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An isolable small-molecule cysteine sulfenic acid (Cys–SOH) protected by a molecular cradle was synthesized by direct oxidation of the corresponding cysteine thiol and its structure was established by X-ray crystallographic analysis. Studies on biologically relevant reactivity indicated its usefulness as a biorepresentative small-molecule sulfenic acid model.

We report the case of a patient who used mascara in an unusual manner, as hair dye, causing artifacts on magnetic resonance (MR) images. A 60-year-old woman was referred to our hospital because of discomfort and mastication difficulty as a result of dislocation of the mandible on the left side. After a general examination, she was diagnosed with temporomandibular joint disorder and MR imaging was performed. The images showed artifacts in the bilateral temporal regions, although the patient had not undergone surgical treatment in the region and there were no metal hair accessories. However, mascara had been applied to the region to dye the patient’s hair black. To verify that mascara could be the cause of the artifacts in the temporomandibular area, we performed mock MR imaging using a phantom and mascara. Artifacts were also observed in the area with mascara, confirming that the mascara caused the artifacts during MR imaging. This case suggests that care should be taken during MR imaging when different cosmetics are used in the head and neck region.

Objectives The purpose of this study was to verify whether application of a quantitative computed tomography (QCT) technique was helpful for quantitative measurement of bone density using dental cone-beam CT (CBCT).

Objectives The aim of this study was to compare cone-beam computed tomography (CBCT) with intraoral radiography (parallel and bisecting techniques) for their detection capabilities of various horizontal angle root fractures in human teeth.

Recent developments in digital computer technology have enabled radiological diagnosis to be performed using a monitor screen. In medical radiography, the importance of monitors has been shown in many diseases. Digital imaging and communication in medicine (DICOM)-compatible monitors are widely used. However, the effect of monitors on the diagnosis of oral disease has not yet been clarified and remains controversial. The aims of this study are to compare the caries diagnostic ability between DICOM monitors and other monitors and to examine if monitor capability affects the diagnosis. One hundred proximal surfaces of 50 extracted human upper premolar teeth were used as specimens. Intra-oral radiographs of all specimens were taken digitally. Three types of monitors were compared in terms of caries diagnostic ability: a DICOM standard-compatible monitor, a standardized personal computer (PC) monitor, and a tablet PC. Six oral radiologists diagnosed each radiograph independently. Areas under the receiver operating characteristic (ROC) curve were generated and compared. Area under the ROC curve (AUC) of the DICOM monitor, PC monitor, and tablet PC was 0.68147, 0.67002, and 0.60189, respectively. There was no significant difference between the DICOM monitor and the PC monitor, but the tablet PC showed significantly lower accuracy. There were no significant differences among the monitors for dentin caries (p > 0.05). DICOM-compatible monitors and PC monitors have similar capabilities, but tablet PCs showed lower diagnostic accuracy, especially for superficial caries. Appropriate monitors are needed for radiographic diagnosis on monitor screens.

The purpose of this study was to compare findings on the relationship between impacted molar roots and the mandibular canal in panoramic and three-dimensional cone-beam CT (CBCT) images to identify those that indicated risk of postoperative paresthesia. The relationship between impacted molars and the mandibular canal was first classified using panoramic images. Only patients in whom the molar roots were either in contact with or superimposed on the canal were evaluated using CBCT. Of 466 patients examined using both panoramic and CBCT images, 280 underwent surgical extraction of an impacted molar, and 15 of these (5%) reported postoperative paresthesia. The spatial relationship between the impacted third molar root and the mandibular canal was determined by examining para-sagittal sections (lingual, buccal, inter-radicular, inferior, and combinations) obtained from the canal to the molar root and establishing the proximity of the canal to the molar root (in contact with or without loss of the cortical border and separate). The results revealed that darkening of the roots with interruption of the mandibular canal on panoramic radiographs and the inter-radicular position of the canal in CBCT images were characteristic findings indicative of risk of postoperative paresthesia. These results suggest that careful surgical intervention is required in patients with the above characteristics.

To evaluate the use of the intravoxel incoherent motion (IVIM) technique in half-Fourier single-shot turbo spin-echo (HASTE) diffusion-weighted imaging (DWI), and to compare its accuracy to that of apparent diffusion coefficient (ADC) to predict malignancy in head and neck tumors.HASTE DW images of 33 patients with head and neck tumors (10 benign and 23 malignant) were evaluated. Using the IVIM technique, parameters (D, true diffusion coefficient; f, perfusion fraction; D*, pseudodiffusion coefficient) were calculated for each tumor. ADC values were measured over a range of b values from 0 to 1000s/mm(2). IVIM parameters and ADC values in benign and malignant tumors were compared using Student's t test, receiver operating characteristics (ROC) analysis, and multivariate logistic regression modeling.Mean ADC and D values of malignant tumors were significantly lower than those of benign tumors (P0.05). Mean D* values of malignant tumors were significantly higher than those of benign tumors (P0.05). There was no significant difference in mean f values between malignant and benign tumors (P0.05). The technique of combining D and D* was the best for predicting malignancy; accuracy for this model was higher than that for ADC.The IVIM technique may be applied in HASTE DWI as a diagnostic tool to predict malignancy in head and neck masses. The use of D and D* in combination increases the diagnostic accuracy in comparison with ADC.

Our previous study showed that the temporomandibular joint (TMJ) with disk displacement without reduction had the largest amount of TMJ fluid and revealed a correlation between the amount of fluid and pain. However, the amount of TMJ fluid in joints with osteoarthritis was not the largest, despite representing the last stage of internal derangement. The reason could be the presence of different types of pathologic conditions in osteoarthritis. Each type of osseous change could be associated with a characteristic pathosis that influences the amount of fluid. The purpose of this study was to analyze the correlation between osseous changes and TMJ fluid in joints with osteoarthritis. The study evaluated 57 joints in 39 patients diagnosed with osteoarthritis on magnetic resonance images. The grading system of Larheim et al. was used to categorize the amounts of TMJ fluid. Osseous changes were divided into four groups on proton density-weighted images: erosion, marginal proliferation, deformity, and erosion and marginal proliferation. There were significant differences in the amounts of fluid among the four osseous change groups (P = 0.0001). The erosion group showed the largest amount of fluid among the groups (P

Objective: To evaluate alternate methods for determining the radio-opacity of restorative resins. Materials and Methods: Disks of five restorative resins were made and placed on the sensor of intraoral X-ray sensor. Exposures were made and the images were generated without using automatic gain control and exported as DICOM files. Gray values were measured from these images using Image-J software. Results: These gray values were used to estimate the equivalent aluminium thickness in mm using the ISO method and using methods described by Vivian et al and Lachowski et al. The equivalent aluminium values obtained from ISO method was statistically compared to the other two methods using ANOVA and Dunnet's test. The level of significance was set at p

Purpose The purpose of this study were to: (1) establish a facial soft tissue morphometric technique employing a 3-dimensional optical device; (2) evaluate its precision; and (3) determine the presence of diurnal variation in facial soft tissue morphology. Materials and methods Ten volunteers were enrolled using a 3-dimensional optical measuring device, SURFLACER VMH-300F. Measurements were conducted in the morning, during the daytime, and in the evening. Two analyses, reproducibility of measurement through comparison between the two measurements in each group (morning vs. morning, daytime vs. daytime, and evening vs. evening), and diurnal variation through inter-group comparison (morning vs. daytime, morning vs. evening, and daytime vs. evening) were carried out. Results The mean difference between two measurements in each group was 0.24 ± 0.06 mm in the morning group, 0.25 ± 0.08 mm in the daytime group, and 0.24 ± 0.06 mm in the evening group. As to diurnal variation, the difference was 0.38 ± 0.07 mm between the morning and daytime groups, 0.39 ± 0.03 mm between the morning and evening groups, and 0.40 ± 0.04 mm between the daytime and evening groups. Conclusions When facial morphology was measured at 3 different time points within a single day, the mean error was 0.24 ± 0.06 mm. Measurement at these 3 time points revealed no significant diurnal variation in facial soft tissue morphology. This technique and its results are anticipated to contribute to quantitative evaluation of facial soft tissue morphology.

Objective This study aimed to determine the relationship between third-molar juxta-apical radiolucencies and mandibular canals on panoramic and cone beam computed tomography (CBCT) images. Study Design Forty-two patients were included in this retrospective study. The root apices and the relationships of the juxta-apical radiolucencies to the mandibular canals were evaluated on both panoramic and CBCT images. The McNemar test (P Results Root apices were visualized clearly with CBCT in most cases for which the apices were not seen clearly on panoramic images. Similarly, juxta-apical radiolucencies were separate from the mandibular canals with CBCT in most cases. Conclusions The present study found that there is no consistent intimate relationship between juxta-apical radiolucencies and the mandibular canals. Similar studies with larger sample sizes are required to further confirm these findings.

We report our experience of a case with a malignant tumor of the mandible in which diagnostic imaging played an important role in the differential diagnosis and therapeutic strategy decisions. The patient was a 78-year-old woman who visited our hospital because of poor healing after tooth extraction. Multiple cytological diagnoses provided class II results, and a histopathological diagnosis of a biopsy also failed to show malignant findings. Therefore, a definitive diagnosis could not be made. Although the patient had a history of osteoporosis treatment, details of her medications were unclear. Therefore, bisphosphonate-related osteonecrosis of the jaw (BRONJ) could not be excluded, causing difficulty in management of the patient’s condition. Eventually, we mainly focused on the diagnostic imaging and planned the therapeutic strategy in accordance with treatment for a malignant tumor. A postoperative histopathological examination of the surgical specimen revealed squamous cell carcinoma. It is sometimes difficult to differentiate among atypical diseases such as malignant tumors of the mandible and BRONJ, based solely on clinical or diagnostic imaging results. However, in the present patient, diagnostic imaging suggested a malignant tumor, and the appropriate treatment could be selected.

To determine the potential of fluid-attenuated inversion recovery (FLAIR) imaging of oral and maxillofacial vascular malformations as an alternative to contrast-enhanced magnetic resonance imaging (MRI), we investigated the influence of differences in T1 and T2 values on image contrast in FLAIR images and evaluated the diagnostic utility of such images.FLAIR imaging and heavily T2-weighted (hT2-weighted) imaging were performed using a phantom. FLAIR and hT2-weighted images of 32 lesions (11 mucous cysts, 12 vascular malformations, and 9 tumors) were also studied retrospectively. The contrast-to-noise ratios (CNRs) and CNR change ratios were compared.All aqueous solutions except those with a short T2 value were discriminated by CNR change ratio (P .05). All 3 types of lesions were discriminated by CNR change ratio (P .05).FLAIR imaging has potential as an alternative to contrast-enhanced MRI in differentiating vascular malformations from other types of lesions in the oral and maxillofacial region.

A case of myoepithelioma presumed to have arisen from an accessory parotid gland is reported. Preoperative fine-needle aspiration cytological findings suggested a malignant tumor, possibly an adenoid cystic carcinoma, while histopathological findings acquired during surgical resection revealed a myoepithelioma. The tumor was located adjacent to the Stensen duct, suggesting an accessory parotid gland origin. The diagnostic potential of magnetic resonance imaging and contrast-enhanced computed tomography in diagnosing this disease is discussed.

Aneurysmal bone cysts, benign lesions of bone tissue, are composed of sinusoidal and vascular spaces filled with blood and surrounded by fibrous tissue septa. They are uncommon, occurring usually in the long bones and spine, and only very rarely in the jaw, where approximately 160 cases have been reported, of which two thirds were located in the mandible and one third in the maxilla. We report two rare cases of aneurysmal bone cyst occurring in the mandible. A literature survey revealed 34 cases of this disease in the jawbone in Japan. An analysis of aneurysmal bone cysts of the jaw was performed in 36 cases, including the present ones. The mandible was affected in 28 cases (78%) and the maxilla in 8 (22%). Aneurysmal bone cyst was observed to occur most frequently between the mandibular body and the ramus. Patient age ranged from 6 to 87 years, with a mean age of 27.7 years. Patients under 30 years of age occupied 60% of the total. Treatment options suggested in the literature include percutaneous sclerotherapy, therapeutic embolization, curettage, block resection and reconstruction, radiotherapy, and systemic calcitonin therapy. The extent of surgery will depend on the size and position of the lesion, ranging from simple curettage to extended resection.

Thionitrates (R-SNO₂) have been proposed as key intermediates in the biotransformation of organic nitrates that have been used for the clinical treatment of angina pectoris for over 100 years. It has been proposed and widely accepted that a thiol would react with an organic nitrate to afford a thionitrate intermediate. However, there has been no example of an experimental demonstration of this elementary chemical process in organic systems. Herein, we report that aryl- and primary-alkyl-substituted thionitrates were successfully synthesized by the reaction of the corresponding lithium thiolates with organic nitrates by taking advantage of cavity-shaped substituents. The structure of a primary-alkyl-substituted thionitrate was unambiguously established by X-ray crystallographic analysis.

Half-Fourier single-shot turbo spin-echo (HASTE) can be applied to diffusion-weighted (DW) imaging of the head and neck. However, HASTE DW imaging has certain drawbacks, such as severe blurring and low signal-to-noise ratio (SNR). The purpose of this study was to evaluate the influence of imaging parameters on image quality using phantoms. We also evaluated the discrimination ability of the apparent diffusion coefficient (ADC) in HASTE DW imaging to assess whether the technique is applicable to head and neck lesions. The modulation transfer function (MTF), SNR, and ADC were compared using dedicated phantoms to evaluate the influence of matrix size (192 × 192 and 256 × 256) and receiver bandwidth (RBW 200, 400, 600, and 789 Hz/pixel) on HASTE DW images. A wide RBW setting tended to improve the MTF, regardless of the matrix size and phase-encoding direction. In contrast, a wide RBW setting tended to impair the SNR, regardless of the matrix size. At the same RBW setting, the MTF and SNR for a matrix size of 192 × 192 were higher than those for a matrix size of 256 × 256. A wide RBW setting tended to improve the discrimination ability of ADCs among the substances, regardless of the matrix size. A wide RBW and small matrix size improved the MTF and SNR of HASTE DW images. A wide RBW also improved the discrimination ability of the ADC. Therefore, HASTE DWI should be performed with a wide RBW setting.

Patients with facial pain and jaw function problems constitute a large and heterogeneous group. Disk displacement and osteoarthritis are the most common intra-articular abnormalities observed at imaging. As disk displacement is seen rather frequently in asymptomatic volunteers, it is a challenge to explain why disk displacement sometimes is symptomatic and sometimes is not. The present review focuses on abnormalities in the condylar bone marrow and the intra-articular soft tissues accompanying the disk displacement. The findings of temporomandibular joint in asymptomatic volunteers and in temporomandibular disorder (TMD) patients are reviewed. Both bone marrow edema and marrow necrosis are documented at histology and at magnetic resonance imaging (MRI) in TMD patients. Intra-articular soft tissue changes, such as synovitis, are additionally documented at arthroscopy. However, there is a controversy concerning which diagnostic imaging information is essential. Although there is no doubt that disk displacement and osteoarthritis may be accompanied by inflammatory alterations in the bone marrow and the intra-articular soft tissues, it has been difficult to consistently relate a specific imaging manifestation (bone edema, joint effusion, and synovitis) to joint pain. Longitudinal studies are needed to evaluate the importance of MRI abnormalities in the management of TMD patients.

Oral appliances (OAs) are widely used for anterior positioning of the mandible, and many studies have investigated change in activity in the jaw-closing muscles, including the masseter muscle, caused by such appliances. Few studies, however, have investigated their effect on the jaw-opening muscles. In the present study, we chose the masseter and jaw-opening muscles because they allow non-invasive measurement by means of surface electromyography. We investigated physiological changes in the digastric and masticatory muscles brought about by OAs using electromyography and an oximeter. Subjects comprised 7 healthy males. Fabricated OAs were placed in the mouth to obtain either 70% maximal protrusion (advanced mandibular position: AMP) or a centric relation (CR). Subjects were then instructed to open their mouth 2 mm vertically for 180 s, during which time electromyograms were obtained and blood flow volume determined. No significant difference was observed between AMP and CR in the frequency analysis of the anterior belly of the digastric muscle (Dig). No significant difference was noted in muscle activity between CR and AMP. No stable tendency was observed in the masseter or temporal muscles. Oxygen content recovery time in Dig was significantly longer at 1, 5 and 7 h in AMP than in CR. Seven-hour retention in AMP caused physiological change in Dig and a delay in recovery time from muscle fatigue. However, recovery from muscle fatigue occurred shortly after OA removal.

Objectives To investigate whether CT images reflect the anatomical condition of mylohyoid muscle defects by confirmation with subsequent dissection of cadavers, and to evaluate whether CT images are useful for detecting such defects.

OBJECTIVE. This article focuses on the anatomy of the mylohyoid muscle, a crucial landmark in imaging of the oral cavity and upper neck, showing dissected specimens and CT and MR images.CONCLUSION. Identification of the relationship of a lesion in the sublingual space to the mylohyoid muscle using MDCT and high-resolution MRI is a key part of the imaging assessment of the oral cavity and upper neck.

Purpose: To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). Materials and Methods: To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl2 aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl2 aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Results: Dual-FS could suppress fat sufficiently within the inversion time of 110–140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. Conclusion: The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. J. Magn. Reson. Imaging 2010;31:1277–1281. ©2010 Wiley-Liss, Inc.

To re-examine the reliability of distance measurements on clinical panoramic radiographs by comparing them with computed tomography (CT) images, from which the most accurate distance measurement is possible. Twenty pairs of images from patients examined both with panoramic radiography and CT for dental implant treatment planning in the premolar and molar regions of the mandible were used. The vertical linear distance between the alveolar crest and the closest mandibular canal was measured by three experienced oral radiologists on both images. The distances measured on panoramic radiographs were corrected for the magnification factor at the focal plane. Double-oblique cross-sectional images were used for CT. Pearson’s correlation coefficient was calculated between distances obtained from both images. The paired t test was performed for statistical comparison. Error levels with the panoramic radiograph versus the CT image were also calculated. Pearson’s correlation coefficient showed a significant strong linear correlation (R = 0.90; p

The inferior alveolar artery (IAA), accompanied by the inferior alveolar nerve, runs through the mandibular canal. The mandibular canal can be observed by conventional radiography and computed tomography, although it is sometimes difficult to identify on these images. This study examined visualization of the IAA with phase-contrast magnetic resonance angiography (PC-MRA). Phase-contrast magnetic resonance angiography images were obtained in the double oblique sagittal plane by using a two-dimensional, fast, low-angle shot (2D FLASH) sequence in five healthy volunteers. A flow-encoding gradient was applied from anterior to posterior, with velocity-encoding numbers (VENCs) of 10, 8, 6, 4, 2, and 1 cm/s. Two observers subjectively evaluated the detectability of the IAA in three mandibular regions on all PC-MRA images. The IAA appeared as a line of high signal intensity on the PC-MRA images. In the mandibular ramus region, the rating scores at VENCs of 1 and 2 cm/s were significantly higher than those at VENCs of 8 and 10 cm/s (p

Objective The aim was to investigate the relationship between the appearance of double contours on the mandibular condyle and changes in articular disc position after splint therapy. Study design Panoramic radiographs and magnetic resonance images of 82 joints in 41 patients taken before and after treatment were studied. The number of cases showing a double contour after treatment was compared between the 2 groups with and without disc displacement before treatment, and between the 2 groups with and without reduction in the displacement group; a comparison was also made among age groups and among 3 groups showing improvement, aggravation, or no change in displacement after treatment. Results All joints showing a double contour after treatment showed articular disc displacement before treatment. No double contours were observed after treatment on joints without articular disc displacement before treatment. All joints showing a double contour showed improvement in disc displacement. Conclusion The results indicate that a double contour on the mandibular condyle is the result of repositioning of, or positional improvement in, a displaced articular disc.

Both benign tumors and cysts in the oral and maxillofacial region show clear borders and homogeneously high signal intensity on magnetic resonance (MR T2-weighted images, making differentiation difficult without contrast enhancement. Windowing for brightness and contrast adjustment may be helpful in interpreting relative signal intensities on MR images. This study was performed to determine whether re-windowing against targeted lesions on T2-weighted images was a useful procedure that would enhance differentiation without invasive contrast enhancement. Twenty-six lesions (13 benign tumors, 13 cysts) that showed clear borders and homogeneously high signal intensity on T2-weighted images were examined. The windowing parameters of axial images were readjusted to emphasize contrast only inside the lesions using automatic density adjustment. Re-windowed images were reviewed by three experienced oral radiologists and categorized based on the internal homogeneity of the lesion into four grades: 0, heterogeneous; 1, slightly heterogeneous; 2, slightly homogeneous; 3, homogeneous. Re-windowing was then evaluated for its usefulness in differentiating between benign tumors and cysts. For cysts, the rates of homogeneous (grades 3 and 2) and heterogeneous intensity (grades 1 and 0) were 66.7 (26/39) and 33.3% (13/39), respectively. For benign tumors, these rates were 33.3 (13/39) and 66.7% (26/39), respectively. Cysts showed a higher rate of homogeneous intensity, while the opposite was true for benign tumors. A significant difference in distribution was observed between cysts and benign tumors (P

Summary The discrepancy between osteoarthritic findings on images and symptomatology can sometimes be problematic in clinical work. In this article, we focus on osteoarthritis and related entities on images, and especially on MR images.

Objective To determine the optimal scan settings (scan mode and position of field of view [FOV]) for cone beam computed tomography to reduce root fracture-like artifacts that are often observed in teeth filled with gutta-percha cones (GPCs). Study Design Fracture-like artifacts that appeared on cone beam computed tomography images of 9 extracted human mandibular premolars filled with GPCs were analyzed using I-mode (FOV, 102 mm; voxel size, 0.2 mm) and D-mode (FOV, 51 mm; voxel size, 0.1 mm) settings. Results The artificial lines were more obvious in I-mode than in D-mode. Increased distance between the center of the FOV and the GPCs produced stronger artificial lines in both I-mode and D-mode. Conclusion To reduce fracture-like artifacts, it is critical to use a mode with small voxel size and to place the target tooth in the center of the FOV.

The purpose of the present study is to analyze the fluid-attenuated inversion recovery (FLAIR) signal intensity of the retrodiscal tissue in a painful temporomandibular joint (TMJ), and to develop a diagnostic system based on FLAIR data.The study was based on 33 joints of 17 patients referred for MR imaging of the TMJ. Regions of interest were placed over retrodiscal tissue and gray matter (GM) on FLAIR images. Using signal intensities of GM as reference points, signal intensity ratios (SIR) of retrodiscal tissue were calculated. SIRs in painful TMJ were compared with those in painless TMJ. Wilcoxon's Rank Sum Test was used to analyze the difference in SIRs between the painful and painless groups (P0·05).The SIRs of retrodiscal tissue were significantly higher in painful joints than in painless joints.FLAIR sequences provide a high signal in patients having painful TMJ, and it suggests that retrodiscal tissue in painful TMJ contains elements such as protein.

The purpose of this study was to clarify the presence of pain and a correlation between pain and characteristics of signal intensity of mandibular bone marrow in temporomandibular joints (TMJ) with osteoarthritis (OA). A total of 196 joints in 98 patients with TMJ disorders were examined using magnetic resonance imaging (MRI). A pain score and signal intensity on mandibular bone marrow were analyzed in the TMJ with OA. TMJ with OA showed a higher degree of pain compared to those without (p

To visualize the temporomandibular joint (TMJ) and the surrounding tissues in detail utilizing high-resolution MR images for the diagnosis of soft- and hard-tissue abnormalities. Clinically routine MR slices are processed by tissue segmentation and three-dimensional (3D) reconstruction and viewed with visualization software.A 1.5 T MRI system was used. The double-echo procedure for taking oblique sagittal images was applied to obtain both proton density-weighted (PDW) and T2 weighted (T2W) images simultaneously, with separate examinations in both open and closed mouth positions. Diagnosis of the abnormality in the placement and morphology of articular discs and the joint effusion status is usually performed using multiple MRI slices. Clinically routine continuous MR slices were processed by segmentation, reconstruction and visualization algorithms, and the mandibular condyle, fossa, articular disc and other intra-articular tissues were visualized on the 3D and two-dimensional (2D)-3D fusion images.In a clinical case, the anterior disc displacement without reduction, with mouth open and closed, was clearly depicted in the 3D images. Also 2D-3D superposed images with changeable tissue transparency successfully depicted the stereoscopic TMJ morphology in three dimensions.High-resolution PDW- and T2W MR images could be processed by tissue segmentation and 3D-reconstruction procedures, and the resultant images showed the anatomical details in an easily recognizable way. By the simultaneous visualization of both bony surfaces and soft tissues, disc displacement and deformity can be recognized in a 3D context. The additional superposition of the 3D visualization with the original 2D MR slices allows for a combination with conventional diagnostics.

In benign tumors in the mandibular condyle such as osteoma and osteochondroma, symptoms such as pain and limited-mouth-opening are rarely observed. Therefore, these tumors are often detected after the development of changes in occlusion and mandibular midline deviation. We encountered a very rare patient with mandibular condyle osteoma who showed acute pain and markedly limited-mouth-opening.

This study compared Ultra Speed Occlusal Film (USOF) and 3 digital systems in determining the radiopacity of 5 different restorative resins in terms of equivalents of aluminum thickness. Whether those digital systems could be used to determine whether radiopacity was in line with International Organization for Standardization (ISO) recommendations was also investigated. Disks of each of 5 restorative resins and an aluminum step wedge were exposed at 65 kVp and 10 mA on USOF and imaged with each digital system. Optical density on the film was measured with a transmission densitometer and the gray values on the digital images using Image J software. Graphs showing gray value/optical density to step wedge thickness were constructed. The aluminum equivalent was then calculated for all the resins using a regression equation. All the resins were more radiopaque than 1 mm of aluminum, and therefore met the ISO 4049 recommendations for restorative resins. Some resins showed statistically higher aluminum equivalents with digital imaging. The use of traditional X-ray films is declining, and digital systems offer many advantages, including an easy, fast, and reliable means of determining the radiopacity of dental materials.

Many studies have shown that MRI findings are reliable when experienced calibrated observers work as a group. The hypothesis was that MRI findings can be used as the gold standard also when evaluation is made by single expert observers.Temporomandibular joint (TMJ) MRIs of 34 patients were evaluated independently by four reviewers with expert knowledge of radiology for the presence of 13 specified pathologic entities, as well as the quality of the images, on a 5-step scale from "Sure Yes" to "Sure No". Intraclass correlation coefficients were calculated to estimate the rating reliability of the examiners. A coefficient of at least 0.8 was deemed good, between 0.60 and 0.80 was deemed acceptable, and less than 0.60 was considered poor. Additionally, weighted kappa statistics were used for pair-wise comparisons across all four reviewers.The hypothesis was not supported by the results. None of the 13 correlation coefficients for comparisons between single examiner evaluations of pathologic entities was good and 8 were poor.A diagnosis of TMD based on MRI examination protocols made by a single examiner should not be accepted as a gold standard with regard to TMJ disorders.

Cone-beam CT (CBCT) systems specifically designed for hard-tissue imaging of the maxillofacial region have recently become commercially available. The newly-developed CBCT system, CB Throne® (Hitachi Medical Corp., Tokyo), is characterized by a number of features such as low dose, sub-millimeter spatial resolution, and a small footprint. This system has been clinically applied at Chiba Hospital, Tokyo Dental College, since April 2005. This article reports the characteristics of this system, and its diagnostic power for maxillofacial lesions and the pre-operative planning dental implants.

The purpose of this study was to investigate the accuracy of distance measurements of implant length based on periapical radiographs compared with that of other modalities. We carried out an experimental trial to compare precision in distance measurement. Dental implant fixtures were buried in the canine and first molar regions. These were then subjected to periapical (PE) radiography, panoramic (PA) radiography, conventional (CV) and medical computed (CT) tomography. The length of the implant fixture on each film was measured by nine observers and degree of precision was statistically analyzed. The precision of both PE radiographs and CT tomograms was closest at the highest level. Standardized PE radiography, in particular, was superior to CT tomography in the first molar region. This suggests that standardized PE radiographs should be utilized as a reliable modality for longitudinal and linear distance measurement, depending on implant length at local implantation site.

The purpose of this study was to determine optimum diffusion parameters for diffusion weighted imaging (DWI) techniques, including echo planer imaging (EPI), single-shot fast spin echo (SSFSE), and steady-state free precession (SSFP) in Magnetic Resonance Imaging (MRI) of the Temporomandibular Joint (TMJ). A polyethylene tube with distilled water was individually positioned at the external acoustic meatus foramen in each of three volunteers with normal healthy TMJs. Images were obtained using three types of DWI at differing diffusion parameters, b-factors, and diffusion moment. Signal intensity and imaging ability for various anatomical structures, including the distilled water, were evaluated from each image. The details of the anatomical structures of the TMJ were unidentifiable in the images produced with EPI and SSFSE, but were identifiable on the SSFP images. A diffusion moment value from 100 mT/m(*)msec to 150 mT/m(*)msec for SSFP, in particular, restrained the signal intensity of the water, thereby protecting the comparably high image quality of the TMJ structure. In conclusion, only SSFP is capable of allowing interpretation of emerging pathologic conditions in the TMJ region, when used with a diffusion moment set at between from approximately 100 mT/m(*)msec to 150 mT/m(*)msec.

To investigate the clinical significance of magnetic resonance (MR) evidence of joint effusion of the temporomandibular joint after mandibular condylar fractures, magnetic resonance imaging (MRI) was performed on 18 joints in 15 patients with either unilateral or bilateral mandibular condylar fractures using a 1.5 Tesla MRI scanner (Signa, General Electric, Milwaukee, WI). MR evidence of joint effusion was evaluated and compared with the types and the positions of the fractures. MR evidence of joint effusion was observed in 11 of 18 TMJs, which was 61% of the condylar fractures. It appeared more frequently after fractures with dislocation than those without dislocation (p0.05). In addition, MR evidence of effusion appeared more frequently in TMJs after high condylar fractures (head to upper neck) than low condylar fractures (lower neck to subcondylar) (p0.05). These findings indicate that MR evidence of joint effusion may serve as a marker for the detection of severe intra-articular damage to the TMJ after mandibular condyle fractures.

Magnetic resonance imaging has evolved as a prime diagnostic method for soft-tissue abnormalities of the temporomandibular joint. The most common temporomandibular joint abnormalities are internal derangement and osteoarthritis, but there are many other reasons for pain and dysfunction that are often overlooked. The purpose of this paper is to illustrate several of these more unusual and less well-recognized causes for temporomandibular joint pain and dysfunction. For example, internal derangement is often seen in asymptomatic individuals. Another purpose is to illustrate the difference in magnetic resonance imaging of asymptomatic and symptomatic internal derangement.

It has been reported that joint effusion, the excessive accumulation of joint fluid in and around the joint, is related to temporomandibular joint (TMJ) disorders such as pain and disk displacement. However, there have been no longitudinal studies of this phenomenon. We performed a longitudinal study on the relationship between joint fluid and various pathological disk conditions. The subjects were 17 patients who visited our facility for orthodontic treatment and were diagnosed using MRI as having internal derangement of one or both TMJs (three males and 14 females; age 12-31 years; mean age 20.5 years). MRI was performed before, during, or after treatment for their disorders. We evaluated the relationship between changes in joint fluid in the joint space and the state of the disk, as well as the presence or absence of pain. Joint fluid was evaluated by classifying the extent of high-signal areas in the upper and lower articular cavities on T2-weighted images. The extent of high-signal areas was classified into five levels. Disk displacement and the extent of displacement were evaluated using proton density-weighted images. Statistical analysis was performed using the chi-square test, and differences in the distribution among the groups were examined. Effusion was noted on the first MRI in nine of the eleven joints (81.8%) in which joint fluid decreased on the second MRI (p

Videofluorography is frequently used to evaluate swallowing and is considered the "gold standard" among imaging modalities. This modality, however, has several disadvantages, including radiation exposure and limitations in the detection of soft tissues. Conversely, magnetic resonance imaging (MRI) offers excellent contrast resolution in soft tissue without radiation exposure. A major drawback of MRI in evaluating swallowing, however, is that temporal resolution is poor. The aim of this study was to investigate a new cine-MRI modality. Imaging parameters were optimized and the efficacy of this new technique is discussed. Three techniques for speeding up MRI were combined: true fast imaging with steady state precession, generalized auto-calibrating partially parallel acquisition, and key-hole imaging. The effects of the receiver coils used, receiving bandwidth, slice thickness, and flip angle on each image were determined. The optimal imaging parameters obtained comprised a reduction factor of 2, receiving bandwidth of 1,000 Hz/pixel (repetition time of 151.7 milliseconds and echo time of 1.4 milliseconds), flip angle of 50°, and slice thickness of 6 mm. Neck and spine coils were used. Under these conditions, the new cine-MR imaging technique investigated showed a temporal resolution of 0.1 sec/slice (10 frames/sec). Even with optimized parameter settings, this technique did not allow a true temporal resolution of 30 frames/sec by a large margin. Motion artifacts persisted. Further study is needed on how to speed up this technique.