PURPOSE: To observe direct effect of irradiation on cariogenic Streptooccus mutans. MATERIALS AND METHODS: S. mutans GS5 was exposed to irradiation with a single absorbed dose of 10, 20, 30, and 40 Gy. Viability and changes in antibiotic sensitivity, morphology, transcription of virulence factors, and protein profile of bacterium after irradiation were examined by pour plate, disc diffusion method, transmission electron microscopy, RT-PCR, and SDS-PAGE, respectively. RESULTS: After irradiation with 10 and 20 Gy, viability of S. mutans was reduced. Further increase in irradiation dose, however, did not affect the viability of the remaining cells of S. mutans. Irradiated S. mutans was found to have become sensitive to antibiotics. In particular, the bacterium irradiated with 40 Gy increased its susceptibility to cefotaxime, penicillin, and tetracycline. Under the transmission electron microscope, number of morphologically abnormal cells was increased as the irradiation dose was increased. S. mutans irradiated with 10 Gy revealed a change in the cell wall and cell membrane. As irradiation dose was increased, a higher number of cells showed thickened cell wall and cell membrane and lysis, and appearance of ghost cells was noticeable. In RT-PCR, no difference was detected in expression of gtfB and spaP between cells with and without irradiation of 40 Gy. In SDSPAGE, proteins with higher molecular masses were gradually diminished as irradiation dose was increased. CONCLUSION: These results suggest that irradiation affects the cell integrity of S. mutans, as observed by SDSPAGE, and as manifested by the change in cell morphology, antibiotic sensitivity, and eventually viability of the bacterium.
Anti-Bacterial Agents ; Cefotaxime ; Cell Membrane ; Cell Wall ; Dental Caries ; Diffusion ; Electrophoresis, Polyacrylamide Gel ; Microscopy, Electron, Transmission ; Penicillins ; Radiotherapy ; Streptococcus mutans* ; Streptococcus* ; Tetracycline ; Virulence Factors ; Xerostomia

PURPOSE: The research was done to investigate the effectiveness of 2D bony morphometry and microstructure of micro-computed tomography (micro-CT) on the osteoporotic bony change. We performed the bone morphometric analysis of proximal femur in ovariectomized rabbits with BMD and micro-CT examination. MATERIALS AND METHODS: Twenty-one female (Newzealand, about 16 weeks old, 2.9-3.4 kg) rabbits were used. Three rabbits were sacrificed on the day when experiment began (Baseline). The remaining 18 rabbits were divided into two groups. One group was ovariectomized bilaterally (OVX) and the other animals were subjected to sham operation (Sham). Bone specimens were obtained from the right and left femur of sacrificed rabbits. At intervals of 1, 2, 3, 5, 6 months respectively, BMD tests were performed on the proximal femur by using PIXImus 2 (GE Lunar Co. USA), 2-dimensional bone morphometric analysis by custome computer program and 2D / 3D bone structure analysis by micro-CT (Skyscan1072, Antwerpen, Belgium). Statistical analysis was carried out for the correlation between bone morphometry , micro-CT and BMD RESULTS: BV/TV, Tb.Th, Tb.N of micro-CT parameters showed higher values in sham group than OVX group. N.Nd/Ar.RI, N.NdNd, N.NdTm, N. TmTm, PmB/Ar.RI, 3-D BoxSlope of 2D morphometric parameters showed higher values in Sham group than OVX group.The micro-CT parameters of Tb.Sp, Tb.N were statistically significant correlated with BMD respectively. Several 2D morphometric parameters were statistically significant correlated with BMD respectively. CONCLUSION: Several parameters of 2D bony morphometry and micro-CT showed effective aspects on the osteoporotic bony change.
Animals ; Bone Density ; Female ; Femur ; Humans ; Ovariectomy ; Rabbits

PURPOSE: To examine whether the maxillofacial skeletal morphology correlates with the condylar position and the anatomic characteristics of articular eminence using measurements of lateral cephalometric radiographs and individualized sagittal temporomandibular joint (TMJ) tomographs. MATERIALS AND METHODS: I compared measurements of 202 TMJs of 101 orthodontic patients of Kangnung National University Dental Hospital. I used Pearson's correlation for comparison of the measuring values in lateral cephalometric radiographs and individualized sagittal TMJ tomographs. RESULTS: Large occlusal plane angle tendency showed decreased width of posterior eminence slope, decreased depth of articular fossa and decreased posterior slope angle of eminence. Large mandibular plane angle tendency showed decreased superior joint space, decreased depth of articular fossa and decreased posterior slope angle of eminence. Large gonial angle tendency showed decreased depth of articular fossa, decreased posterior slope angle of eminence and anterior position of condylar head. Large anterior facial height and large posterior facial height tendency showed increased width of posterior slope of eminence, increased depth of articular fossa, increased posterior slope angle of eminence and posterior position of condylar head. CONCLUSION: Maxillofacial skeletal morphology has correlation with the anatomic characteristics of TMJ. Individualized sagittal TMJ tomographs can provide useful information for anatomical analysis of TMJ.
Dental Occlusion ; Head ; Humans ; Joints ; Temporomandibular Joint*

PURPOSE: Disc and condylar position were observed on MRIs of temporomandibular joint disorder patients and condylar position agreement between MRI and tranascranal radiography was evaluated. MATERIALS AND METHODS: MRI and transcranial radiographs of both TM joints from 67 patients with temporomandibular disorder were used. On MRI, the position and shape of disc and condylar position as anterior, middle, posterior was evaluated at medial, center, and lateral views. On transcranial radiographs, condylar position was evaluated using the shortest distance from condyle to fossa in anterior, superior, and posterior directions. RESULTS: 1. On MRI, 96 joints (71.6%) of 134 had anterior disc dispalcement with reduction and 38 joints (28.4%) without reduction. 2. Fourteen (14.6%) of 96 reducible joints showed anterior condylar position, 19 (19.8%) showed central position, 63 joints (65.6%) showed posterior position. Two joints (5.3%) of 38 non-reducible joints showed anterior condylar position, while 9 (23.7%) showed central position, and 27 (71.1%)-posterior position. 3. In 85 joints (63.4%) of 134, the transcranial condylar position agreed with that of the central MRI view, 10 joints (7.5%) with that of medial, 16 joints (11.9%) with that of lateral, and 23 joints (17.2%) disagreed with that of MRI. CONCLUSION: On MRI, most of the reducible and non-reducible joints showed posterior condylar position. Transcranial radiographs taken with machine designed for TMJ had better agreement of condylar position with that of MRI. Extremely narrow joint spaces or very posterior condylar positons observed on transcranial radiographs had a little more than fifty percent agreement with those of MRIs.
Humans ; Joints ; Magnetic Resonance Imaging ; Mandibular Condyle ; Radiography ; Temporomandibular Joint Disorders* ; Temporomandibular Joint*

PURPOSE: To determine the more valuable information to detect the mandibular canal and the mental foramen in panoramic radiographs of a selected Korean population for the implant. MATERIALS AND METHODS: This study analysed 288 panoramic radiographic images of patients taken at the Dental hospital of Chosun University retrospectively. Indirect digital panoramic X-ray machine (ProlineXC, PLANMECA, Finland) with processing by using Directview CR950@ (Kodak, U.S.A.) and Direct digital panoramic X-ray machine (Promax, PLANMECA, Finland) were used for all exposures. All images were converted into Dicom format. RESULTS: The common position of the mental foramen was in line with the longitudinal axis of the second premolar (68.1%). The mental foramen was symmetrical in 81.8% of cases. The mandibular canal was not identified at anterior portion and discontinued with the mental foramen in 27.8% of all cases, in 42.4% identified with lower border line continued with the mental foramen, in 14.6% with both upper and lower border lines, and in 15.3% unilaterally identified with lower border line. CONCLUSION: Clinicians can estimate the upper border line of the mandibular canal from the confirmation of the mental foramen and the lower border line of the mandibular canal symmetrically on the panoramic radiography taken in adjusted midsaggital plane of patient's head.
Axis, Cervical Vertebra ; Bicuspid ; Head ; Humans ; Mandible ; Mandibular Nerve ; Radiography, Dental, Digital ; Radiography, Panoramic ; Retrospective Studies

Fibro-osseous lesions are composed of connective tissue and varying amount of mineralized substances, which may be bony or cementum-like structures. It is necessary for oral radiologist to differentiate due to the tendency of these fibro-osseous lesions to show similar histopathologic appearances, while the management of each lesion is different. However we often encounter a little difficulty in judgement because there are some overlaps between concept of each lesions. So recently I suggest, we face a need to review basic concept and classification of several fibro-osseous jaw lesions. In this article, several fibro-osseous lesions, such as fibrous dysplasia, cemento-ossifying fibroma and cemento-osseous dysplasia, will be discussed basing on the review of literature. Particular emphasis will be made on the nomenclature revision of WHO's classification in 1992.
Classification ; Connective Tissue ; Dental Cementum ; Fibroma ; Jaw

PURPOSE: The present study was performed to determine the optimum conditions(RPM, load, sharpness of drill) for drilling human cortical bone with standard drill, and to evaluate the histological changes occuring in bone after drilling. MATERIALS AND METHODS: in experiment I, we measured temperature elevations and the durations of temperature elevation in cadaveric femoral cortices at specific distances from the drill hole wall while drilling. The effects of drilling force, speed and new versus worn drill on the termperature were determined. In experiment II, we also measured temperature elevations in the same manner in porcine femoral cortices and evaluated the histological changes occuring in bone after drilling. RESULTS: In experiment I, the most significant temperature elevation(68.4degrees C ) was found when worn drill was used. The lower drilling force and faster speed resulted in 55.1degrees C and 45.8degrees C temperature elevation, respectively. However, drill diameter was not a significant factor for temperature elevation. In experiment II, greater heat production was measured with worn drill, at lower drilling forces, at faster drill speed. The acute histologic reactions in bone were hyperemia, degeneration of osteocytes, change in bone stainability, tears, and fragmentation of the bone edges around the drill holes. The observed histological changes were proportional to the amount of trauma produced, that is, the greater the degree of thermal irritation, the greater the degree of histologic activity. CONCLUSION: In cortical drilling, greater heat production was measured with worn drill, at lower drilling forces, at faster drill speed and the greater the degree of thermal irritation, the greater the degree of histologic activity. A further study of the reaction of bone to drilling at longer intervals of time at different conditions may possibly show whether aseptic thermal necrosis could be prevented.
Cadaver ; Hot Temperature* ; Humans ; Hyperemia ; Necrosis* ; Osteocytes ; Thermogenesis*

We intended to evaluate the Young's modulus of trabecular bone and apparent density from Computed Tomography(CT) and Spherical Indentation test and to quantify relation ship between them. The distal femurs(31 age, male, left and right) were prepared for exprimentatin and were embedded with repect to anatomical orientation. Then the specimens were scnned at 1 mm intervals on GE9800 CT scanner and the Hounsfield Units(HU, or CT number) were extracted from each CT image. After scanning, the bones were sectioned with diamond saw, producing 8 mm cubes of trabecular bone(72 eachs) from the metaphyseal region of both distal femur. The cubes were mechanically tested in inferior-superior(IS), anteriorposterior(AP), and medial-lateral(ML) direction with custom-made device, Spherical Indentatin Tester. After testing, the real apparent density of specimens were measured. The results of this study showed that the IS modulus was singificantly greater than both the AP and ML modulus and the AP modulus was also greater than ML modulus significantly(p<0.01). A linear relation ship between HU and real apparent density was found to be significant(R2=0.68) and significant power relationship between the apparent density and the tangent moduli(either by CT or physical measures) was also found.
Diamond ; Elastic Modulus* ; Femur ; Humans* ; Male ; Ships

Allografts or autografts of bone-tendon unit have been used for ligament injuries or deficiencies after limb salvage operation for malignant bone tumors around joints. While the remodeling process of the ligament or tendon of the allograftor autograft and the microscopic and biomechanical changes of tendon-bone graft interface have been widely investigated, little is known about the ultrastructural and biochemical changes of the transitionall zone in tendon-bone junction. This study was performed to analyzed the ultrastructural and biochemical changes of the transitional zone after tendon-bone auto-and allo-grafting. A total of twenty four rabbits were divided into two group. In 12 animals(allograft group), two Achilles ten-don-bone unit per each animal were taken and transplanted to another rabbit after preservation below -70degrees C for 2 weeks. In the other 12 animals(autograft group), the Achilles tendon-bone unit was harvested from one side and transplanted to the other side of the rabbit. After operation, their legs were immobilized with short leg cast for 4 weeks, and then mobilized freely. Four animals in each group were sacrificed at four, eight and sixteen-weeks after the transplantation, and their grafted Achilles tendon-bone interfaces were used for analysis of the ultrasturctural and biochemical changes. The following results were obtained. 1. Histologically new cartilage cells were observed at postoperative 16 weeks with local presence of faint tidemark in the autograft group but not in the allograft group. Complete remodeling of the transitional zone had not observed histologically in both groups. 2. Ultrasturctural analysis revealed no definite differences between both groups. However, the slightly rapid appearance of parallelism and cross-striation of microfibrils in the autograft group and time-related restoration of fibers and fibroblasts were observed. 3. From biochemical analysis, type I collagen concentratin was increased, and an early rapid increase of type III collagen and glycosaminoglycan were also observed. In conclusion, these data suggested that type III collagen and glycosaminoglycan are important in stabilization of grafted tendon-bone unit, especially in the transitional zone. The histological and biochemical changes in allograft group were relatively similar to that of autograft group although the allograft group showed the delayed pattern of remodeling. Therefore, the tendon- allograft could be used as a good substitute for the autograft for tendon or ligament reconstruction when no suitable autograft is available.
Allografts ; Animals ; Autografts ; Cartilage ; Collagen Type I ; Collagen Type III ; Fibroblasts ; Joints ; Leg ; Ligaments ; Limb Salvage ; Microfibrils ; Rabbits* ; Tendons ; Transplants*

Platelet-derived growth factor(PDGF) is known to accelerate soft tissue fracture and periodontal bone healing, but little information is available for characterizing the healing of articualr cartilage. This study was designed to demonstrate the regeneration potential of pasteurized autogeneous osteochondral graft when PDFG was applied locally in vivo. Eighteen rabbits in two groups were used in the experiment. The free osteochondral fragment(1x1x1 cm) were taken from distal femur. The fragment were pasteurized in 65degrees C for 5 minutes. In experimental group(group II), the fragment were soaked in 0.25 mg/ml of recombinant human PDGF mixed 5 ml normal saline and reimplanted to the resected site, and followed with local administration of 0.25 mg/ml PDGF to knee joint. In control group(group I), the pasteurized fragment were reimplanted in the resected site without any treatments. The histologic characteristics of the transplanted autografts for three rabbits in each group were observed at 3, 5 and 7 weeks postoperatively. The results were as follows; Group II revealed the more favorable regeneration of articular cartilage, less arthritic changes and more mature arrangement of chondrocytes than group I. Even thought the cartilage is avascular and the regeneration capacity of pasteurized cartilage is severely limited, the regeneration of grafted articular cartilage is thought to be accellerated by increased newly formed blood vessels and soft tissues due to the diffusion of PDGF on grafted cartilage, and probably also by differentiation of mesenchymal cells in the initial stage of experiment. The results of this study suggest that local administration of PDGF could be used for the treatment of posttraumatic or degenerative arthritis and various cartilage damages.
Autografts ; Blood Vessels ; Cartilage ; Cartilage, Articular ; Chondrocytes ; Diffusion ; Femur ; Humans ; Knee Joint ; Osteoarthritis ; Platelet-Derived Growth Factor* ; Rabbits* ; Regeneration* ; Transplants*