Bjørndal L, Larsen T
Department of Cariology, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark.
Caries Res. 2000 Nov-Dec;34(6):502-8. doi: 10.1159/000016631.
This study examined the cultivable microflora before and after stepwise excavation procedures in deep carious lesions in 9 permanent teeth, categorized according to degrees of proximal surface destruction. The final excavation was performed 4-6 months after the initial treatment, which included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. Dentine colour and consistency were assessed by means of standardized scales before the application of a Ca(OH)(2) compound and temporary sealing. Reassessments were performed before and after the final excavation. Microbiological samples of the central demineralized dentine were obtained with a sterile bur before and after the first excavation, as well as before and after the final excavation. After anaerobic cultivation on enriched non-selective tryptic soy agar, 30 colonies from a representative area were identified by standardized biochemical and physiological tests. Before temporary restoration, a yellowish and light brown demineralized soft dentine was typically observed, and gram-positive rods accounted for 70% and lactobacilli for 50% of the total colony-forming units. Lactobacillus casei subsp. rhamnosus and Actinomyces naeslundii dominated the lactobacilli and the other gram-positive rods, respectively. Gram-negative rods were the next most frequent isolates, followed by streptococci, each group accounting for about 20% of the colony-forming units in positive samples. Before the final excavation, which did not cause exposure of the pulp in any of the cases, the retained demineralized dentine had changed into a darker and harder tissue, and the total colony-forming units, as well as the frequency and proportions of lactobacilli were substantially reduced. Gram-negative rods also declined, and the flora was dominated by A. naeslundii and various streptococci. In conclusion, the cultivable flora detected following the treatment interval had declined substantially, and the distribution of bacterial species did not represent a typical cariogenic microbiota of deep lesions, confirming the clinical findings of arrested caries progression.
本研究检查了9颗恒牙深龋病变在逐步挖除过程前后的可培养微生物群落，这些恒牙根据邻面破坏程度进行分类。最终挖除在初始治疗后4 - 6个月进行，初始治疗包括外周牙本质挖除以及去除中央致龋生物质和表层坏死牙本质。在应用氢氧化钙复合物和临时封闭之前，通过标准化量表评估牙本质颜色和质地。在最终挖除前后进行重新评估。在首次挖除前后以及最终挖除前后，用无菌钻获取中央脱矿牙本质的微生物样本。在富集的非选择性胰蛋白胨大豆琼脂上进行厌氧培养后，通过标准化的生化和生理试验鉴定来自代表性区域的30个菌落。在临时修复前，通常观察到淡黄色和浅棕色的脱矿软牙本质，革兰氏阳性杆菌占总菌落形成单位的70%，乳酸杆菌占50%。干酪乳杆菌鼠李糖亚种和内氏放线菌分别在乳酸杆菌和其他革兰氏阳性杆菌中占主导地位。革兰氏阴性杆菌是其次最常见的分离菌，其次是链球菌，每组在阳性样本中约占菌落形成单位的20%。在最终挖除前（在任何病例中均未导致牙髓暴露），残留的脱矿牙本质已变成颜色更深、质地更硬的组织，总菌落形成单位以及乳酸杆菌的频率和比例大幅降低。革兰氏阴性杆菌也减少，菌群以内氏放线菌和各种链球菌为主。总之，治疗间隔后检测到的可培养菌群大幅减少，细菌种类分布不代表深部病变典型的致龋微生物群，证实了龋齿进展停止的临床发现。
