Sehy Christina, Drummond James L
Department of Restorative Dentistry, College of Dentistry, University of Illinois, Chicago 60612-7212, USA.
Am J Dent. 2004 Oct;17(5):378-80.
To determine if the cutting procedure utilized in producing a cavity preparation, i.e., a high speed dental handpiece or an Er:YAG laser may be a factor in initiating the formation of micro-cracks during or after preparation of the cavity and before and after placing and curing the dental composite.
Class I occlusal and Class II MOD preparations were prepared in extracted third molars using a high speed dental handpiece equipped with a coarse diamond bur or with an Er:YAG laser at 260mJ and 25Hz. Composite was placed into the cavity level with the occlusal surface and bulk cured. The extreme factors of a coarse diamond bur and bulk curing of the composite were utilized to maximize the stresses at the tooth-composite interface. The teeth were vertically sectioned, facio-lingually, and examined, along with resin replicas, under a scanning electron microscope (SEM) to look for the presence of microcracks at the composite/enamel interface and composite/dentin interface.
SEM examination indicated that micro-cracking of the tooth structure was not significant or consistent in any of the specimens examined. This study was unable to confirm that micro-cracks form at the composite/tooth interface.
确定在制备窝洞时所采用的切割方法，即高速牙科手机或铒钇铝石榴石（Er:YAG）激光，是否可能是在窝洞制备期间或之后、以及在放置和固化牙科复合材料之前和之后引发微裂纹形成的一个因素。
在拔除的第三磨牙上制备I类咬合面和II类近中邻面-咬合面-远中邻面（MOD）窝洞，使用配备粗粒度金刚石车针的高速牙科手机或使用能量为260mJ、频率为25Hz的Er:YAG激光。将复合材料放置到与咬合面齐平的窝洞内并整体固化。利用粗粒度金刚石车针和复合材料整体固化这些极端因素，以使牙齿-复合材料界面处的应力最大化。将牙齿沿颊舌方向垂直剖开，并与树脂复制品一起在扫描电子显微镜（SEM）下进行检查，以寻找在复合材料/牙釉质界面和复合材料/牙本质界面处是否存在微裂纹。
SEM检查表明，在所检查的任何标本中，牙齿结构的微裂纹均不显著或不一致。本研究无法证实微裂纹在复合材料/牙齿界面处形成。
