Fracture resistance and gap formation of MOD restorations: Influence of restorative technique, bevel preparation and water storage
Fracture resistance and gap formation of MOD restorations: Influence of restorative technique, bevel preparation and water storage
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DOI：
10.2341/07-27
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发表时间：
2008-01-01
影响因子：
2.2
通讯作者：
Powers, J. M.
中科院分区：
文献类型：
--
作者：
Coelho-de-Souza, F. H.;Camacho, G. B.;Powers, J. M.
这项体外研究评估了技术、斜面的使用和热循环对树脂复合MOD修复体的抗折性能和缝隙形成的影响。对100颗上前磨牙制备的标准MOD洞进行了抗折性能测试，这些洞在1000次热循环后储存24小时和6个月。亚组(n=10)包括：斜面或非斜面预备材料、直接修复体(Adper Single Bond/Filtek Z250)和间接修复体(预聚Filtek Z250与RELY X ARC粘接)。10颗健康牙和10颗未修复体的MOD标本分别作为阳性对照和阴性对照。试件在万能试验机上以0.5 mm/min的十字头速度进行轴向压缩。用体视显微镜(40倍)分析失效模式。为了评估间隙的存在或不存在，在24颗如上所述修复的人类第三磨牙上准备了近侧盒形洞穴。术后24小时和6个月取材进行扫描电子显微镜检查。数据经方差分析和多重比较检验，在0.05水平上具有统计学意义。24小时后，斜面修复体显示出比非斜面修复体更高的抗折强度，而所有组都表现出与健牙相近或更好的抗力。6个月后，斜面嵌体的抗折强度最高，对接直接修复的抗折强度最低。在大多数组中，热循环降低了断裂抗力。观察到的主要断裂模式是材料的粘结失效，但粘结失效随着时间的推移而增加，特别是在非斜面修复中。扫描电子显微镜观察，24小时后各组间差异无统计学意义。然而，六个月后，斜面修复体没有形成缝隙。结论是，热循环储存降低了抗折能力，斜面提高了抗折能力，总体来说，间接修复并不优于直接修复。
This in vitro study evaluated the effect of technique, use of a bevel and thermal cycling on the fracture resistance and gap formation of resin composite MOD restorations. Fracture resistance was measured on standard MOD cavities prepared in 100 upper premolars that were stored for 24 hours and 6 months with 1000 thermal cycles. Subgroups (n=10) were: beveled or non-beveled preparations and direct restorations (Adper Single Bond/Filtek Z250) and indirect restorations (prepolymerized Filtek Z250 cemented with Rely X ARC). Ten sound teeth and 10 specimens with MOD preparations without restorations served as the positive and negative controls, respectively. The specimens were subjected to axial compression in a universal testing machine at a crosshead speed of 0.5 mm/minute. Failure patterns were analyzed by stereomicroscopy (40x). To evaluate gap presence or absence, proximal box cavities were prepared in 24 human third molars that were restored as described above. The specimens were evaluated under SEM examination after 24 hours and six months. Data were statistically analyzed by ANOVA and multiple comparison tests at the 0.05 level of significance. After 24 hours, the beveled restorations exhibited higher fracture strength values than the non-beveled restorations, and all groups showed resistance similar or superior to sound teeth. After six months, the highest fracture resistance was obtained for beveled inlays and the lowest values were observed for direct restorations with butt joints. Thermal cycling decreased fracture resistance in the majority of the groups. The main fracture pattern observed was cohesive failure in the material, but adhesive failures increased over time, especially in the non-beveled restorations. Under SEM examination, no difference was observed among the groups after 24 hours. However, after six months, the beveled restorations exhibited no gap formation. It was concluded that storage with thermal cycling decreased fracture resistance, bevels improved fracture resistance and, in general, indirect restorations were not superior to direct restorations.