铒铬铱钪镓石榴石激光照射乳牙牙本质粘接强度的变化

Irradiation with erbium, chromium:yttrium scandium gallium garnet laser alters shear bond strength to primary tooth dentin

背景:牙体硬组织表面预处理对粘接修复的成功起着重要作用。目的:探讨铒铬铱钪镓石榴石激光酸蚀乳牙本质表面对树脂粘接牙本质剪切强度的影响。方法:获取120颗离体人乳切牙,去除牙釉质后随机分成3组进行表面预处理:空白对照组(n=12)不进行任何处理;磷酸酸蚀组(n=12)采用35%磷酸酸蚀牙面;激光组(n=48)采用铒铬铱钪镓石榴石激光照射牙面,又分4个亚组,分别为1,2,3,4 W功率组(1 W、50 mJ、20 Hz;2 W、100 mJ、20 Hz;3 W、150 mJ、20 Hz;4 W、200 m J、20 Hz);联合组(n=48)采用铒铬铱钪镓石榴石激光照射磷酸酸蚀后的牙面,又分4个亚组,分别为1,2,3,4 W功率组(1 W、50 mJ、20 Hz;2 W、100 m J、20 Hz;3 W、150 mJ、20 Hz;4 W、200 mJ、20 Hz)。每组随机选2个样本进行扫描电子显微镜观察,将剩余样本与复合树脂进行粘接,进行剪切粘接强度测试。结果与结论:(1)空白对照组剪切粘接强度最低,为(4.03±1.80)MPa;激光2 W功率组剪切粘接强度最高,为(14.12±3.23)MPa;其次为磷酸酸蚀组,为(13.11±3.23)MPa;(2)扫描电子显微镜显示,空白对照组牙本质表面满布碎屑,玷污层覆盖;磷酸酸蚀组牙本质小管口完全开放,管径增大,玷污层清除,表面平坦,可见少量碎屑,管间牙本质与管周牙本质无明显界限;激光组牙本质表面高低不平,呈鱼鳞片状,牙本质小管口开放,清晰可见,管周牙本质突出于管间牙本质呈"袖口状",表面无玷污层,随着激光照射能量的提高,牙本质小管出现管栓,表面出现一些裂隙和断裂;联合组牙本质表面较激光组起伏更明显,整体脱矿程度比激光组更高,牙本质小管内栓塞、闭合现象更显著;(3)结果表明对于乳牙牙本质,最佳的铒铬铱钪镓石榴石酸蚀参数是2 W、20 Hz、100 mJ。

BACKGROUND： Pretreatment of dental hard tissues is critical for a success in tooth bonding repair. OBJECTIVE： To explore the shear bond strength of nano-hybrid resin bonded to the primary tooth dentin after conditioning by 35% phosphoric acid, erbium, chromium：yttrium scandium gallium garnet （Er,Cr：YSGG） irradiation or their combined use. METHODS： 120 extracted primary incisors with enamel removal were randomly divided into three groups and dealt with the following pretreatments： in control group （n=12）, the tooth surface was without any processing; in acid etching group （n=12）, the tooth surface was etched using 35% phosphoric acid; in laser group （n=48）, the tooth surface was treated by Er,Cr：YSGG laser at four power outputs （1 W, 50 mJ, 20 Hz; 2 W, 100 mJ, 20 Hz; 3 W, 150 mJ, 20 Hz; 4 W, 200 mJ, 20 Hz）; in combined group （n=48）, the tooth surface was treated with 35% phosphoric acid followed by Er,Cr：YSGG laser irradiation at four power outputs （1 W, 50 mJ, 20 Hz; 2 W, 100 mJ, 20 Hz; 3 W, 150 mJ, 20 Hz; 4 W, 200 mJ, 20 Hz）. Two samples from each group were randomly selected and observed using scanning electron microscope, and the residual samples were bonded with the composite resin for shear bonding strength test. RESULTS AND CONCLUSION： （1） The shear bond strength of the dentine was lowest in the control group [（4.03±1.80） MPa], and highest in the 2 W laser group [（14.12±3.23） MPa], followed by the acid etching group [（13.11±3.23） MPa]. （2） Under the scanning electron microscope, the dentin surface of the control group was covered with a smear layer and debris. Dentin tubule of the acid etching group completely opened, with increased pipe diameter, the smear layer was removed presenting with the smooth surface on which only a little debris was seen, and no marked boundary existed between the pertitubular dentin and intertubular dentin. The dentin surface in the laser group was rugged andpresented with fish scale-shaped flakes, the dentin tubule opened, and the intertubular dentin seemed to ablate more than the pertitubular dentin, showing a cuff-like protrusion of the dentinal tubules without smear layer. As the laser energy improved, blocking of the dentin tubule occurred, and some cracks and fractures appeared on the dentin surface. Fluctuant dentin surface was detected in the combined group, in which overall demineralization was higher and embolism and clogging of the dentin tubule was more prominent compared with the laser group. Overall, Er,Cr：YSGG laser ablation of the primary teeth, prior to the adhesive protocol, influences the shear bond strength to the primary tooth dentin and the best parameters for Er,Cr：YSGG laser are 2 W, 20 Hz, 100 mJ.