The virtual human face – superimposing the simultaneously captured 3D photorealistic skin surface of the face on the untextured skin image of the CBCT Scan

The aim of this study was to evaluate the impact of simultaneous capture of the three-dimensional (3D) surface of the face and cone beam computed tomography (CBCT) scan of the skull on the accuracy of their registration and superimposition. 3D facial images were acquired in 14 patients using the Di3d (Dimensional Imaging, UK) imaging system and i-CAT CBCT scanner. One stereophotogrammetry image was captured at the same time as the CBCT and another one hour later. The two stereophotographs were then individually superimposed over the CBCT using VRmesh. Seven patches were isolated on the final merged surfaces. For the whole face and each individual patch; maximum and minimum range of deviation between surfaces, absolute average distance between surfaces, and standard deviation for the 90th percentile of the distance errors were calculated. The superimposition errors of the whole face for both captures revealed statistically significant differences (P=0.00081). The absolute average distances in both separate and simultaneous captures were 0.47mm and 0.27mm, respectively. The level of superimposition accuracy in patches from separate captures ranged between 0.3 and 0.9mm, while that of simultaneous captures was 0.4mm. Simultaneous capture of Di3d and CBCT images significantly improved the accuracy of superimposition of these image modalities

Digital replacement of the distorted dentition acquired by Cone Beam Computed Tomography (CBCT): a pilot study

During cone beam computed tomography (CBCT) scanning, intra-oral metallic objects may produce streak artefacts, which impair the occlusal surface of the teeth. This study aimed to determine the accuracy of replacement of the CBCT dentition with a more accurate dentition and to determine the clinical feasibility of the method. Impressions of the teeth of six cadaveric skulls with unrestored dentitions were taken and acrylic base plates constructed incorporating radiopaque registration markers. Each appliance was fitted to the skull and a CBCT performed. Impressions were taken of the dentition with the devices in situ and dental models were produced. These were CBCT-scanned and the images of the skulls and models imported into computer-aided design/computer-aided manufacturing (CAD/CAM) software and aligned on the registration markers. The occlusal surfaces of each dentition were then replaced with the occlusal image of the corresponding model. The absolute mean distance between the registration markers in the skulls and the dental models was 0.09 ± 0.02 mm, and for the dentition was 0.24 ± 0.09 mm. When the method was applied to patients, the distance between markers was 0.12 ± 0.04 mm for the maxilla and 0.16 ± 0.02 mm for the mandible. It is possible to replace the inaccurate dentition on a CBCT scan using this method and to create a composite skull which is clinically acceptable

Mandibular reconstruction in the rabbit using beta-tricalcium phosphate (β-TCP) scaffolding and recombinant bone morphogenetic protein 7 (rhBMP-7) - histological, radiographic and mechanical evaluations

This investigation assesses the histological, radiographic and mechanical properties of regenerated bone in a unilateral critical-size osteoperiosteal mandibular continuity defect in the rabbit model, following the application of beta-tricalcium phosphate (β-TCP) scaffolding and recombinant human bone morphogenetic protein 7 (rhBMP-7). The study was carried out on nine cases; in six cases the critical-size defect was filled with rhBMP-7 in the β-TCP scaffolding, and in three cases the β-TCP was used alone. The cases were sacrificed 3 months post-operatively. Histologically the overall mean of the percentage of regenerated bone volume in the cases that received rhBMP-7 was 29.41% ± 6.25%, which was considerably greater than the 6.35% ± 3.08% in the cases treated with β-TCP alone. Mechanical testing of the cases treated with rhBMP-7 gave failure moments (55 mNm-2.040 Nm) that were consistently greater than those treated with β-TCP alone (0 mNm-48 mNm). In some cases the mechanical properties of the regenerated bone were comparable to those of untreated bone. RhBMP-7 in prefabricated β-TCP scaffolding appeared, radiographically and histologically, to be an effective method for bone regeneration in mandibular critical-size defects in the rabbit model. This points towards possible future clinical applications