关键词: 复合树脂, 微渗漏, 酸蚀模式, 粘接界面, Ⅱ类洞

Abstract: Objective    Class Ⅱ cavities are prepared in vitro in extracted premolars to investigate the effects of three acid etching modes，namely etch-and-rinse（EAR），selective-enamel etch（SEE），and self-etch（SE）on the microleakage of class Ⅱ cavity filled with five composite resins. Methods    A total of 135 premolars extracted from patients were selected，who visited the Department of Oral and Maxillofacial Surgery of the Affiliated Stomatological Hospital of China Medical University due to orthodontic treatment needs from June to August 2023. After preparing class Ⅱ cavities，they were randomly divided into three groups according to the acid etching mode：EAR group，SEE group，and SE group，with 45 teeth in each group. Each group was further randomly divided into five subgroups（9 teeth in each subgroup），and filled with 3M FiltekTM Z350 XT universal nanocomposite resin（Z350 subgroup）and four domestic composite resins ［Dentex resin（Dentex subgroup），Antai biological resin（Antai biological subgroup），Zhangjiang biological resin（Zhangjiang biological subgroup），and Zhenghai biological resin（Zhenghai biological subgroup）］. After thermocycling，the microleakage grades of each group were evaluated under a stereomicroscope using the dye penetration method，and the characteristics of the bonding interface were observed under a scanning electron microscope（SEM）. The degree of microleakage was evaluated by calculating the volume of silver deposits through micro-computed tomography（Micro-CT）scanning. Results    There was no statistically significant difference in the microleakage grades of the distal and gingival walls of class Ⅱ cavities filled with different composite resins using the same acid etching mode（P > 0.05）. For the comparison of microleakage grades of class Ⅱ cavities filled with the same composite resin using different acid etching modes，there were statistically significant differences in the distal wall microleakage grades among the Z350 subgroup，Dentex subgroup，Antai biological subgroup，and Zhenghai biological subgroup（P < 0.05），while there were no statistically significant differences in the gingival wall microleakage grades（P > 0.05）. There were no statistically significant differences in the distal and gingival wall microleakage grades of the Zhangjiang biological subgroup（all P > 0.05）. Within the same composite resin subgroup of each acid etching mode group，the gingival wall microleakage grade was higher than that of the distal wall，and the differences were statistically significant（P < 0.001）. Scanning electron microscopy observations showed that the bonding interface of the distal and gingival walls of class Ⅱ cavities in the EAR group and the SEE group was relatively tight and straight，while in the SE group，the micro-cracks of bonding interface was wide，long，and irregular，with fragmentation. Micro-CT analysis results indicated that both the acid etching mode and the type of composite resin affected the volume of silver deposition，and there was an interaction effect between them （F values were 57.204，501.046，and 3.093，all P < 0.05）. Within the same acid etching mode，the volume of silver deposition in the Zhangjiang biological subgroup was greater than that in the other subgroups；within the same resin type，the volume of silver deposition in the SE group was greater than that in the EAR group and the SEE group，and the differences were statistically significant（P < 0.05）. Conclusion    Domestic composite resins（Dentex resin，Antai biological resin，and Zhenghai biological resin）show similar marginal sealing properties to 3M FiltekTM Z350 XT universal nanocomposite resin when they are used for filling class Ⅱ cavities. The EAR mode and the SEE mode can reduce the microleakage degree compared with the SE mode.

Key words: composite resin, microleakage, acid etching mode, bonding interface, classⅡ cavity