Oral Microbiology and Biomaterials Laboratory, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Milan, Italy.
Clinic of Prosthodontics and Dental Materials Science, University of Leipzig, Leipzig, Germany; Department of Prosthetic Dentistry, Regensburg University Medical Center, Regensburg, Germany.
J Dent. 2022 Dec;127:104333. doi: 10.1016/j.jdent.2022.104333. Epub 2022 Oct 17.
The current study aimed to compare the efficacy of two in vitro microbiological models based on open and closed systems designed to obtain secondary caries in an accelerated and reproducible way.
A conventional resin-based composite (RBC - Majesty ES-2; Kuraray, Japan) and a resin-modified glass-ionomer cement (RMGIC - Ionolux; VOCO, Germany) were used to restore standardized class II cavities (n = 4/tooth, cervical margin in dentin) in 16 human molars. The ability to produce secondary caries with Streptococcus mutans biofilms was tested using either an open-cycle or closed-cycle bioreactor (n = 8 specimens/model). Specimens were scanned before and after the biofilm exposure using micro-CT (Skyscan 1176, 9 µm resolution, 80 kV, 300 mA). Image reconstruction was performed, and demineralization depths (µm) were evaluated at the restoration margins and a distance of 1.0 mm.
Dentin demineralization could be observed in all specimens, and enamel demineralization in 50% of the specimens. The open system bioreactor produced lesions with significantly higher overall demineralization depths (p < .001). However, demineralization depths at a 1.0 mm distance from the restoration margins showed no difference between open and closed systems or materials. In the open system, significantly lower demineralization depths were observed in proximity to RMGIC than RBC (p < .001), which was not significantly different in the closed system (p = .382).
Both systems produced in vitro secondary caries in an accelerated way. However, the open-cycle bioreactor system confirmed the caries-protective activity exerted by the RMGIC material in contrast to the RBC, better simulating materials' clinical behavior.
The possibility of obtaining accelerated and reproducible secondary caries development in vitro is fundamental in testing the behavior of conventional and yet-to-come restorative dental materials. Such systems can provide faster outcomes regarding the performance of dental restorative materials compared to clinical studies, notwithstanding the importance of the latter.
本研究旨在比较两种基于开放式和封闭式系统的体外微生物模型在加速和可重复获得继发龋方面的效果。
使用传统的树脂基复合材料（RBC - Majesty ES-2；Kuraray，日本）和树脂改性玻璃离子水门汀（RMGIC - Ionolux；VOCO，德国）修复 16 个人类磨牙的标准 II 类腔（n = 4/牙，牙颈部位于牙本质）。使用开放式或封闭式生物反应器（n = 8 个标本/模型）测试具有变形链球菌生物膜的继发性龋齿形成能力。使用微计算机断层扫描（Skyscan 1176，9 µm 分辨率，80 kV，300 mA）在生物膜暴露前后对标本进行扫描。进行图像重建，并评估修复边缘和 1.0 mm 距离处的脱矿深度（µm）。
所有标本均可见牙本质脱矿，50%的标本可见釉质脱矿。开放式生物反应器产生的病变具有显著更高的整体脱矿深度（p <.001）。然而，在距离修复边缘 1.0mm处的脱矿深度在开放式和封闭式系统或材料之间没有差异。在开放式系统中，RMGIC 比 RBC 更接近时，观察到的脱矿深度显著降低（p <.001），而在封闭式系统中则无显著差异（p =.382）。
两种系统均以加速方式产生体外继发龋。然而，开放式生物反应器系统证实了 RMGIC 材料的抗龋活性，与 RBC 相比，更好地模拟了材料的临床行为。
在体外测试传统和未来的修复牙科材料的行为时，获得加速和可重复的继发龋发展的可能性是至关重要的。与临床研究相比，此类系统可以更快地提供有关牙科修复材料性能的结果，尽管后者也很重要。
