| BackgroundPeriodontitis is one of the major two categories of oral diseases, with high prevalence in the world. In china, the prevalence of periodontitis increases in recent years[1]. Periodontitis can cause gingival inflammation, periodontal pocket formation, bone absorption and teeth loosening, eventually leading to tooth loss. It is the most common factor of tooth loss. The hypoxia, coldness, low air pressure at high altitude, especially hypoxia, can increase red blood cell count, cause the changes of being "thick, sticky, gathering, condensated" in hemorrheology, easily induce microcirculation disturbance, causing hypoxia in local tissue and decline of defense capabilities. As reported in the literature, the statistic data of WHO from 35 countries, show that the prevalence of periodontitis is over 50%, while in the high altitude environment prevalence of periodontitis is significantly higher than that in plain population (70.4%); the prevalence of immigrations increases with prolongation of migration time, indicating high altitude is an important factor causing periodontitis. The residents are distributed at different altitudes in China, and the high altitude is more likely to cause periodontal diseases, influencing the physical and mental health of people at high altitude and decreasing their life quality. At present, there are few studies on periodontal disease at high altitude at home and abroad, only some small-scale, small-sample epidemiological investigations are available. The further in-depth researches are needed on periodontal tissue ultrastructure, periodontal microcirculation, teeth surrounding microecosystem, cell activity changes of periodontitis at high altitude.Objective and significance:Periodontal disease is one of the common diseases among human beings, and the main reason leading to tooth loss. It occurs at all age groups, closely related with the systemic health of the whole body. Therefore, the researches on the pathogenesis of periodontal disease, prevention and treatment are the main focuses of oral medicine. The incidence of periodontitis is high at high altitude. This study established periodontitis model of SD rats in plateau by imitating plateau condition in laboratory, detecting gingival index (GI), plaque index (PLI), probing depth (PD), the value of alveolar bone loss (ABL) and histopathological changes, as the evaluation criteria to evaluate the modeling. After the successful modeling, in GCF of SD rats, the levels of C-reactive protein (CRP), soluble intercellular adhesion molecule -1 (sICAM-1) and gingival tissues intercellular adhesion molecule -1 (ICAM-1), lymphocyte function associated antigen -1 (LFA-1) changes were analyzed, so as to investigate the mechanism of periodontal disease of the plateau, explore the changes of immune adhesion system under hypoxia and its impact on periodontitis, providing the references for the improvement of prevention and treatment program of periodontal disease.Materials and methods:1. Established rats'model of periodontitis and model assessment .Totally 80 health SD rats, weighing (200±10) g, male and female in half, were randomly divided into 4 groups: normoxic control group (A group, n=20) (average altitude in Chongqing is 400 m), normoxia periodontitis group (B group, n=20), simulated high altitude control group (C group, n=20) (altitude 5000 m) and simulated high altitude periodontitis group (D group, n=20). Ligation of dental cervix by wire, feeding the high-glucose diet, oral inoculating bacteria and intramuscular injection of hormone were performed to establish the normoxic and simulated high altitude periodontitis models of rats. Eight weeks later, then GI, PLI, PD, ABL and histopathological changes were detected in 4 groups of rats to judge whether the models were successfully established.2. Eight weeks after reproduction of periodontitis model of rats, the GCF samples of rats were taken to determine CRP and sICAM-1 concentrations by ELISA methods in 4 groups of rats to further determine whether CRP and sICAM-1 in GCF is correlated with periodontitis in high altitude.3. Eight weeks after reproduction of periodontitis model of rats, the periodontal tissue samples of rats were taken to determine the expression levels of ICAM-1/LFA-1 in gingival tissues of rats by immunohistochemical PowerVision? techniques, in order to explore whether ICAM-1/LFA -1 mediated immune adhesion are involved in occurrence and regulation of periodontitis at high altitude.Results: 1. X-ray observations: In A group and C group, alveolar ridge height of rats was nomal. In B group and D group, alveolar ridge height of ligatured teeth was decreased, indicating the mixed absorption. Histopathological changes: in A group, gingival integrity, combined with the normal epithelial attachment, periodontal ligament fibers arranged regularly, no alveolar bone absorption, no significant histopathological changes; in B group, sulcular epithelial erosion, proliferation into connective tissue, a large number of inflammatory cells infiltration, periodontal ligament fibers arranged in disorder, periodontal ligament space widened, mild alveolar bone resorption, absorption introcession on the surface; in C group, complete dental junctional epithelium, a small amount of inflammatory cell infiltration; in D group, between the ulcers and necrosis of gingival papilla epithelium of operated teeth, epithelial processes hyperplasia, showing inflammatory cell infiltration, and the emergence of deep periodontal pocket, junctional epithelium proliferation and migration to the dental root, periodontal ligament space widened, periodontal ligament fibers arranged irregularly or rupture, alveolar ridge with mixed absorption, osteoclasts located in absorption lacuna, alveolar bone resorption near the dental root, remarkable vascular congestion in dental pulp, trabecular bone rarefaction and bone deposition.GI, PD and ABL index were statistically different between B group and A group, between D group and C group, between C group and A group, between D group and B group (P <0.05). PLI index was statistically significant between the B group and A group, between D group and C group (P <0.05), with no statistical difference between C group and A group, between D group and B group (P >0.05).2. Eight weeks later, CRP and sICAM-1 concentrations in GCF were determined by ELISA assay in 4 groups of rats. CRP concentrations were (6.33±1.58)μg/mL in A group, (13.47±1.98)μg/mL in B group, (7.76±1.84)μg/mL in C group, (16.26±2.14)μg/mL in D group, respectively. There were statistically significant difference between B group and A group, D group and C group, C group and A group, D group and B group (P <0.05), of which the most significant increase was noted in D group. sICAM-1 levels in GCF were (21.98±2.93) ng/mL in A group, (32.20±3.80) ng/mL in B group, (23.44±3.81) ng/mL in C group, (36.64±2.64) ng/mL in D group. There were statistically significant difference between B group and A group, D group and C group, C group and A group, D group and B group (P <0.05), of which the most significant increase was noted in D group. 3. Eight weeks later, rats'ICAM-1/LFA-1 expression in gingival tissue was detected by immunohistochemical PowerVision? techniques. The OD value of ICAM-1 in gingival tissues were statistically different (P <0.05) between B group and A group, D group and C group, C group and A group, D group and B group. The OD value of LFA-1 were statistically significantly different between B group and A group, D group and C group, C group and A group, D group and B group (P <0.05).Conclusion:1. The procedure of dental cervix ligation by wire, feeding high-glucose diet, oral inoculating bacteria and intramuscular hormone injection can successfully establish normoxic rat model of periodontitis. Transfer the rats with integrated approaches to low-pressure chamber of simulated altitude of 5000 m, the rat model of periodontitis at simulated high altitude can be obtained 8 weeks later.2. CRP and sICAM-1 levels in GCF of plateau hypoxic periodontitis rat were higher than those in normoxia periodontitis group, it suggests the periodontitis lesion is more severe at high altitude environment.3. The expression level of ICAM-1/LFA-1 in gingival tissues of periodontitis rats at simulated high altitude is higher than that in normoxia periodontitis group,it suggests that hypoxic environment can influence the immune adhesion ability to a certain extent, resulting in periodontitis. |
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