Super Bond (SB) shows biocompatible and adhesive properties to bone as well as to dentin. In this study, SB induced minimal inflammation when implanted in connective tissue of rat, although Multibond II (MB) and Surgical Simplex® (SX) caused intense inflammatory response. SB was mostly in direct contact with bone without formation of fibrous tissue when implanted in the intramedullary canal of rat, although formation of fibrous tissue between resin cement and bone was mostly observed with MB and SX. Moreover, SEM observation revealed that SB was mostly in direct contact without a gap. Disorders of bone tissue or bone cells were not observed in the case of SB, MB and SX implanted in the intramedullary canal. Thus, 4-META/MMA-TBB cement can be effectively used as a bone cement.
In this study, we investigated the effects of insulin-like growth factor (IGF)-II on the expression and localization of EGR-1 and EGR-2 in cultured human periodontal ligament fibroblasts (PLFs). Three groups of PLF cells were first cultured for two days in serum-free Dulbecco's modified Eagle medium (DMEM), and were then stimulated with various concentrations of IGF-II. Stimulation with IGF-II increased the cell proliferation index in a dose-dependent manner, as measured by 5-bromo 2'-deoxyuridine incorporation. Expression of EGR-1 mRNA peaked after 30 min of incubation with IGF-II at a concentration of 10 ng/mL. Furthermore, dose-dependent expression of EGR-2 mRNA was observed after incubation with IGF-II. These changes correlated well with those seen at the protein level and with the expression of EGRs seen after treatment with 10 ng/mL IGF-II. Immunocytochemical analyses showed strong nuclear immunostaining for EGR-1 in cells treated with 1 ng of IGF-II and for EGR-2 in cells treated with 10 ng of IGF-II. These results suggest that the EGR genes are induced by IGF-II stimulation in human PLFs, and that they have a role in PLF growth during tissue regeneration and healing in vivo.
Generally, bacterial infection may occur in parallel with the phase in which pain is felt in the dental pulp and tissue around the root apex. We investigated the influence of neuropeptides on bacterial inflammation. In this study, we investigated the influence of substance P (SP) on the proinflammatory cytokine mRNA expression level in human dental pulp-derived cells (HDPC) stimulated with a bacterial inflammatory agent, LPS. HDPC collected from the first premolar extracted for orthodontic treatment were used. SP alone did not increase the TNF-α mRNA expression level, but SP induced a significant increase the TNF-α mRNA expression in cells stimulated with low-level LPS (1 μg/mL). However, a significant increase was not induced in cells stimulated with high-level LPS (10 μg/mL). The IL-8 mRNA expression level was increased by SP alone, and SP additionally induced a significant increase in cells stimulated with low-level LPS (1 μg/mL). It was suggested that neuropeptide may enhance early or mild bacterial inflammation.
The quartz crystal microbalance (QCM) method can detect the adsorption amounts of proteins on biomaterials by a frequency shift of the oscillating quartz crystal. In the present study, we observed the adsorption behavior of fibronectin onto a gold surface by using 27 MHz QCM.The QCM apparatus used was a 27-MHz AFFINIX QNμ (Initium Co., Ltd, Tokyo, Japan) with 500 μL cells. The temperature was maintained at 25 ± 1°C and the solution in the cells was stirred during the measurements. Human plasma fibronectin was dissolved in phosphate-buffered saline (PBS) solution (pH 7.4) at a concentration of 200 μg/mL and 500 μg/mL. Each protein solution was injected into the PBS solution in the cells of the QCM apparatus. The frequency decrease was monitored and the amounts of fibronectin adsorbed onto the gold surface at 30 min after the injection were calculated by Sauerbrey's equation.A slight frequency decrease was observed at the injection of fibronectin of 200 μg/mL, and greater degree of frequency decrease was monitored for fibronectin of 500 μg/mL. Significant differences in the adsorbed amounts were seen between 200 μg/mL and 500 μg/mL fibronectin. The adsorbed amounts of 500μg/mL fibronectin was almost twice of 200 μg/mL fibronectin.The QCM method was found to be a very powerful tool for monitoring the adsorption behavior of proteins on the material surface.
The purpose of this study was to examine osteogenic differentiation behaviors at gene expression levels of osteoblast-like cells (SaOS-2) when cultured on polystyrene (PS), hydoroxyapatite (HAP) and titanium (Ti) for 8, 16 and 24 days, using six primer sets such as those for genes (mRNAs) of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), alkaline phosphatase (ALPL), type 1 collagen (COL1A1), osteopontin (SPP1), bone Sialo protein (IBSP) and osteocalcin precursor (BGLAP). With respect to GAPDH control, ALPL and COL1A1; SPP1 and IBSP; and BGLAP were used as initial-stage, middle-to-late-stage, and last-stage osteogenic differentiation phenotype markers, respectively. Quantitative real-time RT-PCR analyses revealed that HAP most differentiated SaOS-2, followed by Ti while PS did least. It was re-confirmed that with respect to PS, HAP was an excellent osteo-conductive material while Ti also exerted moderate osteo-conductive effects on SaOS-2 in the cell culture condition.
To examine the cytotoxicities of 11 commercially available dental adhesive products, mouse Balb/c 3T3 cells or cells derived from mouse uterine tissue origin were three-dimensionally cultured on a type I collagen gel to conduct a cell recovery test. The products showed significantly different cytotoxicities in both cells. The results demonstrated that 4-META products tend to be more cytotoxic than those containing Bis-GMA as the main ingredient, although no significant difference was noted between the cells. However, the manufacturer had not published the amount of each composition. Therefore, we could not fully understand the relationship between the composition and cell viability. All the products allowed cell recovery without any problem.
Many Biomaterials are currently being developed, a method for testing embryotoxicity in vitro in a speedy. In 1997. Spielmann et al. developed the embryonic stem cell test (EST), which is an in vitro embryotoxicity test method that can be used to estimate the risk of embryotoxicity of chemical substances relatively quickly compared to the conventional methods that involve animal experiments. The EST has been evaluated in a formal validation study funded by the European Centre for the Validation of Alternative Methods: ECVAM in which two other in vitro embryotoxicity tests (micromass test, whole embryo culture test) were validated against a set of test chemicals characterized by high levels of in vivo embryotoxicity data in laboratory animals and humans. In a validation study in Europe, the EST was found to be reproducible, demonstrating an overall accuracy of 80% and 100% correct prediction of strong embryotoxicity for chemicals studied under blind conditions. However, use of EST is impossible for the Biomaterials, which is not dissolved in a culture medium. Therefore, some improvement of EST protocol is proposed.