Er：YAG激光预备及酸蚀处理对复合树脂充填体微渗漏的影响

目的 研究Er∶YAG激光备洞及酸蚀处理对复合树脂充填体微渗漏的影响.方法 将40颗离体前磨牙随机平均分为5组制备洞型：A组,高速牙钻预备加酸蚀;B组,Er∶YAG激光预备;C组,Er∶YAG激光预备加酸蚀;D组,高速牙钻预备加Er∶YAG激光蚀刻;E组,高速牙钻预备加Er∶YAG激光蚀刻后酸蚀.所有样本经复合树脂充填后交替放置于5℃与55℃水中各1 min,间隔45 s,共2000个周期进行冷热循环,然后用0.2％亚甲基蓝染色后颊舌向劈开,体视显微镜下观察剖面,记录其微渗漏情况,并进行统计学分析.另选6颗离体前磨牙,随机分为3组,按上述A、B、C三组方法制备,扫描电镜下观察其牙本质界面的结构.结果 在（牙合）壁与龈壁,B组染料渗入严重,到达洞底,微渗漏最大,与其他各组相比有统计学差异（P＜0.05）,A、C、D、E组染料渗入表浅,微渗漏程度之间没有统计学差异（P＞0.05）.扫描电镜下,A组牙本质表面较平整,无玷污层存在,牙本质小管口开放.B组牙本质表面不平整如鳞片状,无玷污层,牙本质小管口开放,直径小于酸蚀组.C组牙本质小管口开放,无玷污层存在,管周牙本质脱矿明显.结论 单纯Er∶YAG激光预备比传统牙钻制备结合酸蚀处理洞型更易发生微渗漏,若Er∶YAG激光预备结合酸蚀剂处理可以使微渗漏程度减小,Er∶YAG激光蚀刻可以达到和酸蚀剂类似的效果.

Effect of cavity preparation and etching with Er:YAG laser on the microleakage of the composite resin

Objective The aim of this study was to investigate the influence of cavity preparation or etching with Er∶YAG laser on the microleakage of the composite resin.Methods Forty extracted premolars were randomly and equally divided into five groups,where class V cavities were prepared by using a high speed handpiece or Er∶YAG laser treatment at the cement-enamel junction of the tooth.Group A：high speed handpiece preparation ＋ acid etching.Group B：Er∶YAG laser preparation.Group C：Er∶YAG laser preparation ＋ acid etching.Group D：high speed handpiece preparation ＋ Er∶YAG laser etching.Group E：high speed handpiece preparation ＋ Er∶ YAG laser and acid etching.All specimens were restored with composite resin,and submitted to a thermocycling regimen of 2000 cycles between 5 ℃ and 55 ℃ in waterbaths.Dwell time was lmin,with a 45s transfer time between baths.Then specimens were immersed in 0.2％ methylene blue for 24 h,and sectioned longitudinally in buccolingual direction.The microleakage was observed and scored with a stereo microscope.Data were analyzed by nonparametric statistics.In addition,six extracted premolars were divided into three groups and cavities were prepared as those in previously described group A,B,C.Then all six teeth were observed by scanning electron microscope.Results At the occlusal margins and gingival margins,group B showed a serious dye penetration where the dye reached the bottom of the cavity and it had the severest microleakage with statistical differences from other groups.Dye permeated shallowly in group A、C、D、E and the microleakage showed no difference among these groups.As revealed by scanning electron microscope,dentine in all groups had no smear layer,with dentine tubule open.Dentine was smooth in group A and was scaly in group B,while peritubular dentin was demineralized in group C.Conclusion The microleakage was more easily occurred in the cavity prepared by Er∶YAG laser alone than that in the cavity prepared with traditional high speed handpiece and acid etching.The use of the Er∶YAG laser combined with acid etching can reduce the microleakage.Etching by Er∶YAG laser can achieve a similar effect with acid etching.