Bacteriological Study for Prevention of Recurrent Caries

预防复发性龋的细菌学研究本研究旨在通过使用杀菌材料对抗人类龋坏牙本质中的细菌来开发预防复发性龋的最有效的临床方法。Hoshino阐明，从牙本质病变的浅层和深层分离的大多数微生物是专性厌氧菌，这表明针对厌氧菌的抗菌治疗可能有效预防并发症。甲硝唑（metronidazole，MN）对专性厌氧菌具有广谱的杀菌作用，本研究对人龋坏牙本质中细菌的杀菌效果进行了如下研究：1.在含MN（10 μ g/ml）和不含MN的BHI-血琼脂平板上测量从患者获得的人龋坏牙本质中的细菌回收<mu>，并且MN的添加引起超过99%的细菌回收减少.当用含有5%MN的-磷酸三钙-TCP粘固剂覆盖病变1-3天时，新鲜拔除的人牙的龋坏牙本质中的绝大多数细菌没有恢复<alpha><alpha>，而当用不含MN的-TCP粘固剂覆盖病变时，获得超过10^3个细菌（CFU）<alpha>。用<alpha>含MN的-TCP粘固剂原位覆盖牙本质病变1天、28天和/或1年和/或2年，在体内均未回收到细菌。MN在原位的杀菌功效被清楚地证明，表明MN的局部应用在龋齿治疗中是有效的，以消毒偶然残留在玷污层中的细菌和在萌出后的儿童恒磨牙的急性牙本质龋的深层中的细菌，或故意残留在玷污层中的细菌，以避免牙髓暴露，或从牙齿表面新侵入。

Bacteriological Study for Prevention of Recurrent Caries This study was projected to develop the most effective clinical method for preventing recurrent caries by using bactericidal material against bacteria in human carious dentin. It was clarified by Hoshino that the majority of microorganisms isolated from both shallow and deep layers of dentinal lesions are obligate anaerobes, which suggests that autimicrobial treatment directed specifically against anaerobes may be effective in preventing complications. And, it has been well known that metronidazole(MN) has a wide spectrum of bactericidal action against obligate anaerobes.Bactericidal efficacy of MN against bacteria in human carious dentin was clarified as follows:1. Bacterial recovery from human carious dentin obtained from patients was measured on BHI-Blood agar plates containing MN(10<mu>g/ml) and on those lacking MN, and the addition of MN caused more than 99% reduction of bacterial recovery.2. Overwhelming majority of bacteria in carious dentin of freshly extracted human teeth was not recovered when the lesions were covered with <alpha>-Tricalcium Phosphate <alpha>-TCP) cement containing 5% MN for 1-3 days, whereas more than 10^3 bacteria(CFU) were obtained when the lesions were covered with <alpha>-TCP cement containing no MN.3. No any bacteria were recovered from the samples of dentinal lesions which hab been covered by <alpha>-TCP cement containing MN in situ for 1 day, 28 days and/or 1 year ana/or 2 years in vivo. The bactericidal efficacy of MN in situ is clearly demonstrated, suggesting that topical application of MN is effective in caries treatment to deisinfect bacteria which remained accidentally in the smear layer and under restorations or intentionally in the deep layers of acute dentin caries of the child's permanent molar just after eruption to avoid pulp exposure, or invade newly from the tooth surfaces.