Dental materials journal最新文献

This study evaluated the shear bond strength (SBS) between cobalt-chromium (CoCr) and titanium (Ti) alloys fabricated via selective laser melting (SLM) and denture base resins with different bonding methods. After surface pretreatment of cylindrical CoCr and Ti alloy specimens, bonding was performed using three methods: the compression molding (CM) method, the pouring (PT) method, and the method using 4-META/MMA-TBB resin (SB). SBS tests were performed after storing all specimens in distilled water at 37ºC for 24 h, either immediately or following 10,000 thermocycles. For CoCr alloys, without thermocycling, the CM method exhibited significantly higher SBS than SB method (p<0.001), but no significant differences were observed with thermocycling. For Ti alloys, the CM method showed significantly higher SBS than the SB method without thermocycling (p=0.018) and was higher than the PT method with thermocycling (p=0.047). These results suggested the CM method may be a promising bonding technique for SLM-fabricated alloys.

This study aimed to evaluate the conditions for the finish line position and gingival retraction width that allow for taking optical impressions using three-dimensional (3D) printed models. Taking an impression using an intraoral scanner (IOS) is widely performed in fabricating crown prostheses. Measuring the subgingival finish line using an IOS is difficult; to obtain optical impressions of the subgingival finish line, the gingival retraction has been recommended. However, no study has evaluated the amount of gingival retraction width and the depth of the finish line. In this study, the measurement limits of the subgingival finish line using an IOS and models fabricated by a 3D printer were investigated. The results of this study revealed that TRIOS3 could not measure the finish line when the gingival retraction width was <0.25 mm, and the finish line was located >0.50 mm below the gingival margin.

In this experiment, calcium salt (MDP-Ca) was synthesized from methacryloyloxydecyl dihydrogen phosphate (MDP), which is an adhesive monomer, and blended into a bonding system (Hybrid Coat: HC). The results from the microtensile and the indentation hardness revealed that HC with 1.50% MDP-Ca (MDCP) had higher values. In the FE-SEM observations, MDCP began to change its structure with a dense etching pattern after 24 h of immersion earlier than HC. These results indicated that MDP-Ca strengthened the mechanical structure of the hybrid layer because the initial bonding strength and indentation hardness of MDCP were greater than those of HC. Then MDCP was observed to have a dense structure that was resistant to ion etching treatment within 24 h. Thus, the addition of an appropriate concentration of MDP-Ca improved the initial bonding strength and mechanical properties of the prototype bonding material and formed a hybrid layer that was useful as a coating material.

Calcium silicate sol-gel derived amorphous materials incorporated with one of three antibacterial metal ions, silver, zinc, or copper, were prepared, and their antibacterial properties and cell compatibility were evaluated using Escherichia coli and a mouse fibroblast-like cell line, respectively. In all samples, the ions derived from the constituent elements of the materials were eluted into the culture medium. However, when antibacterial and cell culture tests were conducted under the same sample concentration conditions, the amount of eluted ions, including antibacterial metal ions, differed depending on the test. Furthermore, the variation in the elution amount depended on the type of antibacterial metal ion. Both antibacterial properties and cell compatibility were confirmed only in the zinc-containing samples. In addition, the prepared materials can be shaped into fibrous forms with cotton-wool-like structures by electrospinning. These materials are expected to serve as flexible bone grafts with antibacterial properties and therapeutic ion-providing ability.

The purpose of this study was to develop and evaluate Bis-GMA-free pulp capping materials incorporating bioactive glass (BG). Experimental Bis-GMA-free resin-based materials (TC2.1) were formulated with varying concentrations of 45S BG (0, 10, and 20 wt%). Degree of conversion (DC) was measured using FT-IR-ATR spectrometry. Cell viability was assessed through MTS assay on human dental pulp stem cells. Wound healing capacity was evaluated using scratch assay, while odontogenic differentiation was assessed through alkaline phosphatase (ALP) activity and Alizarin Red S staining. TC2.1+BG0% achieved highest DC (68.1±3.5%), with values decreasing as BG content increased (TC2.1+BG20%: 34.4±4.2%). All formulations maintained cell viability above 80%, with TC2.1+BG20% demonstrating superior wound healing capacity and highest ALP activity compared to commercial controls. Mineralization assays showed enhanced calcium deposition in TC2.1+BG20% by day 14. This novel material demonstrates promising biocompatibility and mineralization-inducing properties while maintaining adequate polymerization efficiency, offering potential advantages for vital pulp therapy applications.

Phosphate-buffered saline (PBS) is used as the washing solution, diluent, and stock solution to prepare decellularized bone. However, limited information exists regarding the effects of PBS alone on changes in bone structure and mechanical properties. This study examined the effects of prolonged PBS treatment (up to 14 days) on the bone matrix. Histological staining showed a reduction in cellular components (partial decellularization) after extended treatment, while collagen fibers were retained. Although PBS-treated bone showed remarkably decreased bone strength, the loss of inorganic materials was limited to the bone surface of the tibia. Collagen fibers in the PBS-treated bones showed marked irregularity and an increase in their diameter. These results suggest that prolonged PBS treatment affects the structure and network of collagen fibers, similar to inorganic materials, in the bone matrix. Our results provide basic insights into the preparation of functional decellularized bone for dental applications.

This study was aimed to analyze the structural and chemical properties of scaffolds prepared using the bovine rib bone. The bovine rib bone was extracted and processed by water jet washing, hydrogen peroxide treatment, and freeze drying to obtain porous scaffolds. Scanning electron microscopy analysis revealed that the scaffold was composed of interconnected trabeculae networks with an average pore diameter of 223 µm. The bulk density was determined to be 0.582 g/cm³, and the porosity was 70.3%. X-ray diffraction analysis showed that the scaffold consisted of hydroxyapatite at a low crystallinity. It was further observed that the scaffold contained calcium and phosphate at a Ca/P ratio of 1.68, with a trace of proteins. When the scaffold was soaked in the phosphate buffered saline at 37°C, the weight of the scaffold decreased by 5.5% after 28 days. These results will provide a platform for subsequent processing to fabricate decellularized scaffolds.

The introduction of self-adhesive filling materials has shown advantage in clinical use due to reduced procedure time. The newly developed self-adhesive Surefil One (SO) was compared to other current self-adhesive materials Vertise Flow (VF) and GC Fuji II LC (FJ). Shear bond strength (SBS) to dentin, flexural strength and water sorption were measured at 24 h and 4 weeks. Fluoride release was measured up to 4 weeks. SO showed intermediate fluoride-release that was higher than VF, but lower than FJ. SO demonstrated lower flexural strength than VF at 24 h but maintained that same strength to 4 weeks. SO had SBS comparable to FJ and VF at 24 h but it decreased at 4 weeks. Caution should be exercised when selecting and using SO, as well as the other two self-adhesive materials. Further studies are necessary to evaluate the efficacy for their clinical use in direct restorations.

This study investigates the effect of the grams per square meter (GSM) of glass fiber woven cloth used as reinforcement on the flexural properties and color stability of glass fiber-reinforced plastics (GFRPs) applied in computer-aided design-computer-aided manufacturing (CAD-CAM) restorations. Two types of GFRPs were fabricated using glass fiber woven cloth with different GSM values (215 and 47 g/m²), which were impregnated with thermoplastic acrylic resin. The control group consisted of acrylic resin without reinforcement, as well as two types of commercially available CAD-CAM GFRPs with a thermosetting epoxy resin matrix. As a result, GFRPs impregnated with thermoplastic acrylic resin showed higher flexural properties than commercially available GFRPs, and a lower GSM provided improved flexural properties and color stability compared with specimens using a higher GSM.

In this study, we constructed and validated deep learning models capable of predicting the osteogenic differentiation stages of mesenchymal stem cells (MSCs) using only phase-contrast microscopy images. UE7T-13, an immortalized human MSC line, was cultured in osteoinductive medium. Phase-contrast microscopy images were acquired at D0, D1, D5, D10, and D14 of differentiation. Two deep learning models, ResNet-50 and DenseNet-121, were trained to perform multi-class classification of osteogenic differentiation stages. Model performance was evaluated using precision, sensitivity, F1 score, and overall accuracy. The overall accuracy of the ResNet-50 model was 0.700 and that of the DenseNet-121 model was 0.684. The highest F1 scores occurred at D5, which may reflect more distinctive morphological features during mid-stage differentiation. Our results suggest that deep learning has the potential to non-invasively identify osteogenic differentiation stages based on morphological features alone.