• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.1
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• pp.58-65
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• 2012

The crown-root fracture is defined as a fracture of tooth that contains enamel, dentin and cementum with or without pulp exposure. Generally the fracture lines place obliquely from labial surface, between incisal edge of the crown and marginal gingiva, to palatal surface subgingivally. If the fracture line is located supragingivally, the removal of tooth fragment and supragingival restoration can be performed. In subgingival fracture line, the surgical exposure, orthodontic eruption or surgical eruption can be considered. If the fracture line is too deep to restorate, extraction or decoronation can be selected. In children and adolescents, the extraction should be the last option. Another option to select before extraction is the restoration using fiber-reinforced post and the reattachment of tooth fragment. The fiber-rainforced post enhances the retention and the durability of tooth fragment. The reattachment of crown fragment using resin adhesive system is considered minimal invasive treatment biologically. This case reports the treatment of crown-root fracture using the reattachment of crown fragment and the insertion of fiber-reinforced post.

• Journal of Welding and Joining
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• v.21 no.7
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• pp.4-8
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• 2003

• Journal of Welding and Joining
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• v.23 no.2
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• pp.3-5
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• 2005

• Journal of Welding and Joining
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• v.22 no.1
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• pp.10-13
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• 2004

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.297-309
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• 2010

The objective of the present study was to perform a fracture analysis on fractured implant fixture after use in vivo and make clear the cause & mechanisms of failure. In case of fatigue fracture, the fractured surface represents fatigue striation. Fatigue striation indicate the progression of the crack front under cyclic loading, are characteristic of stage 2 crack growth. The site of crack initiation and stage 1 crack growth were not easily identified in any of the failure, presumably because of the complex microstructural features of the polycrystalline sample. In case of fractured by overload, dimpled or cleavage surface were observed. Using the interpretation of characteristic markings(ratchet mark, fatigue striation, dimple, cleavage et al) in fracture surfaces, failure events containing the crack origin, crack propagation, material deficiency could be understand.

• Journal of the Korean Magnetics Society
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• v.20 no.2
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• pp.52-60
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• 2010

The changes of magnetic flux density distribution and the degree of magnetic anomaly on the ground surface by underground fracture zones and empty spaces had been investigated through the variations of the measuring heights. The magnetic flux density distributions were monitored for the ground surfaces of fracture zones, empty spaces and tunnels by fluxgate-type magnetometer. The fracture zones showed the magnetic anomaly with (+) and (-) peak-pairs in the magnetic flux distribution measured at 0.15 m height from the ground surface, and this anomaly disappeared at the height of 1.15 m. The underground empty spaces and tunnels showed the decrease of magnetic flux densities, where the degree of this density decrease diminished with the increase of the underground depth. And, the existence and size of underground empty spaces, such as tunnels and sink holes, could be monitored by the phenomena of this decreasing flux density.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.3
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• pp.219-237
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• 2003

he purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown, and 0.5mm width chamfer finish lines on the maxillary first premolar. 30 sound maxillary first premolars were selected and then storaged in 5% NaOCl and saline. 15 teeth were performed preparation for each group(1.0mm rounded shoulder, 0.5mm chamfer). After 30 stone dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the natural teeth. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co., Germany)was used to measure the fracture strength, with stress loading on the occlusal surface between buccal and lingual cusp. And also, three-dimensional finite element model was used to measure the stress distribution with two types of the finish lines(1.0mm rounded shoulder, 0.5mm chamfer) and two loading conditions(both buccal and lingual cusp inclination, lingual cusp inclination only). The result of the this study were as follows. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(842N) showed higher value than that of the chamfer(590N) (p<0.05). In the three dimensional finite element analysis of all ceramic crown, metal die and natural teeth model did not show any differences in stress distribution between finish lines. Generally, when force was loaded on the occlusal inclination of buccal and lingual cusp, the stress was concentrated on the loading point and the central groove of occlusal surface. When force was loaded only on the occlusal inclination of lingual cusp, the stress was concentrated on the lingual finish line and loading point.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.1
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• pp.43-48
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• 2023

The biocompatibility and durability of implant fixtures are major concerns for dentists and patients. Mechanical complications of the implant include abutment screw loosening, screw fracture, loss of implant prostheses, and implant fracture. This case report aims to describe management of a case of fixture damage that occurred after screw fracture in a tissue level, internal connection implant and microscopic evaluation of the fractured fixture. A trephine bur was used to remove the fixture, and the socket was grafted using allogeneic bone material. The failed implant was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), which revealed a fractured fixture with both normal and irregular bone patterns. The SEM and EDS results give an enlightenment of the failed fixture surface micromorphology with microfracture and contaminated chemical compositions. Noticeably, the significantly high level of gold (Au) on the implant surface and the trace amounts of Au and titanium (Ti) in the bone tissue were recorded, which might have resulted from instability and micro-movement of the implant-abutment connection over an extended period of time. Further study with larger number of patient and different types of implants is needed for further conclusion.

• Journal of Korean Foot and Ankle Society
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• v.8 no.1
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• pp.86-91
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• 2004

Purpose: To evaluate the methods and results of the surgical treatment in the trimalleolar fracture of the ankle. Materials and Methods: We analysed the results of the ankle trimalleolar fracture which were treated with open reduction and internal fixation from January 1999 till September 2003. There were 45 patients who had at least six months follow up, 16 men, and 29 women. We have analysed the mechanism of injury, methods of operation and postoperative complications. Results: The results were assessed on ankle AP, lateral and mortise X-rays and retrospective chart review. There were 30 supination-external rotation, 13 pronation-external rotation, 2 pronation-abduction in the mechanism of injury by Lauge-Hansen classification. Cases of the posterior malleolar fracture which involved more than 25% of the weight bearing surface were 7 (15.6%). Medial malleolar mono-fixation was done in 5 cases, fibular mono-fixation in 2 cases, bimalleolar fixation in 32 cases, trimalleolar fixation in 6 cases. 38 cases (84.4%) were good or excellent in clincal assessment and 39 cases (86.7%) were good or excellent in radiological assessment according to the criteria of the Meyer. There was no difference of results among the surgical treatment methods. Conclusion: The results of our study indicate that the rigid fixation with early ankle motion and weight bearing is needed in ankle trimalleolar fracture. But minimal fixation is not bad in slight displaced fracture. Both anterior approach and posterior approach were useful methods to stabilization the posterior malleolar fracture. And pre-operative evaluation to detect the hidden soft tissue injuries and fracture mechanism is very important to avoid the failure.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.296-307
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• 1997

The purpose of this study was to compare the fracture strength of the IPS-Empress ceramic crown according to margin types such as bevel, shoulder, rounded shoulder, shoulder with bevel, rounded shoulder with bevel and bevel with groove. After 10 metal dies were constructed for each group, the IPS-Empress ceramic crown were fabricated and each crown was cemented on each metal die with Bistite resin cement. The cemented crowns mounted in the testing jig were inclined 30 degree and universal testing machine (Zwick 1456 41, Zwick Co., Germany) was used to measure the fracture strength. The obtained results were as follows : 1. The fracture strength of the crown with rounded shoulder was the highest of all. The mean fracture strength was 484N in rounded shoulder, 357N in bevel, 341N in rounded shoulder with bevl, 300N in shoulder with bevel, 280N in shoulder and 275N in bevel with groove. 2. The fracture strength of rounded shoulder was statistically different from those of shoulder with bevel, shoulder and beve41 with groove. 3. In the strain at fracture, there was no significant difference among each group. 4. The fracture mode of the crown was similar and most of fracture line began at the loading area and extended through proximal surface perpendicularly to the margin, irrespective of margin type.