Objectives

This study aimed to develop a method to induce carious lesions in the pulpal floor dentin of a class II cavity preparation, and to determine the effects of this carious lesion on the biomechanical behavior of the dental composite restoration.

Methods

The pulpal floor dentin of class I cavities in sound third molars were demineralised with acetic acid for 35 days followed by a 7-day exposure to pooled human saliva biofilm and demineralization was verified by micro-CT. Subsequently, the proximal walls were removed forming a class II cavity and the caries lesion was left intact or was completely removed prior to restoration with a bulk-fill dental composite (n = 10). Cuspal deflection was assessed by strain-gauge and micro-CT imaging. The presence of enamel cracks was assessed by transillumination before and after restoration, and again after 1,200,000 cycles of mechanical fatigue in a chewing simulator. Finally, resistance to fracture by axial compressive loading and failure mode was determined. Data were analyzed by 2-way repeated measures ANOVA, Fisher’s exact test, and t-test (α = 0.05).

Results

The presence of carious lesions had no significant effect upon cuspal deflection, formation of enamel cracks, and fracture strength of the dental composite restorations. The restorative procedure increased the number of enamel cracks, which was not affected by mechanical cycling.

Significance

Maintaining carious lesions does not affect the biomechanical behavior of class II restorations performed with bulk-fill dental composite.

中文翻译：

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选择性龋组织的去除对II类散装牙科复合材料修复体生物力学行为的影响

目标

这项研究旨在开发一种方法来诱导II类腔制备物的牙髓基底牙本质中的龋齿病变，并确定这种龋齿病变对牙科复合材料修复体的生物力学行为的影响。

方法

用乙酸使在正常的第三磨牙中的I类腔的牙髓基底牙本质脱矿35天，然后将其暴露于合并的人类唾液生物膜中7天，并通过微型CT验证了脱矿质。随后，将近端壁移除，形成II类腔，并在用散装牙科复合材料（n = 10）进行修复之前，将龋病病变保留完整或完全移除。strain骨挠度通过应变计和微型CT成像进行评估。在修复之前和之后，以及在咀嚼模拟器中进行了1,200,000次机械疲劳循环之后，通过透照法评估搪瓷裂纹的存在。最后，确定了轴向压缩载荷和破坏模式对断裂的抵抗力。通过2次重复测量方差分析（ANOVA），Fisher精确检验和t检验（α  = 0.05）。

结果

龋损的存在对牙尖挠曲，牙釉质裂纹的形成以及牙科复合修复体的断裂强度没有显着影响。修复程序增加了搪瓷裂纹的数量，这不受机械循环的影响。

意义

维持龋病损害不会影响使用散装牙科复合材料进行的II类修复体的生物力学行为。