Studies on Marginal Leakage of Cavities Prepared by Er : YAG Laser

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Two kinds of Composite resin, LI that were seen micro-marginal leakage in class V cavities and MZ that were not recognized micro-marginal leakage, were filled. After 200 thermal scycles, Marginal leakage was tested by Mercox-Rohdamin Method.Test 1 : (1)The class V cavities were prepared only by Er : YAG Laser without rotar cutting instrumens in molar.(2)Only bevel were prepared by Er : YAG laser.(3)Er : YAG laser were irradiated at the floor cavity and the side wall. These thre kinds of cavities were filled with composite resin with or without etching method.Test 2 : The tunnel cavities were prepared in premolar for proximal caries. (1)Th tunnel cavities were prepared by rotaly cutting instrument. (2)Soft dentin was removet by Er : YAG laser, and cavities were finished. These two kinds of cavities were done th ame way as in Test 1.Results were as follows.1. It is difficult to prepare cavity by Er : YAG laser without rotary cutting instrument Er : YAC laser is useful for removing soft dentin.2. The method using laser etching is unstable. It is necessary to change etching tim and etching method, and to develop bonding agents. Using Laser in tunnel cavit incresed micro-marginal leakage.3. unnel cavities filled with MZ are often observed micro-marginal leakage at th proximal enamel cervical wall.