Ⅱ类洞龈壁位置对Palodent重建邻接关系影响的数字模型研究

目的：体外研究Ⅱ类洞龈壁相对邻牙位置的差异对使用Palodent重建邻接关系效果的影响。方法临床选取一典型Ⅱ类病损的下颌第一磨牙患例，经印模并翻制得7个模型。以龈壁外上缘近远中最凸点和邻牙邻面近远中最凸点为测量参照点定水平间距（X）和垂直间距（Y），模型龈壁行树脂修整以符合3组9种条件（其中2种为重复）：A组，参照点Y取0 mm，X分别取0、1、2 mm；B组，参照点Y取0 mm，X分别取1、0、－1 mm；C组，参照点X取1 mm，Y分别取1、0、－1 mm。模型修整后行三维扫描得数字化模型母本，数字模型母本按分组复制，每组12个体共108样本，记录并存档后掩盖原编码，重新随机编号，由一独立医师作数字计算机虚拟修复，第2位医师审核，两位医师共同评估修复操作难度后，第3位高年资医师评估邻接关系重建质量。比较各龈壁条件成形效果构成及修复操作难度。结果 X0 Y0、X0 Y-1、X1 Y-1试验组成形效果优于 X1 Y0、X2 Y0、X0 Y1、X1 Y1试验组（P均＜0．05）。结论Ⅱ类洞龈壁位置可对Palodent重建邻接关系形成显著影响，试验条件下理想成形龈壁位置条件包括X0 Y0、X0 Y-1、X1 Y-1。

Effect of class II direct restorations with Palodent systems at different positions of gingival wall on proximal contacts with digital models

Objective To study the influence in vitro of rebuilding the proximal contacts with Palo-dent system on class II resin composite restorations at different relative positions of gingival wall. Methods The first mandibular molar with typical interproximal decay was collected and then prepared for 7 replicates. All replicates were divided into 3 groups：group A,same interproximal vertical interval （Y）as 0 mm and different horizontal intervals （X）were 0 mm,1 mm and 2 mm;group B ,the same interproximal level interval as 0 mm and different vertical intervals were 1 mm,0 mm and -1 mm;group C,the same interproximal horizontal in-terval as 1 mm and different vertical intervals were 1 mm,0 mm and -1 mm. The distance between the mesio-distal peak point of margo superior gingival wall laterale and adjacent surface of proximal teeth was utilized for measurement. The treated replicates and Palodent matrix were subject to 3D scans to form format digital models and a total of 108 digital models were established （n=12 for each group）. All identifiers of digital models were masked and computer virtual restorations were performed by the same operator. The second operator validated the results. The third independent operator evaluated the efficacy of rebuilding proximal contacts after the first two operators evaluated the level of difficulty. The level of difficult was analyzed with one-way ANOVA and the Tukey test. The component ratio of quality of restoration was analyzed with Chi-square test. Result The quality of rebuilding proximal contacts of X0 Y0 ,X0 Y-1 and X1 Y-1 positions was significantly better compared with those of X1 Y0 ,X2 Y0 ,X0 Y1 and X1 Y1 positions. Conclusions Different relative positions of gingival wall exert sig-nificant effects upon the Palodent system rebuilding proximal contacts. Experimental results revealed that X0 Y0 ,X0 Y-1 and X1 Y-1 positions yielded the best effect.