High-resolution three-dimensional 3D imaging is the standard radiographic evaluation tool. Magnetic resonance imaging is used to determine the actual position of the disc, while multi-slice computed tomography MSCT and Cone-Beam CT CBCT are used to evaluate osseous pathological changes at the condylar level. However, if a follow-up of the surgical stability is indicated, the patient is exposed to a high dose of radiation. Therefore, an alternative low-dose CBCT approach can be recommended. Recent advancements in CBCT technology have allowed sufficient resolution to accurately depict bone structures and render 3D models.
- Cone Beam Imaging in Glen Allen & Richmond.
- Expertise and Decision Support.
- Learn More about Cone Beam CT - 3D Imaging!
Most of the time, methods to assess condylar resorption remain limited to two-dimensional 2D measurements. As a second objective, the reliability and accuracy of this condylar volume quantification were evaluated. All patients provided informed consent, and ethical approval was obtained from the medical ethics committee of University Hospitals KU Leuven, Leuven Belgium S All patients were orthodontically treated before and after surgery.
No subjects had a previous history of maxillofacial trauma or any known autoimmune or metabolic bone disease. The mandibular bone was semi-automatically delineated by using a global threshold algorithm. The computer suggested bone threshold values were visually confirmed in order to allow for the best segmentation overlap with the original image. The segmented mandibles were rendered in 3D and saved in. Subsequently, the pre- and postoperative 3D models were imported in 3-Matic software Version 9.
The anatomical landmarks were selected on the coronoid process and the mandibular ramus and angle, owing to expected changes in the mandibular body and symphysis morphology after orthognathic surgery and the presence of metal braces from orthodontic treatment. On the basis of the best fit of these landmarks, the computer calculated the optimal translation and rotation between the pre- and postoperative 3D mandibles by minimizing the mean square distance between the coronoid and ramus surfaces.
In this way, the left and right condyles were registered separately. To achieve uniform selection of each condyle from the mandible, a standardized sphere with its border passing through the lowest point of the mandibular notch was created around the condyle. After consistent extraction of the condyle, the condylar bone volume was automatically calculated in mm 3. Workflow of the patient data image analysis.
The reproducibility of the condylar volume determination may be affected by subjective VOI and bone threshold selections. Therefore, inter- and intra-observer reliability were calculated between assessments made by two experienced radiologists LFPN and CL at two time points with a 5-month interval T1 and T2 in a set of 10 randomly selected patients.
A VOI selection procedure was performed according to the clinical assessment described above. The resulting 3D models of the corresponding condyles selected by each observer were overlaid to calculate the discrepancies between both models using distance-to-curve and part-comparison analyses Figure 2. First, the mean distance in mm between the lower borders was automatically quantified and used as a measurement of discrepancy in VOI selection.
Dental Cone Beam CT
Second, the shortest distance in mm between each internal and surface part of the two models was automatically calculated after the removal of dissimilarities in VOI selection through model subtraction and used as a measurement of threshold selection discrepancy. Workflow of the method reproducibility with MSCT data.
A distance-to-curve analysis detected differences in the region of interest selection mean: 1. Before the part-comparison analysis, the error generated by the region of interest selection is subtracted red colour. In this way, the calculation of the local differences between the 3D models is possible without counting the error of the region of interest selection. Part-comparison analysis from presented case shows a mean distance of 0. To examine the accuracy of the analytic approach, one dry human mandible was obtained from the Institute for Biomedical Research, Hasselt University and was approved for research by the ethical committee of the University Hospitals KU Leuven S An overview of the image processing steps is shown in Figure 3.
Accuracy of the condyle mineralized bone assessment. First column: The results of image registration between the different modalities. Second column: Image segmentation based on grey values. Third column: rendered 3D condylar models for all imaging modalities. The green colour indicates an overestimation of less than one voxel between both 3D models and yellow and red indicate an overestimation of more than 0. After precise registration, each image was semi-automatically segmented and 3D rendered by using the same processing protocol as in the clinical evaluation.
Cone Beam CT Scan
The mineralized condylar bone volume was automatically calculated and compared among the different imaging modalities. Sex and age were included as covariates. The intra-class correlation coefficient ICC was calculated between condylar volume, as a measure to evaluate the agreement within and between the observers. The two-way mixed single measures for consistency were reported.
Cone Beam CT Mentor OH | 3D Imaging, CBCT, 3D Scanner Mentor OH
The reproducibility of the procedure was influenced by the differences in VOI selection and bone threshold selection. Measurement discrepancies and standard deviations were reported for condylar volume in mm 3 , VOI selection in mm and bone threshold selection in mm. The 40 condyles of 20 patients were analysed. All condyles, except for two from the same patient, exhibited remodelling of the mineralized volume of the condyle ranging up to a maximum of In individual subjects, differences in volumetric remodelling between the left and right condyles varied from 0.
No significant sex effect was observed in the present sample. In females, the condylar remodelling volume decreased on average by Volume, VOI and segmentation discrepancies are shown in Table 1. The part-comparison analysis indicated an overestimation of the bone segmentation of 0. In the present study, preoperative MSCT data and low-dose CBCT data at the 6-month postoperative follow-up from patients who underwent bimaxillary surgery were used to objectively assess condylar volume changes and to validate a new quantification method for condylar volume.
Unfortunately, the assessment of the age predilection is complicated, because most orthognathic surgery is performed in young patients. The female predisposition to condylar resorption, which occurs at a frequency of , 19 , 22 has been suggested to be related to a regulatory effect of oestrogen on bone metabolism in the TMJ. Moreover, as an important consideration, women seek medical help for dentofacial abnormalities more often than men. Because of the study design and the implementation of only clinical and two-dimensional radiological data for the diagnosis of condylar alterations, most published studies have intrinsic limitations, although the diagnosis of condylar resorption in longitudinal studies is often based on a qualitative assessment of the mandibular condyles on OPG.
In contrast with previous studies conducting follow-ups on surface and morphological condylar changes, 12 , 24 , 26 this novel imaging procedure attempted to depict the overall mineralized bone content. The purpose was to assess resorption by quantifying the volume of mineralized bone, both in the cortical surface and in the trabecular bone. In this way, the present study found a greater condylar volume decrease compared with a previous study 14 that has reported no more than a 6.
- Public Health Policy and Ethics!
- Coastal Mass Tourism: Diversification and Sustainable Development in Southern Europe (Aspects of Tourism, 12)?
- Political Self-Sacrifice: Agency, Body and Emotion in International Relations (Cambridge Studies in International Relations).
This contradiction may also be explained by the differences in the follow-up period. Six months is too short to determine the long-term effects of orthognathic surgery on condylar status, because the effects can develop for more than 1 year. Unlike a traditional spiral CT scanner, this 3D system utilizes cone beam CT technology and provides precise, crystal-clear digital images while minimizing your exposure to radiation. Our new 3D system enables us to perform a wider range of diagnoses and treatments in our office, helping to reduce multiple visits.
The CS scanner allows us to choose the field of view, or scanning area, that best suits your specific treatment needs. Our new 3D system enables us to perform a wider range of diagnoses and treatments in our office, helping to reduce multiple visits. The CS scanner allows us to choose the field of view, or scanning area, that best suits your specific treatment needs.
This helps to limit your radiation exposure because we are focusing specifically on your area of concern. Layne, Melzer or Pedroletti can use this innovative technology to quickly and easily share 3D images of the area of concern with your referring doctor — allowing the doctors to collaborate on your care, improving your experience, and delivering a positive treatment outcome. Click for menu.