Global wealth disparities drive adherence to COVID-safe pathways in head and neck cancer surgery

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COMPUTED-TOMOGRAPHY IN THE PREOPERATIVE PLANNING OF ORAL ENDO-OSSEOUS IMPLANT-SURGERY

Computed tomography (CT) is a well-established aid in the preoperative assessment of the dimension of mandible and maxilla for endo-osseous implant installation. CT is a valuable tool for the measurement of the alveolar ridge and recognition of the course of the inferior alveolar nerve canal. In the present study, three different techniques were examined: normal CT images with coronal and sagittal slices, standard reconstructions based on axial slices, and multiplanar reconstruction and display (MPR/MPD), also based on axial slices. Six dissected human jaw bones were examined with these three techniques. Afterwards, these jaws were sawn, and the real values were measured. Comparing these scores with the radiological measurements, the standard reconstruction technique seemed the most reliable method in the preoperative examination of the jaw bone quality and bone proportion.status: publishe

CT scan standard reconstruction technique for reliable jaw bone volume determination

Computed tomography can assist the surgeon in planning the exact three-dimensional positioning of endosseous implants in the jaw bone. This study examined the reliability of three CT techniques: direct imaging (normal coronal and sagittal slices), standard reconstruction (based on axial slices), and multiplanar reconstruction and display (also based on axial slices). The three imaging techniques were used to estimate the bone height, bone width, and maximal implant length in six dissected human jaw bones. These jaws were then sawed perpendicular to their axis to enable measurement of real values for comparison. The sagittal and coronal slices frequently were overestimated, especially in the canine and premolar regions. The mean absolute deviation was 1.4 mm. Standard reconstruction offered the most reliable cross-sectional images, with a mean absolute deviation of 0.5 mm. The multiplanar reconstruction and display technique frequently demonstrated underestimations (mean absolute deviation was 2.3 mm). The standard reconstruction technique seems to be the method of choice in preoperative radiographic examination of patients before implant placement.status: publishe

Computed tomography in the preoperative planning of oral endo-osseous implant surgery

Computed tomography (CT) is a well-established aid in the preoperative assessment of the dimension of mandible and maxilla for endo-osseous implant installation. CT is a valuable tool for the measurement of the alveolar ridge and recognition of the course of the inferior alveolar nerve canal. In the present study, three different techniques were examined: normal CT images with coronal and sagittal slices, standard reconstructions based on axial slices, and multiplanar reconstruction and display (MPR/MPD), also based on axial slices. Six dissected human jaw bones were examined with these three techniques. Afterwards, these jaws were sawn, and the real values were measured. Comparing these scores with the radiological measurements, the standard reconstruction technique seemed the most reliable method in the preoperative examination of the jaw bone quality and bone proportion.status: publishe

Technica standard di ricostruzione mediante TAC per una corretta determinazione del volume dell'osso mascellare

status: publishe

A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface.

Item does not contain fulltextCone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of < or =0.22 mm (25% percentile), < or =0.44 mm (50% percentile) and < or =1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18+/-0.10 mm (range 0.13-0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface

The use of a wax bite wafer and a double computed tomography scan procedure to obtain a three-dimensional augmented virtual skull model.

Item does not contain fulltextA detailed visualization of the interocclusal relationship is essential in a three-dimensional virtual planning setup for orthognathic and facial orthomorphic surgery. The purpose of this study was to introduce and evaluate the use of a wax bite wafer in combination with a double computed tomography (CT) scan procedure to augment the three-dimensional virtual model of the skull with a detailed dental surface. A total of 10 orthognathic patients were scanned after a standardized multislice CT scanning protocol with dose reduction with their wax bite wafer in place. Afterward, the impressions of the upper and lower arches and the wax bite wafer were scanned for each patient separately using a high-resolution standardized multislice CT scanning protocol. Accurate fitting of the virtual impressions on the wax bite wafer was done with surface matching using iterative closest points. Consecutively, automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model (Maxilim, version 2.0; Medicim NV, St-Niklaas, Belgium). Probability error histograms showed errors of < or =0.16 mm (25% percentile), < or =0.31 mm (50% percentile), and < or =0.92 (90% percentile) for iterative closest point surface matching. The mean registration error for automatic point-based registration was 0.17 +/- 0.07 mm (range, 0.12-0.22 mm). The combination of the wax bite wafer with the double CT scan procedure allowed for the setup of an accurate three-dimensional virtual augmented model of the skull with detailed dental surface. However, from a clinical workload, data handling, and computational point of view, this method is too time-consuming to be introduced in the clinical routine