Bacteriological Study for Prevention of Recurrent Caries

预防龋病复发的细菌学研究这项研究旨在开发一种最有效的预防龋病复发的临床方法，即使用杀菌材料来杀灭人类龋齿牙本质中的细菌。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，这表明针对厌氧菌的自菌治疗可能在预防并发症方面有效。同时，甲硝唑(MN)对专性厌氧菌具有广泛的杀菌作用，其杀菌效果如下：1.在含MN(10 mg/ml)和不含MN(10 mg/ml)的BHI-血液琼脂平板上测定MN对人龋牙本质细菌回收率，加入MN可使细菌回收率降低99%以上。用含5%MN的α-磷酸三钙粘固剂覆盖1-3天后，新鲜拔除的人牙本质中的绝大多数细菌仍未恢复，而当覆盖不含MN的-lt；α-磷酸三钙粘固剂时，有超过10^3个细菌(CFU)。含MN的~lt；α&Gt；-TCP粘固剂在体内原位覆盖1天、28天和/或1年和/或2年的牙本质病变标本中未发现任何细菌。MN的原位杀菌效果明显，提示MN在龋病治疗中是有效的，能有效地杀灭萌出后意外残留在涂抹层和修复体下或故意残留在儿童恒磨牙急性牙本质龋深层的细菌，以避免牙髓暴露，或从牙面新侵入。

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.