Dental Materials Journal

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Volume 35 (2016) Issue 2 Pages 250-256
Dimensional accuracy of dental casting patterns created by 3D printers
Yoshiki ISHIDA, Taira MIYASAKA

Contrary to widespread incise CAD/CAM, little is known about the dental application of 3D printing, especially the possibility of using 3D printing with organic material. The resin patterns of a full crown model were created by four types of 3D printers, a thermofusion device (CX), a digital light processing stereo-lithograph device (B9), a laser stereo-lithograph device (DW) and a multi-jet modeling device (PJ). The dimensional accuracy of the outer and inner diameters and depths of the created model crowns, and the surface roughness of sidewall were investigated. The outer diameters were smaller than the designed value in most conditions. The inner diameters were smaller than the designed value in any enlargement ratio except B9. The depth of CX or B9 tended to become shallower, though that of PJ or DW tended to increase. The surface roughness along the tooth axis direction was greater than that perpendicular to the tooth axis.
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Editor's pick
Field Weighted Citation Impact (FWCI) is one of indices to evaluate the scientific publishing by estimating the total citation ratio based on the average of the subject field from Scopus database. FWCI could therefore be used as the index over specific field. Here, we show the example of DMJ articles from 2014 to 2016 with relatively higher FWCI values beyond 1.0 which is considered the average of the subject field. The editors of the DMJ would like to introduce some of the articles here. FWCI score of this article is 2.59.
Volume 33 (2014) Issue 1 Pages 64-69
Genotoxicity and cytotoxicity of mineral trioxide aggregate and calcium enriched mixture cements on L929 mouse fibroblast cells
Neda NAGHAVI, Jamileh GHODDUSI, Hamid R. SADEGHNIA, Elham ASADPOUR, Saeed ASGARY

Mineral trioxide aggregate (MTA) has shown good biocompatibility in several studies. In the present study, the genotoxic and cytotoxic effects of calcium enriched mixture (CEM) were evaluated compared with MTA using MTT and single-cell gel (comet) assays with serial ascending concentrations (0 to 1,000 µg/mL) of tested materials. Cytotoxicity data indicated that there is no significant difference between CEM and MTA at all concentrations except for the full concentration (1,000 µg/mL); CEM had lower cytotoxicity. Genotoxic effects were more evident with CEM at concentrations of 15.6 and 250 µg/mL; however, was less than that of MTA at concentrations of 500 and 1,000 µg/mL. The cytotoxicity and genotoxicity effects of the two experimental groups generally increased with consistency. Under the conditions of this study, CEM is biocompatible in terms of cyto- and genotoxicity. It appears to be an alternative to MTA as an endodontic biomaterial offering several advantages.
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Editor's pick
FWCI score of this article is 2.57.
Volume 35 (2016) Issue 1 Pages 29-36
Bonding effectiveness of self-adhesive and conventional-type adhesive resin cements to CAD/CAM resin blocks. Part 2: Effect of ultrasonic and acid cleaning
Asuka KAWAGUCHI, Mariko MATSUMOTO, Mami HIGASHI, Jiro MIURA, Takuya MINAMINO, Tomoshige KABETANI, Fumio TAKESHIGE, Atsushi MINE, Hirofumi YATANI

The present study assessed the effect of ultrasonic and acid cleaning on resin cement bonding to CAD/CAM resin blocks. One of two resin cements, PANAVIA V5 (PV5) or PANAVIA SA CEMENT HANDMIX (PSA), were bonded to one of 24 CAD/CAM blocks (KATANA AVENCIA BLOCK). Each cement group was divided into four subgroups: no cleaning (Ctl), ultrasonic cleaning (Uc), acid cleaning (Ac) and Uc+Ac. Micro-tensile bond strengths (µTBSs) were measured immediately and 1, 3, and 6 months after water storage. Block surfaces after each treatment were analyzed by scanning electron microscopy. Analysis of variance revealed a statistically significant effect for the parameters ‘surface treatment’ (p<0.001, F=40), ‘resin cement’ (p<0.001, F=696) and ‘water aging’ (p<0.001, F=71). The PV5 group exhibited higher µTBS values than the PSA group. Although cleaning after sandblasting was effective in removing residual alumina particles, it did not affect the long-term bonding durability with non-contaminated CAD/CAM resin blocks.
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Editor's pick
FWCI score of this article is 2.42.
Volume 33 (2014) Issue 1 Pages 79-85
Dental zirconia can be etched by hydrofluoric acid
Tool SRIAMPORN, Niyom THAMRONGANANSKUL, Chumphol BUSABOK, Sushit POOLTHONG, Motohiro UO, Junji TAGAMI

The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25^oC for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80^oC for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25^oC for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface.
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Editor's pick
FWCI score of this article is 2.43.
Volume 34 (2015) Issue 6 Pages 910-917
Translucency and flexural strength of monolithic translucent zirconia and porcelain-layered zirconia
Fumiyori MATSUZAKI, Hideshi SEKINE, Shinya HONMA, Takuya TAKANASHI, Katsunori FURUYA, Yasutomo YAJIMA, Masao YOSHINARI

This study aims to investigate the effectiveness of monolithic translucent TZP with different colors and porcelain-layered TZP by evaluating their colors and strengths. Different mixing ratios of Zpex to Zpex-Yellow as translucent TZP, conventional opaque TZP (TZ-3YB-E) (Tosoh, Tokyo) as a control, and veneering porcelain (CERABIEN ZR, body porcelain, Noritake, Tokyo) with shade A3 as a typical shade. Disk-shaped specimens of 13 mm diameter and 1.5 mm thickness were prepared. These specimens were observed under reflected and transmitted light, and the translucency parameter (TP) values were measured. Strength was also evaluated with flexural strength in a biaxial bending test. The TP values of the monolithic TZP, Zpex100>Zpex70>Zpex50>TZ3YB, were larger in this order. The flexural strength of all the monolithic TZP showed approximately 1,000 MPa. It is suggested that colored translucent TZP is clinically useful when used as monolithic restorations.
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Editor's pick
FWCI score of this article is 2.55.
Volume 33 (2014) Issue 5 Pages 705-710
Mechanical properties of composite resin blocks for CAD/CAM
Sasipin LAUVAHUTANON, Hidekazu TAKAHASHI, Maho SHIOZAWA, Naohiko IWASAKI, Yuya ASAKAWA, Meiko OKI, Werner J. FINGER, Mansuang ARKSORNNUKIT

This study compared commercial composite resin blocks with one ceramic block for use in computer-aided design/computer aided manufacturing (CAD/CAM). Four composite resins, one composite ceramic, and one feldspar-ceramic block were investigated. Flexural strength (FS), flexural modulus (FM), and Vickers hardness (VH) were determined under three conditions: dry storage; immersion in water at 37°C for 7 days; and immersion in water at 37°C for 7 days followed by 10,000 thermocycles. After dry storage, FS ranged from 127 to 242 MPa, FM from 9.6 to 51.5 GPa, and VH from 64 to 455. Two-way ANOVA was performed for FS, FM and VH followed by Tukey’s multiple comparison (α<0.05). Results demonstrated that the materials degraded after water immersion and thermocycling, but their properties were within the acceptable range for fabrication of single restorations according to the ISO standard for ceramics (ISO 6872:2008).
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Editor's pick
FWCI score of this article is 4.29.
Volume 35 (2016) Issue 2 Pages 216-224
Comparative study on the resorbability and dissolution behavior of octacalcium phosphate, β-tricalcium phosphate, and hydroxyapatite under physiological conditions
Susumu SAKAI, Takahisa ANADA, Kaori TSUCHIYA, Hajime YAMAZAKI, Henry C. MARGOLIS, Osamu SUZUKI

The dissolution behaviors of octacalcium phosphate (OCP), β-tricalcium phosphate (β-TCP), and hydroxyapatite (HA) were compared by implanting the materials in rat subcutaneous pouches for 8 weeks using a filter chamber or immersing them in simulated body fluid (SBF) or Tris-HCl buffer for 2 weeks at pH 7.4 and 37^oC. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and chemical analysis were conducted on these materials. Degree of supersaturation (DS) in the two solutions immersed with each calcium phosphate material was calculated from their chemical compositions. The results showed that OCP partially converted to apatitic crystals, while β-TCP and HA remained unchanged after the implantation. The DS of the SBF solution remained slightly supersaturated with respect to OCP and β-TCP, but slightly undersaturated in the Tris-HCl buffer. These findings suggest that previously reported OCP and β-TCP biodegradation could be induced through cell-mediated osteoclastic resorption rather than a simple dissolution process.
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Editor's pick
FWCI score of this article is 3.46.
Volume 35 (2016) Issue 4 Pages 668-674
Effect of surface pretreatments on resin composite bonding to PEEK
Patcharawan SILTHAMPITAG, Pisaisit CHAIJAREENONT, Kittipong TATTAKORN, Chaiyasit BANJONGPRASERT, Hidekazu TAKAHASHI, Mansuang ARKSORNNUKIT

This study evaluated the effect of surface pretreatments on resin composite bonding to polyetheretherketone (PEEK). Four groups of surface pretreatment (no pretreatment, etched with 98% sulfuric acid, etched with piranha solution and sandblasting with 50 µm alumina) were performed on PEEK. Surface roughness, Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis were examined. Shear bond strength (SBS) and interface characteristics were also evaluated after the specimens were bonded with resin materials. Two-way ANOVA analysis revealed significance on two main effects and interactions. Tukey’s multiple comparisons test showed that the SBS of resin composite on PEEK were the highest in the group etched with 98% sulfuric acid and bonded with Heliobond^® (p<0.05). All pretreatments produced similar spectra of FTIR patterns. SEM demonstrated porosities and pitting from chemical etching, which suggested a significant influence on the adhesion between PEEK and resin materials.

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Editor's pick
FWCI score of this article is 3.28.
Volume 35 (2016) Issue 3 Pages 418-424
Mechanical properties, volumetric shrinkage and depth of cure of short fiber-reinforced resin composite
Akimasa TSUJIMOTO, Wayne W. BARKMEIER, Toshiki TAKAMIZAWA, Mark A. LATTA, Masashi MIYAZAKI

The mechanical properties, volumetric shrinkage and depth of cure of a short fiber-reinforced resin composite (SFRC) were investigated in this study and compared to both a bulk fill resin composite (BFRC) and conventional glass/ceramic-filled resin composite (CGRC). Fracture toughness, flexural properties, volumetric shrinkage and depth of cure of the SFRC, BFRC and CGRC were measured. SFRC had significantly higher fracture toughness than BFRCs and CGRCs. The flexural properties of SFRC were comparable with BFRCs and CGRCs. SFRC showed significantly lower volumetric shrinkage than the other tested resin composites. The depth of cure of the SFRC was similar to BFRCs and higher than CGRCs. The data from this laboratory investigation suggests that SFRC exhibits improvements in fracture toughness, volumetric shrinkage and depth of cure when compared with CGRC, but depth of cure of SFRC was similar to BFRC.
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Editor's pick
FWCI score of this article is 2.76.
Volume 34 (2015) Issue 1 Pages 7-12
Three-unit reinforced polyetheretherketone composite FDPs: Influence of fabrication method on load-bearing capacity and failure types
Bogna STAWARCZYK, Marlis EICHBERGER, Julia UHRENBACHER, Timea WIMMER, Daniel EDELHOFF, Patrick R. SCHMIDLIN

To investigate the influence of different fabrication methods of three-unit reinforced polyetheretherketone composite (PEEK/C) fixed dental prostheses (FDPs) on fracture load. Forty-five three-unit anatomically supported PEEK/C FDPs were fabricated as follows: i. milled using a CAD/CAM system from an industrially fabricated PEEK/C blank, ii. pressed from industrially fabricated PEEK/C pellets, and iii. pressed from granular PEEK/C. Fracture load was measured and data were statistically analysed (p<0.05). CAD/CAM fabricated FDPs (2,354 N) presented a higher mean fracture load than those pressed from granular PEEK/C material (1,738 N) (p<0.001). CAD/CAM milled FDPs and those pressed from PEEK/C-pellets showed spontaneous and brittle fractures near the pontic without deformation of the FDP. In contrast, granulate pressed FDPs showed some plastic deformation without fracture. CAD/CAM fabricated FDPs, and FDPs pressed from PEEK/C pellets showed higher Weibull moduli compared to FDPs pressed in granular form. Industrial pre-pressing of blanks (CAD/CAM/pellet) increased the stability and reliability of PEEK restorations.
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Editor's pick
FWCI score of this article is 2.69.

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