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BACKGROUND: Studies have found that myeloid differentiation factor 88 is expressed in rat dental follicles and affects the eruption of teeth and the number of osteoclasts. OBJECTIVE: To further verify the expression of myeloid differentiation factor 88 in an experimental rat model of periapical periodontitis. METHODS: Twenty-five male Sprague-Dawley rats, 6 weeks of age, were provided by the SPF Animal Experimental Center of Dalian Medical University in China. The pulp of the first mandibular molar was exposed to establish the rat model of experimental periapical periodontitis in each rat. Endodontic pulp exposure 0 week was set as control group, while endodontic pulp exposure 1, 2, 3, 4 weeks as experimental group. Five rats were randomly selected at each time point after exposure of the endodontic pulp. Then, paraformaldehyde fixation of the mandible, decalcification, and pathological frozen sections were mode. Hematoxylin-eosin staining and immunohistochemical staining were used to observe the pathological changes of the periapical tissues. RT-PCR was used to detect the expression of myeloid differentiation factor 88 in the rat model of experimental periapical periodontitis. RESULTS AND CONCLUSION: (1) Hematoxylin-eosin staining results showed inflammatory infiltration in the apical area of the experimental group, and spread around, indicating that we successfully established the rat model of experimental periapical periodontitis. (2) Immunohistochemical staining results showed the positive expression of myeloid differentiation factor 88 in the periapical inflammation area at 1, 2, 3, 4 weeks after modeling. The positive expression of myeloid differentiation factor 88 significantly increased within 1-3 weeks, peaked at 3 weeks, but decreased at 4 weeks. There were only a small number of myeloid differentiation factor 88 positive cells in the control group. (3) RT-PCR results showed that the mRNA expression of myeloid differentiation factor 88 increased gradually from 1 week to 3 weeks, and then decreased at 4 weeks. To conclude, myeloid differentiation factor 88 is expressed in the animal model of experimental periapical periodontitis and shows a tendency of expression over time. Myeloid differentiation factor 88 may be involved in the occurrence of periapical periodontitis and the resorption of alveolar bone in periapical periodontitis. [ABSTRACT FROM AUTHOR]

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BACKGROUND: As a bioactive substance, Biodentine has good compressive strength, bonding strength and less micro-leakage. It has been successfully applied to a variety of clinical indications. However, much less is known about whether Biodentine can promote osteogenesis. OBJECTIVE: To explore the effects of Biodentine of different concentrations on proliferation and osteogenesis of MG-63 cells. METHODS: The extracts of Biodentine with different concentration gradients (1, 1/2, 1/4, 1/8, 1/16) were prepared. MG-63 cells were cultured in six groups, with the addition of minimum essential medium (control group) and five concentrations of Biodentine extracts. Cell proliferation was detected by cell counting kit-8 assay at 1, 3, 5 and 7 days, and then the best concentration of Biodentine extract was screened. Another MG-63 cells were cultured in minimum essential medium (blank control group) and Biodentine extract of the optimal concentration (experimental group). The expression of osteogenic factor Runx2 mRNA in MG-63 cells was detected by real-time PCR at 1, 3, 5 and 7 days of culture. Then alizarin red staining was used to observe calcified nodules in MG-63 cells at 10 and 14 days of culture. RESULTS AND CONCLUSION: (1) At 1 and 3 days of culture, the number of viable cells in different concentration groups was similar to that in the control group (P > 0.05). At 5 days of culture, compared with the control group, the number of viable cells in MG-63 cells was significantly lowered in the 1 concentration group, showed no significant changes in the 1/2, 1/4, 1/8 concentration groups (P > 0.05), and was significantly increased in the 1/16 concentration group (P < 0.05). Therefore, the 1/16 concentration of Biodentine extract was used for further experiment. (2) Runx2 mRNA expression of the experimental group at 1, 3, 5 and 7 days of culture was 1.14, 5.29, 1.08 and 2.11 times that of the control group, respectively (all P < 0.05). (3) At 10 days of culture, both the experimental group and blank control group showed no mineralized nodules; at 14 days of culture, mineralized nodules were observed in the two groups, and larger and darker nodules were seen in the experiment group. To conclude, Biodentine at certain concentrations can promote the proliferation and osteogenic activity of human osteosarcoma cell line MG-63. [ABSTRACT FROM AUTHOR]