Department of Pediatric Dentistry, Dental School, University of Marburg and University Medical Center Giessen and Marburg, Campus Giessen, Schlangenzahl 14, D-35392 Giessen, Germany.
Department of Operative Dentistry and Endodontics, Dental School, University of Marburg and University Medical Center Giessen and Marburg, Campus Marburg, Georg-Voigt-Str. 3, D-35039 Marburg, Germany.
Dent Mater. 2018 May;34(5):786-796. doi: 10.1016/j.dental.2018.02.002. Epub 2018 Mar 12.
The present study aimed to establish Lactobacillus casei in a completely automated Streptococcus mutans-based artificial mouth model and to investigate secondary caries inhibiting properties of glass ionomer cements / resin composite groups in vitro.
Sixty extracted, caries-free human third molars were used for preparation of standardized class-V-cavities. Specimens were restored with a resin-modified (Photac Fil; PF) as well as a conventional glass ionomer cement (Ketac Molar; KM) and one resin composite bonded with and without conduction of etch-and-rinse technique (Prime&Bond NT, Ceram X mono; C+ERT, C). Following an incubation in distilled water for 28d at 37°C, specimens were exposed to 10,000 thermocycles (+5 °C/+55°C). A completely automated S. mutans-based (DSM No.: 20523) artificial mouth model was extended by establishment of L. casei (DSM No.: 20021). During microbiological loading, demineralization (4h/d) was caused by acid production resulting from bacterial glycolysis and artificial saliva was used for remineralization (20h/d). For quantitative margin analysis under am SEM, epoxy replicas were produced from impressions taken after thermocycling and after microbiological loading. Specimens were cut in half perpendicularly to restoration surfaces and demineralization depths at restoration margins and in 500μm distance from margins were evaluated by means of a fluorescence microscope (FITC filter).
After microbiological loading, overall demineralization depths in enamel at restoration margin (EM) and in 500μm distance (ED) as well as in cementum/dentin at restoration margin (DM) and in 500μm distance (DD) were measured as follows (μm±SD): PF: EM 42±15, ED 60±17, DM 83±18; DD 127±16; KM: EM 46±22, ED 62±17, DM 104±21, DD 143±28; C+ERT: EM 67±19, ED 61±17, DM 165±31, DD 176±35; C: EM 65±23, ED 64±17, DM 161±27, DD 166±33. For the glass ionomer cements, the overall demineralization depths at restoration margins were significantly lower than in 500μm distance from margins (T-test, p<0.05). Especially at restoration margins in cementum/dentin, the resin composite groups showed significantly larger overall demineralizations than the glass ionomer cements (ANOVA, mod. LSD, p<0.05). Decreases of marginal quality were detected in all groups after microbiological loading (Friedman-test, p<0.05).
The refined experimental setup was suitable for production of artificial secondary caries-like lesions. Glass ionomer cements as fluoride-releasing materials may show an inhibition of secondary caries formation to a certain extent.
本研究旨在建立完全自动化的变形链球菌人工口腔模型中的干酪乳杆菌，并研究玻璃离子水门汀/树脂复合材料组在体外对继发龋的抑制特性。
60 颗无龋坏的人第三磨牙用于制备标准化的 V 类腔。用树脂改性（Photac Fil；PF）和传统的玻璃离子水门汀（Ketac Molar；KM）以及一种用和不用蚀刻冲洗技术（Prime&Bond NT， Ceram X mono；C+ERT，C）结合的树脂复合材料进行修复。在 37°C 的蒸馏水中孵育 28 天后，将样本暴露于 10000 次热循环（+5°C/+55°C）。通过建立干酪乳杆菌（DSM 编号：20021）来扩展完全自动化的基于变形链球菌的（DSM 编号：20523）人工口腔模型。在微生物学负荷期间，通过细菌糖酵解产生的酸导致脱矿（4h/d），并用人工唾液进行再矿化（20h/d）。为了在 SEM 下进行定量边缘分析，在热循环和微生物学负荷后从印模中制作环氧树脂复制品。样本垂直于修复表面的一半进行切割，并在修复边缘处和边缘 500μm 处评估牙釉质（EM 和 ED）、牙骨质/牙本质（DM 和 DD）的脱矿深度，使用荧光显微镜（FITC 滤光片）进行评估。
在微生物学负荷后，在修复边缘的牙釉质（EM）和 500μm 处（ED）以及牙骨质/牙本质的修复边缘（DM）和 500μm 处（DD）的整体脱矿深度如下（μm±SD）：PF：EM 42±15，ED 60±17，DM 83±18；DD 127±16；KM：EM 46±22，ED 62±17，DM 104±21，DD 143±28；C+ERT：EM 67±19，ED 61±17，DM 165±31，DD 176±35；C：EM 65±23，ED 64±17，DM 161±27，DD 166±33。对于玻璃离子水门汀，修复边缘处的整体脱矿深度明显低于距边缘 500μm 处（T 检验，p<0.05）。尤其是在牙骨质/牙本质的修复边缘处，树脂复合材料组的整体脱矿程度明显大于玻璃离子水门汀（ANOVA，mod. LSD，p<0.05）。在微生物学负荷后，所有组均检测到边缘质量下降（Friedman 检验，p<0.05）。
改进的实验设置适合产生人工继发龋样病变。玻璃离子水门汀作为氟释放材料，可能在一定程度上抑制继发龋的形成。
