This study investigated the effect of intermittent polymerization on the rate of polymerization shrinkage and cuspal deflection in composite resins. The linear polymerization shrinkage of each composite was measured using the custom-made linometer along with the light shutter specially devised to block the light at the previously determined interval. Samples were divided into 4 groups by light curing method; Group 1) continuous light (60s with light on); Group 2) intermittent light (cycles of 3s with 2s light on & 1s with light off for 90s); Group 3) intermittent light (cycles of 2s with 1s light on & 1s with light off for 120s); Group 4) intermittent light (cycles of 3s with 1s light on & 2s with light off for 180s). The amount of linear polymerization shrinkage was measured and its maximum rate (Rmax) and peak time (PT) in the first 15 seconds were calculated. For the measurement of cuspal deflection of teeth, MOD cavities were prepared in 10 extracted maxillary premolars. Reduction in the intercuspal distance was measured by the custom-made cuspal deflection measuring machine. ANOVA analysis was used for the comparison of the light curing groups and t-test was used to determine significant difference between the composite resins. Pyramid showed the greater amount of polymerization shrinkage than Heliomolar (p < 0.05). There was no significant difference in the linear polymerization shrinkage among the groups. The Rmax was group 4 < 3, 2 < 1 in Heliomolar and group 3 < 4 < 2, 1 in Pyramid (p < 0.05). Pyramid demonstrated greater cuspal deflection than Heliomolar. The cuspal deflection in Heliomolar was group 4 < 3 < 2, 1 and group 4, 3 < 2, 1 in Pyramid (p < 0.05). It was concluded that the reduced rate of polymerization shrinkage by intermittent polymerization can help to decrease the cuspal deflection.
Acrylic Resins ; Bicuspid ; Composite Resins ; Light ; Polymerization ; Polymers ; Polyurethanes ; Tooth

PURPOSE: The study aimed to determine the personality types of the graduate students in Seoul National University School of Dentistry (SNU SD) and analyze the specific personal types that were linked to their performance in problem-based learning (PBL). METHODS: A total of 263 graduate students in SNU SD from 2011 to 2013, participated in PBL and completed the Myers-Briggs Type Indicator (MBTI) GS form, which was analyzed statistically to determine whether their MBTI personality types were independent of their PBL performance. In particular, MBTI types were regressed on evaluation subcategories, including tutor evaluation and oral test. RESULTS: ESTJ (20.9%) and ISTJ (18.6%) were the most common MBTI personality types in dental graduate students. Compared with males, female students performed significantly better on the PBL. Judging was the most notable type in PBL performance, with its J-P index being statistically significant. CONCLUSION: PBL is implemented, based on the perspective of student-centered education. Accordingly, the types of personality that usually matriculate in dental school should be monitored, and a student-centered approach to dental education should be adopted.
Dentistry ; Education ; Education, Dental ; Female ; Humans ; Male ; Personality Inventory ; Problem-Based Learning* ; Schools, Dental ; Seoul

We report a case of a 50 year-old woman with hepatocellular carcinoma which developed in primary biliary cirrhosis. During follow-up primary biliary cirrhosis, elevation of alpha-fetoprotein was noted. CT and hepatic arteriogram revealed a hypervascular nodule of approkimately 1.5 cm in size in the right posterior inferior segment of liver. Transcatheter hepatic artery chemoembolization was performed. To the author,s knowledge, this is the first case of hepatocellular carcinoma developed in a patient with primary biliary cirrhosis in Korea.
alpha-Fetoproteins ; Carcinoma, Hepatocellular* ; Female ; Follow-Up Studies ; Hepatic Artery ; Humans ; Korea ; Liver ; Liver Cirrhosis, Biliary* ; Middle Aged

The anatomical description and the relationship between the root apex and the inferior wall of sinus are critical in diagnoses and surgeries of the sinus pathoses, and in dental implantation. So, identification of the proximity between the root apex and the inferior wall of sinus and the clarification of cortical thickness of inferior wall of sinus are indicated the topography of spreading dental infection into the maxillary sinus. Therefore, anatomical knowledge of the topography between the root apex and the inferior wall maxillary sinus are important in the diagnosis and treatment planning of the dental implantation, endodontic procedures, and orthodontic treatment. The purposes of this study were to clarify the morphological and clinical characteristics of the maxillary sinus, especially the inferior wall of sinus in Korean, and to identify the relationship between the inferior wall of maxillary sinus and the roots of maxillary teeth. 24 sides of maxillae of the hemi -sectioned Korean heads were used in this study. All specimens were taken DentaScan reformatted cross -sectional images were taken for the radiographic evaluation of the maxillary teeth and inferior wall of maxillary sinus. All specimens were decalcificated and thenp were sectioned coronally. On the sectioned specimen, 21 metric items were measured using the image analyzing system. The results were as follows: 1. The distance between the each root apex and the inferior wall of maxillary sinus were measured. In the 2nd molar area the distance from the root apex to the inferior wall of sinus was the shortest and the longest in the 1st premolar area. 2. The thickness of the cortical plate of the inferior wall of maxillary sinus was thinnest in the 1st premolar area, whereas, the thickest in the 2nd premolar area. 3. The vertical relationship between the inferior wall and the roots of the maxillary molars was classified into 5 types. Type I (the inferior wall of sinus was located above the level connecting the buccal and lingual root apices) was predominant (54.5% in the 1st molar area, 52.4% in the 2nd molar area). 4. The horizontal relationship between the inferior wall of sinus and root apex were classified into 3 types. Type 2 (the alveolar recess of the inferior wall of sinus was located between the buccal and lingual roots) was predominant (80% in the 1st and 2nd molar area). Taken all together, this study demonstrated various anatomical characteristics and relationships between the maxillary sinus and their surrounding structures. Recognition of these findings may have an impact on the clinical management of patients.
Asian Continental Ancestry Group ; Bicuspid ; Dental Implantation ; Dental Implants ; Diagnosis ; Head ; Humans ; Maxilla ; Maxillary Sinus* ; Molar ; Tooth

The anatomical description and the relationship between the root apex and the inferior wall of sinus are critical in diagnoses and surgeries of the sinus pathoses, and in dental implantation. So, identification of the proximity between the root apex and the inferior wall of sinus and the clarification of cortical thickness of inferior wall of sinus are indicated the topography of spreading dental infection into the maxillary sinus. Therefore, anatomical knowledge of the topography between the root apex and the inferior wall maxillary sinus are important in the diagnosis and treatment planning of the dental implantation, endodontic procedures, and orthodontic treatment. The purposes of this study were 1) to clarify the morphological and clinical characteristics of the maxillary sinus, especially the inferior wall of sinus in Korean, 2) to identify the relationship between the inferior wall of maxillary sinus and the roots of maxillary teeth, and 3) to evaluate the degree of accuracy of DentaScan reformatted images of the maxillary sinus. 33 sides of maxillae of the hemi -sectioned Korean heads were used in this study. All specimens were taken periapical radiographs, computed tomography and DentaScan reformatted cross -sectional images were taken for the radiographic evaluation of the maxillary teeth and inferior wall of maxillary sinus. From the CT images, 3 -dimentional reconstructive images of maxillary sinuses were made using the V -works TM 3.0 program. All specimens were decalcificated and then were sectioned coronally. On the sectioned specimen, 21 metric items were measured using the image analyzing system. The results were as follows: 1. In 6 categories of maxillary sinus according to their lateral aspects and shapes of the inferior walls, flat (54.5%) and round (21.2%) inferior wall of maxillary sinus were prominent. In 58.4%, the anterior limit of maxillary sinus was located in the 1st premolar area and the posterior limit was in the 3rd molar and maxillary tuberosity area (93.9%). The lowest level of the maxillary sinus was in the 1st molar and 2nd molar area. 2. From the 3 -dimentional reconstructive images of maxillary sinus, the maximum anteroposterior length of sinus was 39.3 +/-4.2 mm, the maximum height was 37.1 +/-5.6 mm, and the maximum width was 32.6 +/-6.5 mm. And the average volume of sinus was 15.1 +/-6.2 ml. All measurements were larger in male than female. Taken all together, this study demonstrated various anatomical characteristics and relationships between the maxillary sinus and their surrounding structures. Recognition of these findings may have an impact on the clinical management of patients.
Asian Continental Ancestry Group ; Bicuspid ; Dental Implantation ; Dental Implants ; Diagnosis ; Female ; Head ; Humans ; Male ; Maxilla ; Maxillary Sinus* ; Molar ; Tooth

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.
Cone-Beam Computed Tomography ; Dental Implants ; Gutta-Percha ; Humans ; Mandible ; Microcomputers

BACKGROUND: A Stellate ganglion block (SGB) is a sympathetic nerve block method which has been used most frequently in pain clinics due to its wide range of indications. However, SGB leads to regional sympathetic denervation of the heart and to changes in the hemodynamics. The aim of this study was to compare hemodynamic effects as well as echocardiographic changes after a left SGB (LSGB). METHODS: Fourteen healthy male volunteers were studied. The LSGB was performed with 1% mepicacaine 6 ml. Arterial blood pressure, electrocardiographic and echocardiographic variables were measured before the LSGB, 15 and 30 minutes after the LSGB. RESULTS: Arterial blood pressure, ejection fraction and transmitral inflow velocity variables showed no significant changes compared to pre-LSGB values. P-P interval increased significantly 15 minutes after the LSGB, and the Q-T interval increased significantly 30 minutes after the LSGB. The diastolic pulmonary venous flow velocity decreased significantly 15 minutes after the LSGB. CONCLUSIONS: These results showed that a LSGB decreased the heart rate without detrimental changes of left ventricular relaxation in healthy male volunteers.
Arterial Pressure ; Autonomic Nerve Block ; Echocardiography ; Electrocardiography ; Heart ; Heart Rate ; Hemodynamics ; Humans ; Male ; Pain Clinics ; Relaxation ; Stellate Ganglion* ; Sympathectomy ; Ventricular Function, Left* ; Volunteers

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.
Anthropology ; Cadaver ; Forensic Sciences ; Imaging, Three-Dimensional ; Microcomputers ; Tomography, Spiral Computed ; Tomography, X-Ray Computed

Blastocystis is a genus of unicellular heterokont parasites belonging to a group of organisms known as Stramenopiles, which includes algae, diatoms, and water molds. Blastocystis includes several species that habitat in the gastrointestinal tracts of organisms as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches. It is important to public health and distributed globally, but its prevalence in dogs in Korea has not been reported to date. Here, we collected 787 canine fecal samples and assessed Blastocystis infection by age, sex, region, season, and diarrhea symptoms. We determined Blastocystis subtypes using phylogenetic analyses based on 18S rRNA gene sequences. We identified, 10 Blastocystis positive samples (1.3%). A higher proportion of infected dogs was asymptomatic; however, infection rates did not significantly differ according to region, age, sex, and season. Phylogenetic analysis showed that the Blastocystis sp. identified belonged to 4 subtypes (STs), ST1, ST5, ST10, and ST14, thus revealed the genetic diversity of Blastocystis sp. in dogs Korean. This is first report on the presence of Blastocystis sp. in dogs Korean. This study revealed a lower infection rate than expected and differed from previous studies in STs. Further studies are warranted to observe the national infection status of Blastocystis in dogs and the genetic characteristics of this genus.

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.
Cadaver ; Imaging, Three-Dimensional ; Microcomputers ; Tomography, Spiral Computed ; Tomography, X-Ray Computed