Effect of subgingival depth of implant placement on the dimensional accuracy of the implant impression: An in vitro study
Effect of subgingival depth of implant placement on the dimensional accuracy of the implant impression: An in vitro study
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DOI：
10.1016/s0022-3913(08)60026-8
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发表时间：
2008-02-01
影响因子：
4.6
通讯作者：
Feng, Changyong
中科院分区：
文献类型：
--
作者：
Lee, Heeje;Ercoli, Carlo;Feng, Changyong
问题陈述。在某些情况下，种植体需要放置在龈下深处，这可能导致种植体的准确性降低。本研究的目的是评价种植体植入龈下深度对种植体印模准确性的影响。用5个植入物类似物（RN synOcta类似物）制作结石主模型，在中心（E）和4个角（A、13、C和D）彼此平行嵌入。植入物肩部的垂直位置在植入物之间故意不同：A和E与模型的顶面齐平; B低于表面2 mm，C和D低于表面4 mm。用测量显微镜测量种植体A、13、C和D与E的水平距离。然后制造一个十字形金属测量杆并连接到E上，铸件的臂设计为高于模型的顶面2 mm，并包含一个参考标记。将测量杆连接到E，用数字测微计测量A、B、C和D的顶面到测量参考标记的垂直距离。种植体D的印模内冠主体通过增加4 mm的额外印模内冠进行了修改，而所有其他种植体均使用标准印模内冠。使用中等体聚醚材料（Impregum Penta）或油灰和轻质乙烯基聚硅氧烷（VPS）材料（Elite HD+）的组合制作开放托盘印模（n=15）。然后用IV型牙科结石浇注铸件。采用上述主模型的方法测量模型的垂直和水平距离。收集作为主模型测量值和铸件测量值之间的差异确定的失真值用于统计分析。进行双因素和单因素重复测量ANOVA，然后进行Tukey's HSD检验以比较失真值（α =.05）。对于垂直测量，双因素重复测量ANOVA显示无显著深度（P=36）、材料（P= 0.24）或相互作用效应（P= 0.06）。然而，水平测量显示出显著的深度效应（P=.01）。在聚醚组内，单因素重复测量ANOVA显示不同深度种植体之间的水平测量值存在显著差异（P=.03）。事后Tukey检验显示，使用正常印模帽的4 mm深种植体印模（C）的准确性明显低于0 mm深种植体印模（A）（P=.02）。在VPS组内，不同深度的种植体之间没有显著差异（P=.09）。植入深度对VPS组的准确性没有影响。然而，对于聚醚组，种植体放置在龈下4 mm的印模显示出更大的水平变形相比，种植体放置更冠。在印模帽的固位部分增加一个4 mm的延长部分消除了这种差异。
Statement of problem. In some instances, an implant needs to be placed deep subgingivally, which may result in a less accurate impression of the implant.Purpose. The purpose of this study was to evaluate the effect of subgingival depth of implant placement on the accuracy of implant impressions.Material and methods. A stone master model was fabricated with 5 Implant analogs (RN synOcta analog), embedded parallel to each other, at the center (E) and the 4 corners (A, 13, C, and D). The vertical position of the shoulders of the implants was intentionally different among the implants: A and E were flush with the top surface of the model; B was 2 mm below, and C and D were 4 mm below the surface. The horizontal distances of implants A, 13, C, and D from E were measured with a measuring microscope. A cross-shaped metal measuring bar was then fabricated and connected to E, with the arms of the casting designed to be 2 mm above the top surface of the model and incorporating a reference mark. With the measuring bar connected to E, the vertical distances from the apical surface of A, B, C, and D to the measuring reference marks were measured with a digital micrometer. The body of the impression coping for implant D was modified by adding 4 mm of additional impression coping, while standard impression copings were used for all other implants. Open tray impressions were made using medium-body polyether material (Impregum Penta) or a combination of putty and light-body vinyl polysiloxane (VPS) material (Elite HD+) (n=15). Then casts were poured with type IV dental stone. The vertical and horizontal distances of the casts were measured with the methods outlined above for the master model. The distortion values that were determined as differences between the measurements of the master model and those of the casts were collected for statistical analysis. Two-way and 1-way repeated measures ANOVA followed by Tukey's HSD test were performed to compare the distortion values (alpha=.05).Results. For vertical measurements, 2-way repeated measures ANOVA showed no significant depth (P=36), material (P=.24), or interaction effects (P=.06). However, it showed significant depth effect for horizontal measurements (P=.01). Within the polyether group, 1-way repeated measures ANOVA showed significant differences in horizontal measurements among the implants with different depths (P=.03). The post hoc Tukey's test showed that the impression of 4-mm-deep implants with normal impression copings (C) was significantly less accurate than impressions of 0-mm-deep implants (A) (P=.02). Within the VPS group, there was no significant difference among the implants with different depths (P=.09).Conclusions. There was no effect of implant depth on the accuracy of the VPS group. However, for the polyether group, the impression of an implant placed 4 mm subgingivally showed a greater horizontal distortion compared to an implant placed more coronally. Adding a 4-mm extension to the retentive part of the impression coping eliminated this difference.