Statement of problem

Previous studies have analyzed factors influencing intraoral scanner accuracy; however, how the intraoral scan body design affects the implant position on the virtual definitive cast is unclear.

Purpose

The purpose of this in vitro study was to measure the discrepancies of the implant replica positions of the virtual definitive implant cast obtained by using 3 different scan body designs when performing a digital scan.

Material and methods

A partially edentulous typodont with 3 implant replicas (Implant Replica RP Branemark system; Nobel Biocare Services AG) was prepared. Three groups were determined based on the scan body system evaluated: SB-1 (Elos Accurate Nobel Biocare), SB-2 (NT Digital Implant Technology), and SB-3 (Dynamic Abutment). Each scan body was positioned on each implant replica of the typodont, and was digitized by using an intraoral scanner (iTero Element; Cadent) as per the manufacturer’s scanning protocol at 1000 lux illuminance. A standard tessellation language (STL) file was obtained. Before the scan bodies were removed from the typodont, a coordinate measuring machine (CMM Contura G2 10/16/06 RDS; Carl Zeiss Industrielle Messtechnik GmbH) was used to measure the scan body positions on the x-, y-, and z-axis. The linear and angular discrepancies between the position of the scan bodies on the typodont and STL file were calculated by using the best fit technique with a specific program (Calypso; Carl Zeiss Industrielle Messtechnik GmbH). The procedure was repeated until 10 STL files were obtained per group. The Shapiro-Wilk test revealed that the data were not normally distributed. The data were analyzed by using the Mann-Whitney U test (α=.05).

Results

The coordinate measuring machine was unable to measure the scan body positions of the magnetically retained SB-3 group because of its mobility when palpating at the smallest pressure possible. Therefore, this group was excluded. No significant differences were found in the linear discrepancies between the SB-1 and SB-2 groups (P>.05). The most accurate scan body position was obtained on the z-axis. However, the SB-1 group revealed a significantly higher XZ angular discrepancy than the SB-2 group (P<.001).

Conclusions

The scan body systems tested (SB-1 and SB-2 groups) accurately transferred the linear implant positions to the virtual definitive implant cast. However, significant differences were observed in the XZ angular implant positions between the scan body systems analyzed.

中文翻译：

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扫描体设计对转移到虚拟最终种植体模型时种植体位置准确性的影响

问题陈述

先前的研究分析了影响口内扫描仪准确性的因素；但是，口腔内扫描体设计如何影响虚拟固定石膏上的植入物位置尚不清楚。

目的

这项体外研究的目的是测量在执行数字扫描时使用 3 种不同的扫描体设计获得的虚拟最终种植体模型的种植体复制位置的差异。

材料与方法

制备具有3个植入物复制品的部分缺牙型牙印体（Implant Replica RP Branemark system； Nobel Biocare Services AG）。根据评估的扫描体系统确定了三组：SB-1（Elos Accurate Nobel Biocare）、SB-2（NT 数字种植技术）和 SB-3（动态基台）。每个扫描体都被定位在每个牙齿的种植体复制品上，并根据制造商的扫描协议在 1000 勒克斯照度下使用口内扫描仪（iTero Element; Cadent）进行数字化。获得了标准的镶嵌语言（STL）文件。在将扫描体从印刷体上移除之前，使用坐标测量机（CMM Contura G2 10/16/06 RDS；Carl Zeiss Industrielle Messtechnik GmbH）测量 x、y 和 z 轴上的扫描体位置轴。通过使用最佳拟合技术和特定程序 (Calypso; Carl Zeiss Industrielle Messtechnik GmbH) 计算了印刷体和 STL 文件上扫描体位置之间的线性和角度差异。重复该过程，直到每组获得 10 个 STL 文件。Shapiro-Wilk 检验表明数据不是正态分布的。通过使用 Mann-Whitney U 检验 (α=.05) 分析数据。

结果

坐标测量机无法测量磁性保留的 SB-3 组的扫描体位置，因为它在尽可能小的压力下触诊时具有机动性。因此，这个群体被排除在外。SB-1和SB-2组之间的线性差异无显着差异（P > .05）。在 z 轴上获得了最准确的扫描体位置。然而，SB-1 组显示出比 SB-2 组显着更高的 XZ 角度差异（P <.001）。

结论

测试的扫描体系统（SB-1 和 SB-2 组）准确地将线性种植体位置转移到虚拟最终种植体模型。然而，在所分析的扫描体系统之间观察到 XZ 角植入物位置存在显着差异。