[Expression of HIF-1α and VEGF in human dental pulp cells under mechanical stretch].

PURPOSE: To examine the expression of HIF-1α and VEGF after application of mechanical stretch on human dental pulp cells (HDPCs), and to investigate the role of them in maintaining homeostasis of dental pulp during orthodontic movement. METHODS: HDPCs were subjected to 15% elongation by 1.0 Hz stretching frequency for 6, 12, 24, 48 and 72 h. The expression of HIF-1α and VEGF mRNA was measured by real-time polymerase chain reaction (PCR). SPSS12.0 software package was applied for statistical analysis. RESULTS: At the initial time point, HIF-1α mRNA had a weak expression. The mRNA level of HIF-1α increased gradually and then decreased towards its pre-pressure levels. The mRNA level of VEGF was upregulated in a time-dependent manner. CONCLUSIONS: The mRNA expression of HIF-1α and VEGF was enhanced by mechanical stress in HDPCs, which indicates that HIF-1α and VEGF may play an important role in retaining homeostasis of dental pulp during orthodontic movement.

[Comparison of the treatment effects of two molar distal movement appliances: pendulum appliance and face-bow].

PURPOSE: To compare the treatment effects of pendulum appliance and traditional face-bow for distal movement of maxillary first molars. METHODS: Samples (n=30) were randomly divided into two groups, of which Group P was treated with pendulum appliance, while Group F with traditional face-bow. Cephalometric radiographs were taken and analyzed by Pancherz at the pre-treatment time (T1) and the post-treatment time (T2). Student's t test was used to determine if there were significant differences between the 2 time periods and two groups. RESULTS: There was significant difference between Group P and Group F in the treatment duration (20.6+/-4.0 weeks vs 26.0+/-3.6 weeks). There was also significant difference in the changes of (ms/olp- ss/olp) (3.1+/-0.53 mm vs 2.2+/-0.82 mm), (is/olp- ss/olp) (0.8+/-0.78 mm vs-1.0+/-0.88 mm) between the two groups. CONCLUSION: The results indicate that pendulum appliance is clinically more effective and rapid for distal movement of the maxillary first molars, but more attention should be paid to the anchorage control of maxillary anterior teeth.