Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Osaka, Japan.
Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Osaka, Japan.
Dent Mater. 2018 Oct;34(10):1578-1584. doi: 10.1016/j.dental.2018.07.002. Epub 2018 Jul 23.
The aim of this study was to evaluate long-term fatigue behavior using an in vitro step-stress accelerated life test (SSALT), and to determine the crack initiation point using in silico finite element analysis for computer-aided designed and manufactured (CAD/CAM) molar crowns fabricated from three commercial CAD/CAM resin composite blocks: Cerasmart (CS; GC, Tokyo, Japan), Katana Avencia Block (KA; Kuraray Noritake Dental, Niigata, Japan), and Shofu Block HC (HC; Shofu, Kyoto, Japan).
Fifty-one mandibular first molar crowns luted on a resin core die were embedded in acrylic resin and covered with a polyvinyl chloride tube. Single compressive tests were performed for five crowns. SSALT was conducted for 36 crowns using three profiles and reliabilities at 120,000 cycles, and a Weibull analysis was conducted. The maximum principal strain of each CAD/CAM resin composite crown model was analyzed by three-dimensional finite element analysis.
Fracture loads of CS and KA (3784±144N and 3915±313N) were significantly greater than that of HC (2767±227N) (p<0.05). Fracture probabilities at 120,000 cycles were 24.6% (CS), 13.7% (KA), and 14.0% (HC). Maximum principal strain was observed around the mesiolingual cusps of CS and KA and the distobuccal cusp of HC.
CAD/CAM resin composite molar crowns containing nano-fillers with a higher fraction of resin matrix exhibited higher fracture loads and greater longevity, suggesting that these crowns could be used as an alternative to ceramic crowns in terms of fatigue behavior.
本研究旨在通过体外步应变速率加速寿命试验（SSALT）评估长期疲劳行为，并通过计算机辅助设计和制造（CAD/CAM）的模拟有限元分析确定陶瓷冠裂起点。研究采用三种商用 CAD/CAM 树脂复合材料块制造的磨牙冠：Cerasmart（CS；GC，东京，日本）、Katana Avencia Block（KA；Kuraray Noritake Dental，新泻，日本）和 Shofu Block HC（HC；Shofu，京都，日本）。
将 51 个下颌第一磨牙冠粘接到树脂核模具上，嵌入丙烯酸树脂中并用聚氯乙烯管覆盖。对 5 个牙冠进行单次压缩试验。对 36 个牙冠进行 SSALT，使用三个剖面和 120,000 次循环的可靠性进行威布尔分析。通过三维有限元分析分析每个 CAD/CAM 树脂复合材料牙冠模型的最大主应变。
CS 和 KA 的断裂载荷（3784±144N 和 3915±313N）明显大于 HC（2767±227N）（p<0.05）。在 120,000 次循环时的断裂概率分别为 24.6%（CS）、13.7%（KA）和 14.0%（HC）。最大主应变出现在 CS 和 KA 的近中舌侧尖和 HC 的远颊侧尖周围。
含有纳米填料和更高比例树脂基质的 CAD/CAM 树脂复合材料磨牙冠具有更高的断裂载荷和更长的寿命，这表明这些牙冠在疲劳行为方面可以替代陶瓷牙冠。
