The role of cell division cycle 42 in root development of tooth and the involved mechanisms / 中华口腔医学杂志

Objective: To explore the effect of cell division cycle 42 (CDC42) on root development and its regulation on cell proliferation and migration in Hertwig's epithelial root sheath (HERS). Methods: Trace the spatiotemporal expression of CDC42 in root development process [postnatal day 5 (P5), P7, P14] through immunofluorescence staining. Nine eight-week-old C57BL/6J male mice were randomly divided into 3 groups using a simple random sample method (n=3 in each group). P3 tooth germ was cultured in air-liquid system for 1 day and then transplanted to renal capsule each to observe tooth root development. The control group implanted tooth germ only. The phosphate buffered saline (PBS) group implanted tooth germ and gel beads soaked with PBS, while the ML141 group implanted tooth germ and gel beads soaked with CDC42 inhibitor (ML141). Cdc42 in HERS cells was inhibited via lentivirus transfection. Cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and scratch assay were performed. The distribution of Golgi apparatus (GM130) and cytoskeleton (F-actin) in migrated cells were mapped via immunofluorescence staining. Results: CDC42 was expressed in epithelial cells of HERS, polarized ameloblasts and odontoblasts, as well as adjacent dental papilla and dental follicle cells during tooth root development. The root length of the ML141 group [(0.61±0.09) mm] was substantially shorter than that of control group [(1.03±0.19) mm, P=0.007] and PBS group [(0.98±0.10) mm, P=0.021] according to the data of renal capsule transplantation. After lentiviral transfection, the relative expression of Cdc42 in knockdown group (0.31±0.33) was significantly lower than that in control group (1.05±0.08) (t=15.38, P<0.001), demonstrating the knockdown efficiency closed to 70%. Cell viabilities were significantly inhibited in knockdown group (0.87±0.04, 0.96±0.10, 0.59±0.06, respectively) compared with those in control group (1.09±0.13, 1.55±0.32, 1.10±0.09, respectively) after 3, 4 and 5 days (t=3.16, P=0.016; t=4.23, P=0.002; t=5.08, P<0.01), and the cell proliferation ability in knockdown group [(1.65±0.64)%] also decreased than that in the control group [(4.02±1.12)%](t=5.21, P<0.001). In addition, the cell migration rates after 24 and 48 h [(45.1±4.2)%, (56.4±8.3)%] in knockdown group were obviously lower than those in the control group [(63.8±7.4)%, (80.2±7.8)%] (t=3.78, P=0.019; t=3.62, P=0.023). After Cdc42 was knocked down, Golgi apparatus distributed along the nucleus while behaved oriented in the control group. Conclusions: CDC42 plays an important role in the regulation of root length during root development, which may mediate root elongation by affecting the migration and proliferation of HERS cells.

Evaluation of hyperbaric oxygen therapy for the osteoradionecrosis of the jaws: Meta-analysis / 华西口腔医学杂志

OBJECTIVES@#This study was performed to investigate the effects of hyperbaric oxygen and other approaches for treating the osteoradionecrosis of the jaws (ORNJ) systematically.@*METHODS@#According to the preset inclusion and exclusion criteria, randomized controlled trials and cohort studies on hyperbaric oxygen in the treatment of ORNJ were screened, and foreign language databases such as PubMed, EMBASE, and Cochrane library were searched via a computer; Chinese databases such as CNKI, VIP, Wanfang data, and CBM were searched from the established database to September 2020. Relevant books were searched manually to collect all literatures on the efficacy of hyperbaric oxygen and its related therapies in ORNJ treatment. Two researchers were independent and mutually blind, the papers were selected, data were collected, and the bias risk was evaluated. If any difference was detected, it would be decided by discussion or arbitrated by a third party. The data related to the efficacy of hyperbaric oxygen and its related therapy in the treatment of the ORNJ were extracted, and the Revman5.4 software was used for Meta-analysis. In case of large heterogeneity, sensitivity analysis was performed. A funnel chart was used to evaluate possible publication bias qualitatively.@*RESULTS@#Four randomized controlled trials and seven cohort studies were included in Meta-analyses. In ORNJ treatment, no significant differences between the group subjected to hyperbaric oxygen and both surgery and antibiotics and the group that underwent both surgery and antibiotics (RR=1.16, 95%CI: 0.86~1.58, @*CONCLUSIONS@#Hyperbaric oxygen therapy cannot replace surgery and antibiotic therapy. Hyperbaric oxygen therapy is not superior to antibiotics and antifibrotic drugs, but the benefits of antifibrotic drugs should be further explored.

Dentin matrix in tissue regeneration: a progress report / 华西口腔医学杂志

Lesions on tissues and organs critically affect quality of life, due to severe tissue defects that are threatening. Tissue repair and functional reconstruction are concurrent challenges in modern medicine. Tissue engineering brings hope for tissue and organ regeneration. Scaffolds provide a microenvironment for cell growth, proliferation and differentiation. Moreover, scaffolds influence the size and morphology of regenerated tissues. Dentin matrix, which is a natural bioactive and biocompatible scaffold, has become a research hotspot in recent years and has been widely used in tissue engineering. Studies on the use of dentin matrix as scaffolds have made a series of important progress in tooth root, periodontal, dental pulp and bone regeneration. This review demonstrates the biological characteristics of dentin matrix as bioactive scaffolds, describes the application of dentin matrix in tissue regeneration and provides a theoretical basis for the use of a dentin matrix in clinical applications.

Effects of different compressive stress on biological characteristics of condylar chondrocytes of neonatal SD rats / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of different static compressive stress on the biological characteristics of the mandibular condylar chondrocytes (MCC).</p><p><b>METHODS</b>The static compressive stress with a magnitude of 12, 24, 36 kPa were exerted on the third passage of MCC for one hour. The MCC was dyed by immunohisto-chemical method. The changes of the expression of collagen type I , II , III and proteoglycan (PG) were evaluated by a pathologic portraits analytic system.</p><p><b>RESULTS</b>The static compressive stress with a magnitude from 12 to 24 kPa can enforce the expression of collagen type I , II, III and PG of MCC. However, the decrease of expression of collagen type I and PG of MCC was detected when exerted by the static compressive stress with a magnitude from 24 kPa to 36 kPa.</p><p><b>CONCLUSION</b>The static stress of proper magnitude can make MCC more differentiate. However, the static stress of over-magnitude may make the biological characteristics of MCC weaken and express some characteristics of dedifferentiation.</p>