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 本研究评估了酸蚀-冲洗型（etch-and-rinse/ER）与自酸蚀型（self-etching/SE）两种粘结剂应用流程，以及牙面润湿性（湿态、干态）对思高洁™通用粘结剂（ScotchbondTM Universal/SU）的微拉伸粘结强度（microtensile bond strength/μTBS）与跨牙本质细胞毒性的影响。在粘结剂涂布与树脂复合块堆塑24小时后，记录各组微拉伸粘结强度值与断裂模式（每组n=5）。在跨牙本质细胞毒性分析环节，将成牙本质细胞样MDPC-23细胞接种于适配人工牙髓腔（每组n=8）、厚度为0.4mm的牙本质盘的牙髓侧表面，将粘结剂涂布于牙合面后孵育24小时。采用阿利玛蓝（Alamar Blue）法检测细胞活力，通过扫描电子显微镜（scanning electron microscope/SEM）观察细胞形态。本研究分别以阿普德Single Bond 2与可乐菲SE粘结剂作为ER型与SE型应用流程的阳性对照组，未进行任何处理的组别设为阴性对照组（NC）。数据采用方差分析（ANOVA）与Tukey检验进行分析，显著性水平设定为α=5%。结果显示：相较于SE型应用流程，ER型流程的微拉伸粘结强度值更高（p<0.05）；无论采用ER还是SE技术，牙面润湿性对SU的粘结强度均无显著影响（p>0.05）。绝大多数断裂发生于混合层和/或粘结剂层。所有组别均未观察到可缓解粘结剂对MDPC-23培养细胞强毒性的因素：与阴性对照组相比，各组细胞活力均出现约88%的显著下降，细胞形态发生严重改变，且各组间无显著差异（p>0.05）。综上，采用ER型流程涂布SU可获得更优的粘结性能，但无论应用流程与牙面润湿性如何，该粘结剂均会对牙髓细胞产生强烈的跨牙本质细胞毒性。