Bond Strength and Cytotoxicity of a Universal Adhesive According to the Hybridization Strategies to Dentin

Abstract This study evaluated application protocol (etch-and-rinse/ER and self-etching/SE) and dentin wettability (wet and dry) on microtensile bond strength (μTBS) and transdentinal cytotoxicity of ScotchbondTM Universal (SU) adhesive system. The μTBS values and fracture mode were registered 24 h after adhesive system application and resin composite block build-up (n=5). For analysis of transdentinal cytotoxicity, odontoblast-like MDPC-23 cells were seeded on pulpal surface of dentin discs (0.4 mm thick) adapted to artificial pulp chambers (n=8). The adhesive system was applied to occlusal surface, followed by 24-h incubation time. Cell viability (Alamar Blue) and morphology (SEM) were assessed. Adper Single Bond 2 and Clearfil SE Bond were used as positive controls of the ER and SE application protocols, respectively. No treatment was performed on negative control (NC) group. Data were analyzed by ANOVA and Tukey’s tests (α=5%). Higher μTBS values were found for ER mode in comparison with SE protocol (p<0.05). Dentin wettability had no effect on bond strength of SU in both the ER and SE techniques (p>0.05). Most fractures involved hybrid layer and/or adhesive layer. Neither variable prevented the intense toxic effects of adhesive systems on MDPC-23 cultured cells, since intense reduction in cell viability (±88%) and severe alterations in cell morphology were observed for all groups compared to NC, with no differences among them (p>0.05). Therefore, it was concluded that application of SU following the ER protocol had better adhesive performance. However, this adhesive system featured intense transdentinal cytotoxicity to pulp cells, regardless of application protocol and dentin wettability.

摘要 本研究评估了应用方案（酸蚀-冲洗型/etch-and-rinse/ER与自酸蚀型/self-etching/SE）以及牙本质润湿性（湿润型与干燥型）对Scotchbond™ Universal（SU）粘接系统的微拉伸粘接强度（microtensile bond strength, μTBS）与跨牙本质细胞毒性的影响。在粘接系统涂布与树脂复合块堆塑后24小时，记录各组微拉伸粘接强度值及断裂模式（每组n=5）。针对跨牙本质细胞毒性的分析，将成牙本质细胞样MDPC-23细胞接种于厚度为0.4mm、适配人工牙髓腔的牙本质片的牙髓面（每组n=8）。将粘接系统涂布于牙合面后，进行24小时孵育。随后通过阿利玛蓝法（Alamar Blue）检测细胞活力，并借助扫描电子显微镜（SEM）观察细胞形态。本研究以Adper Single Bond 2与Clearfil SE Bond分别作为ER型与SE型应用方案的阳性对照，未进行任何处理的组别设为阴性对照（NC）组。数据采用方差分析（ANOVA）与Tukey多重比较检验（Tukey’s tests）进行分析，检验水准设定为α=5%。结果显示，相较于SE型应用方案，ER型方案的微拉伸粘接强度更高（p<0.05）。无论采用ER还是SE技术，牙本质润湿性对SU的粘接强度均无显著影响（p>0.05）。绝大多数断裂发生于混合层与/或粘接层。与NC组相比，所有实验组的细胞活力均出现显著下降（降幅约88%），且细胞形态发生严重改变，各组间无统计学差异（p>0.05），可见两项考察变量均未能减轻粘接系统对MDPC-23培养细胞的强细胞毒性。综上，本研究得出结论：采用ER型应用方案涂布SU可获得更优的粘接性能。但无论采用何种应用方案与牙本质润湿性处理方式，该粘接系统对牙髓细胞均表现出较强的跨牙本质细胞毒性。