Accuracy of low-cost alternative facial scanners: a prospective cohort study.

INTRODUCTION: Three-dimensional facial scans have recently begun to play an increasingly important role in the peri-therapeutic management of oral and maxillofacial and head and neck surgery cases. Face scan images can be generated by optical facial scanners utilizing line-laser, stereophotography, or structured light modalities, as well as from volumetric data: for example, from cone beam computed tomography (CBCT). This study aimed to evaluate whether two low-cost procedures for the creation of three-dimensional face scan images were capable of producing sufficiently accurate data sets for clinical analysis. MATERIALS AND METHODS: Fifty healthy volunteers were included in the study. Two test objects with defined dimensions (Lego bricks) were attached to the forehead and the left cheek of each volunteer. Facial anthropometric values (i.e., the distances between the medial canthi, the lateral canthi, the nasal alae, and the angles of the mouth) were first measured manually. Subsequently, face scans were performed with a smart device and manual photogrammetry and the values obtained were compared with the manually measured data sets. RESULTS: The anthropometric distances deviated, on average, 2.17 mm from the manual measurements (smart device scanning deviation 3.01 mm, photogrammetry deviation 1.34 mm), with seven out of eight deviations being statistically significant. For the Lego brick, from a total of 32 angles, 19 values demonstrated a significant difference from the original 90° angles. The average deviation was 6.5° (smart device scanning deviation 10.1°, photogrammetry deviation 2.8°). CONCLUSION: Manual photogrammetry demonstrated greater accuracy when creating three-dimensional face scan images; however, smart devices are more user-friendly. Dental professionals should monitor camera and smart device technical improvements carefully when choosing and adequate technique for 3D scanning.

Accurate and cost-effective mandibular biomodels: a standardized evaluation of 3D-Printing via fused layer deposition modeling on soluble support structures.

INTRODUCTION: Medical biomodels can be used for illustration of medical conditions, preoperative planning or to facilitate pre-bending of osteosynthesis material. They have been shown to be an effective and efficient method to reduce operating time, blood loss and wound stress in cranio-maxillo-facial surgery. Lately, new time and cost-efficient 3D-printing methods have been introduced into the mass-market. The aim of this study was to establish a standardized method of evaluation and consequently evaluate Fused Layer Deposition Modeling in combination with soluble support structures for fabrication of medical biomodels regarding precision and cost-effectiveness. MATERIALS & METHODS: Twenty-one biomodels of human mandibles equipped with measuring appliances were printed on a FLDM 3D-printers (Ultimaker 3 Extended) using a polyactate filament and a water-soluble Polyvinyl alcohol-based support structures. Precision of these models was compared to commercial, polyamide sintered models and the planning data. Production costs, printing times and post processing procedures were evaluated. RESULTS: Duration of printing of mandibular biomodels was between 6 h 5 min - 15 h 9 min (mean 9 h 12 min, ±2 h 25 min). The average cost of materials was €5.90 (± €1.28) per model. With an average aberrance of 0.29 mm, FLDM printing delivered a high level of accuracy. It was significantly superior to the polyamide reference models in the area of the semilunar incision, yet inferior at the coronoid process. CONCLUSION: FLDM printers are able to provide very precise biomodels at very low costs. The use of using soluble support structures reduces time, costs and equipment needed for post processing procedures close to zero.