Chang Yen-Hsiang, Yu Jin-Jie, Lin Chun-Li
Department of Biomedical Engineering, National Yang-Ming University, No,155, Sec,2, Linong Street, Taipei 112, Taiwan.
Biomed Eng Online. 2014 Dec 13;13:165. doi: 10.1186/1475-925X-13-165.
This study investigates CAD/CAM ceramic cusp-replacing restoration resistance with and without buccal cusp replacement under static and dynamic cyclic loads, monitored using the acoustic emission (AE) technique.
The cavity was designed in a typical MODP (mesial-occlusal-distal-palatal) restoration failure shape when the palatal cusp has been lost. Two ceramic restorations [without coverage (WOC) and with (WC) buccal cuspal coverage with 2.0 mm reduction in cuspal height] were prepared to perform the fracture and fatigue tests with normal (200 N) and high (600 N) occlusal forces. The load versus AE signals in the fracture and fatigue tests were recorded to evaluate the restored tooth failure resistance.
The results showed that non-significant differences in load value in the fracture test and the accumulated number of AE signals under normal occlusal force (200 N) in the fatigue test were found between with and without buccal cuspal coverage restorations. The first AE activity occurring for the WOC restoration was lower than that for the WC restoration in the fracture test. The number of AE signals increased with the cyclic load number. The accumulated number of AE signals for the WOC restoration was 187, higher than that (85) for the WC restoration under 600 N in the fatigue test.
The AE technique and fatigue tests employed in this study were used as an assessment tool to evaluate the resistances in large CAD/CAM ceramic restorations. Non-significant differences in the tested fracture loads and accumulated number of AE signals under normal occlusal force (200 N) between different restorations indicated that aggressive treatment (with coverage preparation) in palatal cusp-replacing ceramic premolars require more attention for preserving and protecting the remaining tooth.
本研究使用声发射（AE）技术监测，调查在静态和动态循环载荷下，有无颊尖替代的CAD/CAM陶瓷尖替代修复体的抗力。
当腭尖缺失时，将洞形设计为典型的MODP（近中-咬合面-远中-腭侧）修复失败形状。制备两种陶瓷修复体[无覆盖（WOC）和有（WC）颊尖覆盖且尖高度降低2.0 mm]，分别用正常（200 N）和高（600 N）咬合力进行断裂和疲劳试验。记录断裂和疲劳试验中载荷与AE信号，以评估修复后牙齿的抗破坏能力。
结果显示，在断裂试验中的载荷值以及疲劳试验中正常咬合力（200 N）下的AE信号累积数量方面，有和无颊尖覆盖修复体之间无显著差异。在断裂试验中，WOC修复体首次出现AE活动的载荷低于WC修复体。AE信号数量随循环载荷次数增加。在600 N疲劳试验中，WOC修复体的AE信号累积数量为187，高于WC修复体（85）。
本研究中采用的AE技术和疲劳试验用作评估大型CAD/CAM陶瓷修复体抗力的工具。不同修复体在测试的断裂载荷和正常咬合力（200 N）下的AE信号累积数量无显著差异，这表明在腭尖替代陶瓷前磨牙中进行激进治疗（覆盖制备）时，需要更加注意保留和保护剩余牙齿。
