Three-dimensional video recordings: Accuracy, reliability, clinical and research guidelines - Reliability assessment of a 4D camera.

OBJECTIVES: In addition to studying facial anatomy, stereophotogrammetry is an efficient diagnostic tool for assessing facial expressions through 3D video recordings. Current technology produces high-quality recordings but also generates extremely excessive data. Here, we compare various recording speeds for three standardized movements using the 3dMDface camera system, to assess its accuracy and reliability. MATERIALS AND METHODS: A linear and two circular movements were performed using a 3D-printed cube mounted on a robotic arm. All movements were recorded initially at 60 fps (frames/second) and then at 30 and 15 fps. Recording accuracy was tested with best-fit superimpositions of consecutive frames of the 3D cube and calculation of the Mean Absolute Distance (MAD). The reliability of the recordings were tested with evaluation of the inter- and intra-examiner error. RESULTS: The accuracy of movement recordings was excellent at all speeds (60, 30 and 15 fps), with variability in MAD values consistently being less than 1 mm. The reliability of the camera recordings was excellent at all recording speeds. CONCLUSIONS: This study demonstrated that 3D recordings of facial expressions can be performed at 30 or even at 15 fps without significant loss of information. This considerably reduces the amount of produced data facilitating further processing and analyses.

Three dimensional quantitative study of soft tissue changes in nasolabial folds after orthodontic treatment in female adults.

BACKGROUND: With the popularity of medical aesthetic programs, some female adults who will or are undergoing orthodontic treatment often wonder whether orthodontic treatment has adverse effects on the nasolabial folds (NLFs). The aims of the study were to investigate any potential changes in the NLFs and associated peripheral soft tissues after orthodontic treatment of female adults. METHODS: This study compared changes in the NLFs and peripheral soft tissues in female adults undergoing orthodontic treatment using the 3dMD Face system (3dMD, Atlanta, Ga). A total of 52 adult female patient cases (24 teeth extraction, 28 non-teeth extraction) were included to evaluate the effects of different orthodontic treatment regimens on the NLFs and peripheral soft tissues. RESULTS: In the NLFs area, the landmarks of the extraction group were all significantly negatively changed (P < 0.001; the NLF2s average value was - 0.72 mm), and the upper and middle parts of the landmarks were negatively changed in the non-extraction group (P < 0.05; the NLF2s average value was - 0.22 mm). Compared to the non-extraction group, the negative changes in the extraction group were more pronounced (P < 0.005). In the lip region, all landmarks in the extraction group were negative changes (P < 0.05; upper lip (ULP) = - 0.93 mm, lower lip (LLP) = - 1.46 mm), and most landmarks in the non-extraction group were positive changes (P < 0.01; ULP = 0.55 mm). In the cheek area, the left and right buccal of the extraction and non-extraction groups were all negatively changed (P < 0.05), and there was no significant difference between the two groups. CONCLUSION: After orthodontic treatment, the NLFs showed negative changes, which were more obvious in the extraction group. The lip soft tissue had a negative change in the extraction group and a positive change in the non-extraction group, indicating that orthodontic treatment affected the soft tissue around the nasolabial sulcus, and that tooth extraction would lead to more negative changes.

Three-dimensional evaluation of soft tissues in hyperdivergent skeletal class II females in Guangdong.

OBJECTIVES: To establish the three-dimensional facial soft tissue morphology of adolescent and adult females in the Guangdong population and to study the morphological characteristics of hyperdivergent skeletal class II females in Guangdong compared with that of normodivergent class I groups. MATERIALS AND METHODS: The 3dMDface system was used to capture face scans of 160 patients, including 45 normal and 35 hyperdivergent skeletal class II adolescents (aged 11-14 years old) and 45 normal and 35 hyperdivergent skeletal class II adults (aged 18-30 years old). Thirty-two soft tissue landmarks were mapped, and 21 linear, 10 angular and 17 ratio measurements were obtained by 3dMDvultus analysis software. Data were assessed with a t-test of two independent samples between the normal adolescent and adult groups and between the normal and hyperdivergent skeletal class II groups. RESULTS: The linear measurements of the Guangdong adult females were larger than those of the adolescents in both Class I and Class II groups. However, the angular and ratio measurements had no significant difference. The vertical linear measurements were higher and the sagittal and transverse linear measurements were smaller in the hyperdivergent class II group (p < 0.05). The soft tissue ANB angle, chin-lip angle, and mandibular angle were significantly larger and the soft tissue facial convexity angle and nasal convexity angle were significantly smaller in the hyperdivergent class II group (p < 0.05). Additionally, there were significant differences in the ratio measurements between the hyperdivergent class II groups and the control groups (p < 0.05). CONCLUSIONS: The three-dimensional facial morphology of Guangdong adolescent and adult females was acquired. The facial soft tissue measurements of the adults were higher in the three dimensions except for the facial convexity and proportional relationships which were similar, suggesting that the growth pattern remained the same. The three-dimensional facial soft tissue features of hyperdivergent skeletal class II were characterized by the terms "long, convex, and narrow". Three-dimensional facial measurements can reflect intrinsic hard tissue characteristics.

Profiles of facial soft tissue changes during and after orthodontic treatment in female adults.

BACKGROUND: Some female adults who received orthodontic treatment often complain about thinner faces, protruding cheekbones and sunken temples, even at the beginning of treatment. The present research aimed to explore facial soft tissue changes during and after orthodontic treatment, as well as the related factors affecting facial soft tissue changes. METHODS: This study used 3dMD stereo photography technology to compare facial soft tissue changes among adult females who received orthodontics. A total of 52 adult females (24 teeth extraction, 28 non-teeth extraction cases) were included and potential correlations between related factors (facial morphology features, the change of occlusal height and dental arch width) were evaluated during different treatment periods. RESULTS: Overall, 3D-negative soft tissue changes of the buccal region moderately correlated with distances of nasion-menton and subnasale-menton (both rs = 0.30, P < 0.05) as well as the ratio of subnasale-menton/right gonion-left gonion (rs = 0.33, P < 0.05) and nasion-menton/right zygomatic point-left zygomatic point (rs = 0.30, P < 0.05). Among the 3D angle measurements, the right chelion-median upper lip point-left chelion angle was found to have a moderate correlation with 3D negative changes of the upper cheilion region (rs = 0.31, P < 0.01). Analysis of occlusal height changes revealed that an increase in the posterior facial height (nasion-gonial distance) may be a risk factor for negative changes in the zygomatic arch area. In addition, a moderate positive correlation between the maxillary first molar width changes and 3D-negative changes of the lower cheek region was found (rs = 0.41, P < 0.05). CONCLUSIONS: After orthodontic treatment, adult females with wide and short faces may be prone to negative soft tissue changes. Changes of posterior facial height and arch width between the first molars were also risk factors for negative changes of facial soft tissues. Extraction is not a major factor producing facial soft tissue changes.

Three-Dimensional evaluation of the effect of platelet-rich fibrin on edema in lower impacted third molar surgery performed with piezosurgery.

Background: Platelet-rich fibrin (PRF) are widely used in impacted lower third molar (IL3M) 7 surgery and its effect on postoperative edema was generally analysed with linear methods. Aim: To analyze the effectiveness of platelet-rich fibrin (PRF) applied to the socket after tooth extraction in impacted lower third molar (IL3M) surgery performed with piezosurgery in the reduction of edema observed in the postoperative period, together with conventional (linear) and three-dimensional (volumetric) measurement methods. Materials and Method: The study was designed as a prospective randomized split-mouth study and was conducted on 30 patients with bilateral IL3M teeth. Extraction of the patients' IL3M teeth was performed in the same session with the help of piezosurgery. After the extraction, PRF was randomly applied to one socket, but it was not applied to the other socket, which formed the control group. On the first, second, and seventh days after the procedure, volume was measured using 3dMD, and the distance between the topographic guide points was measured using a flexible ruler. The results were analyzed statistically. Alveolar osteitis (AO) presence was also recorded. Results: A significant improvement in edema was observed in both groups, but no significant difference was found between the groups (P > 0.05). A moderate correlation was found between the two methods of measuring edema. AO was not seen in any patient. Conclusions: Although PRF reduces edema after IL3M tooth extraction and 3dMD is effective in its evaluation, it has no statistical advantage over classical methods.

Lip morphology estimation models based on three-dimensional images in a modern adult population from China.

Lips are the main part of the lower facial soft tissue and are vital to forensic facial approximation (FFA). Facial soft tissue thickness (FSTT) and linear measurements in three dimensions are used in the quantitative analysis of lip morphology. With most FSTT analysis methods, the surface of soft tissue is unexplicit. Our study aimed to determine FSTT and explore the relationship between the hard and soft tissues of lips in different skeletal occlusions based on cone-beam CT (CBCT) and 3dMD images in a Chinese population. The FSTT of 11 landmarks in CBCT and 29 lip measurements in CBCT and 3dMD of 180 healthy Chinese individuals (90 males, 90 females) between 18 and 30 years were analyzed. The subjects were randomly divided into two groups with different skeletal occlusions distributed equally: 156 subjects in the experimental group to establish the prediction regression formulae of lip morphology and 24 subjects in the test group to assess the accuracy of the formulae. The results indicated that FSTT in the lower lip region varied among different skeletal occlusions. Furthermore, sex discrepancy was noted in the FSTT in midline landmarks and linear measurements. Measurements showing the highest correlation between soft and hard tissues were between total upper lip height and Ns-Pr (0.563 in males, 0.651 in females). The stepwise multiple regression equations were verified to be reliable with an average error of 1.246 mm. The method of combining CBCT with 3dMD provides a new perspective in predicting lip morphology and expands the database for FFA.

Three-dimensional prediction of nose morphology in Chinese young adults: a pilot study combining cone-beam computed tomography and 3dMD photogrammetry system.

The nose is the most prominent part of the face and is a crucial factor for facial esthetics as well as facial reconstruction. Although some studies have explored the features of external nose and predicted the relationships between skeletal structures and soft tissues in the nasal region, the reliability and applicability of methods used in previous studies have not been reproduced. In addition, the majority of previous studies have focused on the sagittal direction, whereas the thickness of the soft tissues was rarely analyzed in three dimensions. A few studies have explained the specific characteristics of the nose of Chinese individuals. The aim of this study was to investigate the relationship between the hard nasal structures and soft external nose in three dimensions and to predict the morphology of the nose based on hard-tissue measurements. To eliminate the influence of low resolution of CBCT and increase the accuracy of measurement, three-dimensional (3D) images captured by cone-beam computed tomography (CBCT) and 3dMD photogrammetry system were used in this study. Twenty-six measurements (15 measurements for hard tissue and 11 measurements for soft tissue) based on 5 craniometric and 5 capulometric landmarks of the nose of 120 males and 120 females were obtained. All of the subjects were randomly divided into an experimental group (180 subjects consisting of 90 males and 90 females) and a test group (60 subjects consisting of 30 males and 30 females). Correlation coefficients between hard- and soft-tissue measurements were analyzed, and regression equations were obtained based on the experimental group and served as predictors to estimate nasal morphology in the test group. Most hard- and soft-tissue measurements appeared significantly different between genders. The strongest correlation was found between basis nasi protrusion and nasospinale protrusion (0.499) in males, and nasal height and nTr-nsTr (0.593) in females. For the regression equations, the highest value of R2 was observed in the nasal bridge length in males (0.257) and nasal tip protrusion in females (0.389). The proportion of subjects with predicted errors < 10% was over 86.7% in males and 70.0% in females. Our study proved that a combined CBCT and 3dMD photogrammetry system is a reliable method for nasal morphology estimation. Further research should investigate other influencing factors such as age, skeletal types, facial proportions, or population variance in nasal morphology estimation.

Spatially Detailed 3D Quantification of Improved Facial Symmetry After Surgery in Children With Unicoronal Synostosis.

OBJECTIVE: To assess improvement of soft-tissue facial symmetry in children surgically treated for unicoronal synostosis (UCS) in infancy, to correlate pre- and postsurgical facial asymmetry and to evaluate whether the improvement was visually recognizable. DESIGN: Case-controlled follow-up. PATIENTS/SETTINGS: Eleven Danish children diagnosed with UCS were included, 3 of whom had tested positive for Muenke mutation. Preoperative computed tomography scans and postoperative 3dMD surfaces were available for measurements. A control group of healthy children matched for age and sex was employed. MAIN OUTCOME MEASURES: Pre- and postsurgical facial asymmetry was analyzed using a computerized method capable of objective and spatially detailed quantification in 3-dimension (transverse, vertical, and sagittal directions). Asymmetry was evaluated in the facial region and 6 subregions (forehead, mouth, eyes, nose, cheek, and chin). RESULTS: The largest significant improvement was seen in the sagittal direction of the facial (1.9 mm), forehead (2.0 mm), and cheek (3.4 mm) regions. Small but significant improvements were also seen in the mouth, chin, and eye regions. No significant improvement was seen in the nose region. Significant correlations were found between the pre- and postsurgically calculated facial asymmetry and between calculated asymmetry and clinical validation scores. CONCLUSIONS: All patients presented with improved facial symmetry after surgery and the improvements were visually recognizable. However, only 1 (9.1%) of the 11 patients reached a level of facial asymmetry as low as that seen in the control group. The best outcome was, in general, seen in cases with mild facial asymmetry presurgically.

Three-dimensional evaluation of the effect of low-level laser therapy on facial swelling after lower third molar surgery: A randomized, placebo-controlled study.

PURPOSE: This study aimed to evaluate the effect of a low-level laser therapy (LLLT) on pain, trismus, and swelling of patients whose impacted 3rd molar tooth was extracted compared to placebo or "sham" treatment and measure volumetrically the edema with a three-dimensional (3D) surface imaging device (3dMD face system). MATERIALS AND METHODS: Forty-five patients over 17 years of age were included in the study. Patients were randomized to three groups; Group 1, the control group, received only routine management (ice application) (n = 15); Group 2, received single-dose LLLT immediately after surgery (n = 15); and Group 3, placebo group, received sham therapy immediately after surgery (n = 15). In this study, a gallium-aluminum-arsenide diode laser device was used. The laser was applied extraorally (0.3 W, 40 s, 4 J/cm2). The trismus, pain, and facial swelling were evaluated. A 3D surface imaging device (3dMD Photogrammetric System) was used to evaluate the volumetric changes of the swelling. The 3D morphology of the facial swelling was recorded using this imaging device immediately before surgery, the second day after surgery, and the 7th day after surgery. IBM SPSS statistics 22.0 program was used in the statistical assessment and P < 0.05 was considered statistically significant. RESULTS: There was no statistically significant difference in the edema and trismus between the groups. The pain level in Group 2 was significantly lower than that in Group 3 at all-time points. Furthermore, the pain level in Group 2 was significantly lower than that in Group 1 on day 7. CONCLUSIONS: LLLT reduced the intensity of pain following third molar surgery by single dose. The results of this study revealed that LLLT reduced facial swelling, but no significant differences were found among the three groups. In addition, a 3D craniomaxillofacial imaging method provided insight into volume changes after 3rd molar surgery and the evaluation of facial swelling in an objective way.

Evaluation of the 3dMDface system as a tool for soft tissue analysis.

OBJECTIVES: To evaluate the accuracy of three-dimensional stereophotogrammetry by comparing values obtained from direct anthropometry and the 3dMDface system. To achieve a more comprehensive evaluation of the reliability of 3dMD, both linear and surface measurements were examined. SETTING AND SAMPLE POPULATION: UCLA Section of Orthodontics. Mannequin head as model for anthropometric measurements. MATERIAL AND METHODS: Image acquisition and analysis were carried out on a mannequin head using 16 anthropometric landmarks and 21 measured parameters for linear and surface distances. 3D images using 3dMDface system were made at 0, 1 and 24 hours; 1, 2, 3 and 4 weeks. Error magnitude statistics used include mean absolute difference, standard deviation of error, relative error magnitude and root mean square error. Intra-observer agreement for all measurements was attained. RESULTS: Overall mean errors were lower than 1.00 mm for both linear and surface parameter measurements, except in 5 of the 21 measurements. The three longest parameter distances showed increased variation compared to shorter distances. No systematic errors were observed for all performed paired t tests (P<.05). Agreement values between two observers ranged from 0.91 to 0.99. CONCLUSIONS: Measurements on a mannequin confirmed the accuracy of all landmarks and parameters analysed in this study using the 3dMDface system. Results indicated that 3dMDface system is an accurate tool for linear and surface measurements, with potentially broad-reaching applications in orthodontics, surgical treatment planning and treatment evaluation.

Quantitative Assessment of Facial Asymmetry Using Three-Dimensional Surface Imaging in Adults: Validating the Precision and Repeatability of a Global Approach.

OBJECTIVE: Comparison of global versus landmark analyses of facial asymmetry using three-dimensional photogrammetry to establish a precise method for evaluating facial asymmetry. DESIGN: The landmark-based approach utilized anthropometric data points. Our global approach involved registration of mirror images, independent of a midplane, to calculate a root mean square (RMS) value. We analyzed precision and technical and operator error of both methods. PARTICIPANTS: Three hundred fifty adults participated in this study. RESULTS: We found that the global method has better precision and repeatability with a significantly lower error rate than the landmark-based method. In adults, the average RMS was 0.6253 mm with a standard deviation of 0.16. CONCLUSIONS: Our facial asymmetry measurement is more accurate than landmark-based measurements. This method is quick, reliable, and results in generation of a RMS score and a corresponding color-coded facial map that highlights regions of higher and lower asymmetry. This method may be used as a screening tool for asymmetry in both the clinical and research settings.

Quantitative three-dimensional assessment of port-wine stain clearance after laser treatments.

BACKGROUND AND OBJECTIVE: Outcomes analysis of laser treatment for port-wine stains has been hampered by the lack of an objective measure of surface area and volume; moreover, treatment success is often gauged by clinician subjective assessment. Three-dimensional (3D) surface imaging has been applied in several medical disciplines to quantify surface changes, with promising results. We hypothesized that 3D surface imaging could be used to objectively measure changes in area and volume of port-wine stains following laser treatment. STUDY DESIGN/MATERIALS AND METHODS: We performed a retrospective review of consecutive patients with port-wine stains treated over a 20-month time period. Area and volume of the lesions were measured using 3dMD photogrammetric software (3dMD, Atlanta, GA) before and after a series of sequential pulsed dye laser and/or alexandrite laser treatments. RESULTS: Fifty-five patients with 59 port-wine stains were included in the study. The initial average measured area was 44.3 cm(2) ; final average measured area decreased to 36.9 cm(2) (P < 0.001). The average volume change was 1.20 cc for all PWS included in the study and 1.90 cc for lesions that received at least 5 laser treatments within the study period. CONCLUSION: Three-dimensional photography demonstrated area and volume changes in patients with port-wine stains after laser treatments. Future studies to determine if statistically significant changes correlate with clinically appreciable changes are warranted.

Precise maxillofacial soft tissue reconstruction: A combination of cone beam computed tomography and 3dMD photogrammetry system.

Introduction: The reconstruction of both extra- and intra-oral soft tissue defects, particularly in restoring the morphology of the lip and the corners of the mouth, has posed a significant challenge for surgeons. Inappropriate methods often lead to maxillofacial deformity which then causes psychological and functional problems. This study aimed to address the challenge of reconstructing extensive and complex maxillofacial soft tissue defects, mainly focusing on the lip, the corners of the mouth, and the surrounding areas. Materials and methods: We developed a reconstruction approach by combining the 3dMDface System (3dMD) with the cone beam computed tomography (CBCT). Firstly, with the extra-oral incision line, we evaluated the shape and the size of the extra-oral defect with 3dMD digitally. Then we used the corresponding maxillary and mandible tooth positions to record the intra-oral defect, which was then converted to digital images by combining 3dMD and CBCT. The islands of the anterolateral thigh perforator flap were then designed after the locations of the perforators were detected with Doppler ultrasonography. Results: A clinical case diagnosed as dermatofibrosarcoma protuberans was presented to illustrate the approach. The patient's tumor resection and the size of multiple defects were measured and simulated via the virtual surgery system. A three-island perforator flap from the descending branch of the lateral femoral circumflex artery was designed accurately. Two weeks postoperatively, the flap was healed as anticipated and the patient was satisfied with the profile. Conclusion: The combination of the 3dMD and CBCT technologies improves the accuracy and fitness of extra- and intra-oral soft tissue reconstruction.

Quantitative three-dimensional assessment of port-wine stain clearance after laser treatments.

BACKGROUND AND OBJECTIVES: Outcomes analysis of laser treatment for port-wine stains (PWS) has been hampered by the lack of an objective measure of surface area and volume; moreover, treatment success is often gauged by clinician subjective assessment. Three-dimensional (3D) surface imaging has been applied in several medical disciplines to quantify surface changes, with promising results. We hypothesized that 3D surface imaging could be used to objectively measure changes in area and volume of PWS following laser treatment. STUDY DESIGN/MATERIALS AND METHODS: We performed a retrospective review of consecutive patients with PWS treated over a 20-month time period. Area and volume of the lesions were measured using 3dMD photogrammetric software (3dMD; Atlanta, GA) before and after a series of sequential pulsed dye laser and/or alexandrite laser treatments. RESULTS: Fifty-five patients with 59 PWS were included in the study. The initial average measured area was 45.6 cm(2) ; final average measured area decreased to 34.6 cm(2) (P < 0.001). The average volume change was 1.20 ml for all PWS included in the study and 1.90 ml for lesions that received at least five laser treatments within the study period. CONCLUSION: Three-dimensional photography demonstrated area and volume changes in patients with PWS after laser treatments. Future studies to determine if statistically significant changes correlate with clinically appreciable changes are warranted.

Three-dimensional quantitative analysis of temporal region morphology in Chinese young adult.

Background: Temporal filling is commonly used to correct temporal depression. However, there is a lack of quantitative criteria for pre- and post-operative evaluations. The use of three-dimensional scanning may help improving the success of temporal filling by providing quantitative assessments. The study aimed to compare the results of qualitative morphological evaluation of the temporal region with a quantitative, numerical analysis of the temporal difference value (TDV). Methods: We enrolled twenty-six male and forty-nine female volunteers aged 18 to 29 years. Facial images were acquired in OBJ format using 3dMD facial stereo-photography. The morphologies of the temporal regions were separately evaluated by four researchers in the form of two-dimensional (2D) images. Results were classified as either aesthetic or unaesthetic. The quantitative evaluation of the temporal region was then conducted. First, the temporal region was trimmed out from the original 3D image into a new OBJ file. Second, interpolation was used to construct a smooth, adapted surface. Third, a mathematical model of temporal region flatness denoted as the TDV, which was defined as the sum of the Euclidean distances of all 3D points between the constructed surface and the temporal-region OBJ file. The classification of each sample was compared with its TDV to verify the mathematical model's validity. The cutoff threshold and prediction accuracy of this mathematical model were calculated. Results: The cutoff threshold between aesthetic and unaesthetic TDV was found to be 24.66 for males and 28.11 for females. The prediction accuracy rate was 0.73 for men and 0.73 for women. Conclusion: The method has high overlap and good repeatability and minimizes the influence of subjective aesthetics on morphological judgment. TDV has a certain reference value for clinical temporal region evaluation.

Can smartphones be used for routine dental clinical application? A validation study for using smartphone-generated 3D facial images.

OBJECTIVES: To compare the accuracy of smartphone-generated three-dimensional (3D) facial images to that of direct anthropometry (DA) and 3dMD with the aim of assessing the validity and reliability of smartphone-generated 3D facial images for routine clinical applications. MATERIALS AND METHODS: Twenty-five anthropometric soft-tissue facial landmarks were labelled manually on 22 orthognathic surgery patients (11 males and 11 females; mean age 26.2 ± 5.3 years). For each labelled face, two imaging operations were performed using two different surface imaging systems: 3dMDface and Bellus3D FaceApp. Next, 42 inter-landmark facial measurements amongst the identified facial landmarks were measured directly on each labelled face and also digitally on 3D facial images. The measurements obtained from smartphone-generated 3D facial images (SGI) were statistically compared with those from DA and 3dMD. RESULTS: SGI had slightly higher measurement values than DA and 3dMD, but there was no statistically significant difference between the mean values of inter-landmark measures across the three methods. Clinically acceptable differences (≤3 mm or ≤5°) were observed for 67 % and 74 % of measurements with good agreement between DA and SGI, and 3dMD and SGI, respectively. An overall small systematic bias of ± 0.2 mm was observed between the three methods. Furthermore, the mean absolute difference between DA and SGI methods was highest for linear (1.41 ± 0.33 mm) as well as angular measurements (3.07 ± 0.73°). CONCLUSIONS: SGI demonstrated fair trueness compared to DA and 3dMD. The central region and flat areas of the face in SGI are more accurate. Despite this, SGI have limited clinical application, and the panfacial accuracy of the SGI would be more desirable from a clinical application standpoint. CLINICAL SIGNIFICANCE: The usage of SGI in clinical practice for region-specific macro-proportional facial assessment involving central and flat regions of the face or for patient education purposes, which does not require accuracy within 3 mm and 5° can be considered.

Smile Reproducibility and Its Relationship to Self-Perceived Smile Attractiveness.

The reproducibility of facial expressions has been previously explored, however, there is no detailed information regarding the reproducibility of lip morphology forming a social smile. In this study, we recruited 93 young adults, aged 21−35 years old, who agreed to participate in two consecutive study visits four weeks apart. On each visit, they were asked to perform a social smile, which was captured on a 3D facial image acquired using the 3dMD camera system. Assessments of self-perceived smile attractiveness were also performed using a VAS scale. Lip morphology, including smile shape, was described using 62 landmarks and semi-landmarks. A Procrustes superimposition of each set of smiling configurations (first and second visit) was performed and the Euclidean distance between each landmark set was calculated. A linear regression model was used to test the association between smile consistency and self-perceived smile attractiveness. The results show that the average landmark distance between sessions did not exceed 1.5 mm, indicating high repeatability, and that females presented approximately 15% higher smile consistecy than males (p < 0.05). There was no statistically significant association between smile consistency and self-perceived smile attractiveness (η2 = 0.015; p = 0.252), when controlling for the effect of sex and age.

The effect of resting morphological lip shape during lip movement: A three-dimensional motion analysis study.

PURPOSE: The aim of this study was to determine the influence of different morphological lip shape during lip movement. METHOD: A sample of 80 individuals with three-dimensional facial images at rest and during speech were recorded. Subjects were asked to pronounce four bilabial words in a relaxed manner and scanned using the 3dMDFace™ Dynamic System at 48 frames per second. Six lip landmarks were identified at rest and the landmark displacement vectors for the frame of maximal lip movement for all six visemes were recorded. Principal component analysis was applied to isolate relationship between lip traits and their registered coordinates. Eight specific resting morphological lip traits were identified for each individual. The principal component (PC) scores for each viseme were labelled by lip morphological trait and were graphically visualized as ellipses to discriminate any differences in lip movement. RESULTS: The first five PCs accounted for up to 95% of the total variance in lip shape during movement, with PC1 accounting for at least 38%. There was no clear discrimination between PC1, PC2 and PC3 for any of the resting morphological lip traits. CONCLUSION: Lip shapes during movement are more uniform between individuals and resting morphological lip shape does not influence movement of the lips.

Predicting sleep apnea from three-dimensional face photography.

STUDY OBJECTIVES: Craniofacial anatomy is recognized as an important predisposing factor in the pathogenesis of obstructive sleep apnea (OSA). This study used three-dimensional (3D) facial surface analysis of linear and geodesic (shortest line between points over a curved surface) distances to determine the combination of measurements that best predicts presence and severity of OSA. METHODS: 3D face photographs were obtained in 100 adults without OSA (apnea-hypopnea index [AHI] < 5 events/h), 100 with mild OSA (AHI 5 to < 15 events/h), 100 with moderate OSA (AHI 15 to < 30 events/h), and 100 with severe OSA (AHI ≥ 30 events/h). Measurements of linear distances and angles, and geodesic distances were obtained between 24 anatomical landmarks from the 3D photographs. The accuracy with which different combinations of measurements could classify an individual as having OSA or not was assessed using linear discriminant analyses and receiver operating characteristic analyses. These analyses were repeated using different AHI thresholds to define presence of OSA. RESULTS: Relative to linear measurements, geodesic measurements of craniofacial anatomy improved the ability to identify individuals with and without OSA (classification accuracy 86% and 89% respectively, P < .01). A maximum classification accuracy of 91% was achieved when linear and geodesic measurements were combined into a single predictive algorithm. Accuracy decreased when using AHI thresholds ≥ 10 events/h and ≥ 15 events/h to define OSA although greatest accuracy was always achieved using a combination of linear and geodesic distances. CONCLUSIONS: This study suggests that 3D photographs of the face have predictive value for OSA and that geodesic measurements enhance this capacity.

Craniofacial Asymmetry from One to Three Years of Age: A Prospective Cohort Study with 3D Imaging.

Deformational plagiocephaly (DP) is considered a risk factor for facial asymmetry. This cohort-based, prospective, follow-up study used three-dimensional (3D) stereophotogrammetry to assess the development of facial asymmetry in a normal birth cohort and to investigate the impact of DP on facial asymmetry for the age range of one to three years. The study sample consisted of 75 children: 35 girls (47%) and 40 (53%) boys recruited from Oulu University Hospital. A total of 23 (31%) subjects had a history of DP in infancy. 3D facial images were obtained at the mean (SD) age of 1.01 (0.04) year old at T1 and 3.02 (0.14) years old at T2. To determine facial asymmetry, both landmark-based and surface-based facial symmetry methods were used. As measured with the surface-based methods, upper facial symmetry improved from T1 to T2 (p < 0.05). As measured with the landmark-based methods, facial symmetry improved on the upper and lower jaw from T1 to T2 (p < 0.05). The asymmetric effect of DP on the upper parts of the face tends to correct spontaneously during growth. Results indicate that previous DP does not seem to transfer to facial or occlusal asymmetry at the age of three years old.