Tay Franklin R, Pashley David H, Suh Byoung I, Carvalho Ricardo M, Itthagarun Anut
Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong, SAR, People's Republic of China.
J Dent. 2002 Sep-Nov;30(7-8):371-82. doi: 10.1016/s0300-5712(02)00064-7.
This study tested the hypotheses that micro-tensile bond strengths of all currently available single-step adhesives to dentine are adversely affected by delayed activation of a light-cured composite, and that such a phenomenon only occurs in the presence of water from the substrate side of the bonded interface.
In experiment I, a control three-step adhesive (All-Bond 2, Bisco) and six single-step adhesives (One-Up Bond F, Tokuyama; Etch&Prime 3.0, Degussa; Xeno CF Bond, Sankin; AQ Bond, Sun Medical; Reactmer Bond, Shofu and Prompt L-Pop, 3M ESPE) were bonded to sound, hydrated dentine. A microfilled composite was placed over the cured adhesive and was either light-activated immediately, or after leaving the composite in the dark for 20 min. In experiment II, three single-step adhesives (Etch&Prime 3.0, Xeno CF Bond and AQ Bond) were similarly bonded to completely dehydrated dentine using the same delayed light-activation protocol. In experiment III, a piece of processed composite was used as the bonding substrate for the same three single-step adhesives. The microfilled composite was applied to the cured adhesives using the same immediate and delayed light-activation protocols. Bonded specimens were sectioned for micro-tensile bond strength evaluation. Fractographic analysis of the specimens was performed using SEM. Stained, undemineralised sections of unstressed, bonded specimens were also examined by TEM.
When bonded to hydrated dentine, delayed light-activation had no effect on the control three-step adhesive, but significantly lowered the bond strengths of all the single-step adhesives (p < 0.05). This adverse effect of delayed light-activation was not observed in the three single-step adhesives that were bonded to either dehydrated dentine or processed composite. Morphological manifestations of delayed light-activation of composite in the hydrated dentine bonding substrate were exclusively located along the composite-adhesive interface, and were present as large voids, resin globules and honeycomb structures that formed partitions around a myriad of small blisters along the fractured interfaces.
These features resembled the 'overwet phenomenon' that was previously reported along the dentine-adhesive interfaces of some acetone-based three-step adhesives. The cured adhesive layer in single-step adhesives may act as semi-permeable membranes that allow water diffusion from the bonded hydrated dentine to the intermixed zone between the adhesive and the uncured composite. Osmotic blistering of water droplets along the surface of the cured adhesive layer and emulsion polymerisation of immiscible resin components probably account for the compromised bond strength in single-step adhesives after delayed activation of light-cured composites.
本研究旨在验证以下假设：目前所有可用的单步胶粘剂与牙本质的微拉伸粘结强度会受到光固化复合材料延迟激活的不利影响，且这种现象仅在粘结界面的底物侧存在水的情况下发生。
在实验I中，将一种对照三步胶粘剂（全粘结剂2，碧施）和六种单步胶粘剂（一步粘结F，德山；蚀刻与底涂3.0，德固赛；泽诺CF粘结剂，三金；AQ粘结剂，日进医疗；Reactmer粘结剂，松风；以及速易美L-Pop，3M ESPE）粘结到健康的、含水的牙本质上。在固化的胶粘剂上放置一种微填料复合材料，该复合材料要么立即进行光激活，要么在黑暗中放置20分钟后再进行光激活。在实验II中，使用相同的延迟光激活方案，将三种单步胶粘剂（蚀刻与底涂3.0、泽诺CF粘结剂和AQ粘结剂）同样粘结到完全脱水的牙本质上。在实验III中，使用一块加工过的复合材料作为这三种单步胶粘剂的粘结底物。使用相同的立即和延迟光激活方案，将微填料复合材料应用于固化的胶粘剂上。将粘结后的标本切片以进行微拉伸粘结强度评估。使用扫描电子显微镜对标本进行断口分析。还通过透射电子显微镜检查了未受力的粘结标本的染色、未脱矿切片。
当粘结到含水牙本质上时，延迟光激活对对照三步胶粘剂没有影响，但显著降低了所有单步胶粘剂的粘结强度（p < 0.05）。在粘结到脱水牙本质或加工过的复合材料上的三种单步胶粘剂中未观察到延迟光激活的这种不利影响。在含水牙本质粘结底物中，复合材料延迟光激活的形态学表现仅沿着复合材料 - 胶粘剂界面出现，表现为大的空隙、树脂球和蜂窝状结构，这些结构在断裂界面周围围绕着无数小水泡形成分隔。
这些特征类似于先前在一些基于丙酮的三步胶粘剂的牙本质 - 胶粘剂界面报道的“过度湿润现象”。单步胶粘剂中固化的胶粘剂层可能充当半透膜，允许水从粘结的含水牙本质扩散到胶粘剂与未固化复合材料之间的混合区域。沿固化胶粘剂层表面的水滴渗透起泡以及不混溶树脂组分的乳液聚合可能是光固化复合材料延迟激活后单步胶粘剂粘结强度受损的原因。
