[Changes in the expression of Dlx5, Msx2, and Dlx5/Msx2 in hPDLSCs loaded with cyclic tensile stress].

OBJECTIVE: To investigate the changes in the expression of Dlx5 and Msx2 in human periodontal ligament stem cells (hPDLSCs) loaded with cyclic tensile stress. METHODS: hPDLSCs were subjected to cyclic tensile stress (0.5 Hz, 3000 microm strain) for 3, 6, 12, 24 h through a four-point bending strain system. The expressions of Dlx5 and Msx2 mRNA were determined by real time PCR. RESULTS: Strong expressions of Dlx5 and Msx2 were found in the periodontal fibroblasts of the tension side 20 minutes after mechanical loading. The expression of Dlx5 mRNA decreased over time with the stress. The expression of Msx2 mRNA increased over time with the stress. CONCLUSION: Both Dlx5 and Msx2 are sensitive to mechanical stress. Cyclic tensile stress may induce differentiating of hPDLSCs towards mineralized tissue cells by promoting Dlx5 mRNA expression and decreasing Msx2 expression.

[Differences in maxillary growth vector of skeletal class I with various vertical growth types before and after growth spurts].

OBJECTIVE: To identify the differences in maxillary growth vector with different vertical skeletal patterns of skeletal class I before and after growth spurts. METHODS: One hundred and ninety four cases with different vertical skeletal patterns of skeletal class I were selected and categorized into six groups according to their vertical skeletal patterns and cervical vertebral stages: cervical vertebral maturation stage (CVMS)1,2-horizontal pattern (n=30); CVMS1,2-average pattern (n=32); CVMS1, 2-vertical pattern (n=33); CVMS5, 6-horizontal pattern (n=34); CVMS5, 6-average pattern (n=29); and CVMS5, 6-vertical pattern (n=36). Lateral cephalograms were taken on all of the cases. The angle SN-C axis (theta) and angel PP-C axis (alpha) were measured. RESULTS: (1) The skeletal class I with a vertical growth pattern had larger angle SN-C axis than those with a horizontal or average growth pattern before growth spurts (P(average-vertical) < 0.05, P(horizontal-vertical) < 0.001). (2) The skeletal class I with a vertical growth pattern had the largest angle SN-C axis after growth spurts, followed by those with an average growth pattern. Those with a horizontal growth pattern had the smallest angle SN-C axis. The differences were statistically significant (P(horizontal-average) < 0.05, P(horizontal-vertical) < 0.001, P(average-vertical) < 0.001). (3) The skeletal class I with the same vertical growth pattern had slightly larger angle SN-C axis after growth spurts than before growth spurts, but without statistical significance. (4) The skeletal class I had relatively stable angle PP-C axis and no significant differences were found before and after growth spurts or among those with various vertical skeletal facial types. CONCLUSION: The magnitude of angle SN-C axis is closely associated with vertical growth patterns and is weakly influenced by maxillofacial growth and development.

The role of vascular endothelial growth factor in ossification.

Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodelling and repair.Vascular endothelial growth factor (VEGF) is an essential mediator during the process of angiogenesis. Based on an extensive literature search, which was carried out using the PubMed database and the keywords of osteogenesis, VEGF, endochondral ossification and intramembranous ossification, this manuscript reviews the role of VEGF in ossification, with emphasis on its effect in endochondral and intramembranous ossification. Osteogenesis and angiogenesis are closely correlated processes. VEGF acts as an essential mediator during these processes. It not only functions in bone angiogenesis but also in various aspects of bone development.