| Objective: The relationShip between the power density of the Nd:YAP laserand the thermal injury degree of the mucous membrane of nasopharynx isdiscussed, and the healing process of the mucousa after laser exposure isobserved at the Same time.Methods: In this research, New Zealand breed rabbits Were Selected. Theoutput power of the laser changed from 5W, 8W, 10W to 12W, and the exposurealso changed from 1S, 1.5S, 2S to 2.5S. The nasopharynx and cheek mucousa ofrabbits were uncontactly irradiated by Nd:YAP laser for 1S, 1.5S, 2S or 2.5S at5W, 8W, 10W, 12W of output power of the end of the opical fibre. Changes onthe Surface of he mucousa was observed by the endoscope immediately, and thewidth of the thermal injury was measured immediately after irradiated by laser.The extent of the thermal injury was examined through light microscope andelectron microscope. Then mucous membrane of nasopharynx was treated Withthe Same output power and irradiation time. Biopsy taken at 1, 3, 7 and 14 daysafter irradiation was examined and analyzed using histopathological methods.Results: White patch, introcession and charring were observed by nakedeyes. The thermal coagulation effets is mostly and ablation effect is subordinationon biological effect of Nd:YAP laser on mucous membrane of nasopharynx.When the output power was 5W and 8W, the depth of the tissue heat injurybetween nasopharynx and cheek mucosa was Significantly different(P<0.05).When the output power was 10W and 12W, the depth betWeen these two tissueswas not Significantly different(P>0.05). The Width and depth of thermal injurywere significantly related with the output power and irradiation time. On the day14 after laser exposure, though through the naked eyes, the wound healing wasobserved in the group 5W1S,5W1.5S,5W2S,5W2.5S,8W1S ,8W1.5S,10W1S,10W1.5S,12 W1S, through the light microscope, only group 5W1S,5W1.5S,5W2S,5W2.5S,8W1S,8W1.5 Were indeed healed completely. Thetissue healing process mainly include the filling of granulation tissue from thebottom of injury and the creeping of normal ambient epiderm to the center of theinjury. The influence of the output power , the irradiation time and the duration ofobservation to the Width of injury in the process of healing is Significantlydifferent(P<0.05). Conclusion: In our experimental dose, there was linearity between the depthand width of the tissue thermal injury and the laser output power and theirradiation time. The healing process after laser irradiation was significantlyrelated with the output power, the radiation time, probably had the relation withthe residual thermal damage. |
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