Three-dimensional finite element analysis of different reactive force direction of maxillary protraction on temporomandibular joint / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the influence of different reactive force direction of protractions on temporomandibular joint (TMJ) by establishing a three-dimensional finite element model (FEM) of craniomaxillofacial complex.</p><p><b>METHODS</b>The CT image of the head of a healthy young male volunteer was obtained.With the help of Mimics software, we established a three-dimensional finite element model of craniomaxillofacial complex which included TMJ. The force pattern of maxillary protraction appliance was imitated. The force (5 N) was applied on the chin and the direction of force was from 22° to 49° relative to the occlusal plane. The displacement and stress distribution of TMJ were analyzed.</p><p><b>RESULTS</b>The contact stress on the maxilla decreased with the angle of the force direction increased from 22° to 40°, and increased with the angle increased from 40° to 49°. The stress on the condyle decreased with the angle of the force direction increased. The stress on the condylar neck decreased initially and then increased with the angle of the force direction increased. Comprehensively, the stress was the smallest when the angle of the force direction was 40°. The clockwise rotation of the mandible was found when the angle of the force direction was smaller than 40°. The displacement value was relatively small when the angle was 40°.</p><p><b>CONCLUSIONS</b>Stress and displacement were relatively small when the angle of the force direction was 40° relative to the occlusal plane.</p>

Immune regulation effect of rat dendritic cells phagocytosing photochemotherapy-treated allogeneic cells on syngeneic T cells / 中国实验血液学杂志

The aim of this study was to investigate the immune regulatory effect of dendritic cells phagocytosing photochemotherapy-treated allogeneic spleen lymphocytes on syngeneic T cells. DA rat spleen lymphocytes were treated with 8-methoxypsoralen plus UVA irradiation (PUVA). LEW rat bone marrow-derived DCs were co-cultured with PUVA-treated DA spleen lymphocytes (PUVA-SP), and the surface markers (MHC-II, CD86 and CD40) of treated DC were detected by flow cytometry. CFSE-labeled PUVA SP were incubated with LEW DCs and the phagocytosis of DCs on PUVA-SP was observed by using fluorescent microscope. The ability of DC phagocytosing allogeneic PUVA-SP (PUVA-SP DC) to stimulate the proliferation of LEW T cells was analyzed by mixed leukocyte reactions (MLR). The production of IL-4, IL-10, IL-2, IFN-gamma in MLR culture supernatant was determined by luminex method. The results indicated that the PUVA treatment effectively induced early apoptosis of DA rat spleen lymphocytes. After co-culture, DC efficiently phagocytosed allogeneic PUVA-SP and still maintained an immature phenotype with low levels of MHC II, CD40 and CD86. PUVA-SP DC induced LEW T cell hyporesponsiveness to DA rat antigen, and led to skewing of T cell cytokine expression toward Th2 (IL-10 and IL-4). It is concluded that the PUVA-SP DC effectively down-regulate T cell response to alloantigen and induce Th2 immune deviation in vitro.