[A retrospective study on incisor root resorption in patients treated with bracketless invisible appliance and straight wire appliance].

PURPOSE: To assess root resorptions in patients treated with bracketless invisible appliance and straight wire appliance using cone-beam CT (CBCT). METHODS: Twenty-eight patients treated with bracketless invisible appliance (as experimental group) or straight wire appliance (as control group) were randomly selected. CBCT images were analyzed at 3 time points (pre-operation, 6 month after operation, post-operation). Root resorption was calculated using root length at 3 time points. The difference between the 2 groups was analyzed with SPSS16.0 software package. To those teeth with no root length reduction, the bone defect was evaluated using CBCT. RESULTS: After 6-month of treatment, 47.3% teeth from the experimental group had root resorption, while 68.3% in the control group. There was significant difference between the 2 groups (P<0.05). Root absorption of maxillary central incisors from the 2 groups was more severe than other teeth (55% in the experimental group, and 75% in the control group). After orthodontic treatment, the incidence of root resorption in the control groups increased to be 85.3% and 68.3% in the experimental group (P<0.05). To those teeth with no root resorption, bone defect was more common in the palatal side (18% in the experimental group, 14% in the control group). CONCLUSIONS: Compared with straight wire appliance, patients using bracketless invisible appliance suffer from less root resorption.

[Coculture of stem cells from the apical papilla and human umbilical vein endothelial cells enhances the angiogenic potential of dental pulp tissues].

PURPOSE: To observe the effect of coculture of stem cells from the apical papilla (SCAPs) and human umbilical vein endothelial cells (HUVECs) on the angiogenic potential of dental pulp tissues. METHODS: SCAPs were incubated in osteo/odontogenic, adipogenic, neurogenic induction medium and α-MEM medium, whose multilineage differentiation capacities were confirmed using alizarin red staining, oil red O staining and ßIII-tubulin immunofluorescent staining. The tubular length, branching points number and junctional areas were detected after 3, 6, 9 h since cells were seeded onto matrigel, and the data was analyzed using SPSS 16.0 software package. RESULTS: SCAPs in the experimental groups were detected having more lipid droplets, mineralization nodules and neuron-like cells. Coculture of SCAPs and HUVECs formed more vessel-like structures in tubular formation assay. CONCLUSIONS: SCAPs are capable of differentiating into fat, bone, and nerve-like cells in vitro. Coculture of SCAPs and HUVECs can enhance the angiogenic potential of dental pulp tissues.