooth preparation in this area, when compared to metallic crowns.

  • Ayako Okada, Yoshiaki Nomura, Erika Kakuta, Ryoko Otsuka, Hiroshi Maek ...
    Article type: Articles
    2019 Volume 19 Issue 2 Pages 77-84
    Published: 2019
    Released on J-STAGE: October 27, 2021
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    Purpose: Japanese government has been promoted community-based integrated care systems which provide seamless community healthcare resources for elderly people. In this system, medical-dental collaboration and hospital-clinic collaboration play important roles. In this study, to understand the actual the situation, survey was conducted for the member of the Iwate Dental Association and analyzed the difficulty of the collaboration and the regional differences.Materials and Methods: The questionnaires were distributed to 609 all members of Iwate Dental Association. Implementation of dental treatment for mentally handicapped patients, the experiences of dental treatment for patients with diseases, the experiences of participated in nutrition support team and dental rounds at the hospital, dental treatment after nutrition support team rounds, dental and oral care at the hospital or medical clinic, participated in a collaborative conference at the hospital were surveyed. Data were analyzed by item response theory and correspondence analysis.Results: The 354 members retuned the questionnaire (collection rate was 58.1%). The 216/343 (61%) of dental clinic had experienced the dental treatment of the patients with mental handicap. Participation of nutrition support team and dental treatment after nutrition support ream round had high discrimination ability for the medical and dental collaboration. By the correspondence analysis, regional differences can be observed.Conclusion: There were the regional differences in the supply of the medical-dental and hospital-clinic collaboration service in Iwate Prefecture. Providing information for the members of team approach may be one of the resolutions for the regional difference.

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