Parashos Peter, Phoon Amanda, Sathorn Chankhrit
Melbourne Dental School, University of Melbourne, 720 Swanston Street, Melbourne, VIC 3010, Australia.
Biomed Res Int. 2014;2014:191984. doi: 10.1155/2014/191984. Epub 2014 Apr 1.
To evaluate the effect on physical properties of Mineral Trioxide Aggregate (MTA) of using direct hand compaction during placement and when using hand compaction with indirect ultrasonic activation with different application times.
One hundred acrylic canals were obturated in 3 increments with MTA in sample sizes of 10. One group was obturated by hand with an endodontic plugger and the remainder obturated with indirect ultrasonic application, with times ranging from 2 seconds to 18 seconds per increment. Microhardness values, dye penetration depths, and radiographs of the samples were evaluated.
As ultrasonic application time per increment increased, microhardness values fell significantly (P < 0.001) while dye penetration values increased (P < 0.001). Microhardness of MTA ultrasonicated for 2 seconds was significantly higher than hand compaction (P = 0.03). Most radiographic voids were visible in the hand-compacted group (P < 0.001), which also had higher dye penetration depths than the 2-second ultrasonicated samples. Ultrasonication of MTA for 10-18 seconds resulted in significantly more voids than 2-8 seconds of ultrasonication (P = 0.02).
The use of ultrasonics with MTA improved the compaction and flow of MTA, but excessive ultrasonication adversely affected MTA properties. A time of 2 seconds of ultrasonication per increment presented the best compromise between microhardness values, dye penetration depths, and lack of radiographic voids.
评估在放置矿物三氧化物凝聚体（MTA）时直接手工压实以及使用手工压实并结合不同作用时间的间接超声激活对其物理性能的影响。
用MTA分3次增量充填100个丙烯酸根管，每组样本量为10个。一组用牙髓充填器手工充填，其余组采用间接超声，每次增量的作用时间从2秒到18秒不等。对样本的显微硬度值、染料渗透深度和X线片进行评估。
随着每次增量的超声作用时间增加，显微硬度值显著下降（P < 0.001），而染料渗透值增加（P < 0.001）。超声作用2秒的MTA显微硬度显著高于手工压实（P = 0.03）。在手工压实组中可见到大多数X线片上的空洞（P < 0.001），其染料渗透深度也高于超声作用2秒的样本。MTA超声作用10 - 18秒产生的空洞明显多于超声作用2 - 8秒（P = 0.02）。
MTA使用超声改善了其压实和流动性，但过度超声会对MTA性能产生不利影响。每次增量超声作用2秒在显微硬度值、染料渗透深度和X线片上无空洞之间呈现出最佳平衡。
