Triantafyllos Papadopoulos

Purpose. The purpose of this in vitro study was to determine the metal-ceramic bond strength between dental porcelain and cobalt-chromium (Co-Cr) metal substrates fabricated by different techniques. Materials and Methods. Forty Co-Cr metal substrates were fabricated according to ISO 9693-1, by casting, milling, soft milling, and DMLS. Forty additional substrates were fabricated for each technique to record the modulus of elasticity. A commercially available feldspathic porcelain was placed on the substrates, and then the specimens were also tested for metal-ceramic bond strength with the 3-point bend test, according to ISO 9693-1. The fractured specimens were observed with optical and scanning electron microscopy using electron dispersive spectroscopy to define the mode of failure. X-ray diffraction spectroscopy was conducted to determine changes in crystalline phases after fabrication and the 3-point bend test. Statistical analysis was with 1-way analysis of variance and the Tukey post hoc test (α=.05). Results. No statistically significant differences were found for modulus of elasticity among any of the groups. The metal-ceramic bond strength for casting had no statistically significant differences and the mode of failure in all groups was cohesive. The metallographic analysis of the as-received, the after porcelain firing, and the after 3-point bend test specimens revealed changes in microstructure. The crystallographic microstructure revealed that the patterns had minor changes among the groups. Conclusion. The study revealed that all of the techniques showed similar results. The modulus of elasticity and metal-ceramic bond strengths presented no statistically significant differences, and the mode of failure was cohesive.

Introduction. The purpose of this study is to evaluate the biocompatibility and cytotoxicity of Total Fill (FKG Dentaire SA, Switzerland) and compare it with white MTA and Biodentine. Materials and methods. The biocompatibility of Total Fill (FKG Dentaire SA, Switzerland) was tested in comparison with ΜΤΑ (Tulsa Dental, Tulsa, OK) and Biodentine (Septodont, Saint Maur des Fosses, France) bioceramic materials. Cytotoxicity was investigated in terms of cell proliferation throughout the MTT assay, cell viability using FDA/PI test on MG63 pre-osteoblasts cell line for 24h, 48h and 72h. SEM micrographs have been used to describe the morphology of the cells seeded on the different ceramics. The alkaline phosphatase activity (ALP) was measured using the QUANTI-Blue method for experimental and control groups. As control the cells were seeded at the Tissue Culture Plastic (TCP). All the experiments were performed in triplicate in 3 independed runs and statistically analysed using 2-way ANOVA. Results. MTT assay results showed a major rate of proliferation, after 72h of seeding of the MG63 cells on the Total Fill sealing material than MTA and Biodentin. These results were in accordance with those obtained by the FDA/PI double staining and the SEM micrographs. Conclusions. All tested sealing materials performed an optimal biocompatibility, although Total Fill prevailed due to the characteristics of its solid state. In particular Total Fill presented an improved consistency which allowed the cells to populate the entire mass of the material, maintaining their viability.