Clinic for Fixed and Removable Prosthodontics and Dental Material Science, Center for Dental and Oral Medicine, University of Zürich, Switzerland.
J Adhes Dent. 2010 Aug;12(4):279-86. doi: 10.3290/j.jad.a17712.
This study evaluated the marginal adaptation, fracture modes, and loads to failure of different mesio-occlusal- distal (MOD) restorations in root canal treated molars in vitro.
Forty mandibular first molars were randomly assigned to five groups (n = 8): UTR= untreated, RCT-AM= root-canal treated (RCT)+amalgam filling; RCT-COM= RCT+direct composite resin restoration; RCTFRC= RCT+composite resin restoration with two layers of multidirectional woven glass fibers; RCT-CER= RCT+ceramic inlay. All teeth 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 by scanning electron microscopy at 200X at the tooth/restoration interfaces. After TCML, all specimens were loaded to failure in a universal testing machine at 0.5 mm/min. Failure types were analyzed and scored (reparable: modes 1 and 2; catastrophic: modes 3 to 5). Data were analyzed with ANOVA and Bonferroni correction.
Marginal adaptation decreased significantly after TCML in all groups. The highest decrease was observed in RCT-FRC (before: 89.9 ± 2.2%, after TCML: 49.8 ± 11.9%) and the lowest in RCT-CER (before TCML: 90.3 ± 2.6% after TCML 80.4 ± 9.0%). Loads to failure (in N) were in descending order as follows: UTR: 3048 ± 905; RCT-CER: 1853 ± 477; RCT-AM: 1447 ± 363; RCT-FRC: 1066 ± 306; RCT-COM 960 ± 228. While UTR resulted in statistically higher loads to failure than those of all other groups (p < 0.0001), RCT-CER showed significantly higher results than those of RCT-COM (p = 0.0014) and RCT-FRC (p = 0.0042). The UTR group showed exclusively reparable failures in the form of either superficial (mode 1) or complete cusp chipping (mode 2), but all restored teeth exhibited catastrophic failures involving fractures along or through the restoration (modes 3 to 5).
None of the restored teeth in any group were able to bear the same load level as the natural teeth. With regard to marginal adaptation and fracture resistance, luted ceramic inlays were advantageous. The integration of FRC in the restoration had no positive effect on the fracture resistance. FRC application showed a negative effect on marginal adaptation of composite resin restorations.
本研究评估了不同近中-颊-远（MOD）修复体在体外根管治疗磨牙中的边缘适应性、断裂模式和失效载荷。
将 40 颗下颌第一磨牙随机分为五组（n=8）：未处理组（UTR）、根管治疗+银汞合金充填组（RCT-AM）、根管治疗+直接复合树脂修复组（RCT-COM）、根管治疗+两层多向编织玻璃纤维复合树脂修复组（RCT-FRC）、根管治疗+陶瓷嵌体组（RCT-CER）。所有牙齿均在计算机控制的咀嚼机上进行热循环和机械加载（TCML）（120 万次循环，49N，1.7Hz，3000 次 5°C 至 50°C 的温度循环）。在 TCML 前后，通过扫描电子显微镜在 200X 下评估牙齿/修复体界面的边缘适应性。在 TCML 后，所有样本均在万能试验机上以 0.5mm/min 的速度加载至失效。分析和评分失效类型（可修复：模式 1 和 2；灾难性：模式 3 至 5）。数据采用方差分析和 Bonferroni 校正进行分析。
所有组在 TCML 后边缘适应性均显著降低。RCT-FRC 下降最明显（治疗前：89.9%±2.2%，治疗后：49.8%±11.9%），RCT-CER 下降最小（治疗前：90.3%±2.6%，治疗后：80.4%±9.0%）。失效载荷（N）依次降低如下：未处理组：3048±905；RCT-CER 组：1853±477；RCT-AM 组：1447±363；RCT-FRC 组：1066±306；RCT-COM 组：960±228。未处理组的失效载荷显著高于其他所有组（p<0.0001），而 RCT-CER 组的失效载荷显著高于 RCT-COM 组（p=0.0014）和 RCT-FRC 组（p=0.0042）。UTR 组仅表现为可修复性失效，表现为浅表层（模式 1）或完全牙尖崩裂（模式 2），但所有修复牙均表现为灾难性失效，涉及修复体沿或穿过修复体的断裂（模式 3 至 5）。
任何组的修复牙都无法承受与天然牙相同的载荷水平。在边缘适应性和抗断裂性方面，粘固陶瓷嵌体具有优势。纤维增强复合材料在修复体中的整合对断裂阻力没有积极影响。纤维增强复合材料的应用对复合树脂修复体的边缘适应性有负面影响。
