Graduate program in Dentistry, Federal University of Sergipe, Rua Claudio Batista s/n, Sanatorio, Aracaju, SE, 49060-100, Brazil.
Graduate program in Dentistry, Dental School, Federal University of Uberlândia,Av. Pará 1720, Bloco 4LA, Campus Umuarama, Uberlândia, MG, 38400-902, Brazil.
Dent Mater. 2018 Sep;34(9):1289-1298. doi: 10.1016/j.dental.2018.05.014. Epub 2018 May 21.
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.
The pulpal floor dentin of class I cavities in sound third molars were demineralised with acetic acid for 35days 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).
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.
Maintaining carious lesions does not affect the biomechanical behavior of class II restorations performed with bulk-fill dental composite.
本研究旨在开发一种在 II 类洞预备中诱导牙髓底牙本质龋损的方法，并确定该龋损对牙本质复合树脂修复体生物力学行为的影响。
用乙酸对第三磨牙完整牙釉质下的近髓牙本质进行脱矿处理 35 天，随后在人唾液生物膜中暴露 7 天，并通过微 CT 验证脱矿情况。随后，去除近中壁，形成 II 类洞，在使用大块充填牙科复合材料进行修复之前，将龋损保留完整或完全去除（n=10）。通过应变片和微 CT 成像评估牙尖位移。在修复前后以及在咀嚼模拟器中经过 120 万次机械疲劳循环后，通过透照评估釉质裂纹的存在情况。最后，通过轴向压缩加载确定抗断裂能力和失效模式。数据采用双向重复测量方差分析、Fisher 确切检验和 t 检验（α=0.05）进行分析。
龋损的存在对牙尖位移、釉质裂纹的形成以及牙本质复合树脂修复体的断裂强度没有显著影响。修复程序增加了釉质裂纹的数量，但不受机械循环的影响。
保留龋损不会影响使用大块充填牙科复合材料进行的 II 类修复体的生物力学行为。
