Experimental Study Of The Pulsed Nd: YAG Laser In The Chronic Periodontitis Therapy

BackgroundPeriodontitis is one of the common diseases of mankind, and the pathogenic factors of this chronic disease are always complicated. Periodontitis can cause gingival inflammation, periodontal pocket formation and alveolar bone resorption, as a result the affected teeth become mobility and eventually fall off. According to WHO investigations, the overall morbidity of periodontal disease is 75%. In some parts of China, this rate can be as high as 93%. It has been proved that bacterium and its products are the causes of parodontopathy in bacteria plaque, and subgingival plaque is closely related to the destruction of periodontal tissues. Control of specific bacteria relating to the occurring and developing of parodontopathy is the key approach to effective treatment. Fortunately, the pulsed Nd:YAG laser was introduced in 1960. Studies have revealed that the laser had the abilitities of solidify and vaporize both the endepidermis and the inflammatory infiltration soft tissue. Because of the laser can be specificity merging by hemoglobin, fibroglia fibrils fibrinous degeneration , collogen chain shrinkage at the same time seal off the micrangium so by this way it can reduce bleed or not bleed . The laser profit a lot to the patients who suffer from periodontopathy due the good quality of it's electromagnetic field and biostimulation effect there is only lightly reaction after the gingivoectomy or gingival flap operation.The wound of entry of the laser operation is tiny most of the patients can accept . But these studies were more in vitro experiments in which irradiation parameters and experimental condition varied greatly and provided little information for in vivo application. Few investigation at present has been found on the safety and feasibility in clinical treatment.ObjectiveThis study is to obtain an effective energy by comparing the generation effect of 5 different laser energy levels radiation on HPDLFs by cells experiment, and thus to provide theoretical support for the chronic periodontitis therapy by the pulsed Nd:YAG laser. Establish experimental periodontitis animal model similar to periodontitis of mankind in SD rats to approach the 5 energy levels of the pulsed Nd:YAG laser was used to establish the relationship between energy parameters irradiation in periodontal pocket, their safety to periodontal tissue, then the proper parameters may obtain and apply for chronic periodontitis therapy to evaluate the feasibility, reliability and superiority in the healing of periodontitisMaterials and methods1. Cultivation, verification the HPDLFs and the effect of the laser radiation on HPDLFs .Taking use of immunohistochemistry ABC method to human periodontal ligament fibroblast to colour the undee silk protein and cell keratin monoclone antibody coloration and identify the origin of cells .Choosing the five generation well growth ligament fibroblast and then confect hang cell solution at 3×104/L concentration. Cultivation the cells 24h by putting into DMEM which contained 15﹪fetal calf serum .Then radiation on HPDLFs on the energy levels of .OW 20pps,1.5W 20pps,2.0W 20pps,2.5W 20pps and 3.0W 20pps , normal control conventional culture. Taking use of empirical method MTT to test the OD value of each group to evaluate effects of the laser on multiplication of cells . Taking use of 96 holes with the cells have been radiation on by laser ,putting 100ul 0.2% TritonX-100 into each hole. Putting over 20ul solution from each hole into 200ul dying fluid, keeping on surging 10 minutes, testing the OD value at 570 wavelength .Chosing a culture board with 96 holes cultivated for 24 hours under standard condition, and radiation by the laser and putting 1μCi3H-TdR into each holes . Testing glittering count in one minute by glitter counting apparatus to evaluate effects of laser on HPDLFs DNA synthesis .2. Dental cervix ligation was used with the healthy SD rats (half male and half female, 180~220g each) to perform modeling. 8 weeks later, 8 modeling rats and 8normal rats were randomly selected to test the periodontal specifications to conform whether the modeling was successful. Then 48 rats of successful modeling and 8 normal rats were divided into 7 groups to receive experimental treatment of oral prophylaxis and radiation by laser with the energy level of1.0W 20pps,1.5W 20pps,2.0W 20pps,2.5W 20pps,3.0W 20pps. 24 hours later they were sacrificed to test the PD,PLI,GI and SOD,MDA,NO in periodontal to verify the treatment effects of the pulsed Nd:YAG laser.3. 32 Sprague - Dawley rates were randomly assigned to the control group, periodontitis control group, periodontitis with pules Nd:YAG laser iatreusis group and drug treatment group . Radiation on the periodontal pocket of rats of group L by 2.0W 20pps laser energy , Intragastric administration the rats by 200mg/kg arilin to group D.GCF samples were collected with strips of filter paper 24 hours after the last treatment. The activity of GSH - Px and the ALP were measured by automatic biochemistry analyzer. 15 days later they were sacrificed to test the histopathological change of the 4 groups of rats, and to verify the treatment effects of the pules Nd:YAG laser.Results1. The primary cell is long fusiform shape, and it's cytoplam is uniform, with nucleus round or ellipse, chromatospherite clear. Immunohistochemistry coloretur indicated that the undee silk protein is masculine, keratin negative.By analysis of variance of single factor, it's showed that the pules Nd:YAG laser energy level between 1.0 W 20pps-2.0 W 20pps can promote HPDLFs generation,and 1.5 W 20pps most effective. The protein level of N group and 1.0 W 20pps-2.5 W 20pps group was significantly higher than the 3.0 W 20pps group(P < 0. 01),the 2.0 W 20pps group is maxlmum. The DNA's synthesis of 1.0W 20pps-2.5W 20pps groups was significantly higher than the control group but 3.0W 20pps group was significantly lower than N group (P < 0. 01).2. Level of SOD in 1.5W 20pps-2.0W 20pps 20pps groups w as signif icantly higher than the Pgroup (P < 0.05) ; L evel of MDA in 1.5W,2.0W,2.5W 20pps groups were significantly lower than the 0W group (P < 0. 05).Level of NO in each energy level group was signif icantly lower than the P group (P < 0.05) . The NO content of the periodontitis with pules Nd:YAG laser iatreusis group and the drug group is (0.53±0.02)they were significantly higher than the control group, was significantly lower than the periodontitis control group ( P < 0. 05). By radiation on the rats periodontal pocket the PD,PLI,GI can be improved with the proper energy level of pules Nd:YAG laser.3. The GSH-Px activityof the periodontitis with pules Nd:YAG laser iatreusis group is(40.71±6.35)was significantly higher than the periodontitis control group ( P < 0. 05),had no statistic difference to the control group and drug treatment group ( P > 0. 05). The ALP activityof the periodontitis with pules Nd:YAG laser iatreusis group is(16.75±1.47)was significantly higher than the control group, was significantly lower than the periodontitis control group ( P < 0. 05), had no statistic difference to the drug treatment group ( P > 0. 05).The clinical exponents were statistic difference to the three groups( P < 0. 01).In microscopical study, the group of laser was similar to the positive drug group of. In comparison with the periodontitis group, the cellular infiltration of soft tissues in the group of laser was greatly alleviated, periodontal pockets became much shallower, and alveolar resorption ceased.Conclusions1. 1.0W 20pps-2.0W 20pps laser radiation on the HPDLFs can promote the cells generation ,increase protein content.The pules Nd:YAG laser can be effective to treat periodontitis.2. 1.5W 20pps-2.0W 20pps of pulsed Nd :YAG laser irradiation on periodontal pocket of rats is effective to treat chronic periodontitis therapeutic efficacy. Based on the above results, a preliminary parameters both safety and efficacy of the laser could be 2.0 W 20pps with initiator.3. Contrast experiment of two different way treat chronic periodontitis: with laser and with drug the result approved 2.0 W 20 pps laser irradiation periodontitis can be controlled and healing well.