摘要目的 比较不同酸蚀时间处理后牙釉质表面的三维形貌并分析粗糙度的改变,探讨酸蚀对牙釉质微观形貌的影响.方法 将15颗新鲜前磨牙包埋、切割、打磨后得到光滑牙釉质切片,按单纯随机法分为5组,用37％磷酸凝胶分别酸蚀0(对照组)、5、10、20和30s,原子力显微镜观察釉质表面形貌,分析轮廓改变,计算图像的算术平均粗糙度(Ra)、均方根粗糙度(Rq)、十点高度平均差(Rz)值及表面积、容积并对5组的结果数据进行单因素方差分析,用Turkey's法进行组间两两比较,以P＜0.05为差异有统计学意义.结果 镜下形貌观察显示,0～20 s内釉质的釉柱结构逐渐明显,釉质表面由较光滑逐渐变为典型鱼鳞状；20 s后表面形态变化不明显.表面轮廓观察显示,随着酸蚀时间由0s增加至30 s,釉柱间隙首先被溶解,酸蚀深度逐渐增加到2.8μm,30 s后釉柱顶部宽度减小至1.8μm,且高度略降低.从0s到30 s,Ra值由(19.69±3.42) nm增加到(359.51±75.79)nm,Rq值由(22.02±5.57) nm增加到(431.02±83.09) nm,Rz值由(0.24±0.08) μm增加到(2.38±0.26) μm;组间比较显示,Ra和Rq值的20s组与30 s组和Rz值的10、20和30 s组差异无统计学意义(P＞0.05),其余各组间差异均有统计学意义(P＜0.05).同时釉质表面积由(406.77±3.88) μm2 (0 s)增大到(546.69±84.02) μm2 (30 s),容积由(65.73±14.46) μm3 (0 s)增大到(474.63±52.50)μm3(30 s).结论 随着酸蚀时间的增加,釉质表面酸蚀深度不断增大,表面粗糙度增加,表面积及容积增大,酸蚀会造成釉质微观形貌的明显改变.

abstractsObjective To compare the three dimensional morphology and surface roughness changes of enamel eroded for different etching time.Methods Fifteen freshly extracted sound human pre-molars for orthodontic purpose were collated.The buccal surface of teeth were prepared into smooth enamel slices,and then were randomly divided into5 groups based on their etching time 0 s (control group),5 s,10 s,20 s,30 s,respectively by 37％ phosphoric acid.The three dimensional morphology was observed under atomic forcemicroscope(AFM).The profile was analyzed,and the value of Ra,Rq,Rz and the surface area and volume were measured.Results The AFM photograph showed that with the etching time from 0 s to 20 s the enamel surface demineralised gradually,the top structure of enamel rod and the fish scaled structure became obvious.But the morphology only changed a bit after 20 s.The surrounding inter-rod enamel eroded first,the depth increased to 2.8 μm at 20 s but decreased to 1.8 μm at 30 s.The value of Ra increased from (19.69 ± 3.42) nm to (359.51 ±75.79) nm,and Rq from (22.02±5.57) nm to (431.02±83.09) nm,Rz from (0.24±0.08) μm to (2.38 ±0.26) μm Except for groups 20 s and 30 s,the difference among other groups was statistically significant(P＜0.05).The surface area expanded from (406.77 ±3.88) μm2 to (546.69 ±84.02) μm2,and surface volume from ( 65.73 ± 14.46 ) μm3 to (474.63 ± 52.50 ) μm3.Conclusions The depth,surface roughness,surface area and volume caused by erosion increased with etching time.The three dimensional morphology greatly changed by acid-etching process.