Three-dimensional virtual representation by superimposing facial and intraoral digital scans with an additively manufactured intraoral scan body

Accuracy of the 3-dimensional virtual patient representation obtained by using 4 different techniques: An in vitro study

STATEMENT OF PROBLEM

Facial and intraoral scans can be aligned with or without the assistance of extraoral scan body systems to obtain a 3-dimensional (3D) virtual patient representation. However, the accuracy of the virtual patient remains uncertain.

PURPOSE

The purpose of this in vitro study was to measure the accuracy of the virtual patient representation obtained by superimposing facial and intraoral digital scans with 4 different techniques (with and without the usage of extraoral scan bodies) and to measure the operator influence on the accuracy of the virtual patient integration.

MATERIAL AND METHODS

Three markers were placed in the jaw simulation of a mannequin on the right (r), center (c), and left (l) surfaces. Five additional markers were attached to the mesiobuccal cusp of the right first molar (RM), cusp of the right canine (RC), buccal surface of the right central incisor (CI), cusp of the left canine (LC), and mesiobuccal cusp of the left first molar (LM). A reference scan (control scan) of the mannequin was obtained by using an industrial scanner (Gom ATOS Q 3D 12 M). Four different groups were created depending on the technique used: 3D scan body (3D scan body) (3D-SB group), AFT (AFT Dental System) (AFT group), Sat 3D (Sat 3D) (Sat3D group), and without using a scan body system (No-SB group). Additionally, a digital scan of the typodont was obtained with an intraoral scanner (TRIOS 4). The virtual patient integration was performed 10 times per group by 2 independent operators by using a software program (DentalCAD, Galway). Each operator obtained a total of 9 interlandmark measurements on the reference scan and on each virtual patient integration of each group with the measurement tool of the computer-aided design program. The data were analyzed by using 4-way ANOVA followed by the pairwise comparison Tukey tests (α=.05).

RESULTS

The group (P<.001), specimen (P<.001), and operator (P<.001) significantly influenced the trueness discrepancies obtained. Additionally, the 3D-SB group had the best trueness (244 μm), and the No-SB group had the worst trueness (346 μm). Operator 1 (279 μm) obtained significantly better trueness than operator 2 (295 μm). Group (P<.001), specimen (P<.001), and operator (P<.001) significantly influenced precision discrepancies, with the AFT (149 μm) and 3D-SB (154 μm) groups having the best precision and the No-SB group (269 μm) the worst precision. Operator 1 (176 μm) obtained significantly better precision than operator 2 (197 μm).

CONCLUSIONS

The techniques tested influenced the accuracy of the 3D virtual patient representation. The 3D-SB group had the best trueness, and the AFT and 3D-SB groups had the best precision, while the No-SB group showed the lowest trueness and precision values. Operator handling had a significant effect on the trueness and precision values of the virtual patient integrations tested.

Creating three-dimensional virtual patients by superimposing intraoral and facial digital scans guided with an aligner system: A dental technique

A technique for creating 3-dimensional virtual patients (3DVPs) by superimposing intraoral and facial digital scans guided with a novel aligner system is described. This aligner system supports design modifications to adapt to different facial scanning methods (FSMs) and reduce the impact of FSMs on the accuracy of 3DVPs. Two different designs of the aligner system are described: one for use with less-accurate FSMs and another for use with more-accurate FSMs. These virtual designs are available for download and use.

Comparison of the accuracy (trueness and precision) of virtual dentofacial patients digitized by three different methods based on 3D facial and dental images

STATEMENT OF PROBLEM

The accuracy of virtual dentofacial patients has been explored, but the accuracy of virtual patients established by using a straightforward and reliable method and the accuracy of different virtual patients are unclear.

PURPOSE

The purpose of this clinical study was to compare the accuracy of virtual dentofacial patients digitized by using registered-block impression, exposed anterior teeth, and cone beam computed tomography (CBCT) reconstruction methods based on 3-dimensional (3D) facial and dental images.

MATERIAL AND METHODS

From the 15 selected participants who needed CBCT scanning, 3 kinds of virtual dentofacial patients were established by using 3 registration methods based on digital dental casts: 3D facial images, CBCT data, and registered-block impression. Compared with actual measurement, 25 linear distances of all virtual dentofacial patients were selected and measured by using a software program, and 3 separate measurements were calculated by the same person. The 1-way analysis of variance (ANOVA) was used to compare the deviations among 3 kinds of virtual dentofacial patients (trueness) and the deviations within groups (precision). The 1-sample t test was used to compare the difference between the deviation and the ideal error of 0.00 (α=.05).

RESULTS

Compared with the actual measurement, the trueness of the average deviations for registered-block impression (1.02 ±1.24 mm) was better than that of exposed anterior teeth (2.35 ±1.71 mm) and CBCT reconstruction (2.86 ±1.61 mm). The precision of the average deviations for registered-block impression (1.29 ±1.43 mm) was better than that of exposed anterior teeth (2.00 ±1.72 mm) and CBCT reconstruction (2.12 ±1.94 mm). Significant differences in trueness and precision were found among the 3 groups of virtual dentofacial patients (P<.01). Significant differences among the deviations of all linear distances and the ideal error of 0.00 were observed for all groups of virtual dentofacial patients (P<.05).

CONCLUSIONS

The accuracy of registered-block impression was better than that of the exposed anterior teeth and CBCT reconstruction. The accuracy of exposed anterior teeth was lower than that of the other methods but could satisfy the requirements of clinical diagnostics and scientific methods. The accuracy of CBCT reconstruction was poor and could only be used for special situations that permitted low accuracy.

Analysis of the impact of the facial scanning method on the precision of a virtual facebow record technique: An in vivo study

STATEMENT OF PROBLEM

Virtual facebow record techniques typically record the relationship of a maxillary digital scan to facial landmarks by aligning it to a 3-dimensional face scan. Three-dimensional face scans can be acquired with different facial scanning methods, but the impact of the facial scanning method on the accuracy (trueness and precision) of a virtual facebow record technique remains unclear.

PURPOSE

The purpose of this in vivo study was to assess the impact of the facial scanning method on the precision under the repeatability conditions (repeatability) of a virtual facebow record technique.

MATERIAL AND METHODS

Repeatability of the virtual facebow record technique with the following 3 clinical-grade facial scanning methods was determined and compared: a professional handheld scanner based on structured blue light scanning technology (PHS method); an attachment-type 3-dimensional sensor camera connected to a tablet and controlled with a mobile application (3DSC-T method); and a smartphone with an integrated 3-dimensional sensor camera controlled with a mobile application (3DSC-S method). To determine the repeatability of the virtual facebow record technique with each facial scanning method, 8 virtual facebow records of a completely dentate adult with class I occlusion and mesoprosopic facial form were obtained (8×3=24 in total); with these, 8 locations of a maxillary digital scan with respect to a common 3-dimensional face scan were obtained. Repeatability was determined in terms of deviations between located maxillary digital scans, determined, in turn, by calculating the distances between corresponding vertices for each of the possible nonrepeating combinations of pairs of located maxillary digital scans (8C2=28). Finally, the repeatability of the virtual facebow record technique with the different facial scanning methods was compared by using the Welch ANOVA test and the post hoc Games-Howell test (both α=.05).

RESULTS

The repeatability of the virtual facebow record technique with PHS, 3DSC-T, and 3DSC-S facial scanning methods resulted in 0.243 ±0.094 mm, 0.437 ±0.171 mm, and 1.023 ±0.399 mm, respectively. Comparison of these results revealed that the facial scanning method had a statistically significant effect on the repeatability of the virtual facebow record technique (P<.001) and that its repeatability was statistically significantly greater with the PHS facial scanning method than with the 3DSC-T and 3DSC-S facial scanning methods and greater with the 3DSC-T facial scanning method than with the 3DSC-S facial scanning method (P<.001 for all pairwise comparisons).

CONCLUSIONS

This study found that the facial scanning method had a great impact on the repeatability of the virtual facebow record technique and that the virtual facebow record technique was more repeatable with more accurate facial scanning methods.

Virtual patient representation with silicone guide and a 3D scanner accessory for a user-friendly facial scanning workflow: A clinical report of smile design and ceramic veneers

Digital smile design and ceramic veneers are described with virtual patient representation. The procedure included facial scanning with a 3D scanner accessory (Structure sensor pro; Occipital Inc) mounted on a tablet computer (iPad; Apple Inc) and an innovative chairside silicone guide to replace the intraoral scan body for a straightforward and user-friendly workflow.

Virtual 3-dimensional representation of a completely edentulous patient for computer-aided static implant planning

A technique is described to create a virtual 3-dimensional representation of an edentulous patient by aligning the facial, intraoral, and cone beam computed tomography scans guided by an additively manufactured scan body. Having the virtual patient facilitated the prosthetically driven implant planning, the additive manufacturing of the surgical implant guides, and the interim dental restorations.

A guide for maximizing the accuracy of intraoral digital scans. Part 1: Operator factors

OBJECTIVES

To describe the factors related to the operator skills and decisions that influence the scanning accuracy of intraoral scanners (IOSs). A new classification for these factors is proposed to facilitate dental professionals' decision making when using IOSs and maximize the accuracy and reliability of intraoral digital scans.

OVERVIEW

Each IOS system is limited by the hardware and software characteristics of the selected device. The operator decisions that can influence the accuracy of IOSs include the scanning technology and system selection, scanning head size, calibration, scanning distance, exposure of the IOS to ambient temperature changes, ambient humidity, ambient lighting conditions, operator experience, scanning pattern, extension of the scan, cutting off, rescanning, and overlapping procedures.

CONCLUSIONS

The knowledge and understanding of the operator factors that impact scanning accuracy of IOSs is a fundamental element for maximizing the accuracy of IOSs and for successfully integrating IOSs in daily practices.

CLINICAL SIGNIFICANCE

Operator skills and clinical decisions significantly impact intraoral scanning accuracy. Dental professionals must know and understand these influencing operator factors for maximizing the accuracy of IOSs.

Accuracy of RGB-D camera-based and stereophotogrammetric facial scanners: a comparative study

OBJECTIVES

This study aimed to evaluate and compare the accuracy and inter-operator reliability of a low-cost red-green-blue-depth (RGB-D) camera-based facial scanner (Bellus3D Arc7) with a stereophotogrammetry facial scanner (3dMD) and to explore the possibility of the former as a clinical substitute for the latter.

METHODS

A mannequin head was selected as the research object. In the RGB-D camera-based facial scanner group, the head was continuously scanned five times using an RGB-D camera-based facial scanner (Bellus3D Arc7), and the outcome data of each scan was then imported into CAD software (MeshLab) to reconstruct three-dimensional (3D) facial photographs. In the stereophotogrammetry facial scanner group, the mannequin head was scanned with a stereophotogrammetry facial scanner (3dMD). Selected parameters were directly measured on the reconstructed 3D virtual faces using a CAD software. The same parameters were then measured directly on the mannequin head using the direct anthropometry (DA) method as the gold standard for later comparison. The accuracy of the facial scanners was evaluated in terms of trueness and precision. Trueness was evaluated by comparing the measurement results of the two groups with each other and with that of DA using equivalence tests and average absolute deviations, while precision and inter-operator reliability were assessed using the intraclass correlation coefficient (ICC). A 3D facial mesh deviation between the two groups was also calculated for further reference using a 3D metrology software (GOM inspect pro).

RESULTS

In terms of trueness, the average absolute deviations between RGB-D camera-based and stereophotogrammetry facial scanners, between RGB-D camera-based facial scanner and DA, and between stereophotogrammetry facial scanner and DA were statistically equivalent at 0.50±0.27 mm, 0.61±0.42 mm, and 0.28±0.14 mm, respectively. Equivalence test results confirmed that their equivalence was within clinical requirements (<1 mm). The ICC for each parameter was approximately 0.999 in terms of precision and inter-operator reliability. A 3D facial mesh analysis suggested that the deviation between the two groups was 0.37±0.01 mm.

CONCLUSIONS

For facial scanners, an accuracy of <1 mm is commonly considered clinically acceptable. Both the RGB-D camera-based and stereophotogrammetry facial scanners in this study showed acceptable trueness, high precision, and inter-operator reliability. A low-cost RGB-D camera-based facial scanner could be an eligible clinical substitute for traditional stereophotogrammetry.

CLINICAL SIGNIFICANCE

The low-cost RGB-D camera-based facial scanner showed clinically acceptable trueness, high precision, and inter-operator reliability; thus, it could be an eligible clinical substitute for traditional stereophotogrammetry.

An overview of three-dimensional imaging devices in dentistry

OBJECTIVE

To review four types of three-dimensional imaging devices: intraoral scanners, extraoral scanners, cone-beam computed tomography (CBCT), and facial scanners, in terms of their development, technologies, advantages, disadvantages, accuracy, influencing factors, and applications in dentistry.

METHODS

PubMed (National Library of Medicine) and Google Scholar databases were searched. Additionally, the scanner manufacturers' websites were accessed to obtain relevant data. Four authors independently selected the articles, books, and websites. To exclude duplicates and scrutinize the data, they were uploaded to Mendeley Data. In total, 135 articles, two books, and 17 websites were included.

RESULTS

Research and clinical practice have shown that oral and facial scanners and CBCT can be used widely in various areas of dentistry with high accuracy.

CONCLUSION

Although further advancement of these devices is desirable, there is no doubt that digital technology represents the future of dentistry. Furthermore, the combined use of different devices may bring dentistry into a new era. These four devices will play a significant role in clinical utility with high accuracy. The combined use of these devices should be explored further.

CLINICAL SIGNIFICANCE

The four devices will play a significant role in clinical use with high accuracy. The combined use of these devices should be explored further.

Additively manufactured scan body for transferring a virtual 3-dimensional representation to a digital articulator for completely edentulous patients

A technique is described for obtaining a virtual 3-dimensional representation of completely edentulous patients with the virtual definitive casts mounted on the virtual articulator. An additively manufactured intraoral scan body was developed to record the definitive maxillary and mandibular casts and gothic arch interocclusal registration. The intraoral scan body guided the integration of the digital definitive casts and facial scans to obtain the virtual 3-dimensional patient's representation and facilitated the transfer of the definitive casts to the virtual articulator.