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BACKGROUND: Autogenous dentin particles are increasingly used in various bone augmentation surgeries. Moderate demineralization may expose collagen and growth factors on the dentin surface and promote bone regeneration, but the degree of demineralization has not been clearly reported. OBJECTIVE: To evaluate the efficacy of autogenous dentin particles demineralized with different degrees as bone graft materials on promoting bone regeneration in alveolar bone site preservation. METHODS: Six beagles were selected and the second, third and fourth premolars of bilateral mandible were extracted. After grinding, crushing, sifting, pickling, disinfection and cleaning, dentin particles with a diameter of 0.5-1.0 mm were prepared. According to the time of pickling in 2% nitric acid, the samples received undemineralized (0 minute), demineralized for 1 minute (mild), demineralized for 10 minutes (moderate) and demineralized for 40 minutes (severe). The prepared dentin particles were filled into the tooth socket respectively, and the extraction socket without implanted dentin particles was a blank control. At 6 months after surgery, the bone graft area was observed by gross inspection, radiographic examination, and histological observation. RESULTS AND CONCLUSION: (1) Gross observation: The crests of alveolar ridge in the dentin particle groups were full and discontinuous crest with depressions was found in blank control group. (2) Cone beam CT showed that continuous alveolar ridge was formed in the dentin particle groups, discontinuous alveolar ridge and low density in the center of alveolar bone in the blank control group, and uneven density in alveolar socket in the undemineralized and mild demineralized groups with scattered high density image. Uniform and higher density was displayed in alveolar sockets of the moderate demineralized group and the alveolar sockets in the severe demineralized group were empty with low density images. (3) Histological observation: A large amount of dentin particles and insect phagocytic defects in the particles of the undemineralized group were found to be surrounded by scattered new bone tissue. In the mild demineralized group, a small amount of particles remained and were surrounded by new bone. In the moderate demineralized group, there were some residual dentin particles and bone cells arranged in regular order. In the severe demineralized group, there was no residual dentin granule and bone cells were mature and arranged regularly. In the blank control group, the trabeculae in alveolar socket were arranged disorderly and bone marrow cavity was filled with abundant fibrous connective tissue. (4) It is concluded that autogenous dentin particles with different degrees of demineralization possess the potential to guide new bone formation in alveolar bone preservation. The dentin particles that are demineralized for 10 minutes demonstrated the best effects on promoting bone regeneration. [ABSTRACT FROM AUTHOR]

BACKGROUND: MicroRNA is involved in intervertebral disc degeneration, and Yaotu Granule can significantly delay the progress of intervertebral disc degeneration. OBJECTIVE: To investigate the effect of Yaotu Granule in the proliferation and apoptosis of nucleus pulposus cells by regulating the expression of microRNA-221 (miR-221). METHODS: MiR-221 mimics and inhibitors were transfected into rat nucleus pulposus cells to establish miR-221 overexpression and inhibition models. Tumor necrosis factor-α was used to induce nucleus pulposus cell degeneration model. The degenerated nucleus pulposus cells were treated with 100 and 200 mg/L Yaotu Granule freeze-dried powder (low and high dose groups). In the miR-221 mimics + Yaotu Granule group, miR-221 mimic and 200 mg/L Yaotu Granule freeze-dried powder were added. Cell counting kit-8 and TUNEL assay were used to detect the cell proliferation and apoptosis, RT-qPCR was used to detect mRNA expression of miR-221, and western blot was used to detect the expression of Bax and Bcl-2. RESULTS AND CONCLUSION: MiR-221 mimics reduced cell prolifecation at 24, 48, 72 hours (P < 0.05) and promoted cell apoptosis at 48 hours (P < 0.05); miR-221 inhibitors had the opposite results (P < 0.05). Compared with the normal group, tumor necrosis factor-α inhibited cell proliferation, increased cell apoptosis, and upregulated miR-221 expression (all P < 0.05). Compared with the model group, low- and high-dose Yaotu Granules increased cell proliferation, reduced cell apoptosis, and downregulated miR-221 expression (all P < 0.05). Compared with the mimics group, cell proliferation improved, apoptosis rate decreased, the protein expression of Bax reduced, and the Bcl-2 protein expression up-regulated in the miR-221 mimics + Yaotu Granule group (all P < 0.05). To conclude, miR-221 has an effect on the proliferation and apoptosis of nucleus pulposus cells, and Yaotu Granule can delay the progression of intervertebral disc degeneration by downregulating the expression of miR-221. [ABSTRACT FROM AUTHOR]