JoVE Journal > Engineering
Summary
Abstract
Introduction
Protocol
Results
Discussion
Disclosures
Acknowledgements
Materials
References
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공학

测量光学牙科印象的完整拱形失真

Published: May 30, 2019
doi:
10.3791/59261
,
1Department of Prosthodontics, College of Dentistry,Yonsei University

Summary

在这里,我们提出一个协议,用于测量从带有标准几何形状的 3D 打印金属幻象的口腔内扫描仪获得的竞争拱形数字印象的每个部分的失真程度。

Abstract

自从牙医开始通过使用口腔内扫描仪获取 3D 图像来制作数字图像以来,数字工作流程一直积极用于制作牙科修复或口腔器具。由于扫描患者口腔内口腔的性质,口腔内扫描仪是一种手持设备,带有一个小光学窗口,将小数据拼接在一起,完成整个图像。在完整的印记过程中,印象体可能发生变形,并影响修复或装置的配合。为了测量这些变形,使用金属 3D 打印机设计和生产了主试样。设计的参考几何体允许为每个印图设置独立的坐标系,并测量圆柱顶圆中心的 x、y 和z位移,并评估印图的变形。 为了评价该方法的可靠性,计算了圆柱体的坐标值,比较了原始计算机辅助设计(CAD)数据与工业扫描仪获取的参考数据。两组之间的坐标差大多小于50μm,但由于3D打印在摩尔上倾斜设计的圆柱体的z坐标中的公差,偏差很高。但是,由于打印模型设置了新标准,因此不会影响测试评估的结果。参考扫描仪的可重复性为11.0~1.8 μm。此测试方法可用于识别和改进口腔内扫描仪的内在问题,或通过测量完整拱形数字印象的每个部分的失真程度来建立扫描策略。

Introduction

在传统的牙科治疗过程中,固定修复或可拆卸假牙是在石膏制成的模型上,并浸入硅胶或不可逆的氢胶材料。由于间接制造的假肢是在口腔中交付的,因此已经做了大量的研究来克服一系列此类制造工艺1、2的错误。最近,一种数字方法被用来通过CAD过程来制造假肢,在获取3D图像后,在虚拟空间中操作模型,而不是给人留下印象3。在早期,这种光学印模方法在有限的范围内使用,例如对一颗或少量牙齿进行牙科治疗。然而,随着3D扫描仪基础技术的开发,整个拱门的数字印象现在被用于制造大规模固定修复,可拆卸的修复,如部分或全假牙,正畸器具,和植入手术指南4,5,6,7。在短区域(如单边拱门)中,数字印象的准确性令人满意。然而,由于口腔内扫描仪是一种手持式设备,通过将通过狭窄的光学窗口获得的图像拼接在一起来完成整个凹痕,因此在完成 U 形牙科拱后可以看到模型的失真。因此,在这个型号上制成的大范围设备可能不适合病人的口腔,需要很大的调整。

已经报道了各种关于使用口腔内扫描仪获得的虚拟印象体精度的研究,并且有各种研究模型和测量方法。根据研究课题,可分为临床研究8、9、10、11、12、12、体外研究13、14 ,15,16在模型单独生产研究。临床研究的优点是能够评估实际临床环境的条件,但很难控制变量并无限期地增加临床病例数。临床研究的数量并不大,因为能够评估所需的变量是有限度的。另一方面,许多通过控制变量来评估口腔内扫描仪基本性能的体外研究已经报告17。研究模型还包括部分或完整的自然牙齿拱18,19,20,21,22和一个完全凹陷的下颚与所有牙齿失去23,或牙种植体在一定间隔24、25、26、27处安装并间隔的情况,或大部分牙齿保留且仅部分牙齿的形态。牙齿失踪16,28。然而,手持式口腔内扫描仪对虚拟印象体变形的研究仅限于通过将虚拟印象体与参考数据叠加并表示为一个数字而创建的颜色映射对偏差进行定性评估。每个数据的值。很难准确测量完整拱形的 3D 失真,因为大多数研究只检查具有非定向距离偏差的牙科拱门的局部部分。

本研究使用带有坐标系的标准模型,研究了口腔内扫描仪在光学印象过程中牙拱的变形。本研究的目的是提供一种评估口腔内扫描仪精度性能的方法,该扫描仪通过光学硬件和处理软件的差异表现出各种特性。

Protocol

1. 主试样制备 模型准备 取下颌面完整拱形模型上的人造牙齿(左、右母条、第二前摩尔和第二摩尔),仅剩1/5的颈椎部分。 CAD 设计 使用参考扫描仪获取主试样的数据。 使用逆向工程软件在修剪的六齿顶部设计气缸(顶部直径为 2 mm,气缸高度为 7 mm)。 在左二摩尔添加三个参考球体(直径 3.5 mm),以便从反向工程软件定义?…

Representative Results

根据最初设计的CAD数据计算出的每个圆柱体的坐标和工业级模型扫描仪扫描的3D打印金属主样本的参考扫描图像,如表1所示。两者之间的差异显示值低于 50 μm,但 3D 打印主试样中右侧第二摩尔圆柱体的z坐标值较低。虽然金属幻象是由高端工业3D打印机生产的,但发现一个圆柱体的高度有细微差异。当设计使用CAD软件时,金属幻象被用作参考,用各种测试的口?…

Discussion

在通过评估由此产生的数字印图体来评估口腔内扫描仪准确性的研究中,最常见的方法是在参考图像上叠加数字印象数据并计算壳对壳偏差12 ,13,14,15,20,23。但是,此方法仅限于计算与配对数据的偏差值或通过颜色映射定性地评估分布。在一项通过选择?…

Disclosures

The authors have nothing to disclose.

Acknowledgements

这项研究得到了韩国卫生技术研发项目资助,该项目由韩国卫生与福利部资助(赠款号:HI18C0435)。

Materials

EOS CobaltChrome SP2 Electro Oprical Systems H051601 Powder type metal alloy for 3D printing
Geomagic Verify 3D Systems 2015.2.0 3D inspection software
Prosthetic Restoration Jaw Model Nissin Dental Products Inc. Mandibular complete-arch model
Rapidform Inus technology RF90600-10004-010000 Reverse engineering software
stereoSCAN R8 AICON 3D Systems GmbH Industrial-level model scanner
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Tags

Keywords: Optical Dental ImpressionIntraoral ScannersArch DistortionCoordinate System ExtractionReverse EngineeringReference SphereDental Arch DistortionX-y-z DirectionsBest-fit AlignmentMandibular Complete Arch ModelReference ScannerComputer-aided DesignReverse Engineering Software3D PrinterCobalt Chromium AlloyIndustrial Model ScannerIntraoral ScannerReference CoordinateReference GeometrySpherePlane
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Park, J., Shim, J. Measuring the Complete-arch Distortion of an Optical Dental Impression. J. Vis. Exp. (147), e59261, doi:10.3791/59261 (2019).
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