模拟高原低氧环境对牙龈卟啉单胞菌的影响

Effect of simulated high-altitude hypoxia on Porphyromonas gingivalis

目的探讨模拟高原低氧环境对兔龈下菌斑中牙龈卟啉单胞菌(Pg)检出率及内毒素水平的影响。方法 40只雄性家兔随机分为平原对照组(A1组)、平原实验组(A2组)、高原对照组(B1组)及高原实验组(B2组),每组10只。A2、B2组采用联合正畸结扎丝结扎兔双下颌中切牙及牙周炎食谱饲养的方法建立牙周炎模型,B1、B2组送入低压氧舱内饲养(模拟海拔高度5000m,23h/d),A1、B1组在平原环境下常规饮食饲养。8周后观察X线片并在光镜下观察组织病理变化评估建模效果,采集兔双下颌中切牙牙周袋内龈下菌斑进行Pg的分离、培养、鉴定及内毒素水平检测。结果组织病理学观察及X线片结果均显示B2组牙周炎炎症程度较A2组严重。除A1组外,其余3组均成功检出Pg,检出率分别为A2组50%、B1组55%、B2组95%(P<0.05)。与A2组比较,B2组中的Pg检出率及内毒素水平差异有统计学意义(A2、B2组内毒素水平分别为0.38±0.02,0.46±0.04 EU/ml,P<0.05)。结论高原低压低氧的特殊环境加快了牙周炎的进展速度,加重了炎症的破坏程度,且低压低氧的特殊环境更利于内毒素水平较高的Pg在龈下菌斑中的定植。

Objective To investigate the effects of simulated high-altitude hypoxia on the detection rate and endotoxin level of Porphyromonas gingivalis（Pg） of subgingival bacterial plagues in rabbit periodontitis models.Methods Forty male rabbits were randomly divided into four groups,namely,normoxia control group（group A1）,normoxia experimental group（group A2）,hypoxia control group（group B1）,and hypoxia experimental group（group B2）.Each group included 10 rabbits.Periodontitis models was established in groups A2 and B2 combined by ligating both lower central incisors with steel ligature and feeding periodontitis diets,and then the animals were housed in a hypoxia chamber（simulating 5000m altitude,23h per day）.Groups A1 and A2 were raised normal diet in normoxia environment.After eight weeks,the rabbit periodontitis model was evaluated by observing radiographic features of the X-ray films and histopathologic changes under a light microscope.Subgingival plague sample from periodontal pockets on both lower central incisors were collected for isolation,culture and identification of Pg,and for detection of the endotoxin level.Results The histopathologic observation and X-ray examination results showed that the periodontitis of rabbits in group B2 was significantly more severe than that in group A2.The detection rates of Pg in group A1,A2,B1 and B2 was 0%,50%,55% and 95%（P0.05）.Pg detection rate and endotoxin level were higher in group B2（95%,0.46±0.04EU/ml） than in group A2（50%,0.38±0.02EU/ml,P0.05）.Conclusions The process speed and damage degree of periodontitis in hypoxic environment is higher than that in normoxic environment.Moreover,the hypoxic environment is more suitable in the colonization of Pg with higher endotoxin level in subgingival plague.