Assistant Professor and Assistant Program Director AEGD residency, College of Dentistry, Texas A&M University, Dallas, Texas; Affiliate Faculty Graduate Prosthodontics, School of Dentistry, University of Washington, Seattle, Wash; Researcher at Revilla Research Center, Madrid, Spain.
Graduate student AEGD residency, College of Dentistry, Texas A&M University, Dallas, Texas.
J Prosthet Dent. 2021 Jun;125(6):918-923. doi: 10.1016/j.prosdent.2020.03.019. Epub 2020 May 31.
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.
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.
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).
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).
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.
先前的研究已经分析了影响口内扫描仪准确性的因素；然而，口内扫描体设计如何影响虚拟最终模型上的种植体位置尚不清楚。
本体外研究的目的是测量使用 3 种不同扫描体设计进行数字扫描时，虚拟最终种植体模型中种植体复制位置的差异。
准备一个带有 3 个种植体复制体（Implant Replica RP Branemark 系统；Nobel Biocare Services AG）的部分无牙牙列模型。根据评估的扫描体系统，确定了 3 组：SB-1（Elos Accurate Nobel Biocare）、SB-2（NT Digital Implant Technology）和 SB-3（Dynamic Abutment）。每个扫描体都放置在牙列模型的每个种植体复制体上，并按照制造商的扫描协议，在 1000 勒克斯照度下使用口内扫描仪（iTero Element；Cadent）进行数字化。获得标准三角测量语言（STL）文件。在从牙列模型上取下扫描体之前，使用坐标测量机（Contura G2 10/16/06 RDS；Carl Zeiss Industrielle Messtechnik GmbH）测量扫描体在 x、y 和 z 轴上的位置。使用特定程序（Calypso；Carl Zeiss Industrielle Messtechnik GmbH）通过最佳拟合技术计算扫描体在牙列模型上的位置和 STL 文件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 检验表明数据不呈正态分布。使用 Mann-Whitney U 检验（α=.05）对数据进行分析。
由于在最小压力下触诊时的可移动性，坐标测量机无法测量带磁性固位的 SB-3 组的扫描体位置。因此，该组被排除在外。在 SB-1 和 SB-2 组之间，线性差异无显著差异（P>.05）。在 z 轴上获得了最准确的扫描体位置。然而，SB-1 组的 XZ 角度差异明显高于 SB-2 组（P<.001）。
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传输到虚拟最终种植体模型。然而，在分析的扫描体系统之间观察到 XZ 角度种植体位置存在显著差异。
