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Objectives The shapes of gubernaculum tracts (GTs) in molars as accessional teeth remain unidentified. To elucidate imaging peculiarities of GTs in molars with aging on multidetector‐row computed tomography (MDCT). Material and methods This retrospective study was conducted using CT images, including maxillary and mandibular molars, with no abnormal findings from 239 patients. Shapes of alveolar bone, GTs, and dental sacs of the maxillary and mandibular molars were analyzed multi‐sectionally. Correlations between 2‐ and 3‐dimensional imaging figures of GTs in molars and chronological age or stage of molar formation were analyzed. Results Some forms of GTs in maxillary and mandibular third molars were observed. In the early stage, GTs were visualized as bone defect lines on the dentition and grooves on the mesial alveolar crest continuous with the dental sac to mesial tooth bud. GTs of the third molar formed a J‐shape in maxillary teeth and Y‐shape in mandibular teeth in the middle stage, as alveolar bone around the GT developed. In the mature stage, the course of the GT changed to straight and perpendicular. Some GT forms were also identified in first and second molars. Significant correlations were found between GT alterations and chronological age or stage of molar formation. Moreover, tracts continuing from the distal side of mandibular third molars were detected. Conclusions This paper describes the peculiarities and process of progression for GTs in molars, and the existence of tracts continuing from the distal side of mandibular third molars, unlikely dentition with deciduous predecessors. These preliminary data should prove beneficial for studies focusing on GTs in molars.

The aim of this study was to evaluate whether a balanced steady-state free-precession (SSFP) sequence with a time–spatial labeling inversion pulse (time–SLIP) without contrast medium could elucidate branches of the lingual and facial arteries on the lingual aspect of the mandible as a potential technique for preventing severe complications in dental implantation surgery. In this study, magnetic resonance angiography (MRA) using SSFP with a time–SLIP was evaluated in 40 subjects. The outline and course of branches of the lingual and facial arteries near the mandible were assessed clinically in the same subjects against contrast-enhanced computed tomography (CT) images as the gold standard. The submental, sublingual, and deep lingual arteries could be visualized via MRA in 16, 20, and 16 of the 40 subjects, respectively. The major axes of the respective arteries were approximately 24, 24, and 16 mm. The outline and course of all visualized arteries coincided with those on CT. MRA using SSFP with a time–SLIP appears to have potential as a non-contrast technique for visualizing branches of the lingual and facial arteries on the lingual aspect of the mandible. Information regarding the outline and course of these arteries as obtained using this MRA technique could assist in preventing severe complications in dental implantation surgery.

The purpose of this study was to elucidate the imaging characteristics of the gubernaculum tracts in successional teeth related to fused deciduous teeth on computed tomography. The imaging findings of 15 gubernaculum tracts in successional teeth related to fused deciduous teeth were retrospectively analyzed using cone-beam computed tomography or multidetector computed tomography. In cases without a congenitally defected successor, the two gubernaculum tracts of two successional teeth related to fused deciduous teeth were fused into one. Gubernaculum tracts (GTs) in mesial successors were vertical, but in distal successors they were inclined to mesial. The major abnormalities of the successional teeth related to fused deciduous teeth were delayed eruption and delayed formation. No inclined mesial successors were found, whereas most of the distal successors were inclined to mesial along with the inclined GT. The gubernaculum tracts of successors with a congenital defect of the other successors were vertical, and such successors had no abnormalities. The present study showed the imaging characteristics of gubernaculum tracts in successional teeth related to fused deciduous teeth. The abnormal eruption of successional teeth related to fused deciduous teeth may be associated with the characteristics of their gubernaculum tracts.

The objective was to introduce a new technique for visualizing the three-dimensional (3D) movements of velopharyngeal-related muscles using high-speed cine-magnetic resonance imaging (MRI) based on T2-weighted sequences. The evaluation of phonation- and water swallowing-related events was performed in 11 healthy subjects. Specifically, whether cine-MRI could precisely visualize normal velopharyngeal function during these two events was examined. The 3D movements of the soft palate, superior pharyngeal constrictor muscles, and levator veli palatini muscles were visualized in all 11 subjects. A noteworthy finding was that the magnetic resonance signals of the superior constrictor pharyngeal muscles and the levator veli palatini muscles were significantly higher during phonation and during water swallowing than at rest. This initial study suggests that the 3D movements of velopharyngeal-related muscles can be successfully and precisely visualized without side effects. The magnetic resonance signal changes seen in the superior pharyngeal constrictor and levator veli palatini muscles using the technique described here should be useful to develop better methods of evaluation of velopharyngeal function.

The eruption pathway from the dental follicle to the gingiva for permanent teeth is known as the gubernaculum tract (GT), a physiologic structure thought to play a role in tooth eruption. Cone beam computed tomography and multi-detector computed tomography have recently been used to visualize the GT, with the results indicating that this structure might be related to the normal eruption of teeth. By contrast, curved and/or constricted GTs may lead to abnormal tooth eruption. In addition, complex odontomas have been reported from within the GT or dental sac of unerupted permanent teeth. If an odontoma occurs within the GT, the tooth will not erupt normally. Moreover, the imaging characteristics of the GT from the top of the odontogenic mass to the alveolar crest are extremely useful for making a differential pathological diagnosis and for differentiating between odontogenic and non-odontogenic masses. Therefore, radiological studies on the GT have been attracting increasing attention. Given this background, the present review aims to clarify the imaging characteristics and review recent studies on the GT considering the importance of the research.

This study was done to determine whether the sublingual gland ducts could be visualized and/or their function assessed by MR sialography and dynamic MR sialography and to elucidate the clinical significance of the visualization and/or evaluation of the function of sublingual gland ducts by clinical application of these techniques. In 20 adult volunteers, 19 elderly volunteers, and 7 patients with sublingual gland disease, morphological and functional evaluations were done by MR sialography and dynamic MR sialography. Next, four parameters, including the time-dependent changes (change ratio) in the maximum area of the detectable sublingual gland ducts in dynamic MR sialographic images and data were analyzed. Sublingual gland ducts could be accurately visualized in 16 adult volunteers, 12 elderly volunteers, and 5 patients. No significant differences in the four parameters in detectable duct areas of sublingual glands were found among the three groups. In one patient with a ranula, the lesion could be correctly diagnosed as a ranula by MR sialography because the mass was clearly derived from sublingual gland ducts. This is the first report of successful visualization of sublingual gland ducts. In addition, the present study suggests that MR sialography can be more useful in the diagnosis of patients with lesions of sublingual gland ducts.

Objective The aim of this study was to evaluate the characteristics of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values of ranulas. In addition, to elucidate DWI findings and ADC values of other representative masses in and around the floor of the mouth. Study Design DWI findings and ADC values in 35 patients with ranulas and 33 patients with other masses were retrospectively reviewed with a central focus on cystic masses or lesions that may have cyst-like components in and around the floor of the mouth based on the diagnosis of each respective disease. Results Ranulas were all well-defined, homogeneous masses with high signal intensity on DWI. The mean ± standard deviation ADC value of the 35 ranulas was 2.59 ± 0.31 × 10−3 mm2/s. There was a significant difference in ADC values between simple and plunging ranulas. On DWI, most other masses were heterogeneous, and most ADC values, except those for thyroglossal duct cysts, hemangiomas, and pleomorphic adenomas, were significantly lower than those for ranulas. Conclusions The characteristic DWI and ADC findings of ranulas can be determined accurately, and these data can be significantly useful in the differential diagnosis of many kinds of diseases in and around the oral floor.

Numerous studies, including our own, have revealed that positron emission tomography–computed tomography (PET/CT) using fluorine-18-labeled fluoro-2-deoxy-d-glucose (18F-FDG) is effective for the diagnosis of oral cancers. Large amounts of new information about primary tumors and metastatic lymph nodes have been acquired, and the use of 18F-FDG PET/CT has been shown to improve diagnostic precision in determining both the pathological characteristics of primary oral cancers and the presence of metastatic lymph nodes. However, substantial variations in 18F-FDG uptake in the oral and maxillofacial regions have been identified, and the differential diagnosis of some oral cancers and metastatic lymph nodes remains difficult for radiologists. Therefore, based on the previous research, the aim of the present study was to review the basic and important points regarding the diagnosis of primary oral cancers and metastatic lymph nodes using 18F-FDG PET/CT.

Objective The aim of this study was to evaluate whether a new cine-magnetic resonance imaging (CMRI) technique might be useful for evaluating swallowing function in patients with different types of oral cancers by assessing 12 CMRI-related parameters. Study Design In total, 111 patients with oral cancers were evaluated. We examined whether visualization of fluid flow and determination of flow direction to the trachea or the esophagus were possible with CMRI. We evaluated the correlations between CMRI-related parameters and self-reported dysphagia scores as the status of dysphagia, T classification groups as tumor staging for preoperative patients, alterations in CMRI-related parameters between pre- and postoperative patients, and the degree of invasiveness of oral cancer surgery. Results We could judge the flow direction to the esophagus on CMRI in all 111 patients. Six CMRI-related parameters showed significant correlations with dysphagia status. Increases in CMRI-related parameters were significantly related to deterioration of swallowing status, as shown by a decrease in self-reported dysphagia scores, advances in the T classification, and degree of invasiveness of oral cancer surgery. Conclusions The results of the present study suggest that CMRI can be used to directly visualize swallowing dynamics and objectively evaluate the swallowing complaints of patients with oral cancer.

Objectives To elucidate the characteristics of the gubernaculum tracts (GTs) in maxillary anterior teeth with normal or delayed eruption and in mesiodens by using multidetector computed tomography and cone beam computed tomography. Study Design The characteristics of GTs in maxillary anterior teeth of 205 patients with impacted mesiodens were retrospectively analyzed by using multidetector computed tomography and cone beam computed tomography. The GTs of teeth with normal or delayed eruption and the GTs of mesiodens were examined. Results The detection ratio of GTs in impacted mesiodens and anterior teeth with delayed eruption was significantly lower than in teeth with normal eruption. A significant difference in the angulation was found between normal and delayed eruptions. Almost all detectable GTs in the inverted mesiodens were derived from the incisive canal, while the remaining were from the alveolar crest. The connecting area of major GTs to tooth in inverted mesiodens was the cervical or root area, but in all other anterior teeth, it was the crown area. Conclusions GTs of inverted mesiodens may exhibit characteristics that are different from those of normal GTs when the teeth and/or the palate are developing.

The aim of this study was to determine whether the evaluation of neurovascular compression (NVC) using new criteria on magnetic resonance (MR) cisternography improves the prediction of the curative effects of carbamazepine (CBZ) in trigeminal neuralgia (TN). In this study, a new analysis of NVC using MR cisternography was performed retrospectively for 280 patients with clinical signs and symptoms suggesting TN. The new analysis examined whether the site of the NVC was less than 3mm from the edge of the exit point and within the first third of the root entry zone on MR cisternography. Prediction of the curative effects of CBZ using the new evaluation of distance to the NVC improved on the predictive ability of the previous method of calculating the NVC volume (Mantel-Haenszel coefficient, P 5mm3. The evaluation of NVC on MR cisternography using this new approach appears to be more useful than the previous method for predicting the initial treatment response in patients with TN.

Background: 18 F-fluoro-2-deoxy-D-glucose ( 18 F-FDG) accumulations are commonly seen in the neck-related muscles of the surgical and non-surgical sides after surgery with neck dissection (ND) for oral cancers, which leads to radiologists having difficulty in diagnosing the lesions. To examine the alterations in 18 F-FDG accumulation in neck-related muscles of patients after ND for oral cancer. Material and Methods: 18 F-FDG accumulations on positron emission tomography (PET)-computed tomography (CT) in neck-related muscles were retrospectively analyzed after surgical dissection of cervical lymph nodes in oral cancers. Results: According to the extent of ND of cervical lymph nodes, the rate of patients with 18 F-FDG-PET-positive areas increased in the trapezius, sternocleidomastoid, and posterior neck muscles of the surgical and/or non-surgical sides. In addition, SUVmax of 18 F-FDG-PET-positive areas in the trapezius and sternocleidomastoid muscles were increased according to the extent of the ND. Conclusions: In evaluating 18 F-FDG accumulations after ND for oral cancers, we should pay attention to the 18 F-FDG distributions in neck-related muscles including the non-surgical side as false-positive findings

Objectives The purpose of this study was to identify the spatial relationship and/or association between odontomas and the gubernaculum tract or the dental sac and the characteristic findings for radiographic diagnosis of odontomas. Study Design The visualizations of the odontomas and the gubernaculum tract were retrospectively analyzed using cone beam computed tomography or multidetector computed tomography. Results Most of odontomas were within the gubernaculum tract or dental sac of unerupted permanent teeth on computed tomography. In some odontomas, the gubernaculum tract existed as a well-defined low density tract extending from the top of odontomas on computed tomography. Conclusions A close spatial relationship and/or association between odontomas and the gubernaculum tract or dental sac on computed tomography may be used as one of the criteria for radiographic diagnosis of odontomas. Development of odontomas may be associated with the gubernaculum tract or dental sac of unerupted permanent teeth.

A Stafne bone defect is a static bone depression in the mandible that is commonly observed in cortical bone near the mandibular angle. We herein present a rare case in which static bone depressions attached to the three major salivary glands were observed on panoramic radiography and computed tomography (CT). The three static bone depressions in the mandible were visualized on a panoramic radiograph and CT as oval radiolucent masses in a 68-year-old man. The CT numbers in the bone depressions ranged from 10 to 50 HU, and they were close to those of the respective salivary glands. Based on the CT numbers, the areas in the bone depressions were determined to be a normal parotid gland, sublingual gland, and submandibular gland. The patient underwent a follow-up examination and did not request further consultation.

Objectives The aim of this study was to determine the usefulness of evaluating the function of swallowing before and after surgery in patients with tongue cancer by using T2-weighted sequences of high-speed continuous magnetic resonance imaging (HSCMRI). Study Design The imaging findings and related parameters on HSCMRI along with those on routine MRI examinations before and after surgery were examined in 19 patients with tongue cancer. In addition, changes in various parameters during 1 year after surgery were evaluated in 10 patients. Results In most patients examined, the direction of flow to the esophagus could be seen on HSCMRI before and after surgery. Significant correlations were observed among 4 parameters and in the responses to a dysphagia questionnaire. Conclusions The results of the present study suggest that the dynamics of swallowing can be directly visualized on HSCMRI by using 4 parameters that permit the evaluation of changes before and after surgery, and this enables objective evaluation of patients' swallowing complaints.

Objective: The aim of this study was to examine whether a decreased occurrence rate of adverse drug reactions (ADRs) to contrast media in contrast-enhanced CT and MRI was attributable to appropriate criteria for patients with some diseases. A secondary aim was to elucidate safety profiles for contrast media and factors influencing the occurrence of ADRs. Methods: Clinical data of patients who underwent contrast-enhanced CT (5576 cases) or MRI (3357 cases) were retrospectively analyzed to evaluate rates of ADRs to contrast media, symptoms of ADRs, treatments for ADRs, and differences in medical history, blood test results, and other factors between patients with and without ADRs in a dental hospital. Results: The rate of ADRs to contrast media was 0.54% for CT and 0.09% for MRI. The most frequent ADRs in contrast-enhanced CT or MRI were nausea and vomiting as physiologic reactions. Two serious reactions were seen for CT, but none for MRI. Significant differences between patients with and without ADRs were seen in liver function according to blood tests for CT, and in digestive disorders elicited from medical interviews for MRI. Conclusion: The lower occurrence rate of ADRs to contrast media in dental hospitals could be due to the adoption of appropriate criteria for patients with some diseases undergoing enhanced CT or MRI. Complete suppression of ADRs to contrast media for CT or MRI is unrealistic, so attention is warranted for patients with decreased liver function when performing enhanced CT, and for patients with digestive disorders when performing enhanced MRI.

This review article provides doctors and dentists with an introduction to the clinical applications and sig- nificance of magnetic resonance cisternography (MRC) for the evaluation of neurovascular compression of the trigeminal nerve in patients with trigeminal neu- ralgia (TN). Specifically, the method and characteris- tics of MRC are first explained using the relevant MR sequences. Next, clinical applications for the diagnosis of TN are discussed. Finally, the significance and util- ity of MRC for effective treatment of patients with TN, such as carbamazepine administration and/or local anesthetic blocks, are presented.

Objectives To elucidate whether fluorine-18-labeled ( 18 F) fluoro-2-deoxy- d -glucose (FDG) accumulation can reflect the extent of periodontal inflammation, periapical inflammation, or dental caries. Study Design 18 F-FDG accumulations on positron emission tomography (PET)-computed tomography (CT) were retrospectively compared with the size of the bone resorption areas caused by periodontal inflammation, periapical inflammation, or dental caries on panoramic radiographs, CT, and magnetic resonance imaging (MRI) in 44 subjects. Results A significant correlation was found between the size of the bone resorption area caused by periodontal ( r = 0.595, P r = 0.560, P 18 F-FDG accumulation. A significant correlation was found between the periodontal ( r = 0.622, P r = 0.394, P 18 F-FDG accumulation. The SUVmax of 18 F-FDG around most teeth with caries was under 1.5. Conclusions 18 F-FDG accumulation reflects the extent of dental inflammation, not dental caries.

Our aim was to find out whether the quality of bone around the inferior alveolar nerve is correlated with neurosensory disturbance to the nerve after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Computed tomograms (CT) were taken of 35 patients with mandibular prognathism and 35 without. To assess the density of bone around the inferior alveolar nerve, the width of the buccal cortical bone in the mandibular second molar regions was measured on CT. The Hounsfield units (HU) in the same regions were also measured. The number of HU in the mandible around the second molar regions was significantly higher (p

Objectives The aim of this study was to evaluate the 3-dimensional images of thinner main peripheral vessels in oral and maxillofacial regions made without contrast medium by using a new technique, fresh blood imaging (FBI). A second objective was to discern arteries from veins by using the combination of FBI with the subtraction technique. Study design Images from FBI were compared with those from 3-dimensional phase-contrast magnetic resonance angiography (MRA) of blood vessels in 20 healthy subjects. All images were scored for visualization and image quality of the main blood vessels. In addition, appropriate flow-spoiled gradient pulses were applied to differentiate arteries from veins in the peripheral vasculature using a combination of FBI sequences and subtraction between systole- and diastole-triggered images. Results The scores of MRA using FBI for the visualization of thin blood vessels were significantly better than those using phase contrast, whereas scores for the visualization of main blood vessels were equal. Additionally, we succeeded in our initial attempt to differentiate arteries from veins with a reasonable acquisition time. Conclusions Our initial experience shows that FBI could be a useful method to identify 3-dimensional vasculature and to differentiate arteries from veins among thinner peripheral vessels in the oral and maxillofacial regions without using contrast medium.

To elucidate the relationship between the anatomic position of the inferior alveolar nerve (IAN) at the mandibular second molar and the occurrence of neurosensory disturbances of the IAN after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Also, the present study evaluated the difference in anatomic position of the IAN between patients with and without mandibular prognathism.Computed tomography images were taken of 28 patients with mandibular prognathism and 30 without prognathism. On these scans, the IANs from the mandibular second molar region to the mandibular foramen in the mandibular ramus were identified. The present study was designed as a cross-sectional study. The distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar regions was measured on the computed tomography images. Also, the linear distance between the superior aspect of the IAN canal and the alveolar crest in these regions was calculated. In addition, we investigated the presence or absence of contact between the IAN canal and the inner buccal cortical margin of the mandible from the mandibular second molar to the mandibular foramen in the mandibular ramus. Next, we examined whether neurosensory disturbances occurring after SSRO were related to the position of the IAN at the mandibular second molar.A significant difference was found in the occurrence of neurosensory disturbances of the IAN after SSRO between men and women (χ(2) test, P.05). For the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar region, a significant difference was found between groups with and without neurosensory disturbances (Student's t test, P.01). The shorter the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin, the more frequent the occurrence of neurosensory disturbances of the IAN.The present results have demonstrated that gender and the anatomic position of the IAN canal at the mandibular second molar are significantly related to the occurrence of neurosensory disturbances of the IAN after SSRO. Therefore, surgeons should clearly inform patients of the increased possibility of neurosensory disturbances after SSRO when the patients are female and are found to have a shorter distance from the buccal aspect of the IAN canal to the outer buccal cortical margin.

Objective The objective of this study was to evaluate the clinical significance of ultrasonography (US) for screening for thyroid gland diseases when surveying the cervical lymph nodes to detect metastasis in subjects with oral squamous cell carcinoma (SCC). Methods The detection rates and characteristics of abnormal thyroid findings detected by US in 301 subjects with oral SCC were analyzed. Subjects with abnormal findings were referred to thyroid specialists and the diagnoses and treatments from these specialists were noted. The ratio of subjects who consulted a thyroid specialist after indications of thyroid gland abnormalities to analyze subject compliance was also examined. Follow-up examinations were regularly conducted to assess any changes in the thyroid gland. Results Of the 301 subjects with oral SCC, 91 had abnormal thyroid gland findings on US. As subject age increased, the rate of detection of abnormal thyroid gland findings on US significantly increased. The rate of detection of abnormal findings in women by US was significantly higher than that in men, but the male-to-female ratio was lower compared with that in previous reports. It was demonstrated that oral SCC in the floor of the mouth was associated with the highest prevalence of abnormal findings in the thyroid gland (40%), followed by oral SCC of the maxillary gingiva (39%). Of the 91 subjects with abnormal findings, 10 showed enlargement in the size of the lesion on follow-up examination with US. Eleven subjects with no abnormal findings on initial examination showed abnormal findings on follow-up examination. Conclusion The results suggest that subjects with oral SCC have a relatively high rate of abnormal findings in the thyroid gland that can be detected by US. Scans that include the thyroid gland should be performed when surveying cervical lymph nodes for metastasis during US examination. Particular attention should be paid to thyroid gland–related diseases in older men who have oral cancer and to thyroid gland abnormalities if patients had oral SCC in the floor of the mouth or of the maxillary gingiva. It is recommended that follow-up US examinations be regularly performed in cases of oral SCC.

Infectious arthritis of the temporomandibular joint (TMJ) is rare, and previous reports have identified malocclusion resulting from condylar deformity and displacement of the condyle as one of the clinical characteristics of the disease. Here we report the case of a 33-year-old man with chronic infectious arthritis of the TMJ without malocclusion associated with osteomyelitis of the right mandible. Based on radiological findings of more prominent inflammation at the TMJ than in other regions and on the observed efficacy of antibiotic administration, we made a diagnosis of suppurative arthritis of the TMJ. Based on our empirical experience, including the present case, we speculate that refusal to cooperate with medical care may be a factor in the development of infectious arthritis of the TMJ.

Various modalities are available for the diagnosis of diseases affecting the oral and maxillofacial regions. The currently used imaging modalities include intra-oral radiographs, panoramic radiographs, magnetic resonance imaging (MRI), computed tomography (CT) including cone-beam (CB) CT, ultrasonography (US), and nuclear medicine including positron emission tomography (PET). In the present review, we describe the application and significance of each modality in the diagnostic process of oral and maxillofacial diseases. Keywords: Panoramic radiograph, cone beam CT, MRI, PET-CT, US, imaging, oral and maxillofacial. INTRODUCTION The discovery of the X-ray by WC Roentgen in 1895 be-gan the history of diagnostic imaging of the human body, including that of oral and maxillofacial regions. Since then, a number of diagnostic imaging modalities have been devel-oped. Different modalities are applied for the diagnosis of diseases in oral and maxillofacial regions, and many reports have suggested the usefulness of intra-oral radiographs, panoramic radiographs, magnetic resonance imaging (MRI), computed tomography (CT), ultrasonography (US), and nu-clear medicine including positron emission tomography (PET). In the present review, we introduce the applications of each modality and explain the significance of its image in the diagnosis of oral and maxillofacial diseases. The present review discusses the diagnosis of medical diseases using dental panoramic radiographs, the diagnostic significance of computed tomography (CT) including multi detector CT (MDCT) and cone-beam (CB) CT, the application of mag-netic resonance imaging (MRI) for various kinds of oral-related diseases, and computer simulations for dental implant and orthognathic surgery planning using data of helical CT images. The usefulness of ultrasonography (US) for viewing surface soft tissues such as salivary glands, tongue, and lymph nodes, and the advantages and limitations of positron emission tomography (PET) with fluorine-18-labeled fluoro-2-deoxy-D-glucose (18FDG) are also described.

Background Dentists need to be aware of the relationship between malignancies and paresthesia or complete loss of sensation in a jaw segment. In particular, dentists should be aware of numb chin syndrome (NCS) and its clinical manifestations, as well as the limitations of using panoramic radiographs to detect the causative malignancy. Case Descriptions The authors report two cases of paresthesia in the mental region. No lesions were readily apparent on the patients' panoramic radiographs. To exclude the presence of disease in the mandible that could have been responsible for the NCS, the authors obtained computed tomographic (CT) images. They identified metastases to the mandible from primary malignant tumors elsewhere in the body. Clinical Implications To prevent misdiagnosis of NCS, dentists need to be aware of the clinical manifestations of NCS, the need for CT imaging, the shortcomings of panoramic radiographs and the value of obtaining detailed and accurate medical and dental histories from patients.

Objectives:To elucidate the changes in the distributions of fluorine-18-labelled fluoro-2-deoxy-d-glucose (18F-FDG) accumulation in the tongue muscles of patients following four kinds of surgical operations for tongue cancers.Methods:The changes in the distributions of 18F-FDG accumulations in the tongue muscles on positron emission tomography (PET)-CT, in association with imaging findings on CT and MRI, were retrospectively analyzed before and after four kinds of surgical operations for 50 patients with tongue cancers.Results:18F-FDG-PET-positive areas appeared at the back of the intrinsic muscles of the tongue after invasive surgery for tongue cancers despite the absence of abnormal findings on CT and MRI. A correlation between the standardized uptake value maximum of 18F-FDG in the intrinsic muscles and the degree of invasiveness of the surgical procedures for tongue cancers (r = 0.539, p

Purpose To elucidate the appearance and imaging characteristics of the gubernacular tract (GT) during the growth stage of children. Furthermore, this study evaluated the significance of the appearance of the GT. Study Design The visualizations of the GT were retrospectively analyzed by using panoramic radiographs and computed tomography (CT) in children. Results In patients with normal eruption who had unerupted permanent teeth, except maxillary central supernumerary teeth, the GT was clearly visualized as a well-defined low-density tract on CT but not on panoramic radiographs. In patients with obstructive eruption, including impaction, the GT was deformed and not visible on CT. Conclusions This paper describes the frequency of detection and appearance of the GT in unerupted teeth. Preliminary data suggest that any alteration to the GT may be used to predict abnormal eruption of permanent teeth.

Background The purpose of this study was to use functional magnetic resonance imaging (fMRI) to quantify changes in brain activity during experimental occlusal interference. Methods Fourteen healthy volunteers performed a rhythmical tapping occlusion task with experimental occlusal interference of the right molar tooth at 0 mm (no occlusion), 0.5 mm, and 0.75 mm. The blood-oxygen-level dependent (BOLD) signal was quantified using statistical parametric mapping and compared between rest periods and task periods. Results In tapping tasks with experimental occlusal interference of 0.75 mm or 0.5 mm, there was clear activation of the contralateral teeth-related primary sensory cortex and Brodmann’s area 46. At 0 and 30 minutes after removal of the experimental occlusal interference, the activation clearly appeared in the bilateral teeth-related primary sensory cortices and Brodmann’s area 46. At 60 minutes after the removal of the experimental occlusal interference, the activation of Brodmann’s area 46 had disappeared, and only the bilateral teeth-related primary sensory cortices were active. Conclusions The present results suggest that adjustments for experimental occlusal interference can be objectively evaluated using fMRI. We expect that this method of evaluating adjustments in occlusal interference, combined with fMRI and the tapping task, could be applied clinically in the future.

Objectives The purpose of the present study was to elucidate the significance of cone bean computed tomography (CBCT) for patients hoping to undergo implant-supported restorations of the maxilla. Therefore, two studies were planned. One was to compare the prevalence of anatomic variations and lesions in the maxillary sinus on CBCT of patients hoping to undergo implant-supported restorations of the maxilla with that in patients with other chief complaints in a private dental office in Japan. The other study was to elucidate the limitations of panoramic radiographs in the detection of anatomic variations and lesions in the maxillary sinus. Study design Sixty-one pairs of panoramic radiographs and CBCT were retrospectively analyzed in two groups of patients, those who hoped to undergo implant-supported restorations in the maxilla (Implant group) and those who did not (Non-implant group). The presence of anatomic variations and lesions in the maxillary sinus were analyzed. Results The detection rate of mucosal thickening was significantly higher in the Implant group than in the Non-implant group. The detection rates for the features analyzed were significantly lower on panoramic radiographs. In particular, the detection rates of internal and anterior locations of some features were noticeably lower on panoramic radiographs. A significant relationship was found between the change in the detection rate on panoramic radiographs and the widths of mucosal thickening or the lengths of the major axis of SOLs in the maxillary sinus. If the width of mucosal thickening or the length of the major axis of SOLs was

Background Recent studies suggest that tonsilloliths are clinically related to halitosis and tonsillar abscess. Based on our empirical knowledge, tonsilloliths are relatively commonly encountered in daily clinical practice. It has been reported that the detection rate of tonsilloliths was under 24% in previous reports, although experience suggests otherwise. The purpose of the study was to evaluate the prevalence and characteristics of tonsilloliths using computed tomography (CT). In addition, the possible causes of low detection rates on panoramic radiographs were evaluated based on comparisons between CT images and panoramic radiographs in order to elucidate the limitations of visualizing the area around the palatine tonsils on panoramic radiographs. Methods 482 pairs of CT images and panoramic radiographs were retrospectively assessed with respect to the presence and characteristics of tonsilloliths. In addition, the causes in cases of disagreement between the two modalities were analyzed. Results The detection rate of tonsilloliths was 46.1% using CT scans, unlike previous reports. The characteristics of tonsillolith were dot-like figures with about 300-500 Hounsfield units within the palatine tonsil under the soft palate. The most common length of tonsilloliths was about 3 or 4 mm. As the subjects aged, the detection rate increased gradually. A significant difference in the tonsillolith detection rate was found between the over and under 40-year-old groups (p Conclusion The present results suggest that tonsilloliths are relatively more common than previously suggested. However, panoramic radiographs detect only a small percentage of palatine tonsilloliths. The low detection rates on panoramic radiographs might be related to the degree of calcification, size, and number of tonsilloliths.

Objective To elucidate the characteristics of visualizing thin main peripheral vessels in oral and maxillofacial regions of 3-dimensional magnetic resonance angiography (MRA) using a balanced steady-state free-precession (SSFP) sequence with a time-spatial labeling inversion pulse (time-SLIP) and using fresh blood imaging (FBI). Study Design The conspicuity of blood vessels and the characteristics on MRA using SSFP with a time-SLIP was compared with those on MRA using FBI in 20 healthy participants. Results The conspicuity of the main peripheral arteries was significantly higher on MRA using SSFP with a time-SLIP than on MRA using FBI. MRA scans using SSFP were obtained in all participants, and scans using FBI were obtained in 16 of 20 participants. An electrocardiogram was unnecessary when using SSFP but was necessary when using FBI. Conclusions MRA obtained using SSFP with a time-SLIP is a useful technique to visualize thin main peripheral arteries in the oral and maxillofacial regions without contrast medium.

To elucidate whether fluorine-18-labeled ((18)F) fluoro-2-deoxy-d-glucose (FDG) accumulation can reflect the extent of periodontal inflammation, periapical inflammation, or dental caries.(18)F-FDG accumulations on positron emission tomography (PET)-computed tomography (CT) were retrospectively compared with the size of the bone resorption areas caused by periodontal inflammation, periapical inflammation, or dental caries on panoramic radiographs, CT, and magnetic resonance imaging (MRI) in 44 subjects.A significant correlation was found between the size of the bone resorption area caused by periodontal (r = 0.595, P.01) or periapical (r = 0.560, P.01) inflammation and the highest standardized uptake value (SUVmax) of (18)F-FDG accumulation. A significant correlation was found between the periodontal (r = 0.622, P.01) or periapical (r = 0.394, P.01) inflammatory findings on MRI and the SUVmax of (18)F-FDG accumulation. The SUVmax of (18)F-FDG around most teeth with caries was under 1.5.(18)F-FDG accumulation reflects the extent of dental inflammation, not dental caries.

The purpose of this study is to elucidate the criteria and limitations for selecting a sagittal split ramus osteotomy (SSRO) alone for patients with skeletal mandibular prognathism and open bite.The relationship between the mandibular relapse after 1 year and the extent of vertical movement following SSRO alone was investigated for patients with skeletal mandibular prognathism and open bite and the criteria were determined.The limitation in SSRO alone was found to be 3-mm vertical movement at the gonion. There was a significant difference in the mandibular relapse between the patients with3-mm change and3-mm change.For patients with skeletal mandibular prognathism and open bite, if the vertical movement at the gonion is3 mm, SSRO alone could be an effective treatment. However, if the movement is3 mm, SSRO alone should be avoided and bimaxillary osteotomies may be a preferable treatment.

Objectives Whether NVC volume on magnetic resonance (MR) cisternography might be related to the success of local anesthetic block by tetracaine (TNB) as an additional treatment after carbamazepine (CBZ) treatments in patients with trigeminal neuralgia (TN) was evaluated. Study Design Detectable NVC volumes were measured from MR cisternography in 65 patients with TN treated by TNB after CBZ treatments. The correlation between the success of TNB and the NVC volume or the improvement in pain by CBZ was evaluated retrospectively. Results A significant difference was found between the improvement in pain by CBZ and the success of TNB, but not between NVC volume on MR cisternography and the success of TNB. Conclusions The present results suggest that the success of CBZ as initial treatment, but not NVC volume on MR cisternography, may be a significant predictor of the success of TNB as additional therapy in patients with TN.

The present paper provides general dentists with an introduction to the clinical applications and significance of magnetic resonance angiography (MRA) in the oral and maxillofacial regions. Specifically, the method and characteristics of MRA are first explained using the relevant MR sequences. Next, clinical applications to the oral and maxillofacial regions, such as identification of hemangiomas and surrounding vessels by MRA, are discussed. Moreover, the clinical significance of MRA for other regions is presented to elucidate future clinical applications of MRA in the oral and maxillofacial regions.

Computed tomography (CT) scanning is very useful in identifying and evaluating the location, size, and suspected pathological diagnosis of lesions such as cysts, tumors, and infections. At the same time, it aids in the elucidation of bone and surrounding soft tissue invasion of lesions with high resolution.1, 2 In the maxilla and mandible, teeth are included and the CT capacity there can distinguished a foreign body of only 30 μm. Precise size and location are needed in the evaluation of lesions in the maxilla and mandible based on a high resolution in addition to the suspected pathological diagnosis based on CT findings. Therefore, multi-detector CT (MDCT) scanning is commonly applied for various kinds of lesions in the maxilla and mandible because of its precision and diagnostic accuracy. Multidetector CT scanning provides rapid acquisition of numerous thin axial images and more accurate reconstruction images. Multi-detector CT scanning provides accurate information about the height, width, and three-dimensional (3D) evaluation of the maxilla and mandible, as well as detailed information about the location of normal anatomical structures, such as the mandibular canal, mental foramen, mandibular foramen, incisive foramen, and maxillary sinus. In addition, the relationship between lesions and anatomical landmarks, including cortical margins and roots of teeth, can be established. These images are also excellent because MDCT eliminates streak artifacts from dental restorations that degrade direct coronal CT scans. With MDCT, axial images are used to reformat the cross-sectional images, projecting the artifact along the crowns of the teeth rather than over the bone that is the region of interest.3 At the same time, CT readings of lesions in the maxilla and mandible measured by MDCT can reflect the nature and inclusion within lesions, from which

In the present case of a 9-year-old girl with prominent swelling in the mental and facial regions after trauma, repeated magnetic resonance (MR) examinations were performed to evaluate areas of incision, because the swelling became worse and more prominent despite intravenous antibiotic treatment. However, there was no evidence of respiratory tract impingement or deformation, including obliteration, on MR imaging. Therefore, surgical treatment involving an incision because of facial region swelling was cancelled, and the intravenous antibiotic therapy was continued. To prevent misdiagnosis and over-treatment of young children with inflammation of the oral and maxillofacial regions, dentists, including pediatric dentists, should be aware of the clinical usefulness of MR examinations. In particular, MR examinations are non-invasive for young children, because there is no X-ray exposure, and they can be used repetitively. At the same time, the present case demonstrated that it is very difficult to understand and predict changes in the inflammation process associated with children's facial trauma.

To elucidate the clinical significance of imaging modalities for detection of stitch abscess after surgery in patients with oral squamous cell carcinoma (SCC). In 137 patients with oral SCC suspected of having lymph node metastases, local recurrence of tumor, or stitch abscess after surgery, the characteristic imaging findings related to lymph node metastases, local recurrence of tumor, and stitch abscess on ultrasonography (US), computed tomography (CT), magnetic resonance (MR), and (18)fluorodeoxyglucose (18FDG)-positron emission tomography (PET) images were identified and analyzed. In all six patients with stitch abscess, characteristic findings were demonstrated on US, different from those of metastatic lymph nodes and local recurrence on CT, MRI, and 18FDG-PET images. Our results suggest that ultrasonography may be a very useful tool for diagnosis of postoperative stitch abscess and may help improve the quality of life of oral SCC patients.

Various kinds of diseases may be found in the oral and maxillofacial regions and various modalities may be applied for their diagnosis, including intra-oral radiography, panoramic radiography, ultrasonography, computed tomography, magnetic resonance imaging, and nuclear medicine methods such as positron emission tomography. Of these modalities, ultrasound imaging is easy to use for the detection of noninvasive and soft tissue-related diseases. Doppler ultrasound images taken in the B-mode can provide vascular information associated with the morphology of soft tissues. Thus, ultrasound imaging plays an important role in confirming the diagnosis of many kinds of diseases in such oral and maxillofacial regions as the tongue, lymph nodes, salivary glands, and masticatory muscles. In the present article, we introduce three new applications of ultrasonography: guided fine-needle aspiration, measurement of tongue cancer thickness, and diagnosis of metastasis to cervical lymph nodes.

OBJECTIVES: To elucidate the relationship between the extent of pain and neurovascular compression (NVC) volume, measured by magnetic resonance (MR) cisternography, in patients with trigeminal neuralgia. In addition, we aimed to evaluate the relationship between NVC volume and the efficacy of carbamazepine administration in patients with trigeminal neuralgia. METHODS: MR cisternography was performed on 214 patients with clinical signs and symptoms that suggested trigeminal neuralgia retrospectively. The extent of their pain was evaluated using visual analog scales. Next, only carbamazepine was administered as the initial treatment. For the patients with NVC detectable on MR cisternography, the relationship between the extent or nature of the pain and the neurovascular volume was analyzed. In addition, the correlation between the efficacy of carbamazepine treatment and the NVC volume was evaluated retrospectively. RESULTS: Of the 214 patients evaluated, 144 were deemed to have NVC. In these 144 patients, a significant difference was found between the NVC volume and the curative effects of 100 mg/d carbamazepine. However, no significant correlation was found between the extents of pain by visual analog score or between the daily dosage of carbamazepine and the NVC volume measured by MR cisternography. CONCLUSIONS: Three-dimensional MR cisternography is very useful for detecting the site of NVC in patients with trigeminal neuralgia. NVC measured by this technique may indicate the prognosis after initial treatment. The present results suggest that the evaluation of NVC volume by MR cisternography would be useful in choosing the initial treatment for patients with trigeminal neuralgia.