ABSTRACT
Objective:To investigate the relationship between radiation mode and radiation-induced taste cell injury in mouse models.Methods:The head and neck of adult C57/bl mice were exposed to 8 Gy irradiation for 1, 2 and 3 times and sacrificed at 2, 4, 7 and 14 d after irradiation. Frozen sections of taste papilla tissues were treated with specific markers by immunohistochemical staining. The changes of proliferative cells and the number of type Ⅱtaste cells at different time points under different radiation modes were observed. The effect of different radiation dose patterns upon the taste cells was assessed.Results:The count of proliferative cells was decreased significantly on the 2 nd day after radiation, and rapidly recovered to normal level on the 4 th day after radiation, which was not correlated with the dose mode. The number of type Ⅱ taste cells was decreased on the 2 nd day of the first 8 Gy radiation, decreased to the lowest on the 4 th day of the second and third 8 Gy radiation, and rose slowly on the 7 th day. Conclusions:Radiation can initially decrease and subsequently increase the number of proliferative cells to normal range. Besides, it can gradually repair the type Ⅱ taste cell injury. After high-dose irradiation, the decrease of progenitor cells with proliferative function leads to a synchronous decrease in the number of taste function cells, which may be the reason why taste dysfunction cannot be recovered for a long time after radiotherapy.
ABSTRACT
Objective To analyze the stress state of magnetic attachment in mandibular complete overdenture supported by nature roots and implant, and to provide neference for designing of clinical prosthodentics. Methods Three-dimensional finite models (model,Ⅱ,Ⅲ)of three groups of mandibular overdentures depending on the different location of the implant and natural tooth root, placing three pairs of magnetic attachment, were constructed by application of CT scanning,computer photo processing system,and Solidworks finite element model building software.The natural teeth and implant neck bone stress of the models in three groups under different stress were calculated and compared.Results The stress of the bone around the implant in the area of molar teeth in model with both sides of the implants under oblique load (Model Ⅱ)was significantly increased compared with the model with one side of the implant (Model Ⅲ). The supporting bone stress of oblique load was increased compared with the vertical load;among them under the oblique load at one side’ s molar teeth, the stress of the bone around the implant in the area of molar teeth in modelⅠ,modelⅡ and model Ⅲ was increased about 30%, 43%,and 55%.Conclusion When there only one nature teeth remain,two implants should be at least added, one in the area of opposite cuspid, and the other in the area of molar teeth of the same side. The magnetic attachment is better than other kinds of attachment in preventing the damage of abutment when it suffers inclined load.