The normal anatomical structural interpretation in the panoramic radiograph is important in clinical dentistry. In this time, it is textbooks published until the present that we use for references, however, widely used anatomical terms are not unification, and there are differences within the textbooks by authors. Purpose: To help the routine dental care, it is to show that the relations of landmarks of the anatomical structures and its terms in the panoramic radiograph. Material & Methods: Using 17 representative textbooks (eleven were Japanese, and six were written in foreign language), we examined relations of anatomical landmarks of the normal image of the panoramic radiograph and the described terms. Results: Cutline in the textbooks and the used anatomical terms were various and were not uniform.
Objective: In order to establish a response indicator for predicting the treatment effects of oral appliances in patients with obstructive sleep apnea syndrome, we examine the utility of synchronous real-time dynamic ultrasound monitoring of the motion of the hyoid bone and the mandibular condyle during anterior mandibular movement. Materials and methods: Eight healthy volunteers, including three females and five males, were recruited for this study. None of the subjects had a history of sleep-related disorders. The synchronous real-time dynamic monitoring of mandibular protrusion was performed using two ultrasound systems with dedicated intraoperative probes. We measured five consecutive movements of the lateral portion of the mandibular condyle as an indicator of the anterior movement of the mandible and five consecutive movements of the lateral edge of the hyoid body as an indicator of the caudal movement of the hyoid bone. Results: The variation coefficient of the response ratio, which was defined as the ratio between hyoid caudal movement and mandibular anterior movement, was smaller than the amount of hyoid caudal movement in every subject. The mean amount of hyoid movement ranged from 2.0mm to 9.0mm, and the mean response ratio ranged from 0.28 to 0.87. The mean variation coefficient ranged from 5.2% to 19.5% for hyoid movement and from 4.6% to 16.1% for the response ratio. Conclusion: It was speculated that interpersonal comparisons could be performed using representative individual response ratio values as an indicator of the treatment effects of oral appliances.
Background and purpose: Diffusion-weighted imaging （DWI） has become an essential magnetic resonance imaging （MRI） technique in the head and neck region. However, metal artifacts arising from dental implants can reduce image quality. Methods for reducing metal artifacts are essential during clinical MRI examinations. However, few studies have investigated metal artifact reduction during DWI. The purpose of this study was to investigate techniques for reducing metal artifacts caused by dental implants during DWI. Materials and methods: A cylindrical phantom with an outer diameter of 20cm and a cylindrical rod with a 1.0cm diameter were used in this study. MRI was performed with a 1.5T MRI machine （Philips Co. Intera Achieva 1.5T） and a sensitivity-encoding （SENSE） head coil. While the repetition time/echo time ratio and b-value remained constant, the field of view （FOV）, rectangular field of view （RFOV）, SENSE factor, scan matrix, and scan percentage were changed. ImageJ was used to analyze the gray values of coronal MR images, which were then compared with the baseline values in order to detect changes of 30％. Results: The signal intensity decreased as the FOV changed from 100 to 250mm. However, increased signal intensity was observed when the FOV exceeded 300mm. At the lowest RFOV, the signal intensity was 50％, whereas it rose to over 100％ as the RFOV increased. A reduction in the SENSE factor resulted in the signal intensity changing from 1.0 to 3.0. Changes in the scan matrix and scan percentage increased the signal intensity from 64 to 256. Conclusions: In order to reduce metal artifacts due to dental implants during DWI: 1） the FOV and RFOV should be set as small as possible while still ensuring coverage of the target area, 2） the SENSE factor should be increased as much as possible, and 3） the scan matrix and scan percentage should be reduced as much as possible.
Objective: To determine the optimal angle at which the head should be positioned to clearly visualize the pterygopalatine fossa （PPF） during panoramic radiography, we investigated which anatomical components of the PPF most affect its visualization. Materials and methods: Ten dry adult skulls were used. The rotation angle （RA） of the skull in the Frankfurt plane parallel to the floor was defined as 0 degrees on the sagittal plane at the upper margin of the external auditory canals. The skull was then imaged every 5° in the range of +15° from -15°. Three radiologists evaluated 5 regions （the whole of the PPF, the middle cranial fossa （region A）, the posterior wall of the maxillary sinus （region B）, the anterior border of the lateral plate of the pterygoid process （region C）, and the part where the lateral plate and the posterior wall of the maxillary sinus come closest to each other （region D）） on each image and rated each region on a 5-point scale. The results were then categorized into clear （Group A） and unclear （Group B） groups. Binominal logistic regression analysis （LRA） was used for the statistical analysis. Results: Many of the examinations performed at RA of -5°, 0°, and +5° resulted in clear results and so were classified into Group A, and thus, the other RA were categorized as Group B. The LRA detected significant odds ratios （OR） for region B （OR ＝ 6.344）, region C （OR ＝ 4.678）, and region A （OR ＝ 2.117） in Group A, and region C （OR ＝ 4.582） and region A （OR ＝ 2.472） in Group B. Conclusion: Panoramic radiographs taken at RA of -5°, 0°, and -5° clearly depicted the PPF. The most critical structure for ensuring clear visualization of the whole pterygopalatine fossa is the posterior wall of the maxillary sinus, followed by the anterior border of the lateral plate of the pterygoid process, and the middle cranial fossa.
Objective: The purpose of this study is to evaluate the reliability of a macroscopic personal identification test based on reconstructed panoramic radiographs obtained with dental cone beam computed tomography （dental-CBCT） and standard panoramic radiographs. Materials and methods: We selected 100 consecutive patients who underwent dental-CBCT and panoramic radiography. However, we excluded 30 patients who had tumors and/or cysts in the maxillofacial region or in whom not all teeth were located in the field of view. Thus, 70 patients were chosen and randomly allocated to three groups （20 patients per group）. Reconstructed panoramic radiographs were produced using the ray-summation technique without reference to any panoramic radiographs or personal information. Both the reconstructed panoramic radiographs and panoramic radiographs were output to 300 dpi films. The evaluators were four dentists with 35 years, 30 years, 21 years, and 3 years’ experience of diagnostic imaging, respectively. Using the Kappa coefficient, we examined inter-rater reliability during macroscopic comparisons between the 20 reconstructed panoramic radiographs and 20 panoramic radiographs in each group （in the absence of any other personal information）. Personal identification tests of each group were conducted after an interval of at least one month. Results: All evaluators showed a very high concordance rate （100％） within the three groups. Furthermore, when the inter-rater concordance rate for the four evaluators who examined the three groups was investigated, the Kappa coefficient was found to be 1, indicating ‘almost perfect’ reliability. In addition, changes in dental condition （the numbers of residual teeth, treated teeth, and dental implant） did not have any effect on the evaluators’ results. Conclusion: This study showed that a macroscopic personal identification test based on the use of reconstructed panoramic radiographs derived from dental-CBCT and standard panoramic radiographs exhibited high reliability and validity.
Emphysema can develop in the maxillofacial region after root canal treatment, laser therapy, or the use of air turbine handpiece, but it spontaneously disappears in many cases. When such emphysema occurs, computed tomography (CT) is useful for determining the extent of the condition. Here, we report a case of widespread emphysema that developed after surgery for tongue cancer and a thyroid tumor. The patient was an 87-year-old female with tongue cancer and thyroid neoplasms, who underwent tracheotomy, bilateral neck dissection, thyroid neoplasm resection, and lingual reconstruction. At 4 days after the operation, swelling occurred in both the buccal and neck regions. CT showed that pneumatic spaces were widely distributed throughout the maxillofacial fascial spaces, anterior neck, and chest. We left the surgical wound open, and an antimicrobial agent was administered. As a result, the patient's emphysema disappeared. In the present case, exhaled air passed directly into the cervical dissection wound from the trachea incision, resulting in widespread emphysema.
This report is proceedings of workshop at committee on PACS and medical information in Japanese society for oral and maxillofacial radiology on March 2016. Multiple use of dental image data, such as in the tele-radiology, computer assisted detection / diagnosis （CAD）, computer assisted surgery and forensic dentistry are proceeding. However, standardization of dental image data is not reached a sufficient level. Therefore, we establish a correction proposal of DICOM standard （CP1444） for viewing protocol of intraoral radiographs. In addition, we discussed about several aspects regarding the usage of dental data, such as the identity of the natural disaster related dead bodies and the development of new medical devises.