印模方式及预备体设计对全瓷高嵌体适合性的影响

Influence of impression technique and preparation design on adaptation of all-ceramic onlays

目的:研究不同印模制取方式及预备体设计对全瓷高嵌体边缘与内部适合性的影响。方法:制备洞深分别为2mm及5mm的下颌第一磨牙高嵌体预备体标准树脂代型各16个,分为四组,分别为A组(2mm硅橡胶组)、B组(2mm扫描组)、C组(5mm硅橡胶组)、D组(5mm扫描组),每组8个代型。采用硅橡胶印模和模拟口内数字化扫描获取各组印模并制作e. max全瓷高嵌体。粘接、包埋、切割后,用扫描电镜测量边缘及内部8个位点的粘接剂厚度并进行统计学分析。结果:印模方法及预备体设计对边缘间隙无影响(P> 0. 05);硅橡胶组在洞底及凹面转折点处的粘接剂厚度小于扫描组(P<0. 05);2mm组在近咬合面处适合性更优(P<0. 05),而5mm组在轴壁和凸面转折点处适合性更优(P<0. 05)。各组的边缘粘接剂厚度均小于120μm,4组不同位点间的粘接剂厚度差异均有统计学意义(P<0. 05),边缘的适合性优于内部适合性。修复体边缘点处4组间隙剂厚度差异无统计学意义,内部点处4组间差异有统计学意义(P<0. 05)。结论:对于不同洞深的预备设计,硅橡胶印模与数字化印模均能获得良好的高嵌体边缘和内部适合性;对有一定洞型深度(5mm)的高嵌体预备体制取数字化印模,高嵌体可获得良好的边缘适合性和更优的轴壁适合性。

Objective: To investigate the influence of different impression technique and preparation design on the marginal and internal adaptation of all-ceramic onlays. Methods: Resin dies of standard first mandible molar of onlay preparations were made, and-16 samples of each cavity depth(2 mm and 5 mm). 4 subgroups were assigned, A(2 mm/silicon),B(2 mm/scanning), C(5 mm/silicon). D(5 mm/scanning), each of 8 dies. Impressions from silicon or simulated oral digital scanning were made for each subgroup and e.max CAD onlays were fabricated. After cementing, embedding and cutting of samples, thickness of adhesive layer were measured at 8 points of marginal and internal places by scanning electron microscope and data were analyzed. Results: The influence of impression technique and preparation design on marginal discrepancy were not significant(P>0.05). At the point of cavity bottom and concave turning points, the adhesive film thickness were smaller in silicon group than in scanning group(P <0.05);at occlusion point, the adaptation of 2 mm-depth cavity group was better(P <0.05);at axis wall and convex turning point, the adaptation of 5 mm-depth cavity group was better(P<0.05). The adhesive film thickness at marginal points were below 120μm for all samples, the adhesive film thickness had significant differences at all measured points in each subgroup(P<0.05), and the adaptation were better at marginal points than at internal points. At marginal points, there were no significant differences in adhesive film thickness among 4 subgroups, but at internal points, the differences were statistically significant(P<0.05). Conclusions: For different cavity depths of preparation design, good internal and marginal adaptation of onlays could be achieved from both silicon impression and digital impression. By taking digital impression for the onlay preparations with a definite cavity depth(5 mm), good marginal adaptation and better axis wall adaptation of onlays could be obtained as well.