Bjørndal L, Larsen T, Thylstrup A
Department of Cariology and Endodontics, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Denmark.
Caries Res. 1997;31(6):411-7. doi: 10.1159/000262431.
Concern about the survival of microorganisms in deep carious lesions may often lead to unnecessary exposure of the pulp during final excavation. There are reasons, therefore, to initiate systematic studies on the alternative procedure known as stepwise excavation. Clinical evaluation of stepwise excavation was performed on 31 deep carious lesions considered to result in pulp perforation by traditional excavation. This study examines the clinical and microbiological alterations during the final excavation performed during long intervals (6-12 months) after the initial treatment that included peripheral dentine excavation and removal of the central cariogenic biomass and the superficial necrotic dentine. The dentine colour and consistency were assessed by means of standardized scales before application of a Ca(OH)2 compound and a temporary sealing for 6-12 months. Reassessments were performed before the after final excavation. Microbiological dentine samples were obtained in 19 randomly selected lesions by a sterile bur, transferred to and diluted in reduced transport fluid, and plated on tryptic soy agar. After anaerobic incubation at 37 degrees C for 7 days, total colony-forming units per millilitre were counted from (1) peripheral excavated and hard dentine (control), (2) central demineralized dentine before and final excavation, and (3) central dentine after the final excavation. Six samples of central demineralized dentine were without any cultivable flora increasing to 9 samples after the final excavation. The clinical dentine changes occurring during stepwise excavation were characterized by enhanced hardness of the dentine which was associated with a marked reduction in bacterial growth after the final excavation. Despite the presence of bacteria in the excavated dentine none of the carious lesions resulted in pulp perforation, suggesting that the initial removal of the cariogenic biomass appears to be essential for control of caries progression. Stepwise excavation is not only an appropriate treatment of deep carious lesions but is also considered a suitable model for microbiological studies to determine the bacteria persisting in clinically excavated lesions.
对深龋病变中微生物存活情况的担忧常常会导致在最终去龋时不必要地暴露牙髓。因此，有理由开展对一种名为逐步去龋的替代方法的系统研究。对31例被认为采用传统去龋方法会导致牙髓穿孔的深龋病变进行了逐步去龋的临床评估。本研究考察了在初始治疗（包括外周牙本质去龋、去除中央致龋物质和表层坏死牙本质）后的较长间隔时间（6 - 12个月）进行最终去龋时的临床和微生物学变化。在应用氢氧化钙制剂并进行6 - 12个月的临时封闭之前，通过标准化量表评估牙本质的颜色和质地。在最终去龋前后进行重新评估。通过无菌钻在19个随机选择的病变中获取微生物学牙本质样本，转移至还原运输液中并稀释，然后接种于胰蛋白胨大豆琼脂平板上。在37℃厌氧培养7天后，对以下样本每毫升的总菌落形成单位进行计数：(1)外周去龋后的硬牙本质（对照），(2)最终去龋前后的中央脱矿牙本质，以及(3)最终去龋后的中央牙本质。中央脱矿牙本质的6个样本在最终去龋前没有任何可培养菌群，最终去龋后增加到9个样本。逐步去龋过程中发生的临床牙本质变化的特征是牙本质硬度增加，这与最终去龋后细菌生长显著减少相关。尽管在去龋后的牙本质中存在细菌，但没有一个龋损导致牙髓穿孔，这表明最初去除致龋物质似乎对控制龋病进展至关重要。逐步去龋不仅是深龋病变的一种合适治疗方法，而且还被认为是一种用于微生物学研究的合适模型，以确定在临床去龋病变中持续存在的细菌。
