OBJECTIVES: To evaluate the accuracy of a self-developed extraoral scanning system based on four-camera stereophotogrammetric technology in the acquisition of three-dimensional positional information on dental implants and conduct a comparative study involving an intraoral scanning system. METHODS: With the use of an in vitro edentulous jaw model with implants, extraoral (experimental group) and intraoral (control group) scanning systems were employed to obtain STL (Standard Tessellation Language) datasets containing three-dimensional morphological and positional information on scan bodies. In addition, a dental model scanner was used to obtain reference data. The three-dimensional morphological, linear, and angular deviations between groups and reference data were analyzed using Geomagic Wrap 2021 software to compare trueness and precision. RESULTS: The extraoral scanning system demonstrated superior trueness in three-dimensional morphological, linear, and angular deviations compared with the intraoral scanning system, with statistically significant differences (P<0.001). The extraoral scanning system also showed a higher precision in three-dimensional morphological deviation (P<0.001). As the number of implants increased, the extraoral scanning system exhibited increased three-dimensional morphological and linear deviations (P<0.001) but maintained a stable angular deviation. The intraoral scanning system displayed significant increases in three-dimensional morphological, linear, and angular deviations with the increase in the number of implants (P<0.05). CONCLUSIONS The stereophotogrammetry-based extraoral scanning system outperforms intraoral scanning system in terms of the accuracy for multi-unit implant positioning and provides a novel approach for attaining a fully digital workflow for implant rehabilitation in edentulous jaws.
Jaw, Edentulous ; Humans ; Dental Impression Technique ; Dental Implants ; Imaging, Three-Dimensional/methods* ; Photogrammetry/methods* ; Models, Dental

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: 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*

The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional (3D) position of the occlusal plane in the face is assessed. Dental virtual models and soft tissue facial morphology of 20 adult subjects were digitally integrated using a 3D stereophotogrammetric imaging system. The digital 3D coordinates of facial and dental landmarks were obtained by two different operators. Camper's (facial) and occlusal (dental) planes were individuated, and their 3D relationships were measured. The repeatability of the protocol was investigated and showed no significant differences in repeated digitizations. The angle between occlusal and Camper's planes was smaller than 2° in the frontal and horizontal projections. In the sagittal projection, the angle was observed to be, on average, 4.9°. The determined occlusal plane pitch, roll and yaw values show good agreement with previously published data obtained by different protocols. The current non-invasive method was repeatable, without inter-operator differences and can facilitate assessment of healthy subjects.
Adolescent ; Adult ; Anatomic Landmarks ; Cephalometry ; methods ; Computer Simulation ; Dental Models ; Dental Occlusion ; Face ; anatomy & histology ; Female ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; methods ; Male ; Observer Variation ; Pattern Recognition, Automated ; Photogrammetry ; Reproducibility of Results ; Young Adult

Reconstruction of 3D structure of an object from 2D views plays an important role in plastic surgery and orthopedics. This method doesn't need camera to do specific movements, such as translation or rotation independently. It only needs a hand-hold camera arbitrarily to take a few pictures, and apply the geometry relationship among the three views to obtain the projective reconstruction of the object. Then, it needs to introduce cheirality constraint in stratified reconstruction to determine the search area of the infinity plane, and finally achieve the camera intrinsic parameters calibration, and complete the metric reconstruction. This model has also been reconstructed with mouse and keyboard response coordinates to observe the model from different angles. Experiments with both pictures of object and face pictures show that the proposed method is very robust and accurate.
Algorithms ; Calibration ; Face ; anatomy & histology ; Humans ; Image Enhancement ; methods ; Imaging, Three-Dimensional ; Pattern Recognition, Automated ; methods ; Photogrammetry ; methods

OBJECTIVEThree-dimensional (3-D) facial images are very useful for orthodontic diagnosis. Three-dimensional facial imaging system (DSC-2) based on phase measuring profilometry (PMP) was used to obtain images and tested for accuracy.

METHODSGeometric strips (20 mm in width) was used to test the accuracy of the obtained images. Three-dimensional images of plaster head model with marker of 5 mm x 5 mm were taken by DSC-2 three-dimensional facial imaging system. The difference of measurements was compared between both methods. Measurements were repeated twice by three different doctors.

RESULTSThe average value of width in 3-D mode was 19.5 mm. No significant difference was found, compared with actual width (20 mm). There was no significant difference between computer measurement and manual measurement of the plaster head model (P > 0.05).

CONCLUSIONSDSC-2 three-dimensional facial imaging system was accurate and reliable to obtain 3-D facial images.

Face ; anatomy & histology ; Humans ; Imaging, Three-Dimensional ; Photogrammetry ; methods

Iris image quality evaluation plays a very important part in iris computer recognition. An iris image quality evaluation method was introduced into this study to distinguish good image from bad image caused by pupil distortion, blurred boundary, two circles appearing not concentric, and severe occlusion by eyelids and eyelashes. The tests based on this method gave good results.
Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; Iris ; anatomy & histology ; Pattern Recognition, Automated ; methods ; Photogrammetry ; methods ; standards

OBJECTIVEThe purpose of this study was to compare the data of three-dimensional soft tissue obtained by using a three-dimensional digital photogrammetry and the two-dimensional data obtained by using a conventional cephalometry.

METHODSThree-dimensional characters of facial soft tissue were obtained by using four digital cameras. The authors developed necessary hardware and software systems and applied in stereophotogrammetry to obtain the data of three-dimensional facial soft tissues. A total of 40 people with normal occlusion, including 20 males and 20 females, were examined with both three-dimensional soft tissue facial morphometry and cephalometry. Three-dimensional soft tissue facial morphometry was performed, and their relations with facial cephalometry were analyzed.

RESULTSSignificant correlations were found between 6 pairs of linear measurements, 4 pairs of angular measurements and 3 pairs of linear distant ratio measurements. The data obtained by three-dimensional facial soft tissue morphometry and two-dimensional cephalometry was identical.

CONCLUSIONThere was a correlation between the three-dimensional soft tissue facial morphometry and facial cephalometry. The data obtained by the three-dimensional soft tissue facial morphometry can partially represent facial hard tissue.

Adult ; Cephalometry ; Face ; anatomy & histology ; Female ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Male ; Photogrammetry ; methods ; Radiography ; Reference Values ; Skull ; diagnostic imaging