Objective: To compare the accuracy of photogrammetry and conventional impression techniques for complete-arch implant rehabilitation. Methods: An edentulous maxillary stone cast containing 8 screw-retained implant abutment replicas was derived from a 74-year-old male patient who visited the Department of Dental Implant Center, Capital Medical University School of Stomatology in September 2019. The stone cast was copied through the open-tray splinted impression, and the copied cast was used as the master cast for this study. The abutment-level impressions of master cast were made by photogrammetry (PG) and the conventional impression technique (CNV) by one attending doctor. Group PG: after which scan bodies were connected to each implant replica, a photogrammetry system was used to obtain digital impressions of the master cast (n=10); Group CNV: conventional open-tray splinted impression technique was performed to fabricate conventional definitive casts (n=10). After connecting the scan bodies onto each implant replicas, the master cast and the 10 definitive casts from group CNV were digitized with a laboratory reference scanner. All data of group PG, group CNV and mater cast were saved as ".stl" files. For all test scans and reference scan, the three-dimensional information of scan bodies were converted to implant abutment replicas using a computer aided design software (Exocad). The data of the group PG and the group CNV were respectively registered with the reference data (trueness analysis) and pairwise within group (precision analysis) for accuracy evaluation in a three-dimensional analysis software (Geomagic Control X). Results: The trueness and precision of group PG [(17.33±0.34) and (2.50±0.79) μm ] were significantly statistically better than those of group CNV [(24.30±4.16) and (26.12±4.54) μm] respectively (t=-5.29 and -34.35, P<0.001). Conclusions: For complete-arch implant abutment-level impression, photogrammetry produces significantly better accuracy than conventional impression technique.
Aged ; Computer-Aided Design ; Dental Implants ; Dental Impression Materials ; Dental Impression Technique ; Humans ; Models, Dental ; Photogrammetry

OBJECTIVE: To assess the reproducibility of non-verbal facial expressions (smile lips closed, smile lips open, lip purse, cheek puff) in normal persons using dynamic three-dimensional (3D) imaging and provide reference data for future research. METHODS: In this study, 15 adults (7 males and 8 females) without facial asymmetry and facial nerve dysfunction were recruited. Each participant was seated upright in front of the 3D imaging system in natural head position. The whole face could be captured in all six cameras. The dynamic 3D system captured 60 3D images per second. Four facial expressions were included: smile lips closed, smile lips open, lip purse, and cheek puff. Before starting, we instructed the subjects to make facial expressions to develop muscle memory. During recording, each facial expression took about 3 to 4 seconds. At least 1 week later, the procedure was repeated. The rest position (T0) was considered as the base frame. The first quartile of expressions (T1), just after reaching the maximum state of expressions (T2), just before the end of maximum state of expressions (T3), the third quartile of expressions (T4), and the end of motion (T5) were selected as key frames. Using the stable part of face such as forehead, each key frame (T1-T5) of the different expressions was aligned on the corresponding frame at rest (T0). The root mean square (RMS) between each key frame and its corresponding frame at rest were calculated. The Wilcoxon signed ranks test was applied to assess statistical differences between the corresponding frames of the different facial expressions. RESULTS: Facial expressions like smile lips closed, smile lips open, and cheek puff were reproducible. Lip purse was not reproducible. The statistically significant differences were found on the T2 frame of the repeated lip purse movement. CONCLUSION The dynamic 3D imaging can be used to evaluate the reproducibility of facial expressions. Compared with the qualitative analysis and two-dimensions analysis, dynamic 3D images can be able to more truly represent the facial expressions which make the research more reliable.
Adult ; Face/diagnostic imaging* ; Facial Expression ; Female ; Humans ; Imaging, Three-Dimensional ; Lip/diagnostic imaging* ; Male ; Photogrammetry ; Reproducibility of Results ; Smiling

Objective To assess the accuracy and reliability of the two 3D measuring methods, structured-light scanning and single-camera photogrammetry in forensic body surface damage and scar measurement. Methods The measuring results of 86 injuries by the ruler method, structured-light scanning and single-camera photogrammetry were compared and evaluated. The area measuring results of 13 simulated scars by the structured-light scanning, single-camera photogrammetry, Photoshop lasso pixel method and PDF reading software were compared and evaluated. The time consumed was recorded. The known specification information of the stickers was used as the standard value to compare the measuring accuracy of the ruler method, structural-light scanning and single-camera photogrammetry, and to calculate the root mean square error （RMSE）. The consistency evaluation of intraclass correlation coefficient （ICC） for the repeatability of 3 measuring results obtained by different operators and the same operator. Results The differences in results of the two 3D measuring methods and the ruler method had no statistical significance; the differences between measuring results made by the structured-light scanning, single-camera photogrammetry and PDF reading software and that of the Photoshop lasso pixel method had no statistical significance. The post-processing of the single-camera photogrammetry consumed more time than that of other methods. When the long-distance group （10-40 cm） was measured, the results obtained by the ruler method were shorter than the standard value. The RMSE value results were structured-light scanning < single-camera photogrammetry < ruler method. The ICC value intragroup and intergroup were greater than 0.99. Conclusion Both structured-light scanning and single-camera photogrammetry can be applied in recording and measuring forensic body surface damage. The former has better performance in measurement accuracy and stability, while the latter has better color performance but longer post-processing time.
Cicatrix ; Humans ; Imaging, Three-Dimensional ; Photogrammetry ; Reproducibility of Results ; Software

Objective To evaluate the influence of factors such as the selection of equipment, focal length and the selection of reconstruction quality in the reconstruction software on the reconstruction results of single camera photogrammetry and provide reference for the forensic application of single camera photogrammetry. Methods The 19 skulls were measured by traditional measurement method and single camera photogrammetry. The differences between the two measurement methods and within the group with same equipment but different focal length were analyzed. One skull and one corpse were selected as the research objects. According to the reconstruction quality selection conditions in the photogrammetric software, the experimental group was divided into five grades. The model reconstructed by optical scanner was defined as reference model, while the model reconstructed by single camera photogrammetry was defined as test model. The test model was aligned with the reference model, 3D deviation analysis was carried out and the mean error and root mean square （RMS） values were calculated. Results The differences between EOS 7D zoom group and traditional measurement, and within the group with same equipment had statistical significance （P<0.05）. The mean error value and minimum RMS value of the skull reconstructed by single camera photogrammetry and the three-dimensional model of the corpse existed in the medium quality group, and the trend was basically the same. Conclusion The equipment and focal length has no obvious influence on the results of single camera photogrammetry. Lower reconstruction quality can easily cause distortion, while higher reconstruction quality can easily generate noise, so medium quality is preferred.
Forensic Medicine ; Imaging, Three-Dimensional ; Photogrammetry ; Skull/diagnostic imaging* ; Software

PURPOSE: The goal of this study was to assess the accuracy and reliability of a low-cost portable scanner (Scanify) for imaging facial casts compared to a previously validated portable digital stereophotogrammetry device (Vectra H1). This in vitro study was performed using 2 facial casts obtained by recording impressions of the authors, at King's College London Academic Centre of Reconstructive Science. MATERIALS AND METHODS: The casts were marked with anthropometric landmarks, then digitised using Scanify and Vectra H1. Computed tomography (CT) scans of the same casts were performed to verify the validation of Vectra H1. The 3-dimensional (3D) images acquired with each device were compared using linear measurements and 3D surface analysis software. RESULTS: Overall, 91% of the linear Scanify measurements were within 1 mm of the corresponding reference values. The mean overall surface difference between the Scanify and Vectra images was <0.3 mm. Significant differences were detected in depth measurements. Merging multiple Scanify images produced significantly greater registration error. CONCLUSION: Scanify is a very low-cost device that could have clinical applications for facial imaging if imaging errors could be corrected by a future software update or hardware revision.
Imaging, Three-Dimensional ; In Vitro Techniques ; Photogrammetry ; Reference Values

BACKGROUND: Identifying problems and making a surgical plan through a preoperative analysis is important in facial aesthetic surgery. Thus, popular conceptions of an attractive face must be analyzed beforehand. The landmarks used as reference points may change after rhinoplasty, resulting in errors in the prediction and assessment of outcomes. To reduce such errors, it is advantageous to use reference points and landmarks that are subject to minimal variation. This study measured and analyzed landmarks with little preoperative and postoperative variation in rhinoplasty, and established appropriate standards for landmarks indicative of ideal profiles. METHODS: A photogrammetric analysis was performed of 80 famous and attractive celebrities from Korea, Southeast Asia, Japan, China, and America. The nasofrontal angle, nasal angle, nasolabial angle, angle of facial convexity, and angle of total facial convexity were measured. RESULTS: The angle of total facial convexity differed significantly among countries (P=0.013). No significant difference in nasal angle, facial convexity, or total facial convexity was observed between Western and Eastern countries. A significant difference in the nasofrontal angle (Asian: 138.66°, Western: 134.35°; P=0.006) was observed. The nasolabial angle (Asian: 97.09°, Western: 104.59° degrees; P=0.007) was significantly more acute in Asian than in Western subjects. CONCLUSIONS: In this study, we performed a more accurate analysis using the glabella instead of the nasion to measure the facial profiles of patients planning to undergo rhinoplasty and proposed standard values through an analysis of ideal and attractive facial profiles.
Americas ; Anthropometry ; Asia, Southeastern ; Asian Continental Ancestry Group ; China ; Fertilization ; Humans ; Japan ; Korea ; Photogrammetry ; Rhinoplasty*

BACKGROUND: This study evaluated dynamic changes in eyebrow position related to aging. METHODS: Female participants were recruited and separated into two groups aged 20–30 years (the younger group, n=20; mean age, 24.8 years) and 50–70 years (the older group, n=20; mean age, 55.8 years). Photogrammetry was used to determine the eyebrow position at the medial canthus (MC), lateral limbus, lateral canthus, and lateral end point (EP) for 6 actions: smooth opening (the reference action) and closing of the eye, forward gaze, maximum opening and closing of the eye, and maximum frown. Videos were also recorded. RESULTS: No differences in eyebrow position were detected at the MC when opening or closing the eyes smoothly, gazing straight ahead, or closing the eyes maximally. For all 6 actions, the position of the lateral EP in the older group was significantly lower than in the younger group (P=0.003), and the smallest degree of vertical movement at this point was found in both age groups (P<0.001). Vertical movement at the 4 landmarks of the eyebrows decreased with aging. CONCLUSIONS: Eyebrow position was unchanged at the MC with aging, except at maximal eye opening and maximal frown. No differences in eyebrow position were observed between the younger and older groups when eyes were maximally closed, except at the EP. It is important to focus on correction of the lateral EP for periorbital rejuvenation.
Aging* ; Anthropometry ; Eyebrows* ; Female ; Humans ; Lacrimal Apparatus ; Photogrammetry ; Physiology ; Rejuvenation

BACKGROUND: A quantitative, rather than visual, assessment of the outcomes of facial surgery has recently become increasingly important, and this is best accomplished using anthropometry. However, most anthropometric methods have limited applicability in office settings. METHODS: We conducted preliminary studies on images of a 30-cm straight edge ruler with various camera-to-object distances (OD) and aperture sizes, and identified a convenient range of ODs and the most reliable aperture size of our camera for photogrammetry. Subsequently, we measured various lengths circumjacent to the center of the ruler in the images of different ODs with a graphics viewer program and calibrated the raw data using the central 20-mm length. We obtained a reliable circle in our camera's viewfinder from a chart of percentage differences between the calibrated data and coupled real ruler lengths. Following this, we replaced the concept of the central 20-mm length with a geometric sphere 20-mm in diameter, and applied it to clinical photogrammetry. RESULTS: The percentage differences were almost directly proportional to the real lengths. This value was below 0.48% in the central 160-mm of all images within an OD range of 50 to 125 cm. In clinical applications, the greatest difference compared to direct measurements was 0.97 mm. CONCLUSIONS: Using a graphics viewer program, we performed anthropometric measurements of images that included a sphere of known size, without printing the images; the difference between these and direct measurements was <1 mm. This method is simple enough for use in an office setting.
Anthropometry ; Methods ; Photogrammetry*

BACKGROUND: The aim of this study is to validate a new three-dimensional craniofacial stereophotogrammetry imaging system (3dMDface) through comparison with manual facial surface anthropometry. The null hypothesis was that there is no difference between craniofacial measurements using anthropometry vs. the 3dMDface system. METHODS: Facial images using the new 3dMDface system were taken from six randomly selected subjects, sitting in natural head position, on six separate occasions each 1 week apart, repeated twice at each sitting. Exclusion criteria were excess facial hair, facial piercings and undergoing current dentofacial treatment. 3dMDvultus software allowed facial landmarks to be marked and measurements recorded. The same measurements were taken using manual anthropometry, using soluble eyeliner to pinpoint landmarks, and sliding and spreading callipers and measuring tape to measure distances. The setting for the investigation was a dental teaching hospital and regional (secondary and tertiary care) cleft centre. The main outcome measure was comparison of the craniofacial measurements using the two aforementioned techniques. RESULTS: The results showed good agreement between craniofacial measurements using the 3dMDface system compared with manual anthropometry. For all measurements, except chin height and labial fissure width, there was a greater variability with the manual method compared to 3D assessment. Overall, there was a significantly greater variability in manual compared with 3D assessments (p < 0.02). CONCLUSIONS: The 3dMDface system is validated for craniofacial measurements.
Anthropometry* ; Chin ; Hair ; Head ; Hospitals, Teaching ; Imaging, Three-Dimensional* ; Methods ; Outcome Assessment (Health Care) ; Photogrammetry

BACKGROUND: The objective of this study was to assess the attractive facial features of the Indian population. We tried to evaluate subjective ratings of facial attractiveness and identify which facial aesthetic subunits were important for facial attractiveness. METHODS: A cross-sectional study was conducted of 150 samples (referred to as candidates). Frontal photographs were analyzed. An orthodontist, a prosthodontist, an oral surgeon, a dentist, an artist, a photographer and two laymen (estimators) subjectively evaluated candidates' faces using visual analog scale (VAS) scores. As an objective method for facial analysis, we used balanced angular proportional analysis (BAPA). Using SAS 10.1 (SAS Institute Inc.), the Turkey's studentized range test and Pearson correlation analysis were performed to detect between-group differences in VAS scores (Experiment 1), to identify correlations between VAS scores and BAPA scores (Experiment 2), and to analyze the characteristic features of facial attractiveness and gender differences (Experiment 3); the significance level was set at P=0.05. RESULTS: Experiment 1 revealed some differences in VAS scores according to professional characteristics. In Experiment 2, BAPA scores were found to behave similarly to subjective ratings of facial beauty, but showed a relatively weak correlation coefficient with the VAS scores. Experiment 3 found that the decisive factors for facial attractiveness were different for men and women. Composite images of attractive Indian male and female faces were constructed. CONCLUSIONS: Our photogrammetric study, statistical analysis, and average composite faces of an Indian population provide valuable information about subjective perceptions of facial beauty and attractive facial structures in the Indian population.
Beauty ; Cross-Sectional Studies ; Dentists ; Female ; Humans ; India ; Male ; Photogrammetry ; Statistics as Topic ; Visual Analog Scale