MTAD清除根管隐蔽部位感染物效果的研究

### ###
（##大学口腔医学院 牙体牙髓科）

【摘要】 目的: 比较MTAD和次氯酸钠清除根管隐蔽部位感染的能力。材料及方法：（1）收集人离体前牙30颗，建立粪肠链球菌感染模型，分为三组，分别以生理盐水、MTAD和次氯酸钠冲洗，取样培养测定菌落形成单位评价冲洗液的即刻杀菌效果。然后在根管内加入BHI培养液孵育72h复苏细菌，取样测定细菌浓度评价冲洗液的持续杀菌效果；（2）收集正畸拔除的上颌第一前磨牙12颗，建立粪肠链球菌感染根管模型，分为生理盐水组、MTAD组、次氯酸钠组和次氯酸钠+EDTA组，共4组，以相应的冲洗液冲洗根管，扫描电镜观察对根管峡部感染细菌的清除效果。结果：（1）冲洗前三组根管内原始细菌数量相当（106～107 CFU/ml），根管冲洗后，生理盐水组细菌数下降为2.9×105CFU/ml，MTAD组降为3.3×104CFU/ml，次氯酸钠组根管内细菌下降至0，各组间的差异均有显著性， p＜0.01。72小时复苏后生理盐水组根管内细菌回复至106CFU/ml，次氯酸钠组根管内细菌有所回复（3.6×104CFU/ml），而MTAD组根管内的细菌数却持续下降（2.1×105CFU/ml），残余细菌仍高于次氯酸钠组，但差异没有显著性（p＞0.01）；（2）扫描电镜观察显示生理盐水没有杀菌作用，MTAD对散在分布的细菌有杀菌效果，对细菌膜作用有限，次氯酸钠可完全杀灭细菌，次氯酸钠加EDTA除了灭菌效果外还可去除玷污层。结论：MTAD可以渗入到根管峡部发挥作用，杀菌效果弱于次氯酸钠。
【关键词】MTAD，次氯酸钠，峡部
基金资助情况：####

Antibacterial efficacy of MTAD on Enterococcus faecalis biofilm colonization in the irregular areas of root canal system
###, ### (Department of Cariology and Operative Dentistry,### University School and Hospital of Stomatology,Beijing 100081,China)
[Abstract] OBJECTIVE: to compare the antibacterial activity of MTAD with 5.25%NaOCl on Enterococcus faecalis biofilm colonization in irregular areas in root canal system. MATERIALS AND METHODS: (1) Thirty extracted single-rooted human teeth were contaminated in vitro with E. faecalis and randomly divided into three groups：normal saline in group A serving as negative control, MTAD in group B, and 5.25% NaClO in group C. Microbial samples were taken and enumerated by CFU counts after biomechanical preparation to evaluate the prompt antibacterial efficacy of irrigant. Subsequently, E. faecalis was recovered by anaerobic incubated for 72h, and microbial samples were also taken to evaluate the persistent antibacterial efficacy. (2) Twelve extracted human maxillary first premolars were also contaminated in vitro with E. faecalis and randomly divided into four groups：normal saline in group A, MTAD in group B, 5.25% NaClO in group C, and 5.25% NaClO + EDTA in group D. When treated with respective irrigant, the roots were split longitudinally and a scanning electron microscope was used to evaluate the cleansing ability of MTAD in isthmus. RESULTS: (1) Before treatment, the CFU counts were similar (about 106～107 CFU/ml) in all three groups. After irrigation, the CFU counts dropped moderately (about 2.9×105CFU/ml) in group A, and it descended significantly in group B to the extent of 3.3×104CFU/ml. For group C, the bacteria was extinguished completely. When recovered, the CFU counts raised again to the primitive level (106CFU/ml) in group A, and ascended moderately in group C (3.6×104CFU/ml), but declined continually in group B (2.1×105CFU/ml) and have no statistically significance with that of group C. (2) The results indicated that MTAD have the limited antibacterial activity to biofilm colonized in isthmus, 5.25% NaClO + EDTA produced a cleaner isthmus surface and had an more effective antimicrobial ability comparable with that obtained with the other irrigants tested. CONCLUSION: MTAD may permeate into the irregular area in root canal system and play a role in disinfection, but the antibacterial activity is weaker than that of sodium hypochlorite.
[Key words] MTAD, NaClO, isthmus