Ortho cubic super-high resolution computed tomography: a new radiographic technique with application to the temporomandibular joint

[Comparative evaluation of the accuracy of 3D TMJ analysis performed by different methods of processing computed tomograms]

OBJECTIVE

The aim of this study. Comparison of the accuracy of segmentation of TMJ elements in different ways and assessment of the suitability of the data obtained for the diagnosis of TMJ dysfunction.

MATERIALS AND METHODS

To study the segmentation of the bone elements of the TMJ (articular fossa, head of the LF), 60 computed tomograms of the maxillofacial region of patients were randomly selected in various ways (archival material). In group 1, the results of CT processing by AI diagnostics algorithms (Russia) were collected; in group 2, the results of CT processing based on the semi-automatic segmentation method in the Avantis3D program. The results of CT processing by Avantis3D AI algorithms (Russia) with different probability modes - 0.4 and 0.9, respectively, were selected for the third and fourth groups. Visually, the coincidence of the contours of the LF heads and articular pits isolated using different methods with their contours on all possible sections of the original CT itself was evaluated. The time spent on TMJ segmentation according to CT data was determined and compared using the methods described above.

RESULTS

Of the 240 objects, only 7.5% of the cases showed a slight discrepancy between the contours of the original CT in group b1, which was the lowest of all. A slight discrepancy in the TMJ contours to be corrected is characteristic of the semi-automatic method of segmentation by optical density was detected in 50.4% (group 2). The largest percentage of significant errors not subject to correction was noted in the first group, which made it impossible to perform a full 3D analysis of the TMJ, and the smallest in the second and fourth. The magnitude of the error in determining the width of the articular gap in different groups is comparable to the size of one voxel per CT. When segmentation is carried out using AI, the difference between segmented objects is close to zero values. The average time spent on TMJ segmentation in group 1 was 10.2±1.23 seconds, in group 2 - 12.6±1.87 seconds, in groups 3 and 4 - 0.46±0.12 seconds and 0.46±0.13 seconds, respectively.

CONCLUSION

The developed automated method for segmenting TMJ elements using AI is obviously more suitable for practical work, since it requires minimal time, and is almost as accurate as other methods under consideration.

Dental Undergraduates and Interns’ Awareness, Attitudes, and Perception of Radiological Protection

Medical ionizing radiation is widely used in hospitals, in particular dental clinics, and in medical research to facilitate the diagnosis and treatment of patients. The awareness, attitude, and perception of ionizing radiation exposure among dental undergraduate students and interns in radiological investigations and dental care clinics were investigated. A cross-sectional study was conducted; 17 questions were designed online using the software “QuestionPro,” which was licensed to the University of Imam Abdulrahman Bin Faisal. Participants included senior medical dental students from Imam Abdulrahman Bin Faisal University in their third to fifth years, as well as interns from King Fahad University Hospital and private dental care clinics. A total of 855 participants viewed, 360 started the questionnaire, and 258 (72%) completed it online. Overall, knowledge was lacking; 32% of respondents incorrectly believed that magnetic resonance imaging and ultrasound used ionizing radiation, while 38% were unsure. Dental X-rays were deemed harmful by 40% (n = 104) of respondents. According to 33% (n = 85) of participants, there is no radiation scatter during an X-ray or CT scan, while 30% (n = 76) are unsure. Respondents (44%; n = 104) were unaware of the radiation dose from a chest radiograph and (45%; n = 116) overestimated the radiation dose. The effects of ionizing radiation on healthy tissue are known to more than half of the participants (54%). According to 39% of respondents, digital radiography exposes them to less radiation than traditional radiography. In terms of radiation protection and hazard, 46% said personal monitoring badges should be always worn and 58% (n = 150) said lead aprons should be used on a regular basis. 63% of the subjects had received radiation protection education, such as formal lectures, tutorials, or workshops, while 37% (n = 95) had not. 53% of the respondents were not aware of the international recommendations from the International Commission on Radiological Protection. When asked if they would follow radiation protection protocols if they opened a private dental clinical practice in the future, 50% (n = 129) said they would.

Local cone beam CT: how did it all start?

The mathematical theory of CT was proposed by J. Radon in 1917. It was declared that the projection of whole data sets was needed to reconstruct CT images. Therefore, according to J. Radon's original theory, local cone beam CT (local CBCT) was impossible to achieve.In this paper, I discuss how local CBCT was discovered and developed. Its development required many technical elements, such as a turntable and X-ray television system, for basic experiments such as those on which narrow collimation theory and multifunctional panoramic tomography were based. These experiments endured many failures during development.Now, local CBCT is extremely popular in dental practice because local CBCT has a low radiation dose and high resolution. This paper introduces the technical elements and outlines the important stages during the development of local CBCT in the 1990s.

Are Signs of Degenerative Joint Disease Associated With Chin Deviation?

PURPOSE

Degenerative joint changes commonly affect the temporomandibular joint (TMJ) and can result in chin deviation. However, the extent of degenerative TMJ changes and chin deviation has not been well-characterized. The present study sought to correlate degenerative TMJ changes with condylar volume, grayscale measures, and chin deviation.

MATERIALS AND METHODS

The present cross-sectional study had enrolled women with skeletal Class III malocclusion. Cone-beam computed tomography scans were acquired preoperatively. For each condyle, degenerative TMJ signs were analyzed and the condylar volume and grayscale were measured. The predictor variable was the presence of degenerative TMJ signs, classified as categorical data: 0, if none; 1, only present in 1 joint; and 2, present in both joints. The primary outcome variable was a chin deviation of 3 mm or more. Other associated variables were grouped by age, cephalometric data, and 3-dimensional condylar measurements. Descriptive bivariate statistics were computed, and univariate and multiple logistic regression analyses were conducted to identify any associations between degenerative TMJ disease and chin deviation.

RESULTS

We included 85 patients, who were classified into 2 groups: less than 3 mm of chin deviation (n = 43) and 3 mm or more of chin deviation (n = 42). The presence of more than 10 degenerative TMJ signs was significantly associated with the presence of 3 mm or more of chin deviation (P < .001). In multiple regression models, the presence of subcortical sclerosis in 1 joint and in both joints (adjusted odds ratio [OR], 3.698; 95% confidence interval [CI], 1.051 to 13.012; adjusted OR, 5.001; 95% CI, 1.461-17.119, respectively) correlated significantly with the presence of 3 mm or more of chin deviation (P < .05). The volume difference between the 2 condyles was significantly greater in the group with more than 10 degenerative TMJ signs and 3 mm or more of chin deviation than in the group with 10 or fewer degenerative TMJ signs and less than 3 mm of chin deviation (P = .016 and P < .001, respectively).

CONCLUSIONS

In women with skeletal Class III malocclusion, the presence of more than 10 degenerative TMJ signs increased the prevalence of 3 mm or more of chin deviation. The presence of subcortical sclerosis in either 1 or both joints and volume differences between the 2 condyles were associated with greater chin deviation.

Clinical guidelines for dental cone-beam computed tomography

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan's universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan's aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation's oral health by encouraging efficient use of dental CBCT.

Cone beam computed tomography: basics and applications in dentistry

The introduction of cone beam computed tomography (CBCT) devices, changed the way oral and maxillofacial radiology is practiced. CBCT was embraced into the dental settings very rapidly due to its compact size, low cost, low ionizing radiation exposure when compared to medical computed tomography. Alike medical CT, 3 dimensional evaluation of the maxillofacial region with minimal distortion is offered by the CBCT. This article provides an overview of basics of CBCT technology and reviews the specific application of CBCT technology to oral and maxillofacial region with few illustrations.

Effectiveness of digital subtraction radiography in detecting artificially created osteophytes and erosions in the temporomandibular joint

Purpose

Erosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ.

Materials and Methods

Five intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods.

Results

The area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes.

Conclusion

The accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.

Temporomandibular joint diagnostics using CBCT

The present review will give an update on temporomandibular joint (TMJ) imaging using CBCT. It will focus on diagnostic accuracy and the value of CBCT compared with other imaging modalities for the evaluation of TMJs in different categories of patients; osteoarthritis (OA), juvenile OA, rheumatoid arthritis and related joint diseases, juvenile idiopathic arthritis and other intra-articular conditions. Finally, sections on other aspects of CBCT research related to the TMJ, clinical decision-making and concluding remarks are added. CBCT has emerged as a cost- and dose-effective imaging modality for the diagnostic assessment of a variety of TMJ conditions. The imaging modality has been found to be superior to conventional radiographical examinations as well as MRI in assessment of the TMJ. However, it should be emphasized that the diagnostic information obtained is limited to the morphology of the osseous joint components, cortical bone integrity and subcortical bone destruction/production. For evaluation of soft-tissue abnormalities, MRI is mandatory. There is an obvious need for research on the impact of CBCT examinations on patient outcome.

Application of cone beam computed tomography for assessment of the temporomandibular joints

Radiographic examination is essential for the diagnosis and management of temporomandibular joint (TMJ) disorders. The goals of TMJ radiography are to evaluate cortical and trabecular architecture of the bony structures and confirm their integrity, to assess the extent and monitor progression of osseous changes, and to evaluate the response to treatment. Accurate evaluation of the TMJ by conventional radiography is limited by structure superimposition. Cone beam computed tomography (CBCT) provides high-resolution multiplanar images and delivers substantially lower radiation dose, compared with multislice CT. CBCT allows examination of TMJ anatomy without superimposition and distortion to facilitate analysis of bone morphology, joint space and dynamic function in all three dimensions. This article will describe the role of CBCT imaging for the assessment of the TMJ osseous structures and present typical appearances of common pathological conditions of the TMJ.

The usefulness of three-dimensional imaging in the diagnosis and treatment of clinically ambiguous gingival swelling

We evaluated and treated a 54-year-old woman with gingival swelling. Conventional intraoral and panoramic radiography did not provide sufficient information for either determining the cause of gingival swelling or planning treatment of clinical symptoms. The 3D Accuitomo XYZ Slice View Tomograph (3DX) is a compact dental computed tomography device that allowed for accurate identification and optimal treatment of the causes of gingival swelling. At four years after treatment, 3DX radiographs showed no abnormalities in treated teeth or healing of surrounding structures. We conclude that high-resolution 3D images obtained with 3DX promise to be very effective for diagnosing oral diseases and determining effective treatment.

Evaluation of the severity of temporomandibular joint osteoarthritic changes related to age using cone beam computed tomography

OBJECTIVES

The aim of this study is to evaluate and correlate with age the severity of temporomandibular joint (TMJ) osteoarthritic changes using cone beam CT (CBCT).

METHODS

The images of 71 patients with findings of degenerative arthritis were retrieved from the computer data base. All patients had been examined with CBCT (NewTom 9000 QR-DVT). Left and right TMJs were evaluated independently for each patient. TMJ evaluation included: (a) bony changes of the condyle (flattening, erosion, sclerosis, osteophytes, resorption); (b) joint space (normal, increased, reduced, bony contact between the condyle and the mandibular fossa); and (c) bony changes of mandibular fossa (normal, sclerosis, erosion, resorption). The radiographic findings were statistically analysed.

RESULTS

Significant differences in the mean age were found: (a) between absent and moderate erosion (P = 0.019), as well as between absent and extensive erosion (P = 0.048); (b) between absent and extensive formation of osteophyte (P = 0.003), as well as between slight and extensive formation of osteophyte (P = 0.025); (c) between normal joint space and bony contact (P = 0.0002), as well as between reduced joint space and bony contact (P = 0.001).

CONCLUSIONS

Degenerative arthritis is an age-related disease. The progression and severity of osseous changes in the condylar head and mandibular fossa are increased with age. In older age groups, patients are expected to have more frequent and severe progressive degenerative bony changes due to the development of TMJ osteoarthritis than patients in younger age groups.

First molar radicular bone near the maxillary sinus: a comparison of CBCT analysis and gross anatomic dissection for small bony measurement

OBJECTIVES

This study assessed agreement of cone-beam computerized tomography (CBCT) measurements against those obtained by gross dissection and physical calipers for dimensions of maxillary bone around first molar roots in cadaveric specimens.

STUDY DESIGN

A total of 37 human maxilla pairs with 69 first molars were analyzed by CBCT with a resolution of 200 microm and the results compared with gross dissection. Matched data sets of 414 data points (6 data points per tooth) were compared using Bland-Altman statistics. An operational definition of clinical accuracy was proposed.

RESULTS

The data sets displayed a Pearson correlation coefficient of r = 0.85. Analysis revealed a positive bias for CBCT of 0.4 mm with a standard deviation of 1.1 mm relative to gross dissection. Less bone around first molar roots was demonstrated than reported in available literature.

CONCLUSIONS

High-resolution CBCT measurements were acceptable for clinical accuracy and study of the maxillary sinus.

Contemporary imaging of the temporomandibular joint

This article discusses imaging techniques for visualization of the temporomandibular joint. Conventional plain film modalities are discussed briefly, with an emphasis on the more contemporary modalities, such as CT with cone-beam technology, MRI, and nuclear imaging, including single-photon emission computed tomography, and positron emission tomography. Indications, advantages, and limitations are discussed. As advancements in this area continue, our understanding of this complex joint and its pathology will follow, which will lead to more defined imaging indications and ultimately, to improved treatment outcomes.

Relationship between density variability and imaging volume size in cone-beam computerized tomographic scanning of the maxillofacial region: an in vitro study

OBJECTIVE

In limited-volume cone-beam computerized tomography (CBCT) imaging, projection data discontinuity caused by maxillofacial hard tissue structures outside the reconstructed volume are reported to affect the density value of the hard and soft tissue structures within the volume. The intensity of this effect is purported to be related to the size of the imaging volume. The aim of this study was to characterize the effect of the size of the scanned volume on density values in vitro.

STUDY DESIGN

Test objects were positioned in a custom phantom in the following 4 patterns: bimandible and vertebrae, bimandible, left mandible and vertebrae, and left mandible. We used a newly developed flat panel detector CBCT system (Alphard Vega; Asahi Roentgen, Kyoto, Japan) to acquire scans of the left molar region using cylindrical volumes of approximately 5, 10, 15, and 20 cm in diameter and height. The density values of the mandible and the adjacent soft tissue regions were analyzed.

RESULTS

Highest density variability was observed in the smallest-volume (5 cm) scans. Density variability increased when more objects were included outside the area being imaged. Fewer effects were noted in CBCT scans of larger (10, 15, and 20 cm) volumes.

CONCLUSION

Larger-volume CBCT scans may yield more consistent density values. Smaller CBCT volumes have the advantages of better image resolution and lower radiation doses. The optimization of the image characteristics is maximized by careful consideration of the purpose of the CBCT examination.

Accuracy of cone-beam computed tomography imaging of the temporomandibular joint: comparisons with panoramic radiology and linear tomography

INTRODUCTION

Cone-beam computed tomography (CBCT) is increasingly being used as an imaging modality, particularly in the assessment of the temporomandibular joint (TMJ). A blinded observational cross-sectional in-vitro study was conducted to compare the diagnostic accuracy of observers viewing images made with CBCT, panoramic radiography, and linear tomography. The task was to detect cortical erosions affecting the mandibular condylar head.

METHODS

The sample consisted of 37 TMJ articulations from 30 skulls with either normal condylar morphology (n = 19) or erosion of the lateral pole (n = 18). The articulations were imaged by using corrected angle linear tomography (TOMO), normal (Pan-N) and TMJ-specific (Pan-TM) panoramic radiography, and CBCT. Digital images were obtained with photostimulable phosphor plates for all modalities except CBCT. The CBCT detector used an amorphous silicon flat-panel array combined with cesium iodide. Images and 10 rereads were presented to 10 observers on a flat-panel display at a pixel-to-monitor ratio of 1:1. CBCT multi-planar images were presented both statically (CBCT-S) and interactively (CBCT-I). The observers were permitted to scroll through axial (0.4 mm) and para-sagittal (1 mm) sections and then independently rate their confidence about the presence or absence of cortical erosion. Intraobserver reliability was determined by weighted kappa and diagnostic accuracy by the fitted area under the ROC curve. Means were compared by using ANOVA (P < or =.05).

RESULTS

Intraobserver reliability was moderate (0.57 +/- 0.22; range, 0.34-0.78). Pan-N (0.72 +/- 0.15), CBCT-I (0.65 +/- 0.21), and CBCT-S (0.65 +/- 0.17) reliability was significantly greater than TOMO (0.44 +/- 0.25). The diagnostic accuracy of CBCT-I (0.95 +/- 0.05) and CBCT-S (0.77 +/- 0.17) was significantly greater than all other modalities (Pan-N [0.64 +/- 0.11], Pan-TM [0.55 +/- 0.11], TOMO [0.58 +/- 0.15]). CBCT-I was also more accurate than CBCT-S, and Pan-N was more accurate than Pan-TM and TOMO.

CONCLUSIONS

CBCT images provide superior reliability and greater accuracy than TOMO and TMJ panoramic projections in the detection of condylar cortical erosion.

Accuracy of linear measurements from imaging plate and lateral cephalometric images derived from cone-beam computed tomography

INTRODUCTION

As orthodontic practice moves toward 3-dimensional cephalometric analyses, a solution is required to ensure sustained availability of well-established projected treatment outcomes based on 2-dimensional analyses. This ex-vivo study was conducted to compare the accuracy of linear measurements made on photostimulable phosphor cephalograms with 3 methods for simulating lateral cephalograms with cone-beam computed tomography (CBCT).

METHODS

The linear distances between anatomical landmarks on dentate dry human skulls were measured by observers using digital calipers for S-N, Ba-N, M-N, ANS-N, ANS-PNS, Pog-Go, Go-M, Po-Or, and Go-Co. The skulls were imaged with CBCT with a single 360 degrees rotation, producing 306 basis images and achieving 0.4 mm isotrophic voxel resolution on volumetric reconstruction for making ray-sum reconstructed cephalograms. Two other cephalogram approaches were used with the CBCT system--a single transmission image generated as a scout image designed to check patient positioning before CBCT, and a single-frame lateral basis image. Conventional digital lateral cephalograms (LCs) were acquired with the photostimulable phosphor system. Images were imported into a cephalometric analysis program (Dolphin Imaging Cephalometric and Tracing Software, Chatsworth, Calif) to compute the included linear measurements. Analyses were repeated 3 times and statistically compared with measured anatomic truth with ANOVA (P < or =.05). The intraclass correlation coefficient was determined as an index of intra- and interobserver reliability.

RESULTS

The intraclass correlation coefficient for the LCs was significantly less than for the measured anatomic truth and for all CBCT-derived images. CBCT images either produced with individual frames or reconstructed from the volumetric data set were accurate for all measurements except Pog-Go and Go-M. CBCT scout images had the second highest accuracy for all measurements except Pog-Go, Go-M, and Go-Co. Conventional LCs had the least accuracy; they were accurate only for Po-Or and ANS-N.

CONCLUSIONS

CBCT-derived 2-dimensional LCs proved to be more accurate than LCs for most linear measurements calculated in the sagittal plane. No advantage was found over single-frame basis images in using ray-sum generated cephalograms from the CBCT volumetric data set.

The 3DX multi image micro-CT device in clinical dental practice

OBJECTIVES

To evaluate the usefulness of 3DX multi-image micro-CT device in clinical dental practice.

METHODS

Images of 198 examinations performed with a 3DX device during a 6 month period in a private dental practice were evaluated retrospectively for the benefit of additional information compared with panoramic or intraoral radiographs.

RESULTS

The main indication for the use of 3DX micro-CT was planning of dental implant placement in 49% of the examinations. Diagnosis or exclusion of dental infection or peri-implantitis represented 28% of the examinations and tooth, root or foreign body localization represented 13%. Temporomandibular joint (TMJ) imaging and cyst or tumour diagnosis represented 7.5% and 2.5% of the examinations, respectively. In implant planning and tooth, root or foreign body localization examinations, the required information was obtained in every case except three implant planning examinations, in which the exact measurements were hampered by artefacts caused by root fillings and retrograde fillings or metal posts. When compared with conventional radiography, additional radiographic information was obtained in 51% of the micro-CT examinations performed to confirm or exclude dental infection or peri-implantitis. Micro-CT also showed the bone structure of TMJs precisely.

CONCLUSIONS

The 3DX micro-CT device visualizes bony anatomical structures precisely, which makes it a reliable tool for, for example, planning of implant treatment. The device is highly suitable for diagnosing dental infections. Dental restorations may cause disturbing artefacts and in 4.5% of the examinations the small imaging area resulted in re-examination.

Reproducibility and accuracy of measuring unerupted teeth using limited cone beam X-ray CT

OBJECTIVE

The purpose of this investigation was to determine the reproducibility among observers and accuracy of the measurement of the tooth crown width of unerupted teeth using limited area cone beam X-ray CT.

METHODS

3DX multi-image micro-CT (3DX, Morita Co., Kyoto, Japan) images of impacted supernumerary teeth in the median maxillary region taken prior to extraction were used for the samples. The width of the tooth on the 3DX image was measured five times by five individual observers. Significant differences in values among the observers in the measurement were determined by one-way analysis of variance for examining reproducibility. The measurement results of the ten samples on 3DX images were compared with the laboratory measurements using a three-dimensional co-ordinate measuring apparatus, using the Wilcoxon signed-rank sum test.

RESULTS

There was no significant difference among the observers in the measurement (P>0.05). The measurement results shown on 3DX images were significantly larger than those of the laboratory measurements (P<0.05). The mean difference was +0.088 mm.

CONCLUSIONS

3DX has high reproducibility for measuring the tooth crown width of unerupted teeth. While 3DX measurement values were larger than the laboratory measurements, the difference is clinically insignificant.

Effects of image artifacts on gray-value density in limited-volume cone-beam computerized tomography

OBJECTIVE

An in vitro study was designed to investigate the influence of projection data discontinuity-related artifacts in limited-volume cone-beam computerized tomography (CBCT) imaging of the jaws.

STUDY DESIGN

Test objects were positioned in 4 patterns in a water-filled phantom as follows: bimandible and vertebrae, bimandible, left mandible and vertebrae, and left mandible. The CT imaging of the left molar region was performed using image intensifier (II)- and flat panel detector (FPD)-based CBCT scanners. The CT value of the mandible and the adjacent soft tissue region were analyzed for density by means of an 8-bit grayscale.

RESULTS

The effects of artifacts were scored as the difference in relative density between the lingual and buccal soft tissue. The intensity of artifacts increased when more objects were presented outside the area being imaged. Fewer artifacts were noted in images produced by the particular FPD CBCT used in this investigation.

CONCLUSION

The CBCT system using an FPD resulted in fewer artifacts than the CBCT system using an II in this particular study.

Effectiveness of dental computed tomography in diagnostic imaging of periradicular lesion of each root of a multirooted tooth: a case report

Radiography by use of the three-dimensional (3D) Accuitomo XYZ Slice View Tomograph (3DX), a device for compact computed tomography in dentistry, was performed as a new diagnostic imaging technique for a patient who needed endodontic therapy. The 3DX was used for examining and diagnosing the presence and expansion of periradicular lesions in each root of a multirooted tooth. High-resolution 3D images were observed and compared with those obtained by routine conventional radiography. It was difficult to diagnose the cause of clinical symptoms by general examinations including the usual intraoral radiography and panoramic radiography. The images obtained by the 3DX, however, clearly showed the apparent presence and expansion of a periradicular lesion in only one root of the multirooted tooth. The 3DX, a newly developed dental computed tomography, provides abundant new image information not attainable by either intraoral radiography or panoramic radiography, and its application for clinical use is very effective for examining and diagnosing regions of interest for endodontic therapy.

Digital Volume Tomography in the Diagnosis of Peri-Implant Defects: An In Vitro Study on Native Pig Mandibles

BACKGROUND

The aim of this study of native pig mandibles was to investigate the accuracy and quality of the representation of peri-implant defects by intraoral radiography (IR), panoramic radiography (PR), computer tomography (CT), and digital volume tomography (DVT).

METHODS

The examination was carried out on 19 native pig mandibles. In the toothless sections of the mandibles, one or two implants were inserted. Following the standardized preparation of peri-implant defects (11 each of dehiscences, fenestrations, and 2- to 3-walled intrabony defects), IR, PR, CT, and DVT were performed. The peri-implant defects were measured using appropriate software on the digitized IR and PR image programs. As a control method, the peri-implant bone defects were measured directly using a reflecting stereomicroscope with measuring ocular. The statistical comparison between the measurements of the radiographic scans and those of the direct readings of the peri-implant defects was performed with Pearson's correlation coefficient. The quality of the radiographic scans was determined through the subjective perception and detectability of the peri-implant defects by five independent observers.

RESULTS

In the DVT and CT scans, it was possible to measure all the bone defects in three planes. Comparison with the direct peri-implant defect measurements yielded a mean deviation of 0.17+/-0.11 mm for the DVT scans and 0.18+/-0.12 mm for the CT scans. On the IR and PR images, the defects could be detected only in the mesio-distal and cranio-caudal planes. In comparison with the direct measurements of the peri-implant defects, the IR images revealed a mean deviation of 0.34+/-0.30 mm, and the PR images revealed a mean deviation of 0.41+/-0.35 mm. The quality rating of the radiographic images was highest for the DVT scans.

CONCLUSIONS

Overall, the CT and DVT scans displayed only a slight deviation in the extent of the peri-implant defects. Both radiographic imaging techniques permitted imaging of peri-implant defects in three planes, true to scale, and without overlay or distortion. The DVT scans showed the best imaging quality.

Image-guided puncture technique for the superior temporomandibular joint space: value of cone beam computed tomography (CBCT)

OBJECTIVE

Temporomandibular joint (TMJ) disk perforation or adhesion requires arthrographic examination. However, puncture of the TMJ may result in damaging penetration of the middle cranial fossa. We investigated the effectiveness of penetrating the superior TMJ space using a safe image-guided puncture technique (IGPT).

STUDY DESIGN

Fifty-two patients underwent cone beam computed tomography (CBCT) examination. Optimum angles and distances from the puncture site to the thinnest point of the glenoid fossa to penetrate the superior joint space were measured using three-directional images.

RESULTS

Puncturing the superior articular cavity was immediately successful in 50 cases. Image measurements gave an average horizontal angle of 8.0 degrees (standard deviation [SD]: 9.2), an average coronal angle of 16 degrees (SD: 11.3), and an average distance of 27 mm (SD: 2.8).

CONCLUSION

Variation in puncture angle among individuals indicated that CBCT examination is necessary preceding TMJ puncture. Preliminary clinical application has demonstrated the safety of IGPT using CBCT.

Osseous abnormalities of the mandibular condyle: diagnostic reliability of cone beam computed tomography compared with helical computed tomography based on an autopsy material

OBJECTIVES

We compared the diagnostic reliability of cone beam computed tomography (3DX) and helical computed tomography (helical CT) for the detection of osseous abnormalities of the mandibular condyle, using macroscopic observations as the gold standard.

METHODS

Twenty-one temporomandibular joint autopsy specimens underwent imaging with 3DX and helical CT. The specimens were macroscopically evaluated for cortical erosion or osteophytosis and sclerosis. The images were independently assessed for the same osseous abnormalities. Observations with the two imaging modalities were compared with the macroscopic observations using the McNemar test.

RESULTS

According to the macroscopic observations, 10 of the 21 mandibular condyles and one fossa showed osseous abnormalities. 3DX detected abnormalities in eight of these condyles and helical CT identified abnormalities in seven, giving a sensitivity of 0.80 for 3DX and 0.70 for helical CT. The specificity of the condyle assessment was 1.0 for both 3DX and helical CT and hence, the accuracy was 0.90 and 0.86, respectively. No significant differences were detected between the 3DX and helical CT for assessment of osseous abnormalities of the mandibular condyle (P=0.286).

CONCLUSIONS

The cone beam CT equipment 3DX is a dose-effective and a cost-effective alternative to helical CT for the diagnostic evaluation of osseous abnormalities of the mandibular condyle.

Image artifact in dental cone-beam CT

PURPOSE

The purpose of this study was to investigate the appearance and possible cause of an artifact seen in limited-volume cone-beam CT imaging.

METHODS

A water-filled plastic cylinder was used as a phantom of the head. A test object was constructed as a bone-equivalent phantom to be imaged. The test object was variously positioned at the center of the phantom and near its margins. CT images of the test object were acquired using a 3DX Accuitomo system.

RESULTS

In slice images with the test object positioned near the margin of the phantom, arch-shaped defects or deformities were observed on the side of the object. There was a negative correlation between the artifact and the CT value of the object. The artifact was larger in images scanned with a higher voltage.

CONCLUSION

The probability that this artifact is caused by halation from the image intensifier (II) system is suggested.

Condylar head remodeling following mandibular setback osteotomy for prognathism: A comparative study of different imaging modalities

PURPOSE

Condylar remodeling, which develops after mandibular setback osteotomy, was evaluated and compared in CT, plain film radiographs, and MR images acquired postoperatively.

METHODS

Thirty-nine patients treated with sagittal split ramus osteotomy (SSRO) and 46 patients treated with intraoral vertical ramus osteotomy (IVRO) were studied. Remodeling as seen in the images and the diagnostic agreement between imaging modalities was evaluated.

RESULTS

A newly formed bone layer in the posterior part of the condylar head was identified as a sign suggestive of remodeling. This sign was seen predominantly at periods over 6 months postoperatively. IVRO subjects had a higher incidence of remodeling than did the SSRO group. The diagnostic agreement between the 3 imaging modalities was substantial. There was a positive correlation between postoperative condylar displacement and the incidence of remodeling.

CONCLUSIONS

The incidence of postoperative condylar head remodeling may be predictable. High-dose postoperative imaging studies to assess the TMJ should be restricted to those cases having a clear need for such studies.

State-of-the-art on cone beam CT imaging for preoperative planning of implant placement

Orofacial diagnostic imaging has grown dramatically in recent years. As the use of endosseous implants has revolutionized oral rehabilitation, a specialized technique has become available for the preoperative planning of oral implant placement: cone beam computed tomography (CT). This imaging technology provides 3D and cross-sectional views of the jaws. It is obvious that this hardware is not in the same class as CT machines in cost, size, weight, complexity, and radiation dose. It is thus considered to be the examination of choice when making a risk-benefit assessment. The present review deals with imaging modalities available for preoperative planning purposes with a specific focus on the use of the cone beam CT and software for planning of oral implant surgery. It is apparent that cone beam CT is the medium of the future, thus, many changes will be performed to improve these. Any adaptation of the future systems should go hand in hand with a further dose optimalization.

μ-CT

While many radiologists are aware of the revolutionary development of computed tomography (CT)-scanners and their diagnostic implications, some researchers have focused on studying the potentials of mu-CT. The aim of this article is to give a brief overview of its physical properties and outline possible indications both for the real ex vivo and small animal mu-CT studies, as well as the modified mu-CT units used in dental practice.

Imaging of maxillofacial trauma: Evolutions and emerging revolutions

The aim of diagnostic imaging for maxillofacial trauma is to provide additional information that can positively influence medical or surgical patient management. Current advances in diagnostic imaging have come from the confluence of 3 driving forces: (1) the demand from clinicians to enhance and expand their diagnostic abilities; (2) the development of new theoretical concepts by basic scientists; and (3) the application of concepts by engineers and manufacturers to provide increasingly sophisticated imaging capabilities. The role of imaging within the health care environment is, however, also buffeted by the complex, sometimes competing, interactions of external social, political, economic, and technological pressures at the national, regional, and local levels. The purposes of this review are to provide a perspective on current imaging modalities used for maxillofacial trauma and to provide an insight into the influences, both technologic and external, on future developments and applications.

Application of limited cone beam computed tomography to clinical assessment of alveolar bone grafting: a preliminary report

OBJECTIVES

The aim of this study was to demonstrate the clinical applicability of limited cone beam computed tomography (Dental 3D-CT) for assessment of bone-grafted alveolar cleft.

PATIENTS AND METHODS

Seventeen bone bridges were examined after alveolar bone grafting in 13 patients with cleft lip and palate. All bone bridges, including cleft-adjacent teeth, were examined by plain radiography and the Dental 3D-CT imaging system.

RESULTS

The plain radiographs showed the approximate condition of the bone bridge and cleft-adjacent teeth. The Dental 3D-CT images clearly showed precise three-dimensional (3D) morphology of the bone bridge, 3D relationships between the bone bridge and the roots of cleft-adjacent teeth, and their periodontal condition. In addition, the conditions surrounding dental implants installed in the bone bridge could be observed three-dimensionally.

CONCLUSIONS

The results indicate that the Dental 3D-CT imaging system is suitable for clinical assessment of alveolar bone grafting before and after installation of dental implants or orthodontic treatment of the cleft-adjacent teeth.

Single air contrast arthrography for temporomandibular joint disorder using limited cone beam computed tomography for dental use

MRI has the problem of artefacts caused by metal or body motion and is also incompatible for patients with claustrophobia. Arthrography is invasive and involves the risk of perforation or allergy to a contrast medium. This report discusses a patient with temporomandibular joint (TMJ) disorder who required soft tissue imaging of the TMJ. As she had claustrophobia and a reaction to iodine, air contrast arthrography and pumping manipulation therapy using limited cone beam computed tomography for dental use (3DX) was performed. We conclude that the 3DX examination method used in the study is practical as a diagnostic procedure and thus recommend this method to be used for patients with TMJ disorder in the presence of iodine contraindication.