Cone-beam Tomography Research Articles

A three-dimensional topology optimization model for tooth-root morphology

To obtain the root of a lower incisor through structural optimization, we used two methods: optimization with Solid Isotropic Material with Penalization (SIMP) and Soft-Kill Option (SKO). The optimization was carried out in combination with a finite element analysis in Abaqus/Standard. The model geometry was based on cone-beam tomography scans of 10 adult males with healthy bone-tooth interface. Our results demonstrate that the optimization method using SIMP for minimum compliance could not adequately predict the actual root shape. The SKO method, however, provided optimization results that were comparable to the natural root form and is therefore suitable to set up the basic topology of a dental root.

Perspectives of the Tooth Restoration Technology Based on the Computed Tomography Data

The aim of the study is to create an image processing system, which allows dentists to create tooth surface automatically. X-rays images of jaws from the cone beam tomography or the spiral computed tomography and images from the micro-computed tomography are the initial data for processing. Example of using the combination of optical and x-ray images in the dentistry is described. Also, it was shown how to use the microcomputed tomography method to plan the placement of orthopedic structures on the lost teeth sites.

Cone-beam CT functional imaging method by using volume integral model

In order to improve the precision of functional imaging of cone beam computed tomography (CBCT), this paper firstly uses the dynamic contrast enhancement tomography (DCE-CT) of the white rabbit as the measured object and establishes volume integral model to obtain the projection data. Then the optimization method is used to solve the optimal parameter pairs of the voxel time density curve (TDC). Finally, the results of the perfusion are obtained by the deconvolution method. The results show that the TDC correlation coefficient is 83.99% after, and the maximum of Spearman correlation coefficient of the perfusion parameter is 0.5125, and the projection time consumption is 7.633 seconds through the volume integral model. It can be seen that the volume integral model is closer to the real projection and it can obtain more accurate perfusion data.

Multidisciplinary oral rehabilitation in partially edentulous adult patients with malocclusion: A cross-sectional survey study.

BackgroundA cross-sectional survey was conducted to gather information regarding the opinion of Brazilian specialists in both orthodontics and implantology on multidisciplinary oral rehabilitation in partially edentulous patients with malocclusion.Material and MethodsA total of 305 specialists participated in a telephone survey and answered an ad hoc 10-item questionnaire, including the request of total skull cone-beam tomographies (CBCT) and the use of 3D digital planning software, the best moment of treatment to place dental implants, and the integration of orthodontics in implantology.ResultsMost participants did not request CBCT (90.8%) or 3D digital planning software images (92.3%) to diagnose and plan multidisciplinary oral rehabilitation. By contrast, 91.1% of participants would use an already dental implant as anchorage for orthodontics, 73.8% had already used implants for this purpose, 47.9% selected 4 months as the waiting time between implant placement and its use as anchorage, and 58.4% had already placed dental implants having in mind using them as anchorage for orthodontics and anticipating the oral rehabilitation process. Moreover, 93.4% of participants stated to avoid applying orthodontic forces in implants with unfavourable prognosis. A total of 67.9% of participants got the degree of specialist in Orthodontics before that of specialist in Implantology. The main reason for obtaining the other specialty degree was to be able to thoroughly exercise the two specialties.Conclusions The use of technological advances, such as CBCT and 3D digital planning software was limited. Most dental specialists would wait the osseointegration recommended time before applying orthodontic forces and thus using them as anchorage for orthodontics. The majority of interviewed dentists sought the other specialty to acquire multidisciplinary knowledge. Key words:Cross-sectional study, orthodontics, implantology, partially edentulous, malocclusion, oral rehabilitation.

Chondroblastic osteosarcoma of the mandible: case report

ABSTRACT We report the case of a 32-year-old male patient, who was subjected to cone-beam tomography for planning the removal of an unerupted tooth. Cone-beam CT scans revealed the presence of a mixed lesion with poorly defined limits in the left posterior mandibular region, with sun-ray periosteal reaction. An incisional biopsy was performed and the diagnosis was chondroblastic osteosarcoma. In this paper, a discussion of the differential diagnosis criteria and treatment of this unusual malignant neoplasm is performed. Thus, it is intended to provide information that will help in the study of management protocols for the increasingly effective treatment of gnathic osteosarcomas.

Penalized-Likelihood Reconstruction With High-Fidelity Measurement Models for High-Resolution Cone-Beam Imaging.

We present a novel reconstruction algorithm based on a general cone-beam CT forward model, which is capable of incorporating the blur and noise correlations that are exhibited in flat-panel CBCT measurement data. Specifically, the proposed model may include scintillator blur, focal-spot blur, and noise correlations due to light spread in the scintillator. The proposed algorithm (GPL-BC) uses a Gaussian Penalized-Likelihood objective function, which incorporates models of blur and correlated noise. In a simulation study, GPL-BC was able to achieve lower bias as compared with deblurring followed by FDK as well as a model-based reconstruction method without integration of measurement blur. In the same study, GPL-BC was able to achieve better line-pair reconstructions (in terms of segmented-image accuracy) as compared with deblurring followed by FDK, a model-based method without blur, and a model-based method with blur but not noise correlations. A prototype extremities quantitative cone-beam CT test-bench was used to image a physical sample of human trabecular bone. These data were used to compare reconstructions using the proposed method and model-based methods without blur and/or correlation to a registered CT image of the same bone sample. The GPL-BC reconstructions resulted in more accurate trabecular bone segmentation. Multiple trabecular bone metrics, including trabecular thickness (Tb.Th.) were computed for each reconstruction approach as well as the CT volume. The GPL-BC reconstruction provided the most accurate Tb.Th. measurement, 0.255 mm, as compared with the CT derived value of 0.193 mm, followed by the GPL-B reconstruction, the GPL-I reconstruction, and then the FDK reconstruction (0.271 mm, 0.309 mm, and 0.335 mm, respectively).

Three-dimensional reconstructions of CT scans and cone beam CT of impacted maxillary canines in order to locate areas of ankylosis before orthodontic traction

The aim of this study was to model impacted maxillary canines and determine whether areas of ankylosis were present before undertaking orthodontic traction. Amira/ResolveRT™ software, version 5.0, by FEI Company is a meshing and surface-rendering program that was used to produce three-dimensional reconstructions from CT scans and cone beam images of the impacted canines of 30 patients (10 cone beam files and 20 CT scan files). The presence of zones of ankylosis on the roots of certain impacted canines is revealed by the inversion of the direction of meshing on the tooth surface and on a larger scale by invagination of bone tissue into the tooth tissue at various densities measured in Hounsfield units by the AMIRA™ software program. This observation can guide treatment towards extraction of the impacted tooth, its autotransplantation, or deep alveolar corticotomy, followed by mobilization when the canine is in a vestibular position. AMIRA™ software made it possible to detect zones of ankylosis on the roots of certain impacted canines and to adopt a treatment program different from conventional surgico-orthodontic traction. The final aim is to reposition the impacted canine without endangering the adjacent teeth.

An Innovative Regenerative Endodontic Procedure Using Leukocyte and Platelet-rich Fibrin Associated with Apical Surgery: A Case Report

Regenerative endodontic procedures (REPs) associated with apical surgery could represent an alternative treatment strategy for patients whose teeth present incomplete root formation and extensive apical lesions. Leukocyte platelet-rich fibrin (L-PRF) has potential benefits in REPs; it could promote apical root formation and optimal bone healing. The aim of this case report was to describe innovative regenerative endodontic therapy using L-PRF in the root canal and an extensive apical lesion in an immature tooth with dens invaginatus and asymptomatic apical periodontitis. A healthy 20-year-old woman was referred to the dental clinic of the Universidad de Los Andes, Santiago, Chile, for endodontic treatment in tooth # 22 with incomplete root development and an extensive apical lesion. The diagnosis was asymptomatic apical periodontitis associated with dens invaginatus type II. The patient was treated with an innovative approach using L-PRF in REPs associated with apical surgery. Follow-ups were performed at 6 months and 1 year later. They included periapical radiographs, cone-beam computed tomographic imaging, sensitivity, and vitality tests. The clinical evaluations performed at 6 months and 1 year revealed an absence of symptoms. The radiographic evaluations showed that the apical lesion was resolved. The cone-beam images indicated that the root length increased and the walls had thickened. The sensitivity tests were positive, and the laser Doppler flowmetry showed positive blood flow after 1 year. The success of the results in this case report indicate that L-PRF can be used as a complement in apical surgery and REPs and could provide an innovative alternative treatment strategy for complex clinical cases like these.

Intrafraction Motion of Patients during Cranial Treatments in Two Different Head Immobilization Systems

To determine the effectiveness of two different methods (reusable or patient specific) for head and neck immobilization during intracranial robotic radiosurgery treatments and infer the consequences of this motion for cone beam image guided treatments on conventional linacs. During intracranial robotic radiosurgery, the patient’s position is evaluated by acquiring a pair of orthogonal x-ray images of their skulls every 30-60 seconds. The robotic arm, on which the radiation treatment unit is mounted, corrects for patient position based on the last pair of images. For this system, the errors introduced by patient motion during treatment can be estimated from the difference between subsequent pairs of images. For most conventional linac treatments, the patient’s position is only determined at the start of treatment using 3D cone-beam imaging. For these systems, errors introduced by patient motion during treatment can also be estimated using the robotic system data, using the difference between the initial position and the average position over the typical duration of treatment (10 minutes). We examined the magnitude of patient motion during treatment for 59 patients using a reusable headrest and 36 patients using a disposable patient specific headrest. The positioning errors were evaluated using a well-known margin recipe which separates patient setup error into random, σ, and systematic, Σ, components. Results are summarised in table 1 for both headrests and both types of treatment modalities.Abstract 3738; Table 1Analysis of residual setup errors due to patient motion during treatment. Errors are estimated for the imaging systems used for the robotic radiosurgery system and for conventional radiation therapy treatments using a reusable headrest or a disposable but patient specific headrestHeadrestTranslational component (mm)Rotational component (degree)σΣMargin (mm)σΣRobotic Radiosurgery TreatmentsDisposable(Patient Specific)0.100.050.20.140.07Reusable0.290.180.60.260.15Conventional TreatmentsDisposable(Patient Specific)0.310.190.70.330.17Reusable0.460.261.00.340.17 Open table in a new tab For robotic radiosurgery treatments, random and systematic errors are approximately three to four times higher for the reusable headrest than for the patient specific system, stressing the importance of precise immobilization for this system, since no margin between the tumour and treated volume is typical. For conventional treatments, the relative differences between the two headrest systems are smaller, but relatively large compared the 3 mm margin currently used in our clinic for brain treatments. Care should be taken when considering changes to clinical practice which can impact the precision of radiation treatments.

Оценка взаимосвязи между объемом языка и скученностью резцов нижней челюсти с использованием конусно-лучевой компьютерной 3D-томографии

Оценка взаимосвязи между объемом языка и скученностью резцов нижней челюсти с использованием конусно-лучевой компьютерной 3D-томографии

3D Print of the Maxillary Sinus for Morphological Study

The maxillary sinus (MS) is described as a pyramid-shaped cavity of the maxilla. Knowledge of its morphology makes it possible to define normality and abnormality so that its three-dimensional analysis can be a valuable preoperative tool during surgery in this anatomical area. The aim of this study is to present a strategy of morphological analysis of the MS using 3D printing acquired through computed cone beam tomography (CBCT) images. A cross-sectional descriptive study was conducted, including 15 subjects (8 women and 7 men). The 3D virtual reconstruction and modeling was done on the MSs bilaterally, and 30 physical models were produced on a 3D printer. The results revealed that the MSs obtained exhibited various morphologies. An individual analysis of each MS allowed the tripod nature of the MS to be defined. We also were able to observe anatomical repairs such as the MS ostium, as well as complex areas affecting important surgical decisions. This method for creating 3D models of MSs provides a new approach to understanding the precise anatomical characteristics in these structures, which cannot be assessed in the same way on a 2D screen. It may be concluded that 3D printouts of the MS are a suitable method of preoperative analysis that can be useful in educating the patient, however, less time-consuming strategies should be explored. © 2017, Universidad de la Frontera. All rights reserved.

Accuracy of Proximal Caries Depth Measurements: Comparison of Two Computed Cone Beam Tomography and Storage Phosphor Plate Systems

Accuracy of Proximal Caries Depth Measurements: Comparison of Two Computed Cone Beam Tomography and Storage Phosphor Plate Systems

Residents' journal review

Residents' journal review

Linac-based stereotactic radiation therapy for canine non-lymphomatous nasal tumours: 29 cases (2013-2016).

Twenty-nine dogs were treated with linac-based stereotactic radiation therapy (SRT) for non-lymphomatous nasal tumours. Only dogs with a follow-up time >365 days were included in this retrospective analysis. No dogs had evidence of distant metastasis at diagnosis. Treatment was planned and a total of 30 Gy in 3 daily 10 Gy fractions was delivered using intensity-modulation, cone-beam CT-based image guidance and a robotic treatment couch. Clinical signs improved in all cases. Nineteen dogs had CT scans 3-4 months post-SRT and all had partial or complete tumour response. Minimal acute toxicities were detected. Clinically significant late toxicities included oronasal or nasocutaneous fistulas (N = 3) and biopsy-confirmed fungal rhinitis with no evidence of tumour progression (N = 2). The median progression-free survival (PFS) was 354 days, with 49% and 39% progression-free at 1 and 2 years post-SRT, respectively. The median survival time (ST) was 586 days, with 69% and 22% alive 1 and 2 years post-SRT, respectively. Neither the clinical parameters evaluated (modified Adams' stage, histopathology, presence of intracranial extension of the tumour) nor dosimetric data were predictive for PFS or ST. This SRT protocol appears to be well tolerated, and PFI and ST are comparable or superior to those reported in other definitive-intent radiotherapy protocols.

Evaluating the scattered radiation intensity in CBCT

In this work we calculate the ratio between scattered and transmitted photons (STRR) by a water cylinder reaching a detector matrix element (DME) in a flat array of detectors, similar to the used in cone beam tomography (CBCT), as a function of the field of view (FOV) and the irradiated volume of the scanned object. We perform the calculation by obtaining an equation to determine the scattered and transmitted radiation and building a computer code in order to calculate the contribution of all voxels of the sample. We compare calculated results with the shades of gray in a central slice of a tomography obtained from a cylindrical glass container filled with distilled water.The tomography was performed with an I-CAT tomograph (Imaging Science International), from the Department of Dental Clinic – Oral Radiology, Universidade Federal de Juiz de Fora. The shade of gray (voxel gray value – VGV) was obtained using the software provided with the I-CAT.The experimental results show a general behavior compatible with theoretical previsions attesting the validity of the method used to calculate the scattering contributions from simple scattering theories in cone beam tomography.The results also attest to the impossibility of obtaining Hounsfield values from a CBCT.

An iterative weighted method based on YALL1 for cone-beam X-ray luminescence optical tomography imaging: A phantom experimental study.

Cone-beam X-ray luminescence optical tomography (CB-XLOT) plays an important role in in vivo small animal imaging study, which can non-invasively image the three-dimensional (3-D) distribution of x-ray-excitable nanophosphors deeply embedded in imaged object. However, CB-XLOT suffers from a low spatial resolution due to the ill-posed nature of optical reconstruction. To alleviate the ill-posedness of reconstruction and improve the imaging performance of XLOT, in this paper, we propose an iterative weighted L1 minimization method which is achieved by incorporating YALL1 (Your algorithm for L1 norm problems). The physical phantom experiment was conducted to evaluate the performance of the proposed method, where a custom-made cone-beam XLOT system was used as the imaging platform. The experimental results indicate that by applying the proposed iterative weighted strategy to YALL1 method, the reconstruction performance of XLOT can be improved when compared with the conventional YALL1 method.

Osseointegration of dental implants without primary stability: an experimental study in sheep

Background and objective: Primary implant stability is considered necessary forachieving and maintaining osseointegration. This experimental study aimed to evaluate theoutcome of implants without primary stability, clinically and radiographically.Methods: Two adult sheep (3-4 years of age), 70 kg in weight, were included in the study.After sedation and local anesthesia, the lateral side of the basal bone of mandible isexposed by a single long incision. The implant bed performed in the inferior border of thebasal bone of mandible drilling to 5 mm in diameter and 10 mm in length. Five implantswere inserted into the basal bone of mandible for each side (right and left), but the sizes ofinserted implant was 3.8 mm in diameter and 10 mm in length, after 4 months the 2 sheepwere sacrificed and the universal torque ratchet was used to measure the stability of theimplant by a counter torque 30 N/cm test. Cone Beam Tomography (CBCT) was used toevaluate the implants radiographically.Results: Nineteen (from 20) implants successfully tolerated a 30 N/cm countertorque testcomprising (95%). Only one implant failed to osseointegrate (5%). During the healingperiod, no any adverse clinical signs reported.Conclusion: Dental implants may have a chance to osseointegrate even in the lack ofprimary stability.

Characterization of continuous and pulsed emission modes of a hybrid micro focus x-ray source for medical imaging applications

The aim of this study was to quantitatively characterize a micro focus x-ray tube that can operate in both continuous and pulsed emission modes. The micro focus x-ray source (Model L9181-06, Hamamatsu Photonics, Japan) has a varying focal spot size ranging from 16µm to 50µm as the source output power changes from 10 to 39W. We measured the source output, beam quality, focal spot sizes, kV accuracy, spectra shapes and spatial resolution. Source output was measured using an ionization chamber for various tube voltages (kVs) with varying current (µA) and distances. The beam quality was measured in terms of half value layer (HVL), kV accuracy was measured with a non-invasive kV meter, and the spectra was measured using a compact integrated spectrometer system. The focal spot sizes were measured using a slit method with a CCD detector with a pixel pitch of 22µm. The spatial resolution was quantitatively measured using the slit method with a CMOS flat panel detector with a 50µm pixel pitch, and compared to the qualitative results obtained by imaging a contrast bar pattern. The focal spot sizes in the vertical direction were smaller than that of the horizontal direction, the impact of which was visible when comparing the spatial resolution values. Our analyses revealed that both emission modes yield comparable imaging performances in terms of beam quality, spectra shape and spatial resolution effects. There were no significantly large differences, thus providing the motivation for future studies to design and develop stable and robust cone beam imaging systems for various diagnostic applications.

Predictive factors for resorption of teeth adjacent to impacted maxillary canines.

The aim of this study was to assess the link between the degree of resorption of teeth adjacent to an impacted maxillary canine and the situation of the latter so as to identify factors predictive of resorption. This was a retrospective study concerning all patients with impacted maxillary canines who consulted the orthodontics department at the Center for dental care, teaching and research (CSERD) in Montpellier between 2010 and 2015, with a full radiological file including panorex, periapical long-cone and cone-beam images. In all, 25 patients with 31 impacted maxillary canines were analyzed. Measurements were made by a single operator using 2D images and 3D analysis; they concerned the quantitative and qualitative aspects of resorption of teeth adjacent to the impacted canines and also evaluation of the position of the maxillary canine and its follicular sac. The X2 test was used to compare percentage resorption in men and women. Analysis of variance (ANOVA) was applied to compare the average degree of resorption of the adjacent teeth depending on the sagittal or vertical position of the impacted maxillary canine. Covariance analysis (ANCOVA) was used to study the average degree of resorption taking jointly into account the sagittal, vertical and transverse positions and adjusting for age and sex. Calculations were performed with a significance threshold of 5% using MyStat® software. Women made up 60.6% of the study population, with no significant age differences between the two sexes (21±5 years). The risk of adjacent resorption was not linked to age but was significantly greater (P-value=0.03) for women (60%) than for men (23%). The average degree of resorption is explained jointly by sagittal position (P-value=0.0001) and transverse position (P-value=0.01), after adjustment for age and sex. On the other hand, the average degree of resorption was not linked to vertical position, nor to the shape or size of the follicular sac. This study leads to the conclusion that the risk of resorption of the lateral incisor is not linked to the buccal or palatal situation of the canine. The risk is greater when the canine is vertically above the lateral incisor root and close to the median palatine suture, suggesting a mechanical blockage by the apex of the lateral incisor.

Morphology of palatally impacted canines: A case-controlled cone-beam volumetric tomography study.

The aim of this study was to investigate the relationships between an apical curvature or a hook and the crown/root ratio in subjects with and without palatally impacted maxillary canines. An experimental group of 44 patients (17 boys, 27 girls; mean age, 13.6years) with 59 palatally impacted maxillary canines was selected from the records of patients referred to a radiology practice for cone-beam imaging. If a patient had bilateral palatally impacted canines, 1 canine was randomly selected for analysis. The palatally impacted canine group was matched for age and sex with 49 normal subjects (25 boys, 24 girls; mean age, 13.2years) with 98 canines. Cone-beam DICOM files were imported into InVivo imaging software (version 5.3; Anatomage, San Jose, Calif) for analysis. The angulations and linear variables of the maxillary canines were measured by using the software measurement tools. Chi-square and independent t tests were used to test for differences between the groups. The presence of a hook at the apical third and other root curvature were significantly different between the 2 groups (P<0.001 and P<0.05, respectively). Of the 44 palatally impacted canines, 16 (36.4%) had an apical hook and only 1 canine in the control group had an apical hook (1.0%). The mean root length of the palatally impacted canines was 2.66mm shorter (P<0.001), and the mean crown/root ratio was significantly greater for the palatally impacted canines compared with the nonimpacted group (P<0.001). Palatally impacted canines have a greater tendency to develop apical hooks and are less likely to develop other root curvatures than are nonimpacted canines. Also, they have shorter roots resulting in larger crown/root ratios compared with the control group.