三维点激光扫描仪的扫描可靠性研究

目的全面评价Roland LPX-1200三维点激光扫描仪的扫描可靠性，为临床研究提供参考。方法规则加工的仿牙齿样模具，使用Roland LPX 1200点激光扫描仪获得其数字化模型，通过比较不同起始位置的扫描结果，评价扫描仪的扫描可重复性；选择长，宽，高三维方向上65项测量项目，比较数字化模型测量与实物测量之间的差异，评价其扫描准确性。结果连续扫描以及改变扫描初始位置引起的扫描随机误差在0．02mm以内；数字化模型测量与实物测量之间的差值均数为0．0012±0．05mm，P〈0．05。结论扫描仪具有良好的可靠性，能满足正畸临床对模型测量精度的要求。     

三维激光扫描测量外鼻形态的可靠性研究

目的 :验证三维激光扫描测量系统测量外鼻形态的技术可靠性。方法 :取 11个石膏鼻模型为研究对象 ,通过三维激光扫描测量系统获取外鼻的三维数字化模型 ,利用相关测量软件对其进行形态测量 ,并以手工测量得到的测量结果为对照组进行统计学分析。结果 :激光三维扫描测量结果与手工测量结果高度相关。结论 :三维激光扫描测量系统进行鼻形态测量结果完全可靠 ,测量误差符合人体测量学的要求。     

基于激光扫描的面部软组织三维模型准确性评估

目的 评估基于激光扫描所建立的面部软组织三维模型和软组织测量标志点的准确性.方法 在一受试者的面部进行标志点标记,直接测量各标记点间的距离,之后使用Minolta Vivid 9i三维激光扫描仪进行面部扫描合成三维图像后,应用软件测量标记点间距离,对比两种方法的差异.另选择10名成年女性,在激光扫描前预先标记左右耳屏中点为固定标志点,再选取面部其余测量标志点22个.直接测量耳屏点与测量标志点间的距离,之后测量三维成像后耳屏点与测量标志点间距离,对比两者的差异.所有数据进行配对t检验.结果 基于激光扫描所建立的面部软组织三维模型的准确度为（0.72±0.51）mm.其中水平向、垂直向和前后向的准确度分别为（0.70±0.41）mm、（0.73±0.47）mm和（0.72±0.54）mm.59％的软组织测量标志点具有较高的准确性.结论 基于激光扫描的面部软组织三维模型具有较好的准确性.     

基于激光扫描的面部软组织三维模型的重叠和分析方法的建立

目的：确定同一个体正畸治疗前后面部软组织三维模型的重叠方法,并建立一个可以客观评估面部软组织形态和大小改变的分析方法。方法对一受试者进行6次面部激光扫描,分别为受试者额头区域预先标记一矩形标记物,并在面部预先标记7个标志点。口内配戴一前庭盾活动矫治器。去除标记物,保留标志点,口内不配戴前庭盾。去除标记物,保留标志点,口内配戴前庭盾。去除标记物和标志点,口内不配戴前庭盾。去除标记物和标志点,口内配戴前庭盾。使用Rapidform XOV软件进行点重叠和额部区域重叠。再对重叠图像进行截面分析。结果3次点重叠的结果具有可重复性,且与区域重叠相比,点重叠更好的反映了戴入前庭盾后面部的变化。图像总体对比法和截面分析法分别定性和定量的显示了面部软组织的变化。结论建议使用点重叠的方法对比正畸治疗前后面部软组织的变化。图像总体对比法和截面分析法各具特点,均可反映面部的变化。     

基于激光扫描的面部软组织三维模型三种重叠方法的对比

目的 对比面部软组织三维模型重叠的3种重叠方法.方法 选择22例正畸治疗前后的成人患者,在正畸治疗前后拍摄头颅侧位片并同期进行面部软组织激光扫描.测量鼻尖点(Pn)、鼻下点(Sn)、上唇缘点(Ls)、下唇缘点(Li)、下唇凹点(B')和颏前点(Pos)在头颅侧位片上的变化.使用Rapidform XOV和XOR软件进行点重叠、额部区域重叠和软件自动重叠,以额点、软组织鼻根点和鼻尖点确定正中矢状向平面,分别测量不同方法重叠后Pn、Sn、Ls、Li、B'和Pos点的变化量.并以头颅侧位片的结果为标准,对比3种重叠方法的差异.进而,对比使用3种重叠方法后面部10个区域最大变化值的差异.结果 使用头颅测量片测得的Pn、Sn、Ls、Li、B'和Pos点正畸治疗前后的变化值,与软组织三维模型的测量值间无显著差异.点重叠、区域重叠和自动重叠后面部10个区域的最大变化值也均无显著差异.结论 对于成人而言,点重叠、额部区域重叠和软件自动重叠这3种软组织重叠方法没有显著差异.     

一种新型三维牙颌模型激光扫描仪可靠性对比研究

目的：检验新型三维牙颌模型激光扫描仪的可靠性。方法：分次利用不同方法，扫描和测量8副牙列石膏模型上的解剖标志点，对测量结果进行统计分析。结果：同一激光扫描两次定点的线距和角度的测量结果之间差异没有显著性；两次激光扫描分别定点测量的线距和角度结果之间差异也没有显著性；激光扫描定点测定和三维测量仪分别测得的线距和角度结果之间差异也没有统计学意义。结论：D.0.2-L-3D SCANNER激光扫描仪具有较高的精度，较好的可靠性，扫描速度快，扫描盲区少，该系统可以用于以后修复体CAD/CAM系统光学印模的制取。     

Soft tissue changes after orthodontic surgical correction of jaws asymmetry evaluated by three-dimensional surface laser scanner

ABSTRACT: Aesthetic improvement is an essential goal of treatment of facial asymmetry, and it is often difficult to achieve. Reliable three-dimensional measurements are required to support outcome studies.In this study, 15 white adult subjects, 9 females and 6 males, with maxillomandibular asymmetry and malocclusion were studied. The patients were treated with orthodontics and different surgical procedures in single or multiple steps. All patients received double-jaw surgery, except 1 patient who underwent only maxillary osteotomy. Nine of the 15 patients received additional procedures (genioplasty and rhinoplasty) to achieve better symmetry. Posterior-anterior and lateral cephalometry and three-dimensional facial surface data were obtained before (T0) and 1 year (T1) after surgery. Scan data at T0 and T1 were pooled by electronic surface averaging to obtain the mean pretreatment and posttreatment facial model. A symmetric model was constructed by averaging the actual T0 scans and their mirrored models to obtain the virtual optimal symmetric face. Different linear and angular measurements were then calculated for comparison of the mean T0 and T1 models. The normalization of facial proportion and a high increase in symmetry were evident. Residual defects were documented in the postoperative symmetry of the chin. Treatment of facial asymmetry, combined with dental occlusion problems, is still a challenge for maxillofacial surgeons. Orthognathic surgery provides an important improvement of symmetry, but further refinements of technique are still required. Three-dimensional evaluation results in an effective method to support outcome studies on the surgical correction of complex facial deformities.     

A three-dimensional evaluation of a laser scanner and a touch-probe scanner

STATEMENT OF PROBLEM: The fit of a dental restoration depends on quality throughout the entire manufacturing process. There is difficulty in assessing the surface topography of an object with a complex form, such as teeth, since there is no exact reference form. PURPOSE: The purpose of this study was to determine the repeatability and relative accuracy of 2 dental surface digitization devices. A computer-aided design (CAD) technique was used for evaluation to calculate and present the deviations 3-dimensionally. MATERIAL AND METHODS: Ten dies of teeth prepared for complete crowns were fabricated in presintered yttria-stabilized tetragonal zirconia (Y-TZP). The surfaces were digitized 3 times each with an optical or mechanical digitizer. The number of points in the point clouds from each reading were calculated and used as the CAD reference model (CRM). Alignments were performed by registration software that works by minimizing a distance criterion. In color-difference maps, the distribution of the discrepancies between the surfaces in the CRM and the 3-dimensional surface models was identified and located. RESULTS: The repeatability of both scanners was within 10 microm, based on SD and absolute mean values. The qualitative evaluation resulted in an even distribution of the deviations in the optical digitizer, whereas the dominating part of the surfaces in the mechanical digitizer showed no deviations. The relative accuracy of the 2 surface digitization devices was within +/- 6 microm, based on median values. CONCLUSION: The repeatability of the optical digitizer was comparable with the mechanical digitization device, and the relative accuracy was similar.     

The use of a 3D laser scanner using superimpositional software to assess the accuracy of impression techniques

Objective. Several studies have made comparisons in the dimensional accuracy of different elastomeric impression materials. Most have used two-dimensional measuring devices, which neglect to account for the dimensional changes that exist along a three-dimensional surface.

Purpose. The aim of this study was to compare the dimensional accuracy of an impression technique using a polyether material (Impregum) and a vinyl poly siloxane material (President) using a laser scanner with three-dimensional superimpositional software.

Materials and methods. Twenty impressions, 10 with a polyether and 10 with addition silicone, of a stone master model that resembled a dental arch containing three acrylic posterior teeth were cast in orthodontic stone. One plastic tooth was prepared for a metal crown. The master model and the casts were digitised with the non-contacting laser scanner to produce a 3D image. 3D surface viewer software superimposed the master model to the stone replica and the difference between the images analysed.

Results. The mean difference between the model and the stone replica made from Impregum was 0.072 mm (SD 0.006) and that for the silicone 0.097 mm (SD 0.005) and this difference was statistically significantly, p=0.001.

Conclusions. Both impression materials provided an accurate replica of the prepared teeth supporting the view that these materials are highly accurate.     

国产三轴牙颌模型扫描仪的一种标定方法

目的 建立国产牙颌模型三维扫描仪的标定方法，并对标定结果进行检验。方法 设计专用定制的带有量化指标的标准块，对其采集三维数据后用最小二乘法对数据进行拟合，从而获得系统参数。标定完成后分别与手工测量和机械式三坐标测量仪(YM-2115)进行了牙颌模型测量的相关对比实验。结果 实验结果显示经标定完成后对牙颌模型测量结果与手工测量和机械式三坐标测量仪的测量结果没有显著性差异，初步验证了该标定方法的可行性。结论 研究表明该标定方法简便、准确，可以作为一种常规方法对国产D．02-L-3DSCANNER牙颌模型扫描仪进行日常维护性标定。     

Craniofacial applications of three-dimensional laser surface scanning

Recent innovations in technology have generated a variety of techniques for medical imaging. One of these initially developed for industry is laser surface scanning. Laser surface scanning is a noninvasive method for acquiring three-dimensional (3D) images. In this article, the technology of 3D laser surface scanning is described, and a few applications are reported as it relates to craniofacial research and clinical practice. Advantages and disadvantages of this imaging modality are discussed. Three-dimensional laser surface scanning holds great promise as it relates to the documentation, analysis, and evaluation of treatment results in craniofacial anomalies.     

Reliability of measuring facial morphology with a 3-dimensional laser scanning system.

INTRODUCTION: The purpose of this prospective clinical trial was to evaluate the reliability of a 3-dimensional facial scanning technique for the measurement of facial morphology. METHODS: A field study was conducted in 2 comprehensive schools in the South Wales region of the United Kingdom. Forty subjects, mean age 11 years 3 months, were analyzed for soft tissue changes at baseline (T1), within 3 minutes (T2), and 3 days later (T3) by using 2 commercially available Minolta Vivid 900 (Osaka, Japan) laser-scanning devices assembled as a stereo pair. Left and right images were merged to form the whole face, and these images were superimposed to assess the errors at T1 and T2, and T1 and T3. RESULTS: The results showed that premerged left and right mean shell deviations were 0.38 +/- 0.14 mm for scans at T1, 0.31 +/- 0.09 mm at T2, and 0.34 +/- 0.12 mm at T3. The mean differences of the merged composite face were 0.31 +/- 0.08 mm between T1 and T2, and 0.40 +/- 0.11 mm between T1 and T3. Paired t tests showed no significant difference between these groups (P > .05). Shell deviation facial maps of the merged scans showed that 90% of the created composite facial scans were within an error of 0.85 mm. CONCLUSIONS: Capturing the soft tissue morphology of the face with this technique is clinically reproducible within 3 minutes and 3 days of the initial records.     

Reliability of digital orthodontic setups

Objective:To evaluate the reliability of digital orthodontic setup technology by comparing it with manual setups and models cast at the end of orthodontic treatment.Materials and Methods:Initial models, manual setups, and final models of 20 patients were used. The initial and final models, as well as the manual setups, were scanned using a 3Shape R-700 scanner, while the digital setups were fabricated based on the initial models using 3Shape OrthoAnalyzer software. Evaluation of the models based on the manual setup, digital setup, and final models of each patient was performed using the following linear measurements: intercanine widths, intermolar widths, and length of the upper and lower dental arches.Results:The results disclosed that none of the measures assessed through the manual setup, digital setup, and final models showed statistically significant differences (P > .05).Conclusions:Based on these findings, it can be inferred that digital setups are as effective and accurate as manual setups and constitute a tool for diagnosing and treatment planning that can be reliably reproduced in orthodontic treatments.     

Nd: YAG laser for debonding ceramic orthodontic brackets.

INTRODUCTION: The purpose of this study was to develop an effective method for debonding ceramic orthodontic brackets with a high-peak power Nd:YAG laser. METHODS: Two types of ceramic brackets (single crystal and polycrystalline) were bonded to mandibular bovine teeth with 2 types of bonding resins (4-META/MMA and Bis-GMA). The laser was applied to 2 points on each bracket, each with a 1-pulse-per-second shot. Bond strength and thermal effects of the laser on the dentin surface were assessed at 3 laser energy levels: 1.0, 2.0, and 3.0 joules (J). Shear tests were performed on the irradiated test group and on a nonirradiated control group. ANOVA was used to determine significant differences. RESULTS: The shear test (P < .05) showed that every specimen in the 2.0-J and 3.0-J groups underwent a significant decrease in bonding strength compared with the nonirradiated group. However, the 1.0-J group did not exhibit any such difference. In the 2 former groups, laser irradiation alone was sufficient to debond some specimens. No significant difference was found between bonding resins. The maximum temperature rise measured on the pulpal walls at the lasing points was 5.1 degrees C. CONCLUSIONS: The application of a high-peak power Nd:YAG laser at 2.0 J or more is effective for debonding ceramic brackets.     

Integration of 3-D shapes of dentition and facial morphology using a high-speed laser scanner

PURPOSE: The purpose of this study was to develop a method to integrate three-dimensional data of dentition and facial morphology measured by a high-speed laser scanner, and visualize them by computer graphics. The accuracy of integration was also examined. MATERIALS AND METHODS: The 3-D shapes of upper and lower dental casts and the face of a subject were measured by a high-speed laser scanner with zoom lens facility. As an interface to integrate the coordinates between dentition and face, an extraoral marker plate attached to the occlusal record plate was devised. It was applied between the upper and lower dental casts, and with the subject, and measured. Integration was attempted by coinciding the data of the interface. The accuracy of integration was examined using the conditions of the marker plate such as surface shape and attachment angle. RESULTS: Integration of the data of dentition and face was accomplished. The 3-D relationship between them could be visualized in any direction or section by computer graphics. For optimal accuracy of integration, the marker plate with a mixed shape of flat and sinusoidal wave attached at 45 degrees to the occlusal record plate showed the most appropriate results. CONCLUSION: An original method to integrate the 3-D data of dentition and face measured by 3-D laser scanner was developed and shown to have acceptable accuracy.