RESUMO
Orthognathic surgery enables patients with severe jaw malocclusions to normalise their chewing function and, as such, to improve their quality of life. Over the last few years, digitalisation has been set in motion by intraoral scanners and the improvement of planning software in the field of oral and maxillofacial surgery. Previous studies based on plaster cast models showed that the virtual occlusion based on digitally scanned models can be comparable to conventional methods. This retrospective crossover study aimed to prove that the virtual occlusion finding with the IPS CaseDesigner® (version 2.3.5.2, KLS Martin, Tuttlingen, Germany) is accurate enough to use intraoral scans exclusively. MATERIALS AND METHODS: A total of 23 orthognathic surgery patients receiving an intraoral scan for their treatment were included in this study. Two experienced maxillofacial surgeons haptically performed the occlusion finding on three-dimensional (3D) stereolithographic models using the fully digital pathway. One surgeon repeated the procedure a second time to evaluate intra-observer variability. The study aimed to show the difference between these two planning methods by upholding the surgical accuracy of less than 2 mm in translation and 2° in rotation. The conventional haptic occlusion was set as a reference throughout the whole study. The data were tested with a one-sample Wilcoxon test for the fit into the surgical accuracy. RESULTS: The difference between the virtual and conventional groups was significantly smaller than the surgical accuracy (all p < 0.001). Both translational movements (anterior/posterior (median 0.51 mm [0.28, 0.88]), left/right (median 0.46 mm [0.20, 0.87]), cranial/caudal (median 0.37 mm [0.11, 0.69])) and rotations (Roll (median 0.71° [0.29, 1.35]), Pitch (median 0.72° [0.29, 1.44]), Yaw (median 1.09° [0.33, 1.60])) were in the range of surgical accuracy (2 mm/2°). The most significant differences were found in the anterior/posterior translation (median 0.51 mm [0.28, 0.88]) and the Yaw rotation (median 1.09° [0.33, 1.60]). CONCLUSION: These results demonstrate that the entirely virtual workflow in orthognathic surgery, including intraoral scanning and the virtual semi-automatic occlusion finding, represents a reliable and state-of-the-art alternative to the conventional haptic method.
RESUMO
The application of biomaterials used in regenerative endodontics should be traceable. In this study, we checked some basic effects of rendering a fibrin hydrogel radiopaque using an iodine-based contrast agent (iodixanol) approved for systemic application. Fibrin hydrogels were prepared from a fibrin sealant (Tisseel) using either an isotonic iodixanol solution (Visipaque 320, test) or Tris buffer (control) as a diluent. Gelation kinetics, radiopacity, and swelling of lyophilized hydrogels were tested using standard methods. Hydrogel structure was evaluated using scanning electron microscopy (SEM). Furthermore, iodixanol release from the test gels was assessed using spectrophotometry, and tissue compatibility was compared between test and control hydrogels using the chick chorioallantoic membrane (CAM) assay. Results were compared using pairwise t-test, p < 0.05. Iodixanol caused a 70-fold delay in gelation to 26 min in the test compared to the control hydrogels (22 ± 1 s). Radiopacity of the test gels was 1.9 ± 0.2 mm Al/mm, compared to zero in the control hydrogels. Lyophilized hydrogel swelling was strongly reduced when iodixanol was added to the hydrogel (p < 0.05). Test hydrogels had an altered SEM appearance compared to controls, and exhibited a reduced porosity. Iodixanol release from the test hydrogels reached 14.5 ± 0.5% after 120 h and then ceased. This release did not have any apparent toxic effect and neither affected the viability, nor the physiology or vascularization of the CAM of fertilized chicken eggs. Iodixanol can render a fibrin hydrogel radiopaque and maintains its tissue compatibility, yet impacts gelation kinetics and hydrogel porosity.