School of Dentistry, The University of Manchester, Manchester, UK. ahmad.el-ma'
Dent Mater. 2013 Jul;29(7):797-803. doi: 10.1016/j.dental.2013.04.020. Epub 2013 May 22.
The aim of this study was to evaluate the effect of smear layer removal on the push-out bond strength between radicular dentin and three calcium silicate cements (CSC) in comparison with gutta percha and sealer.
Eighty human anterior extracted teeth were decoronated, cleaned and shaped to size 50/0.05 apically and randomly divided into 2 major groups: (A) smear layer preserved, and (B) smear layer removed using irrigation with 17% EDTA. Roots within each major group were further divided into 4 subgroups according to the obturation material used: (1) ProRoot MTA, (2) Biodentine, (3) Harvard MTA, (4) Gutta percha and AH-plus sealer. Obturated roots were stored in synthetic tissue fluid for 7 days to allow maximum setting of the root filling materials. Three 2-mm-thick slices were obtained from each root at different section levels (coronal, middle, apical). The canal diameters and slice thickness were measured, and the adhesion surface area for each slice was calculated. Push-out bond strength test was carried out using a universal testing machine. The bond failure mode was assessed under an optical microscope at 40×.
The mean push-out bond strength in groups 1A, 2A and 3A were 7.54 (±1.11), 7.64 (±1.08) and 8.79 (±1.55)MPa respectively, while those for groups 1B, 2B and 3B were 6.58 (±1.13), 6.47 (±1.08), 7.71 (±1.81)MPa, respectively. In the gutta percha and sealer groups the push-out bond strength means were: 1.98 (±0.48) and 2.09 (±0.51)MPa in the preserved and removed smear layer groups respectively. The push-out strength values were significantly reduced when the smear layer was removed in the CSC groups (P<0.05) while no significant difference was detected in the gutta percha and sealer groups.
Based on the conditions of this ex vivo study, it can be concluded that smear layer removal is detrimental to the bond strength between calcium silicate cements and dentin.
本研究旨在评估清除玷污层对根管牙本质与三种硅酸钙水泥（CSC）之间推出粘结强度的影响，并与牙胶和根管封闭剂进行比较。
80 颗人离体前磨牙经冠方去釉、清洗和根管预备至 50/0.05 根尖大号，随机分为 2 大组：（A）保留玷污层，（B）使用 17% EDTA 冲洗清除玷污层。每组内的牙根根据使用的充填材料进一步分为 4 个亚组：（1）ProRoot MTA，（2）Biodentine，（3）Harvard MTA，（4）牙胶和 AH-plus 根管封闭剂。将充填后的根管在合成组织液中储存 7 天，以最大限度地促进根充材料的凝固。从每个根的不同节段（冠方、中部、根尖）获得 3 个 2mm 厚的切片。测量根管直径和切片厚度，并计算每个切片的粘结表面积。使用万能试验机进行推出粘结强度测试。在 40×光学显微镜下评估粘结破坏模式。
在 1A、2A 和 3A 组中，保留玷污层组的平均推出粘结强度分别为 7.54（±1.11）、7.64（±1.08）和 8.79（±1.55）MPa，而清除玷污层组分别为 6.58（±1.13）、6.47（±1.08）和 7.71（±1.81）MPa。在牙胶和根管封闭剂组中，保留玷污层组的推出粘结强度平均值分别为 1.98（±0.48）和 2.09（±0.51）MPa。当清除 CSC 组的玷污层时，推出强度值显著降低（P<0.05），而牙胶和根管封闭剂组则无显著差异。
根据本离体研究的条件，可以得出结论，清除玷污层会损害硅酸钙水泥与牙本质之间的粘结强度。
