Clinic of Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University of Zürich, Switzerland.
J Adhes Dent. 2010 Aug;12(4):287-94. doi: 10.3290/j.jad.a17711.
To evaluate marginal quality, fracture modes, and loads-to-failure of different overlay restorations in rootcanal treated molars in a laboratory setup.
Thirty-two mandibular first molars were randomly assigned to four groups (n = 8): UTR= untreated (control), RCT-COM= root canal treated (RCT)+ lab-made composite overlay, RCT-FRC= RCT+composite resin overlay with two layers of multidirectional woven glass fibers; RCT-CER: RCT+ceramic overlay. The teeth in all groups were subjected to thermocycling and mechanical loading (TCML) in a computer-controlled masticator (1,200,000 loads, 49 N, 1.7 Hz, 3000 temperature cycles of 5°C to 50°C). Marginal adaptation was evaluated before and after TCML with scanning electron microscopy at 200X at the tooth-to-luting composite (IF1) and luting composite-to restoration (IF2) interfaces. After TCML, all specimens were loaded to failure in a universal testing machine at 0.5 mm/min. Data were analyzed with ANOVA and Bonferroni correction.
Marginal adaptation decreased from 93 ± 3.4 to 82 ± 6.5 % at IF1 after TCML (p > 0.001) but the decrease was not significant between the groups (p = 0.8130). At IF2, ceramic overlays showed about 10% lower marginal adaptation than composite overlays (p < 0.0001). Loads-to-failure (in N) were as follows in descending order: RCT-FRC: 3619 ± 520; UTR: 3048 ± 905; RCT-COM: 2770 ± 457; RCT-CER 2036 ± 319. RCT-FRC showed significantly higher results than those of RCT-COM (p = 0.0077) and RCT-CER (p < 0.0001). Only RCT-CER showed significantly lower results than that of the control (p = 0.0019). While the fractures in the UTR occurred exclusively above the cementoenamel junction (Mode 1 and Mode 2) and were rated reparable, RCT-COM and RCT-CER showed exclusively catastrophic failures in varying modes (nodes 3 to 5). Only in group RCT-FRC, half of the specimens fractured in a reparable fracture mode (modes 1 and 2) with veneering composite delamination from the glass-fiber weaver layer.
As cusp-covering overlay restorations in root canal treated molars, composite resin overlays with and without fiber reinforcement performed similar to intact teeth with varying failure types. While intact teeth failed exclusively in reparable modes, all other restorations failed in a catastrophic manner, except half of the fiber reinforced composite group.
在实验室环境下，评估根管治疗后的磨牙不同覆盖修复体的边缘质量、断裂模式和失效载荷。
32 颗下颌第一磨牙随机分为 4 组（n=8）：未处理（对照）、根管治疗+实验室复合覆盖、根管治疗+两层多向编织玻璃纤维增强复合树脂覆盖、根管治疗+陶瓷覆盖。所有组的牙齿均在计算机控制的咀嚼机中进行热循环和机械加载（TCML）（120 万次循环，49 N，1.7 Hz，3000 个 5°C 至 50°C 的温度循环）。在 TCML 前后，使用扫描电子显微镜在 200X 下评估牙齿与粘固复合层（IF1）和粘固复合层与修复体（IF2）之间的边缘适应性。TCML 后，所有标本均在万能试验机上以 0.5 mm/min 的速度加载至失效。使用方差分析和 Bonferroni 校正对数据进行分析。
TCML 后 IF1 的边缘适应性从 93±3.4%下降到 82±6.5%（p>0.001），但组间无显著差异（p=0.8130）。IF2 处，陶瓷覆盖层的边缘适应性比复合覆盖层低约 10%（p<0.0001）。失效载荷（N）依次降低如下：RCT-FRC：3619±520；UTR：3048±905；RCT-COM：2770±457；RCT-CER：2036±319。RCT-FRC 的结果明显高于 RCT-COM（p=0.0077）和 RCT-CER（p<0.0001）。仅 RCT-CER 的结果明显低于对照组（p=0.0019）。UTR 的骨折仅发生在牙釉质牙骨质界以上（模式 1 和模式 2），且可修复，而 RCT-COM 和 RCT-CER 则以不同模式（节点 3 至 5）显示出完全破坏的失效。仅在 RCT-FRC 组，一半的标本以可修复的骨折模式（模式 1 和模式 2）断裂，复合树脂面层从玻璃纤维编织层分层。
作为根管治疗后磨牙的覆盖修复体，带纤维增强的复合树脂覆盖层与完整牙体具有相似的性能，但其失效类型不同。完整牙体仅发生可修复性失效模式，而所有其他修复体均发生完全破坏失效模式，除了纤维增强复合组的一半标本。
