Department of Prosthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey.
Int Endod J. 2011 May;44(5):407-15. doi: 10.1111/j.1365-2591.2010.01843.x. Epub 2011 Jan 10.
To compare mean cusp movement in molar teeth with endodontic access and mesial-occlusal-distal (MOD) cavities before and after restoration with several fibre-reinforced composite restoration techniques under loading and to evaluate the effect of restoration technique on fracture strength.
Reference points were marked at the mesial cusp ridges of extracted human mandibular molar teeth. Digital images were taken under loading (300 N) using a stereomicroscope (Leica MZ16A; Wetzlar, Germany). Three-dimensional (3D) distances between the reference points were recorded (Leica, Stereo-Explorer, 2.1) as controls. Standard MOD cavities were prepared and restored as follows (n = 10), group 1: composite restoration (Clearfil AP-X; Kuraray, Tokyo, Japan); group 2: cavity lined with polyethylene fibre (Ribbond, Ribbond Inc., Seattle, WA, USA) in combination with flowable resin (Protect-Liner F; Kuraray, Tokyo, Japan) before composite restoration; group 3: polyethylene fibre inserted on occlusal surface of the tooth from buccal to lingual after finishing the composite restoration; group 4: missing walls were restored with composite resin and inner surfaces of the axial walls were then reinforced with polyethylene fibre placed circumferentially before the composite restoration. The restored teeth were re-loaded, digital images were re-taken and the 3D distance between the reference points was recorded in μm. Comparisons of the restoration techniques, the effectiveness of restoration for each group were analysed statistically (Kruskall-Wallis, paired-samples t-test). The teeth were then loaded until failure (5 mm min(-1) ), the data were recorded (N) and analysed statistically (Kruskall-Wallis test).
A significant difference occurred amongst the groups in terms of cusp movement (P = 0.018). All the groups revealed a decrease in inter-cuspal width when compared to their initial records. The mean values of these decreases were as follows: group 1 17.6 (P = 0.003), group 2 6.7 (not sig), group 3 6.6 (not sig) and group 4 0.85 (not sig) μm. No significant difference was found amongst the fracture strength values (P = 0.22). In group 1, 90% of the fractures were non-restorable, whereas in group 3 100% of the fractures were restorable.
Regardless of restoration technique, fibre reinforcement of composite restorations decreased cusp movement in molar teeth with MOD and endodontic access cavities but did not affect fracture strength.
比较在负载下使用几种纤维增强复合修复技术对磨牙进行根管治疗和近中-颊-舌（MOD）腔修复前后牙尖运动的平均值，并评估修复技术对断裂强度的影响。
在提取的下颌磨牙的近中牙尖脊处标记参考点。使用立体显微镜（徕卡 MZ16A；德国威茨拉尔）在负载下（300N）拍摄数字图像。记录参考点之间的三维（3D）距离（徕卡，立体探险家，2.1）作为对照。以下列方式制备和修复标准 MOD 腔（n = 10）：组 1：复合修复（Clearfil AP-X；Kuraray，东京，日本）；组 2：在复合修复前用聚乙烯纤维（Ribbond，Ribbond Inc.，西雅图，WA，美国）包埋的腔；组 3：复合修复完成后从颊侧到舌侧在牙的咬合面上插入聚乙烯纤维；组 4：用复合树脂修复缺失的壁，然后在复合修复前在轴向壁的内表面上用聚乙烯纤维环绕放置进行加固。重新加载修复后的牙齿，重新拍摄数字图像，并以 μm 为单位记录参考点之间的 3D 距离。统计分析了修复技术之间的比较，以及每组修复的效果（ Kruskall-Wallis ，配对样本 t 检验）。然后以 5mmmin(-1) 的速度加载牙齿直至失效，记录数据（N）并进行统计分析（ Kruskall-Wallis 检验）。
在牙尖运动方面，各组之间存在显著差异（P = 0.018）。与初始记录相比，所有组的牙尖宽度都减小。这些减小的平均值如下：组 1 17.6（P = 0.003），组 2 6.7（不显著），组 3 6.6（不显著）和组 4 0.85（不显著）μm。断裂强度值之间无显著差异（P = 0.22）。在组 1 中，90%的骨折为不可修复性骨折，而在组 3 中，100%的骨折为可修复性骨折。
无论修复技术如何，纤维增强复合修复都可以减少具有 MOD 和根管治疗的磨牙的牙尖运动，但不会影响断裂强度。
