Face Scanning Research Articles

Comparing analog and 3D measurements of vertical dimension in edentulous subjects.

This study aimed to explore the feasibility and reliability of measuring the vertical dimension of occlusion/rest (OVD/RVD) on 3D facial scans of edentulous patients. Nineteen edentulous participants rehabilitated with complete removable dental prostheses (CDs) participated in this study. Analog measurements (control) were obtained directly on the face for each participant with the jaws positioned at the rest position (without CDs, RVD) and at central occlusion (OVD), between the facial landmarks: Glabella (G) and Soft Pogonion (SP), Pronasale (PN) and SP, and Subnasale (SN) and SP. Participants' faces were scanned twice, using a face-scanner (Class 1 LASER, Obiscanner). Scans were imported into a mesh-processing software, and the OVD/RVD were measured digitally. Two investigators performed all the measurements and were blinded. Data analysis included intra-class correlation coefficient (ICC) and pairwise comparison tests (p<0.05). Digital measurements were higher than analog measurements, and the mean paired difference ranged from -4.86±3.2 to 0.42±2.7 mm. All the differences were statistically significant, expect for SN-SP (p=0.110). Magnitude of the differences for the RVD were large for G-SP and SN-SP (ES>0.80) and moderate for PN-SP (ES>0.50). There was a large effect for G-SP when measuring OVD (ES>0.50), and small effect for PN-SP and SN-SP (ES≤0.20). Considering the limitations associated with the specific type of facial scanner used in this study, it can be concluded that registering the resting vertical dimension in edentulous patients through digital methods may not be recommended. This is due to the potential errors that may arise during the data acquisition process, which could compromise the accuracy and reliability of the measurements. Digital methods for registering the vertical dimension of rest (RVD) in edentulous patients can introduce errors, resulting in occlusal errors and discomfort. Clinicians must, for the moment, still use conventional analog methods to ensure accurate RVD measurement for a successful denture therapy.

Ocular Injuries in Patients with Old Blow-out Fractures Following Blunt Trauma.

To analyze the frequency, and clinical characteristics of ocular injuries in patients with prior blow-out fractures who experience new blunt trauma, and to assess whether old orbital fractures provide a protective effect against subsequent ocular trauma. The medical records of 1,315 ocular trauma patients were reviewed. A total of 927 patients who had orbital or facial CT scans and ophthalmologist evaluations were considered. After applying exclusion criteria, 568 patients with 581 affected eyes were included in the final analysis. The patients were divided into two groups based on the presence of old blow-out fractures, identified on CT scan. The clinical characteristics and the frequency of ocular injuries were compared between the two groups. The risk of ocular injury according to the presence of old blow-out fracture ware studied using multiple logistic regression after controlling age and sex. Among the 581 eyes examined, 140 (24.1%) had old blow-out fractures. The incidence of intraocular complications was significantly higher in the no orbital fracture group (20.4%) compared to the old blow-out fracture group (2.1%) (p < 0.001). Specifically, the incidence of complications such as gross hyphema (p = 0.001), globe rupture (p = 0.006), and vitreous hemorrhage (p = 0.027) was significantly greater in the group without old blow-out fractures than in those with them. Multiple logistic regression showed that the presence of old blow-out fractures was significantly associated with reduced risk of ocular injury (p < 0.001). The patients with old blow-out fractures had a lower risk of ocular injuries following subsequent blunt trauma. The findings suggest that old fractures may provide protective effect. These results may have important implications for the clinical management of patients at risk of recurrent orbital trauma.

Fibre type differences in the organisation of mononuclear cells and myonuclei at the tips of human myofibres.

The myotendinous junction (MTJ) is a weak link in the musculoskeletal system. Here, we isolated the tips of single myofibres from healthy human hamstring muscles for confocal microscopy (n=6) and RNAscope in situ hybridisation (n=6) to gain insight into the profiles of cells and myonuclei in this region, in a fibre type manner. A marked presence of mononuclear cells was observed coating the myofibre tips (confirmed by serial block face scanning electron microscopy and cryosection immunofluorescence), with higher numbers for type I (median 29; range 16-63) than type II (16; 9-23) myofibres (p<0.05). The number of these cells expressing COL22A1 was comparable between fibre types. Myonuclear number and density gradually increased from the myofibre proper towards the tip for both fibre types (p<0.05). COL22A1 was expressed by similar proportions of myonuclei in type I (median 26%; range 13-56) and type II (19%; 3-67) myofibre tips. 70% of the COL22A1+ nuclei in the MTJ region were myonuclei, and the remaining 30% were MTJ cells. This insight refines our fundamental understanding of the human MTJ at the cell and structural levels.

Image analysis of kimchi cabbage penetrated with brine and seasoning using a serial block face scanning electron microscope and energy dispersive X-ray spectroscopy

Image analysis of kimchi cabbage penetrated with brine and seasoning using a serial block face scanning electron microscope and energy dispersive X-ray spectroscopy

Managing Low-Velocity Mandibular Gunshot Wounds: An Institutional Review and the "FLOSS" Severity Scoring System.

Management of mandibular ballistic trauma is poorly delineated, given the variable injury complexity. This study examines surgical outcomes and presents a novel scoring system to define and guide the management of low-velocity ballistic mandibular fractures. A retrospective chart review was performed from 2015 to 2022 to collect data on patients who suffered ballistic mandibular fractures. Computerized tomography facial bone scans were analyzed to determine a mandible severity scoring based on the following "F.L.OS.S." variables: fracture description (F), location of fracture (L), other surrounding fractures (OS), and soft tissue involvement (S). Sixty-six patients suffered handgun-related mandibular fractures and 54 underwent surgical intervention. The mean FLOSS score was 7.9 for all surgical patients and significantly differed between treatment groups (P = 0.011). Certain injury-specific variables were significantly associated with higher FLOSS scores including >2 areas of comminution along load bearing, bony gap >10mm, or intraoral involvement with soft tissue avulsion; however, the degree of displacement, bilateral involvement, or presence of concomitant fractures did not predict higher scores. The types of complications did not significantly vary for total FLOSS score or FLOSS subcategories; the only exception being, an association between bony gap (>10mm) and hardware exposure (P = 0.045). Overall surgical complication rate was 26.9% and presence significantly varied between surgical treatments (P = 0.019); specifically, nonunion was the only significant subcategory (P = 0.030). The FLOSS scoring system may be a useful adjunct in defining fracture characteristics that guide appropriate surgical intervention for low-velocity ballistic mandibular injuries.

Orienting to and away from the eyes in infants at high likelihood for autism when scanning faces.

This study employed eye-tracking technology to investigate the mechanisms underlying reduced gaze towards the eyes in infants at high likelihood (HL) for autism, specifically examining whether it results from avoidance triggered by heightened arousal when looking at the eyes or due to indifference to the eyes (i.e., unwilling to orient to the eyes). Infants at HL for autism and typically developing (TD) infants aged within 24 months were tested. In the experiment, participants' gaze was initially guided to the eye or mouth region immediately before the onset of the face. Latency to orient away from the guided regions, latency to orient to the eyes, and the location of the secondary fixation following the onset of the face were measured. The results showed that: (1) The HL infants looked less at eyes than TD infants; (2) Compared with TD infants, HL infants oriented towards eyes more slowly after being guided to the mouth; (3) After being guided to the eyes, HL infants' secondary fixation fell less in the eye region, and their latency to orient away from the eyes was also tended to be shorter. These results suggest that reduced eye-looking time was presented in HL infants, which was further explained by both eye avoidance and indifference to the eyes. Our study contributes theoretically to understanding the atypical face scanning pattern in autistic people and its related underlying mechanisms. Furthermore, our study provides important insights into the development of early screening tools and intervention protocols for autistic people.

Accuracy Evaluation of a Three-Dimensional Face Reconstruction Model Based on the Hifi3D Face Model and Clinical Two-Dimensional Images.

Three-dimensional (3D) facial models have been increasingly applied in orthodontics, orthognathic surgery, and various medical fields. This study proposed an approach to reconstructing 3D facial models from standard orthodontic frontal and lateral images, providing an efficient way to expand 3D databases. A total of 23 participants (average age 20.70 ± 5.36 years) were enrolled. Based on the Hifi3D face model, 3D reconstructions were generated and compared with corresponding face scans to evaluate their accuracy. Root mean square error (RMSE) values were calculated for the entire face, nine specific facial regions, and eight anatomical landmarks. Clinical feasibility was further assessed by comparing six angular and thirteen linear measurements between the reconstructed and scanned models. The RMSE of the reconstruction model was 2.00 ± 0.38 mm (95% CI: 1.84-2.17 mm). High accuracy was achieved for the forehead, nose, upper lip, paranasal region, and right cheek (mean RMSE < 2 mm). The forehead area showed the smallest deviation, at 1.52 ± 0.88 mm (95% CI: 1.14-1.90 mm). In contrast, the lower lip, chin, and left cheek exhibited average RMSEs exceeding 2 mm. The mean deviation across landmarks was below 2 mm, with the Prn displaying the smallest error at 1.18 ± 1.10 mm (95% CI: 0.71-1.65 mm). The largest discrepancies were observed along the Z-axis (Z > Y > X). Significant differences (p < 0.05) emerged between groups in the nasolabial, nasal, and nasofrontal angles, while the other 13 linear and 3 angular measurements showed no statistical differences (p > 0.05). This study explored the feasibility of reconstructing accurate 3D models from 2D photos. Compared to facial scan models, the Hifi3D face model demonstrated a 2 mm deviation, with potential for enriching 3D databases for subjective evaluations, patient education, and communication. However, caution is advised when applying this model to clinical measurements, especially angle assessments.

Influence of Simulated Skin Color on the Accuracy of Face Scans

Aims: this study aims to investigate the impact of simulated skin color and the use of fiducial markers on the accuracy of 3D facial scans, comparing two types of structured light scanners under constant ambient lighting conditions. Materials and Methods: Three mannequins with different skin colors—black, white, and pink—were scanned using two light based hand-held scanners (infrared light and blue-light). Each mannequin was scanned with and without fiducial markers placed on defined anatomical landmarks. A total of one hundred thirty-two scans were performed and converted into standard tessellation language (STL) files. STL files from each scanner were compared to their respective control scans using point cloud comparison software. Accuracy was evaluated based on root mean square (RMS) values. Descriptive statistics summarized the data, and a t-test was performed to assess differences in RMS values between scans with and without fiducial markers for each scanner type. Results: The infrared light scanner showed the highest accuracy for the white mannequin, as evidenced by lower RMS values compared to the pink and black mannequins. Adding fiducial markers significantly enhanced scan accuracy for the pink and black mannequins. The blue-light scanner achieved accuracy for the white and pink mannequins comparable to that of the infrared scanner. However, it was unable to scan the black mannequin, even with the use of markers. Conclusions: Within the limitations of this study, simulated skin color significantly affects the accuracy of facial 3D scans. Scans of lighter (white) tones demonstrate higher accuracy compared to darker tones. Fiducial markers enhance the accuracy for an infrared scanner; however, a blue-light scanner is unable to capture dark simulated skin, even with the addition of fiducial markers.

Automated pipeline for linear and volumetric assessment of facial swelling after third molar surgery

BackgroundExtraction of mandibular third molars (M3Ms) is a routine procedure in oral and maxillofacial surgery, often associated with postoperative symptoms like pain, facial swelling, and trismus. This study aimed to introduce a standardized and automated protocol for swelling analysis following M3M surgery, presenting results regarding clinical conditions immediately and one-week after surgery.MethodsIn a prospective study, 35 patients were enrolled (mean age: 24.4 ± 5.8 years) for removal of 54 M3Ms. Facial swelling was evaluated through 3D facial scans before surgery (T0), at three days (T1), and seven days (T2) post-surgery. The open-source software 3DSlicer facilitated automated analysis, including data anonymization, orientation, surface registration, qualitative comparisons, linear measurements, and volumetric quantification. Pairwise superimposition of facial models enabled qualitative, vectorial, and quantitative assessments, comparing initial conditions with swelling development at T1 and T2. Additionally, changes between T1 and T2 were also evaluated. Secondary outcomes encompassed clinical evaluations of pain, trismus (maximum mouth opening), and surgery time. Statistical analysis involved the paired Student t-test to assess longitudinal changes and analysis of variance to evaluate outcome variables concerning difficulty scores. Linear regression models correlated primary outcome variables with secondary study variables (α < 0.05).ResultsLongitudinal analysis demonstrated significant but variable facial swelling, pain, and trismus at T1, followed by improvement at T2 (p < 0.001). Linear and volumetric differences correlated positively with surgery time (p < 0.05). A direct proportionality between linear and volume differences was observed, higher values at T1 correlated with higher values at T2 (p < 0.05).ConclusionsAn innovative digital workflow for precise quantification of postoperative facial changes was implemented, incorporating volumetric measurements that surpass linear assessments. Clinical conditions demonstrated a direct correlation with surgery time, deteriorating immediately and improving one-week after surgery.

Evaluating sagittal condylar inclination: a comparative analysis of various digital workflow measures

IntroductionThis study aims to compare sagittal condylar inclination (SCI) measurements derived from three workflows: intraoral scan (IOS) aligned with cone-beam computed tomography (CBCT), IOS aligned with facial scan (FS), and a jaw motion analyzer (JMA) system, in a cohort of young individuals with established normal occlusion. Additionally, the study aims to identify sources contributing to variance in these measurement approaches.MethodsTwenty-four healthy individuals exhibiting normal occlusion were enrolled in this clinical trial. The SCI was delineated using a virtual articulator (VA) by aligning IOS with both CBCT and FS, creating two distinct workflows labeled CBCT-IOS and FS-IOS, respectively. Concurrently, SCI measurements were also acquired using a JMA. The normality of data distribution for the difference in bilateral SCI measurements within each workflow was tested using the Shapiro-Wilk test. Depending on the outcomes of this test, we utilized either a paired-sample T-test or Wilcoxon test for bilateral SCI comparisons. The inter-workflow differences were assessed using the Kruskal-Wallis H test. Bland-Altman plots were assess the interchangeability and consistency across each pair of digital methods and to evaluate the aggregate consistency among the trio of digital approaches.ResultsThe analysis revealed that the CBCT-IOS workflow yielded the lowest average SCI measurements, whereas the JMA workflow produced the highest values. No significant differences were found in the SCI measurements between the left and right sides obtained by CBCT-IOS and JMA (P > .05), with the exception of the FS-IOS workflow (P = .002). Additionally, inter-flow comparisons revealed no significant differences in SCI measurements (P > .05), except when contrasting the SCI as measured by CBCT-IOS and JMA (P = .0131). The Bland-Altman plots demonstrated a high degree of consistency and 95% limits of agreement across the three digital workflows.ConclusionSCI measurements obtained from the three digital workflows exhibit a high degree of consistency and are interchangeable, affirming their clinical applicability for precise SCI assessment in young individuals with normal occlusion.

Adaptive representation learning and sample weighting for low-quality 3D face recognition

3D face recognition (3DFR) algorithms have advanced significantly in the past two decades by leveraging facial geometric information, but they mostly focus on high-quality 3D face scans, thus limiting their practicality in real-world scenarios. Recently, with the development of affordable consumer-level depth cameras, the focus has shifted towards low-quality 3D face scans. In this paper, we propose a method for low-quality 3DFR. On one hand, our approach employs the normalizing flow to model an adaptive-form distribution for any given 3D face scan. This adaptive distributional representation learning strategy allows for more robust representations of low-quality 3D face scans (which may be caused by the scan noises, pose or occlusion variations, etc.). On the other hand, we introduce an adaptive sample weighting strategy to adjust the importance of each training sample by measuring both the difficulty of being recognized and the data quality. This adaptive sample weighting strategy can further enhance the robustness of the deep model and meanwhile improve its performance on low-quality 3DFR. Through comprehensive experiments, we demonstrate that our method can significantly improve the performance of low-quality 3DFR. For example, our method achieves competitive results on both the IIIT-D database and the Lock3DFace datasets, underscoring its effectiveness in addressing the challenges associated with low-quality 3D faces.

Comparative Accuracy of Stationary and Smartphone-Based Photogrammetry in Oral and Maxillofacial Surgery: A Clinical Study.

Background: Three-dimensional facial scan technologies, such as stereophotogrammetry, are frequently used in oral and maxillofacial surgery, dentistry, and plastic surgery to assess patient outcomes and plan surgical procedures. Most facial scanners rely on stationary clinical systems, which provide high accuracy and reliability in generating 3D representations of the human face; however, they are cost-intensive and immobile. Recently, smartphone-based facial scan applications that use stereophotogrammetry have been developed. These applications are cost-effective and more accessible than existing stationary systems. Methods: In this study, we compared the accuracy of three different smartphone applications-EM3D, Polycam, and ScandyPro-on an iPhone 14 Pro, which utilizes Apple's LiDAR (Light Detection and Ranging) technology, to a stationary system by 3DMD, which is considered a gold standard in many studies. Results: The applications included in the study have demonstrated the capability to perform accurately in clinical settings, with mean surface distances of 1.46 mm for EM3D, 1.66 mm for Polycam, and 1.61 mm for ScandyPro. Conclusions: These results suggest that smartphone-based facial scan systems could be a viable alternative, particularly in resource-limited settings. However, further research and collaboration between academia and industry are necessary to fully integrate these technologies into clinical practice.

Assessing 3D volumetric asymmetry in facial palsy patients via advanced multi-view landmarks and radial curves

The research on facial palsy, a unilateral palsy of the facial nerve, is a complex field with many different causes and symptoms. Even modern approaches to evaluate the facial palsy state rely mainly on stills and 2D videos of the face and rarely on dynamic 3D information. Many of these analysis and visualization methods require manual intervention, which is time-consuming and error-prone. Moreover, they often depend on alignment algorithms or Euclidean measurements and consider only static facial expressions. Volumetric changes by muscle movement are essential for facial palsy analysis but require manual extraction. We propose to extract an estimated unilateral volumetric description for dynamic expressions from 3D scans. Accurate landmark positioning is required for processing the unstructured facial scans. In our case, it is attained via a multi-view method compatible with any existing 2D predictors. We analyze prediction stability and robustness against head rotation during video sequences. Further, we investigate volume changes in static and dynamic facial expressions for 34 patients with unilateral facial palsy and visualize volumetric disparities on the face surface. In a case study, we observe a decrease in the volumetric difference between the face sides during happy expressions at the beginning (13.8 ± 10.0 mm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {mm}^{3}$$\\end{document}) and end (12.8 ± 10.3 mm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {mm}^{3}$$\\end{document}) of a ten-day biofeedback therapy. The neutral face kept a consistent volume range of 11.8-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-$$\\end{document}12.1 mm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {mm}^3$$\\end{document}. The reduced volumetric difference after therapy indicates less facial asymmetry during movement, which can be used to monitor and guide treatment decisions. Our approach minimizes human intervention, simplifying the clinical routine and interaction with 3D scans to provide a more comprehensive analysis of facial palsy.

Innovative hybrid approach: digital and analog fabrication of orbital prosthesis for post-COVID-19 mucormycosis defects using photogrammetry technique

In addition to anatomical loss, removal of the full or portion of the orbit results in a facial deformity and psychological distress for the patient. This article details a practical case of prosthetic rehabilitation using digital workflow for an orbital deformity caused by post-COVID-19 Mucor mycosis. The main goal of this case study was to create a maxillofacial orbital prosthesis that is well-retained, simple to use, and accurate in terms of appearance. The study addresses the problems involved in fabricating the orbital prosthesis, particularly the unique dimensions and form of the defect, replicating the natural skin tone, and accomplishing retention by the most prudent and patient-friendly approach. Through this article, a digitised algorithm, using photogrammetry technique for facial scan, is suggested for fabricating the prosthesis.

3D printed customized facemask for early treatment of Class III malocclusion: a two-center case series feasibility study.

This prospective two-center case series feasibility study aimed to investigate the potential of a novel maxillary protraction facemask customized to the patients' anatomy recorded with 3D face scanning and then produced by digital design and additive manufacturing. Ten subjects (5 females and 5 males, average age 7.7±1.0 years) with Class III malocclusion were treated with a rapid maxillary expander (RME) and a Petit-type facemask (FM), whose components were digitally designed on a 3D scan of the patient's face. Subjects' face scans were obtained either with a tablet or with face scanner. FM components were modelled with a 3D software. The pads were 3D printed in biocompatible resin, and the bar was printed in stainless steel. A questionnaire investigating the patients' experience was filled in after the first week of treatment and after 3, 6, and 9 months. The customized FM showed an excellent adaptation to the anatomy of the face. No severe complications were reported during the 9 months of appliance wearing. Some reversible episodes of skin irritation were reported below the pads, mainly in the chin area. The reported time wearing ranged between 8.2±2.3 and 9.5±1.2 hours per day, mainly at night. Reported pain was overall low (maximum after 1 week with an average value of 1.9±1.7 on a visual analog scale [VAS] 0-10) and patients' satisfaction was adequate at the end of the facemask wear after 9 months (8.7±1.4 on a VAS 0-10). The customized FM was overall well accepted by the patients and represents a valid alternative to conventional ones.

A Facial Motion Retargeting Pipeline for Appearance Agnostic 3D Characters.

3D facial motion retargeting has the advantage of capturing and recreating the nuances of human facial motions and speeding up the time-consuming 3D facial animation process. However, the facial motion retargeting pipeline is limited in reflecting the facial motion's semantic information (i.e., meaning and intensity), especially when applied to nonhuman characters. The retargeting quality heavily relies on the target face rig, which requires time-consuming preparation such as 3D scanning of human faces and modeling of blendshapes. In this paper, we propose a facial motion retargeting pipeline aiming to provide fast and semantically accurate retargeting results for diverse characters. The new framework comprises a target face parameterization module based on face anatomy and a compatible source motion interpretation module. From the quantitative and qualitative evaluations, we found that the proposed retargeting pipeline can naturally recreate the expressions performed by a motion capture subject in equivalent meanings and intensities, such semantic accuracy extends to the faces of nonhuman characters without labor-demanding preparations.

Assessing last month's stress levels with an automated facial behavior scan.

Stress is one of the most pressing problems in society as it severely reduces the physical and mental wellbeing of people. It is therefore of great importance to accurately monitor stress levels, especially in work environments. However, contemporary stress assessments, such as questionnaires and physiological measurements, have practical limitations, mostly related to their subjective or contact-based nature. To assess stress objectively and conveniently, we developed an automated model that detects biomarkers in webcam-recorded facial behavior indicative of heightened stress levels, using computer vision, artificial intelligence, and machine learning techniques. Heart-rate induced skin pulsations and facial muscle activity were extracted from videos of 264 participants that performed an online mental capacity test under considerable time pressure. The model could successfully use these facial biomarkers to explain a significant proportion of individual differences in scores on a self-perceived stress scale. Next, we used the model to objectively score stress levels of 63 military candidates (pre-hiring) and 69 military personnel (post-hiring) that also performed the mental capacity test. Results showed that military personnel expressed facial behavior indicative of significantly higher stress levels than military candidates. This suggests that joining the military heightens overall stress levels. With this study we take the first steps towards a non-contact, automated, and objective measure of stress that is easily applicable in a variety of health and work contexts.

Accuracy of a facebow record: A comparison between a conventional facebow and a smartphone 3D scanner

Statement of problemAccurately transferring the maxillary cast to the articulator is an essential step in most prosthodontics procedures in both digital and conventional workflows. Recently, the use of a smartphone 3-dimensional (3D) scanner-based virtual facebow record has been reported, but its accuracy is unclear. PurposeThe purpose of this clinical study was to compare the trueness and precision of a virtual facebow record made with a smartphone 3D scanner with that of a conventional facebow technique. Material and methodsOne hundred facebow records were obtained from 10 participants using a virtual facebow record made with a smartphone 3D scanner (VFR_SP) and with a conventional facebow record (CFR) (n=10). In the VFR_SP group, a printed facebow fork was used to obtain virtual facebow records by using a smartphone-based face scanner. For the CFR group, an analog facebow record was obtained and scanned by using an industrial scanner. A cone beam computed tomography (CBCT) scan with an aligned maxillary arch scan was used as the control for each participant. Three reference points were placed on the maxillary arch scan on the right first molar, left central incisor, and left first molar. Scans from each group were superimposed on the CBCT scan to determine trueness. Scans within each group were also superimposed on each other to determine precision. Linear deviation at the 3 reference points and the angular deviation of occlusal planes were measured using a Python script. The trueness and precision of the 2 groups were compared by using a linear mixed model to account for repeated measures (α=.05). ResultsNo significant linear trueness differences between the 2 groups were found (P>.05). However, the VFR_SP group showed significantly less angular deviation: 1.53 degrees for the virtual facebow and 2.03 degrees for the conventional facebow group (P=.046). Regarding precision, the VFR_SP group showed significantly less linear deviation: 1.59 mm for the virtual facebow group and 2.33 mm for the conventional facebow group (P<.001), as well as angular deviation: 1.03 degrees for the virtual facebow group and 2.17 degrees for the conventional facebow (P<.001). ConclusionsThe VFR_SP group showed better accuracy compared with the CFR group. Further research with a larger sample size is needed.

Digital Approach Provides Predictability in Increasing the VDO in Erosive Wear: Clinical Technique and 9-Year Follow-Up.

This clinical case describes a digital workflow using face scans and CAD/CAM technology for a full-mouth rehabilitation with increased vertical dimension of occlusion (VDO) with adhesive lithium disilicate restorations after 9 years. A healthy, 46-year-old man displaying severe tooth wear, underwent an extensive full-mouth rehabilitation involving an increase of the VDO through laminate veneers and adhesive partial coverage lithium disilicate restorations. Anatomical landmarks of the face and reference planes were captured using a digital face scanning system. The anatomical position of the maxilla was registered with a transfer device. Digital data sets of the intraoral situation combined with a facial scan enabled precise virtual planning, guiding minimally invasive preparations. Long-term provisional restorations, milled from high-performance polycarbonate, were used to test the novel VDO before the final lithium disilicate restorations were fabricated. This approach provided a time- and cost-efficient treatment solution. No failures were observed at the 9-year follow-up. Utilizing face scans and design software enable a virtual visualization and comprehensive quality control for patients with dental wear, resulting in significant time savings and increased predictability for the dental technician, dentist and patient. The described digital workflow optimizes the planning and implementation of a comprehensive adhesive full-arch rehabilitation with an increase of the VDO. The clinical long-term follow up result of CAD/CAM assisted minimally invasive lithium disilicate restorations after 9 years demonstrates to clinicians a reliable treatment concept for patients with dental wear.

The Orientation in Space of the Maxillary Arch: New and Old Devices in the Prosthetic Digital Workflow.

In extensive prosthetic rehabilitations and in those involving the anterior area, a correct 3D spatial position is of fundamental importance for effective communication between the clinician and the dental technician. The aim of this article is to analyze the different methods used to position in space and/or in an articulator the maxillary arch in analog workflows highlighting shortcomings and difficulties in order to understand how to overcome them when employing digital workflows. Traditional mechanical devices, such as anatomical, kinematic, esthetic and postural facebows, have clear indications, but also limitations, especially in cases of skeletal asymmetries. Modern digital tools, including photography, CBCT, facial scanners and jaw recording devices, are here critically analyzed to illustrate the advantages of working in a virtual space. The adoption of digital tools in the prosthetic workflow represents a significant improvement compared to traditional techniques, as it reduces errors and artifacts of registration and transfer of the position of the maxillary arch in the articulator space. This contributes to more predictable esthetic and functional results, with a positive impact for clinicians and technicians, improving clinical-laboratory communication, operational efficiency and overall quality of work. The integration of digital tools into prosthetic workflows represents an important advancement in clinical practice since they reduce human error and facilitate communication between the clinician and the laboratory. When carrying out rehabilitations involving changes in esthetics or occlusal plane orientation, the proper and accurate positioning of the upper arch in space is particularly relevant.