Dental materials journal最新文献

Dental bases require low thermal conductivity and good mechanical properties, such as bonding with composite resins. This study aims to elucidate the physicochemical properties of premixed mineral trioxide aggregate (MTA) for its suitability as a dental base and to explore the optimal adhesive strategy with composite resin. The thermal conductivity and compressive strength of this premixed MTA are 0.12 W/(m•K) and 93.76 MPa, respectively, Which are deemed adequate for its application as dental base. When bonded to composite resin, the use of 37% phosphoric acid etching before applying the Clearfil SE bond significantly reduced the bonding strength between composite resin and premixed MTA. This was because the compressive strength and Vickers hardness of premixed MTA decreased, and tricalcium silicate was dissolved from the surface during acid etching. Therefore, it is recommended to avoid using 37% phosphoric acid etching when bonding premixed MTA and composite resin as a dental base.

The aim of this study was to demonstrate the vertical and volumetric wear characteristics of CAD/CAM materials. The microhardness and color stability were evaluated. A polymer infiltrated ceramic network CAD/CAM block, resin nanoceramic CAD/CAM blocks, a resin composite, and enamel tissue were investigated. Samples were loaded in a chewing simulator. Other samples were aged and immersed in coffee. Color change was evaluated using the digital image analysis and a spectrophotometer. The data were analyzed using Kolmogorov-Smirnov, Kruskal Wallis, Mann Whitney U, Friedman, Spearman's rho tests (p<0.05). The lowest level of wear was obtained in enamel tissue group 0.20 (Q1:0.14; Q3:0.27μm). Resin composite group 2.48 (Q1:2.12; Q3:2.92) showed lower level of discoloration. No agreement was obtained between the digital image analysis and spectrophotometer data (Spearman's rho -0.314, p=0.014). Similar wear rate to the natural enamel tissue was obtained for Vita Enamic. Digital image analysis was considered a promising technique for monitoring the color change.

This study aimed to evaluate the thermocycling effect on the retentive force of 3 different retentive inserts in 3 denture attachments (Blue, Pink, Clear retentive inserts in LOCATOR; Blue, Pink, Clear retentive inserts in LOCATOR R-Tx; and White, Yellow, Green retentive inserts in Novaloc) (n=10). Maximum retentive force of each retentive insert was evaluated at baseline, 7-day water storage, and after 5,000-, and 10,000- cycle thermocycling. The water absorption percentage of the retentive inserts was also determined. Comparing between baseline and 7-day water storage, the retentive forces of the LOCATOR and LOCATOR R-Tx groups were significantly reduced (p<0.05), while the retentive force of the Novaloc group was significantly increased (p<0.05). Comparing between 7-day water storage and 10,000-cycle thermocycling, the retentive force of most retentive inserts remained unchanged (p>0.05). The water absorption percentage of the LOCATOR and LOCATOR R-Tx groups was significantly greater than that of the Novaloc group (p<0.05).

This study investigated the degree of phase transformation, surface roughness, and bond strength of zirconia immersed for various times in a 40% hydrofluoric acid (HF) solution. Non-etched sintered zirconia specimens were used as the control, while experimental groups were etched with a 40% HF solution for 5, 10, 20, 40, 80, 160 and 320 min. In each of the control and experimental groups, five specimens for X-ray diffraction analysis, four for surface morphology and surface roughness analysis, and ten for bonding strength measurement were used. As a result, the surface roughness of zirconia increased as the application time increased during the 40% HF etching, but the bond strength between zirconia and resin cement did not increase proportionally. The phase transformation from tetragonal to monoclinic also gradually increased with application time.

Monetite granules were reported to be able to balance osteoclastic resorption and new bone formation. However, to date, the dehydration of preset brushite has been the well-known method for preparing monetite granules. In the present study, for the first time, monetite granules could be prepared from the phase transformation of calcium sulfate dihydrate (CSD) granules through immersion in NaH₂PO₄ solution under hydrothermal conditions. CSD granules could be fully transformed into monetite granules at a reaction temperature of 125°C for 24 h. The obtained monetite granules were eight times more soluble in acetate buffer than in Tris-HCl buffer. Furthermore, monetite granules were two times more soluble in acetate buffer but comparable in Tris-HCl buffer compared to xenograft HA. The initial cytotoxicity test indicated that the novel monetite granules were nontoxic. In short, novel monetite granules were successfully prepared, exhibited better solubility in osteoclastic simulation than xenograft HA and were nontoxic.

This study aimed to evaluate the influence of surface pretreatment on the shear bond strength of resin luting cement to saliva-contaminated resin core foundation. The surface free energy (γ^S) of the adherent surfaces was examined. The two-way analysis of variance revealed that the surface pretreatment and storage conditions had a significant effect on the strength of the bond to resin core foundation. The γ^S values of the saliva-contaminated group were significantly lower than those of the other groups, and they tended to improve after surface pretreatment. The tendency of improvement in γ^S values differed depending on the type of pretreatment agents. Surface treatment with solutions containing functional monomers is effective in removing saliva contaminants from the resin core foundation surfaces and in creating an effective bonding surface for the resin luting cement.

This study evaluated the influence of different translucent resins (Z350 and Opallis) for customizing fiber posts and light-curing the cementation system using different LED equipment (V, Valo or R, Radii-Cal) on the bond strength and adhesive failure pattern at 24 h and 6 months. Eighty roots were prepared and divided into 4 groups (n=20): ZV (Z350 resin and LED Valo), ZR (Z350 resin and LED Radii-Cal), OV (Opallis resin and LED Valo), OR (Opallis resin and LED Radii-Cal). After post space preparation, the fiber post was customized and cemented with self-adhesive cement and light-curing using V or R LED equipment. Bond strength values were submitted to 2-way ANOVA test. ZV and ZR showed higher bond strength values than the other groups at 6 months of evaluation (p<0.05). The Z350 resin has a favorable influence on the bond strength of self-adhesive cement to root dentin, regardless of the LED polymerization equipment used.

Functional nano-fillers are commonly used to reduce bacterial colonization in dentistry. This study aimed to synthesize, characterize, and evaluate the biological effects of magnesium oxide (MgO) nanoparticles (NP) obtained by mechanosynthesis. XRD, TEM, FT-IR, and UV-Vis were used to characterize MgO-NP which were subsequently tested for their activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli (E. coli). The effects of MgO-NP on osteoblast cells were also analyzed. Three variables were studied: microbial inhibition by optical density (OD; 570-nm), viability estimated by colony-forming-units, and cell proliferation. The characterization of NP is consistent with nanostructures, minimum inhibitory concentration between 1.5-5 mg/mL, and microbial inhibition at 9.75 ug/mL concentration for E. coli were determined. There were different concentration-dependent effects on cell proliferation. Results were observed with 0.156 mg/mL MgO-NP, which increased cell proliferation at 24 and 48 h. The results suggest the antibacterial suitability of MgO-NP, with tolerable viability of mammalian cells for dental applications.

Transparency to UV-Vis light and radiopacity of dental resin composites containing zirconia (ZrO₂) fillers were investigated. The transparency of the resin composite containing porous ZrO₂ spheres was much higher than that containing irregularly shaped ZrO₂ particles. Calcination of the porous ZrO₂ spheres at high temperatures led to dramatically reduced specific surface areas and pore volumes. The transparency of the resin composite containing the calcined porous ZrO₂ spheres drastically decreased as the calcination temperature increased. Then, the enhanced UV-Vis transmittance of the resin composite containing porous ZrO₂ spheres is attributed to the concentration and physical characteristics of the pores. The radiopacity of the resin composites containing porous ZrO₂ spheres increased slightly with increasing calcination temperature. This study revealed that the internal structure of the ZrO₂ fillers mainly influenced in the UV-Vis light transmittance of the resin composites.

Mesenchymal stem cells (MSCs) and induced pluripotent stem (iPS) cells have great potential as cell sources for tissue engineering and regenerative medicine. This study aimed to investigate whether iPS cells can be differentiated into MSCs using MSCGM, a commercially available MSC culture system. The cells were characterized by flow cytometry, immunostaining, and gene expression analyses. We also examined their potential to differentiate into osteoblasts and chondrocytes. Our results showed that iPS cells cultured in MSCGM (iPS-MSCGM) exhibited a fibroblast-like morphology and expressed CD73 and CD90 genes, as well as positive markers for CD73, CD90, and CD105. Moreover, iPS-MSCGM cells demonstrated the ability to differentiate into osteoblasts and chondrocytes in vitro. This study demonstrates a new and simple method for inducing the differentiation of iPS cells to MSCs using MSCGM.