Dental materials journal最新文献

This study compared the chemical and physical properties of an experimental radiopaque white Portland cement (REPC) with reduced particle size to ProRoot white mineral trioxide aggregate (WMTA). The particle size distribution of experimental Portland cement (EPC) was examined, and then nano-zirconium oxide (nano-ZrO) was added to produce REPC. Chemical analysis, initial setting time, pH values, and push-out bond strength were evaluated. Results showed that REPC had smallest particle size (354.5±26.45 nm), while PC had the largest (1,309.67±60.54 nm) (p<0.05). Differences in chemical composition were observed. REPC exhibited shorter setting time (32.7±0.58 min) compared to WMTA (131.67±2.89 min) and PC (163.33±2.89 min) (p<0.05). All groups showed alkaline pH (p<0.05). REPC demonstrated the highest push-out bond strength (22.24±4.33 MPa) compared with WMTA (15.53±3.26 MPa) and PC (16.8±5.43 MPa) (p<0.05). This cost-effective PC formulation reduced the setting time and increased the push-out bond strength while maintaining the alkaline properties of the original cements.

Bone tissue engineering using biodegradable porous scaffolds is a promising approach for restoring oral and maxillofacial bone defects. Recently, attempts have been made to incorporate proteins such as growth factors to create bioactive scaffolds that can engage cells to promote tissue formation. Collagen-based scaffolds containing bone morphogenetic protein-2 (BMP2) have been studied for bone formation. However, controlling the initial burst of BMP2 remains difficult. Here we designed a functional chimeric protein composed of BMP2 and a collagen-binding domain (CBD), specifically the A3 domain of von Willebrand factor, to sustain BMP2 release from collagen-based scaffolds. Based on the results of computer-based structural prediction, we prepared a chimeric protein consisting of CBD and BMP2 in this order with a peptide tag for affinity purification. The chimeric protein had a collagen-binding capacity and enhanced osteogenic differentiation of human mesenchymal stem cells. These results are consistent with insights from in silico structural prediction.

This study compared the effects of two surface preparation methods on two types of zirconia. Immediately prior to the placement of a monolithic zirconia crown, its morphology may be modified using a rotary cutting instrument for occlusal adjustments. The crown surface is scratched during the grinding process and, thus, requires polishing. Simplified zirconia crowns of 3Y and 5Y were fabricated and used as specimens. The surface roughness and gloss of the occlusal surfaces of specimens were measured and compared when a polishing compound was used after polishing points and when a silica-based coating was sintered. No significant differences were observed in surface roughness between 3Y and 5Y zirconia. The use of polishing compounds was effective because polishing points alone only resulted in a level of surface roughness that may cause wear on antagonist teeth. Although the silica-based coating improved surface properties, the polishing compound more effectively improved surface roughness.

To study the biocompatibility of nanohydroxyapatite (nmHA)-SiO₂ fiber material and its efficacy in guided bone regeneration. ① The cytotoxicity of the nmHA-SiO₂ fiber material to MC3T3-E1 cells was determined by CCK-8 assay. The adhesion of cells on the surface of the material was observed. ② Bone defects were prepared in the skull of three groups of New Zealand white rabbits. The following treatments were administered: implantation of nmHA-SiO₂, implantation of Bio-Oss, and no treatment. The defects were then covered with nmHA-SiO₂ membrane or Hai'ao oral repair membrane. Animal samples were analyzed by gross observation, micro-computed tomography, hematoxylin-eosin staining and Masson staining. The data were statistically analyzed by multivariate analysis of variance to evaluate the repair of bone defects. ① The nmHA-SiO₂ fiber material has suitable biocompatibility. ② The nmHA-SiO₂ fiber material performed more effectively as a barrier membrane than other bone substitute materials in GBR model rabbits.

This study investigated the usefulness of a dental laboratory polymerization unit with light-emitting diode (LED) as a light source. The depth of cure (n=15), water absorption and solubility (n=9) of two indirect composite materials (Cesead N and Solidex Hardura) were evaluated by five dental laboratory polymerization units (LED Cure Master, Twinkle LED, α-Light V, α-Light II, and Hyper LII). Statistical analysis was performed by one-way ANOVA and Tukey test or non-parametric tests. Comparison of light sources for curing depth showed that metal halide had the highest value, followed by the LED group with similar values, and halogen lamps with the lowest value. The water absorption and solubility of the composite specimens polymerized with the three LED laboratory polymerization units were within the ISO recommended limit.

The purpose of this study was to evaluate the effect of the atmospheric pressure plasma treatment as a surface treatment method on the contact angle and shear bond strength (SBS) of zirconia ceramics and the failure mode between the self-adhesive resin luting agent and zirconia. The zirconia specimens were divided into eight groups based on the surface treatment method: alumina blasting, air plasma, argon plasma (AP), Katana cleaner, ozonated water, ozonated water+AP, Katana cleaner+AP, and tap water+AP. The contact angles, SBS, and fracture modes were tested. AP treatment significantly reduced the contact angle (p<0.0001). The combination of AP and other cleaning methods showed a higher bond strength and more mixed fractures. Our findings indicate that using atmospheric pressure plasma with argon gas, combined with other cleaning methods, results in a stronger bond than when using alumina blasting alone.

The aim of this study was to evaluate the effects of the application of universal adhesive in the etch-and-rinse (ER) strategy with a manual brush (MB) or rotary brush (RB) in adhesion to dentin impregnated (WB) or not (NB) with bioceramic sealer, at 24 h and 1 year. Eighty-eight crowns of bovine incisors were divided into four groups (n=22): WB-MB, WB-RB, NB-MB, NB-RB. After the restorative protocol, dentin penetrability was evaluated by confocal microscopy. Bond strength was evaluated by microtensile test. Data were analyzed using one-way ANOVA/Tukey tests (α=0.05). NB-RB and WB-RB exhibited greater extensions of resin tags in dentin. At 24 h, WB-RB and NB-MB showed the highest and lowest values of bond strength, respectively. At 1 year, WB-MB and WB-RB demonstrated the highest bond strength values. The RB increases the formation of resin tags and residues of bioceramic sealer provides higher bond strength in the ER strategy.

The glass infiltration technique was employed for surface modification of zirconia implants in this study. The prepared glass-infiltrated zirconia with low infiltrating temperature showed excellent mechanical properties and enough infiltrating layer. The zirconia substrate was pre-sintered at 1,200°C and the glass infiltration depth reached 400 μm after infiltrating at 1,200°C for 10 h. The infiltrating glass has good wetting ability, thermal expansion match and good chemical compatibility with the zirconia substrate. Indentation fracture toughness and flexural strength of the dense sintered glass-infiltrated zirconia composite are respectively 5.37±0.45 MPa•m^1/2 and 841.03±89.31 MPa. Its elasticity modulus is 163.99±7.6 GPa and has about 500 μm infiltrating layer. The glass-infiltrated zirconia can be acid etched to a medium roughness (1.29±0.09 μm) with a flexural strength of 823.65±87.46 MPa, which promotes cell proliferation and has potential for dental implants.

The surface treatment of glass-ceramic-based materials, namely, lithium disilicate glass (IPS e.max CAD), feldspar porcelain (VITABLOCS Mark II), and a polymer-infiltrated ceramic network (VITA ENAMIC), using aqueous fluoride solutions and their influence on luting agent bonding were investigated. Six experimental aqueous fluoride solutions were applied to these materials, and their effects were assessed by surface topological analysis. The obtained results were compared using non-parametric statistical analyses. Ammonium hydrogen fluoride (AHF) etchant demonstrated the greatest etching effect. Subsequent experiments focused on evaluating different concentrations of the AHF etchant for the bonding pretreatment of glass-ceramic-based materials with a luting agent (PANAVIA V5). AHF, particularly at concentrations above 5 wt%, effectively roughened the surfaces of the materials and improved the bonding performance. Notably, AHF at a concentration of 30 wt% exhibited a more pronounced effect on both etching and bonding capabilities compared to hydrofluoric acid.

This study aimed to clarify the fracture resistance of resin abutments built on endodontically treated roots with the remaining coronal teeth via static and cyclic loading tests. Endodontically treated bovine roots, which had a remaining coronal tooth covered with an occupied area for a quarter and half of the circumference at the tensile side or covered the circumference at both the tensile and compressive sides, were fabricated to build up to the resin abutment. Fracture resistance was evaluated via static and cyclic loading tests by applying a load of 30° to the tooth axis. Half of the circumference of the remaining coronal tooth showed a significantly higher static fracture load and survival rate. The remaining coronal tooth on the compressive side improved the dynamic fracture resistance associated with severe fractures. The occupied area and location of the remaining coronal tooth affected the static and dynamic fracture resistances.