| Arch expansion techniques have to be used when a patient has a narrow arch, but we don't know much about how and why different patients have different effects when their arches were expanded, so as to how the mechanical force is transducted to effecting cells. We designed this research in order to have a better understanding on arch expansion and the cytoskeleton-integrin pathway of mechanical force signal transduction.In order to study the effects of age on arch expansion and the cytoskeleton-integrin pathway of mechanical force signal transduction,we established an arch expansion model of palate in different age of rats(6wk,pre-adolenscence group; 12wk, adolescence group; 36wk,adult group) ,the arch wides were measured, the histological changes of midpalatal suture and periodontal tissues including new bone formation, cell reproduction,apoptosis,cytoskeleton staining and integrin é”(1) expression were studied using HE,IHC,TUNEL techniques. We found that the dental arches of younger rats(6wk,preadolenscence group; 12wk, adolescence group) were expanded and related tissues reestablished quickly, there are different responses of cytoskeleton arrangement and integrin é”(1) expression in the midpalatal suture and different sides of anchorage teeth. Cytoskeleton filaments arranged parallel to4the force direction in tensile side, while it was destroyed in some extent in pressure side of the rats' periodontium after arch expansion. Integrin é”(1) was heavier stained in expanded palatal suture and both sides of periodontium. We assume that the midpalatal suture of younger rats were more plastic and reproductive to expansion than older ones, and different forces can cause different effects on cytoskeleton arrangement and integrin é”(1) expression that may be related to mechanical force signal transduction.In the interest of effects of different forces(tension, pressure and shear forces) on palatal expansion associated cells such as rMSCs, chondrocytes and HPDLC, as well to the cytoskeleton-integrin pathway of mechanical force signal transduction in vitro, cyclic strain force(6cycle/min), fluid shear stress(30r/min) and compressive pressure force (50,100,200kPa)were applied on the third passage of these cells respectively. Cell reproduction rate and ALP activity,cytoskeleton,integrin P i were studied using MTT, Coomassie BB and IHC staining. As a result, these cells(rMSCs, chondrocyte and HPDLC)were disturbed in different ways,cytoskeleton rearranged,integrin é”(1) more expressioned by three different forces. Contrary to fluid shear force and pressure force, circled tension force can stimulate rMSCs and HPDLCs' reproduction and its ALP activity. We concluded that different forces can cause different effects on cell reproduction, bone remodeling,cytoskeleton arrangement and integrin é”(1) expression of these cells. This may due to their adapt ability to different forces, as HPDLC,osteoblasts and chondrocytes used to live in a pressure environment such as in periodontium. Forces might affect cell proliferation, differentiation and function through the cytoskeleton-integrin pathway of stress signal transduction.
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