Objectives

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.

Methods

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 28 d 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 (4 h/d) was caused by acid production resulting from bacterial glycolysis and artificial saliva was used for remineralization (20 h/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 500 μm distance from margins were evaluated by means of a fluorescence microscope (FITC filter).

Results

After microbiological loading, overall demineralization depths in enamel at restoration margin (EM) and in 500 μm distance (ED) as well as in cementum/dentin at restoration margin (DM) and in 500 μm 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 500 μm 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).

Significance

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.

中文翻译：

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具有两种生物膜人工嘴的继发龋形成

目标

本研究的目的是在完全基于变形链球菌的人工口腔模型中建立干酪乳杆菌，并研究玻璃离子水泥/树脂复合基团在体外对龋齿的抑制作用。

方法

提取六十个无龋的人类第三磨牙用于制备标准的V类腔。用树脂改性的（Photac Fil; PF）以及常规的玻璃离聚物水泥（Ketac Molar; KM）和一种树脂复合材料（通过和不使用蚀刻和漂洗技术进行粘结）（Prime＆Bond NT，Ceram X）修复标本。单声道; C + ERT，C）。在37°C的蒸馏水中孵育28天后，将样品暴露于10,000个热循环（+5°C / + 55°C）。通过建立干酪乳杆菌扩展了基于变形链球菌的全自动口腔模型（DSM号：20523）（DSM号：20021）。在微生物负荷期间，脱盐（4 h / d）是由细菌糖酵解产生的酸产生的，人工唾液用于再矿化（20 h / d）。为了在am SEM下进行定量裕度分析，从热循环后和微生物装载后获得的印模中产生了环氧复制品。将样品垂直于修复体表面切成两半，并通过荧光显微镜（FITC过滤器）评估修复体边缘和距边缘500μm处的脱矿质深度。

结果

微生物负荷后，修复边缘（EM）和500μm距离（ED）的牙釉质以及修复边缘（DM）和500μm距离（DD）的牙骨质/牙本质的总脱矿质深度如下测量（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，修复边缘的总软化深度明显小于距边缘500μm的脱矿深度（T检验，p <0.05）。尤其是在牙骨质/牙本质的修复边缘，树脂复合材料组的整体脱矿物质量比玻璃离聚物胶粘剂大得多（ANOVA，mod LSD，p <0.05）。在微生物负荷后，所有组的边际质量均下降（弗里德曼检验，p <0.05）。

意义

完善的实验装置适用于生产人造继发性龋齿样病变。玻璃离聚物粘固剂作为氟化物释放材料可以在一定程度上抑制继发龋的形成。