Bacteriological Study for Prevention of Recurrent Caries

预防龋齿复发的细菌学研究本研究的目的是通过对龋齿牙本质中的细菌使用杀菌物质来预防龋齿复发的最有效的临床方法。Hoshino澄清说，从牙本质病变的浅层和深层分离的大多数微生物都是专性厌氧菌，这表明专门针对厌氧菌的自体微生物治疗可能有效预防并发症。众所周知，甲硝唑（MN）对专性厌氧菌具有广谱的杀菌作用。MN对人龋齿牙本质细菌的杀菌作用如下：在含MN（10<mu>g/ml）的BHI-Blood琼脂板和不含MN的琼脂板上测定患者龋齿牙本质的细菌回收率，MN的加入使细菌回收率降低99%以上。用含5% MN的< α >-磷酸三钙< α >-TCP)骨水泥覆盖1 ~ 3天后，人新拔牙牙本质龋齿内绝大多数细菌未恢复，而用不含MN的< α >-TCP骨水泥覆盖1 ~ 3天后，细菌数量超过10^3。用含锰< α >-TCP水泥原位覆盖1天、28天和/或1年和/或2年的牙本质病变样本中未检出任何细菌。原位锰的杀菌效果得到了明确的证明，这表明局部应用锰对龋齿治疗有效，可以对儿童恒磨牙刚出牙后急性牙本质龋齿中偶然残留在涂片层和修复体中，或故意残留在深层的细菌进行消毒，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.