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BACKGROUND: In our preliminary experiments, calcium phosphate cement, magnesium phosphate cement, calcium silicate and bismuth were mixed to manufacture a novel inorganic composite material, which would be used to repair furcal perforation. This novel composite cement has been confirmed to have excellent physiochemical and mechanical properties. OBJECTIVE: To study the biocompatibility of calcium phosphate-magnesium phosphate-calcium silicate-bismuth cement (CMSBC). METHODS: Cytotoxicity test: Relative growth rate of L929 cells cultured in CMSBC extract was analyzed using cell counting kit-8 assay. Acute hemolysis test: The leaching solution of test samples, saline and distilled water were added into the rabbit anti-clotting, to detect the rate of hemolysis.Acute systemic toxicity test:CMSBC lead liquor and normal saline were respectively injected via the tail vein into the mice in experimental group and control group, respectively. The general situation of mice was observed at 24, 48, 72 hours respectively and body weight change was valued. Ames test: In the flat-plate incorporation test of Salmonella typhimurium, the average number of spontaneous revertants of TA97, TA98, TA100 and TA102 of CMSBC leaching liquor was calculated after incubation at 37 ℃ for 72 hours. S-9 mixture was added to the plates as an in vitro activation system. RESULTS AND CONCLUSION:The cytotoxicity of CMSBC in vitro was grade 0.Negative results from the acute hemolytic test,acute systemic toxicity test and Ames test of CMSBC indicate that this novel inorganic composite material has good biocompatibility and biosecurity.
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BACKGROUND: To date, there is no report on the successful construction of a three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post.OBJECTIVE: To establish the three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post. METHODS: Micro-CT was used to obtain imaging information of the human maxillary first premolar sample. Then Mimics, Geomagic and Hypermesh were used to establish a clear-structured three-dimensional finite element model of pulp-exposed maxillary premolar with wedge-shaped defect restored by fiber post. RESULTS AND CONCLUSION: The three-dimensional finite element model of normal maxillary premolar had 180 119 units and 33 289 nodes. Compared with the real subject, the three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post had vivid appearance, good image quality and accurate grid partitioning with 237 496 units and 43 965 nodes in total, which could obtain good results in the aspects of geometry, boundary constraint and mechanical compatibility. Moreover, it could better simulate the mechanical stress distribution of diseased teeth under occlusion to further confirm the magnitude and distribution of forces, thereby providing a better basis for future biomechanical studies.
RESUMEN
<p><b>OBJECTIVE</b>To investigate the marginal adaptation of crowns fabricated by selective laser melting (SLM) and wax-lost-casting method, so as to provide an experimental basis for clinic.</p><p><b>METHODS</b>Co-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group. All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine. The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope (SEM). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically.</p><p><b>RESULTS</b>The gap between SLM crowns were (36.51 ± 2.94), (49.36 ± 3.31), (56.48 ± 3.35), (42.20 ± 3.60) µm, and wax-lost-casting crowns were (68.86 ± 5.41), (58.86 ± 6.10), (70.62 ± 5.79), (69.90 ± 6.00) µm. There were significant difference between two groups (P < 0.05).</p><p><b>CONCLUSIONS</b>Co-Cr alloy full crown fabricated by wax-lost-casting method and SLM method provide acceptable marginal adaptation in clinic, and the marginal adaptation of SLM is better than that of wax-lost-casting method.</p>