Perceptions and attitudes of dental hygienists toward radiation safety and protection in the Republic of Korea

To investigate the perceptions and attitudes of dental hygienists toward radiation safety management in Korea. A total of 800 dental hygienists were randomly selected for an anonymous survey, and 203 of them participated. The questionnaire items included the following: sex, career period, type of installed radiographic equipment, recognition of the diagnostic reference level (DRL), participation in radiation safety education, and attitudes toward radiation protection for both patients and dental hygienists. The participants were divided into two groups according to their years of experience (< 10 years versus ≥ 10 years). The difference between the groups was investigated according to frequency distribution. Fisher’s exact test or Pearson’s chi-square (χ2 ) test was used as appropriate. A regression analysis was performed to investigate the impact of wearing a thyroid collar for personnel protection during patient radiation exposure. The types of installed radiographic equipment included panoramic radiography (96.1%), cephalometric radiography (76.9%), intraoral radiography (72.9%), and cone-beam computed tomography (69.5%). Significant differences were observed in the learning pathway for the DRL (Fisher’s exact test, p < 0.05), satisfaction with radiation safety education (Pearson’s χ2 test = 5.3975, Pr = 0.02), and use of personnel radiation monitoring systems (Pearson’s χ 2 test = 18.1233, Pr = 0.000) between the groups. Significant differences were also observed in personnel protection using a thyroid collar and patient protection during panoramic radiography (odds ratio = 14.2). Dental hygienists with more than 10 years of experience were more satisfied with radiation safety education and more interested in radiation monitoring. Considering career experience, customized, continuous, and effective radiation safety management education should be provided.

Risk factors of osteonecrosis of the jaw after tooth extraction in osteoporotic patients on oral bisphosphonates

PURPOSE: The aim of this study was to investigate the incidence of bisphosphonate-related osteonecrosis of the jaw (BRONJ) after tooth extraction in patients with osteoporosis on oral bisphosphonates in Korea and to evaluate local factors affecting the development of BRONJ. MATERIALS AND METHODS: The clinical records of 320 patients who underwent dental extraction while receiving oral bisphosphonates were reviewed. All patients had a healing period of more than 6 months following the extractions. Each patient's clinical record was used to assess the incidence of BRONJ; if BRONJ occurred, a further radiographic investigation was carried out to obtain a more definitive diagnosis. Various local factors including age, gender, extraction site, drug type, duration of administration, and C-terminal telopeptide (CTx) level were retrieved from the patients' clinical records for evaluating their effect on the incidence of BRONJ. RESULTS: Among the 320 osteoporotic patients who underwent tooth extraction, 11 developed BRONJ, reflecting an incidence rate of 3.44%. Out of the local factors that may affect the incidence of BRONJ, gender, drug type, and CTx level showed no statistically significant effects, while statistically significant associations were found for age, extraction site, and duration of administration. The incidence of BRONJ increased with age, was greater in the mandible than the maxilla, and was associated with a duration of administration of more than 3 years. CONCLUSION: Tooth extraction in patients on oral bisphosphonates requires careful consideration of their age, the extraction site, and the duration of administration, and close postoperative follow-up should be carried out to facilitate effective early management.

The impact of reorienting cone-beam computed tomographic images in varied head positions on the coordinates of anatomical landmarks

PURPOSE: The aim of this study was to compare the coordinates of anatomical landmarks on cone-beam computed tomographic (CBCT) images in varied head positions before and after reorientation using image analysis software. MATERIALS AND METHODS: CBCT images were taken in a normal position and four varied head positions using a dry skull marked with 3 points where gutta percha was fixed. In each of the five radiographic images, reference points were set, 20 anatomical landmarks were identified, and each set of coordinates was calculated. Coordinates in the images from the normally positioned head were compared with those in the images obtained from varied head positions using statistical methods. Post-reorientation coordinates calculated using a three-dimensional image analysis program were also compared to the reference coordinates. RESULTS: In the original images, statistically significant differences were found between coordinates in the normal-position and varied-position images. However, post-reorientation, no statistically significant differences were found between coordinates in the normal-position and varied-position images. CONCLUSION: The changes in head position impacted the coordinates of the anatomical landmarks in three-dimensional images. However, reorientation using image analysis software allowed accurate superimposition onto the reference positions.

Mandibular metastasis of cholangiocarcinoma: A case report

Tumors metastasizing from distant regions to the oral and maxillofacial region are uncommon, comprising only 1%-2% of all malignancies. Cholangiocarcinoma is a malignancy that arises from cholangiocytes, which are epithelial cells that line the bile ducts. These cancers are difficult to diagnose and have a poor prognosis. In this paper, we report a rare case of mandibular metastasis of cholangiocarcinoma diagnosed at the primary site and discuss the radiographic findings observed in this case.

Comparison of conventional lateral cephalograms with corresponding CBCT radiographs

PURPOSE: This study was performed to assess the compatibility of cone beam computed tomography (CBCT) synthesized cephalograms with conventional cephalograms, and to find a method for obtaining normative values for three-dimensional (3D) assessments. MATERIALS AND METHODS: The sample group consisted of 10 adults with normal occlusion and well-balanced faces. They were imaged using conventional and CBCT cephalograms. The CBCT cephalograms were synthesized from the CBCT data using OnDemand 3D software. Twenty-one angular and 12 linear measurements from each imaging modality were compared and analyzed using paired-t test. RESULTS: The linear measurements between the two imaging modalities were not statistically different (p>0.05) except for the U1 to facial plane distance. The angular measurements between the two imaging modalities were not statistically different (p>0.05) with the exception of the gonial angle, ANB difference, and facial convexity. CONCLUSION: Two-dimensional cephalometric norms could be readily used for 3D quantitative assessment, if corrected for lateral cephalogram distortion.

Comparative evaluation of computed tomography for dental implants on the mandibular edentulous area / 대한구강악안면방사선학회지

PURPOSE: The purpose of this study was to evaluate the clinical usefulness of the recently developed multi-detector computed tomography and cone beam computed tomography in pre-operative implant evaluation, by comparing them with the single detector computed tomography, already confirmed for accuracy in this area. MATERIALS AND METHODS: Five partially edentulous dry human mandibles, with 1x1 mm gutta percha cones, placed in 5 mm intervals posterior to the mental foramen on each side of the buccal part of the mandible, were used in this study. They were scanned as follows: 1) Single detector computed tomography: slice thickness 1 mm, 200 mA, 120 kV 2) Multi-detector computed tomography: slice thickness 0.75 mm, 250 mA, 120 kV 3) Cone beam computed tomography: 15 mAs, 120 kV Axial images acquired from three computed tomographies were transferred to personal computer, and then reformatted cross-sectional images were generated using V-Implant 2.0(R) (CyberMed Inc., Seoul, Korea) software. Among the cross-sectional images of the gutta percha cone, placed in the buccal body of the mandible, the most precise cross section was selected as the measuring point and the distance from the most superior border of the mandibular canal to the alveolar crest was measured and analyzed 10 times by a dentist. RESULTS: There were no significant intraobserver differences in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). There were no significant differences among single detector computed tomography, multi-detector computed tomography and cone beam computed tomography in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). CONCLUSION: Multi-detector computed tomography and cone beam computed tomography are clinically useful in the evaluation of pre-operative site for mandibular dental implants, with consideration for radiation exposure dose and scanning time.

Three dimensional linear measurement of proximal tibia in medial and lateral approach for bone harvesting

PURPOSE : The aim of this study was simply assessing linear measurements in the lateral and medial approach, respectively, for bone harvesting using anatomic and three-dimensional (3D) computed tomographic (CT) analyses on a dried cadaveric proximal tibia. In addition, the availability of the three-dimensional computed tomographic (3D-CT) analysis was also estimated. MATERIALS AND METHODS : Ten dried proximal tibia were obtained from five Korean cadavers. Four the reference points, the SM (superior-medial), IM (inferior-medial), SL (superior-lateral), and IL (inferior-lateral) were marked around the tibial tuberosity. The PM (posterior-medial) and PL (posterior-lateral) points were randomly marked at points farthest from the lateral and medial reference points, respectively, in the posterior border of the superior articular surface of both condyles. All measurements were obtained on the dried proximal tibia. After computed tomography had been performed, the three dimensional images were reconstructed using V works 4.0(TM) (Cybermed Inc., Seoul, Korea), and the length between the reference points were measured three dimensionally using the method described above. The error between the mean actual and mean 3D-CT measurements was calculated in order to determine the availability of the three dimensional computed tomographic analysis. RESULTS : The length between the reference points was greatest at the IL-PM, which averaged 65.39 mm+/-10.35. This was followed by the SL-PM with 63.24 mm+/-8.10, the IM-PL with 58.09 mm+/-10.02, and the SM-PL with 51.99 mm+/-9.06. The differences between the IL-PM and SM-PL were 13.4 mm. The mean values were 55.04 mm in the medial approach and 64.32 mm in the lateral approach, and the differences between medial and lateral were 9.28 mm. The error between the mean actual and mean 3D-CT measurements was 0.31% and the standard deviation was 0.28%. CONCLUSION : The anatomical and three dimensional computed tomographic analysis indicates that there was only a 9.28 mm linear difference between the lateral and medial approach. This is consistent with previous studies, which showed that there was little difference between the two approaches in terms of the bone volume. In addition, the error (0.31%) and the standard deviation (0.28%) were considered low, demonstrating high accuracy of 3D-CT. Therefore it can be used in preoperative treatment planning.

Characteristics of a new cone beam computed tomography / 대한구강악안면방사선학회지

PURPOSE: To determine the physical properties of a newly developed cone beam computed tomography (CBCT). MATERIALS AND METHODS: We measured and compared the imaging properties for the indirect-type flat panel detector (FPD) of a new CBCT and the single detector array (SDA) of conventional helical CT (CHCT). RESULTS: First, the modulation transfer function (MTF) of the CBCT were superior to those of the CHCT. Second, the noise power spectrum (NPS) of the CBCT were worse than those of the CHCT. Third, detective quantum efficiency (DQE) of the indirect-type CBCT were worse than those of the CHCT at lower spatial frequencies, but were better at higher spatial frequencies. Although the comparison of contrast-to-noise ratio (CNR) was estimated in the limited range of tube current, CNR of CBCT were worse than those of CHCT. CONCLUSION: This study shows that the indirect-type FPD system may be useful as a CBCT detector because of high resolution.

Measurement of facial soft tissues thickness using 3D computed tomographic images / 대한구강악안면방사선학회지

PURPOSE: To evaluate accuracy and reliability of program to measure facial soft tissue thickness using 3D computed tomographic images by comparing with direct measurement. MATERIALS AND METHODS: One cadaver was scanned with a Helical CT with 3 mm slice thickness and 3 mm/sec table speed. The acquired data was reconstructed with 1.5 mm reconstruction interval and the images were transferred to a personal computer. The facial soft tissue thickness were measured using a program developed newly in 3D image. For direct measurement, the cadaver was cut with a bone cutter and then a ruler was placed above the cut side, The procedure was followed by taking pictures of the facial soft tissues with a high-resolution digital camera. Then the measurements were done in the photographic images and repeated for ten times. A repeated measure analysis of variance was adopted to compare and analyze the measurements resulting from the two different methods. Comparison according to the areas was analyzed by Mann-Whitney test. RESULTS: There were no statistically significant differences between the direct measurements and those using the 3D images (p>0.05). There were statistical differences in the measurements on 17 points but all the points except 2 points showed a mean difference of 0.5 mm or less. CONCLUSION: The developed software program to measure the facial soft tissue thickness using 3D images was so accurate that it allows to measure facial soft tissues thickness more easily in forensic science and anthropology.

Inflammatory myofibroblastic tumor: A case report / 대한구강악안면방사선학회지

The inflammatory myofibroblastic tumor (inflammatory pseudotumor) is a rarely occurring soft tissue lesion of unknown etiology. It can be of any location, but commonly it is found in lungs. It has been considered as a nonneoplastic reactive inflammatory lesion, but nowadays, confusion and dispute about its character is increasing due to its high recurrence rate and metastasis. We present a patient who had been diagnosed with an inflammatory pseudotumor in the right maxilla area, 1 year before visiting our hospital. After that, her pain and swelling did not resolved and she visit our hospital. On radiographic examination, aggressively infiltrative growth of the lesion with destruction of adjacent bony structure was noted. We found unusual aggressiveness of the inflammatory myofibroblastic tumor of the head and neck region. Because the typical behavior of the inflammatory myofibroblastic tumor is not defined yet, we recommend the surgical excision of the lesion and close follow-up.

Clinical usefulness of facial soft tissues thickness measurement using 3D computed tomographic images / 대한구강악안면방사선학회지

PURPOSE: To evaluate clinical usefulness of facial soft tissue thickness measurement using 3D computed tomographic images. MATERIALS AND METHODS: One cadaver that had sound facial soft tissues was chosen for the study. The cadaver was scanned with a Helical CT under following scanning protocols about slice thickness and table speed; 3 mm and 3 mm/sec, 5 mm and 5 mm/sec, 7 mm and 7 mm/sec. The acquired data were reconstructed 1.5, 2.5, 3.5 mm reconstruction interval respectively and the images were transferred to a personal computer. Using a program developed to measure facial soft tissue thickness in 3D image, the facial soft tissue thickness was measured. After the ten-time repeation of the measurement for ten times, repeated measure analysis of variance (ANOVA) was adopted to compare and analyze the measurements using the three scanning protocols. Comparison according to the areas was analyzed by Mann-Whitney test. RESULTS: There were no statistically significant intraobserver differences in the measurements of the facial soft tissue thickness using the three scanning protocols (p>0.05). There were no statistically significant differences between measurements in the 3 mm slice thickness and those in the 5 mm, 7 mm slice thickness (p>0.05). There were statistical differences in the 14 of the total 30 measured points in the 5 mm slice thickness and 22 in the 7mm slice thickness. CONCLUSION: The facial soft tissue thickness measurement using 3D images of 7 mm slice thickness is acceptable clinically, but those of 5 mm slice thickness is recommended for the more accurate measurement.

Benefits and problems in implementation for integrated medical information system / 대한구강악안면방사선학회지

PURPOSE: Once the decision has been made to adopt an integrated medical information system (IMIS), there are a number of issues to overcome. Users need to be aware of the impact the change will make on end users and be prepared to address issues that arise before they become problems. The purpose of this study is to investigate the benefits and unexpected problems encountered in the implementation of IMIS and to determine a useful framework for IMIS. MATERIALS AND METHODS: The Yonsei University Dental Hospital is steadily constructing an IMIS. The vendor's PACS software, Piview STAR, supports transactions between workstations that are approved to integrating the healthcare enterprise (IHE) with security function. It is necessary to develop an excellent framework that is good for the patient, healthcare provider and information system vendors, in an expert, efficient, and cost-effective manner. RESULTS: The problems encountered with IMIS implementation were high initial investments, delay of EMR enforcement, underdevelopment of digital radiographic appliances and software and insufficient educational training for users. CONCLUSIONS: The clinical environments of dental IMIS is some different from the medical situation. The best way to overcome these differences is to establish a gold standard of dental IMIS integration, which estimates the cost payback. The IHE and its technical framework are good for the patient, the healthcare provider and all information systems vendors.

A radiologic study of ameloblastoma using computed tomography / 대한구강악안면방사선학회지

PURPOSE: To reveal what is the distinct differential diagnostic differences between unicystic ameloblastoma and solid or multicystic ameloblastoma. MATERIALS AND METHODS: 56 cases of ameloblastoma were retrospectively reviewed and evaluated among the patients who had taken CT scans at the department of Oral and Maxillofacial Radiology in Yonsei University Dental Hospital from January 1996 to December 2003. RESULTS: In 56 cases, 21 cases (37.5%) were unicystic ameloblastoma, 35 cases (62.5%) were solid or multicystic ameloblastoma. Only 1 case (4.8%) of unicystic ameloblastoma and 4 cases (11.4%) of solid or multicystic ameloblastoma were occurred in maxilla. 13 cases (61.9%) of unicystic ameloblastoma were observed as unilocular, and 8 cases (38.1%) as lobulated. 5 cases (14.3%) of solid or multicystic ameloblastoma were observed as unilocular, 13 cases (37.1%) as lobulated, and 17 cases (48.6%) as multilocular. In the results from the measurements after correction of the buccolingual widths and heights to the mesiodistal lengths, there is a statistically significant difference between unicystic ameloblastoma and solid or multicystic ameloblastoma in ANCOVA test (p 0.05). CONCLUSION: Characteristic differences between unicystic ameloblastoma and solid or multicystic ameloblastoma is that there is higher prevalence of solid or multicystic ameloblastoma that have lobulated or multilocular patterns. To measure the Hounsfield units in the lesion is helpful, but it is not a differential diagnostic point between unicystic ameloblastoma and solid or multicystic ameloblastoma.

Bony change of apical lesion healing process using fractal analysis / 대한구강악안면방사선학회지

PURPOSE: To investigate the change of bone healing process after endodontic treatment of the tooth with an apical lesion by fractal analysis. MATERIALS AND METHODS: Radiographic images of 35 teeth from 33 patients taken on first diagnosis, 6 months, and 1 year after endodontic treatment were selected. Radiographic images were taken by JUPITER Computerized Dental X-ray System (R). Fractal dimensions were calculated three times at each area by Scion Image PC (R) program. Rectangular region of interest (30 x 30) were selected at apical lesion and normal apex of each image. RESULTS: The fractal dimension at apical lesion of first diagnosis (L0) is 0.940+/-0.361 and that of normal area (N0) is 1.186+/-0.727 (p< 0.05). Fractal dimension at apical lesion of 6 months after endodontic treatment (L1) is 1.076+/-0.069 and that of normal area (N1) is 1.192+/-0.055 (p< 0.05). Fractal dimension at apical lesion of 1 year after endodontic treatment (L2) is 1.163+/-0.074 and that of normal area (N2) is 1.225+/-0.079 (p< 0.05). After endodontic treatment, the fractal dimensions at each apical lesions depending on time showed statistically significant difference. And there are statistically significant different between normal area and apical lesion on first diagnosis, 6 months after, 1 year after. But the differences were grow smaller as time flows. CONCLUSION: The evaluation of the prognosis after the endodontic treatment of the apical lesion was estimated by bone regeneration in apical region. Fractal analysis was attempted to overcome the limit of subjective reading, and as a result the change of the bone during the healing process was able to be detected objectively and quantitatively.

Three-dimensional image analysis of the skull using variable CT scanning protocols-effect of slice thickness on measurement in the three-dimensional CT images / 대한구강악안면방사선학회지

PURPOSE: To evaluate the quantitative accuracy of three-dimensional (3D) images by means of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. MATERIALS AND METHODS: An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0 TM (Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. RESULTS: 11 line items in Conventional 3 mm, 8 in Helical 3 mm, 11 in Conventional 5 mm, 10 in Helical 5 mm, 5 in Conventional 7 mm and 9 in Helical 7 mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2 mm in 19 line items of Conventional 3 mm, 20 of Helical 3 mm, 15 of Conventional 5 mm, 18 of Helical 5 mm, 11 of Conventional 7 mm and 16 of Helical 7 mm. CONCLUSION: Considering image quality and patient's exposure time, scanning protocol of Helical 5 mm is recommended for 3D image analysis of the skull in CT.

Current status and installation standard of dental PACS / 대한구강악안면방사선학회지

PURPOSE: Picture Archiving and Communication System (PACS) is difficult to implement in the best of situations, but evidence is growing that the benefits are significant. The aims of this study are to analyze the current status of full PACS and establish successful installation standard of dental PACS. MATERIALS AND METHODS: Materials and methods were based on the investigation of current working status and installation standard of PACS, and observation of variable issues to installation of dental PACS. RESULTS: By September 30, 2004, full PACS implementations in their facilities were 88.1% in specialized general hospitals (37 installations out of total 42 hospitals), 59.8% in general hospitals (144 installations out of total 241 hospitals), 12.3% in medical hospitals (116 installations out of total 941 hospitals) and 3.6% in dental hospitals (4 installations out of total 110 hospitals) Only 4 university dental hospitals currently have installed and are operating full PACS. Major obstacle to wide spread of dental PACS is initial high investments. CONCLUSIONS: Clinical environments of dental PACS differed from medical situation. Because of characteristic dental practice, the initial investments for dental PACS are generally much greater than those of medical PACS. Also new economic crisis makes users scruple. The best way to overcome these limitations is to establish an economic installation standard for dental PACS. Also the clear technical communication between the customer and the supplier before both sides are committed to the obstacles are critical to its success.

Clinicoradiologic Differential Diagnosis of Odontogenic Keratocyst and Ameloblastoma / 대한구강악안면방사선학회지

PURPOSE: To clarify the clinical and radiologic parameters that can be used to differentiate odontogenic keratocyst and ameloblastoma MATERIALS AND METHODS: The records of 46 patients of ameloblstoma and 48 patients of odontogenic keratocyst at the Yonsei University Dental Hospital during the period of 1979 to 1995 were retrospestively reviewed. As a possible means for differentiating between the odontogenic keratocyst and ameloblastoma, the clinical parameters and the radiologic parameters were evaluated. RESULTS: In the clinical parameters, there was no significant defference in age, sex, and sign and symptoms(p>0.05).In the radiologic parameters, there was significant difference in site, shape of the lesion, and external root resorption of adjacent teeth(p<0.05). CONCLUSION: The site, shape of the lesion, and external root resorption of adjacent teeth can be the parameters to differentiate odontogenic keratocyst and ameloblastoma, but a definite differentiation of these two lesions needs a more specialized imaging modality.

Age-dependent difference in the computed tomography numbers of the normal parotid gland of Koreans / 대한구강악안면방사선학회지

PURPOSE: To determine normal CT number range of parotid gland by analyzing the change by age increase and the difference among individuals and between both sexes in CT number of normal parotid gland. MATERIALS AND METHODS: 134 subjects who took the CT scan between the period of Jan. 1996 and Dec. 1997 at Yonsei University, Dental Hospital were selected. Criteria for selection were that the patients must be within the normal range clinically and radiologically, and the entire parotid gland on the axial view must be shown. Among the axial views, the one showing the greatest parotid gland size was selected and its CT number was recorded. Also, CT numbers from both masseter muscle were recorded as its control. RESULTS: There was statistically significant correlation between CT number of right and left of parotid glands and masseter muscles. With the increase of age, there is a significant decrease in the CT number of parotid gland (p0.05). CONCLUSION: As age increases, CT number of parotid gland has a tendency to decrease, and there is no significant difference in the CT numbers between left and right parotid gland. Therefore in the CT scan of patients suspected of having an salivary gland disease of the parotid gland, to consider normal range of the age-dependent CT numbers of parotid gland and compare the CT numbers of the right and left parotid gland might be useful in diagnosing the disease.