• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2381-2386
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• 2000

Surface replication is playing an important role in the assessment of creep damage and remaining life of high temperature components. As the replication procedures, however, have not been standardized in domestic industry, its standardization is proposed in this study. For this purpose, the 2.25Cr-IMo steel was heat treated(5 min at 1,300 0C and oil quenched) to produce a simulated HAZ microstructure, and crept in air at 575 0C and under 120 MPa to produce artificial cavities. Then, the effect of surface preparation procedures on the quality of replicas was investigated using this sample. As a result, it was demonstrated that the presence of cavities may be observed readily or missed depending on the surface preparation procedures followed. Therefore it is essential to repeat three polishing/etching cycles at least in order to reveal cavitation damage accurately, even though it may be tedious or time-consuming.

• The magazine of the Korean Society for Advanced Composite Structures
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• v.5 no.2
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• pp.19-25
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• 2014

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.90-91
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• 1997

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.21-21
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• 2002

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.156-156
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• 2006

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.141-141
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• 2005

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.144-145
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• 1998

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.10a
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• pp.33-34
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• 2006

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.444-450
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• 2014

PURPOSE. To compare the accuracy of marginal and internal adaptation of zirconia (Zr) copings fabricated on anatomic (A), semi-anatomic (SA) and non-anatomic (NA) occlusal surface preparations. MATERIALS AND METHODS. 45 extracted bicuspid teeth were prepared for receiving zirconia crowns, with different occlusal preparation designs A=15, SA=15 & NA=15. The Zr copings were fabricated by using CAD4DENT, CAD/CAM. The copings were adjusted, cemented and were cross sectioned centrally from buccal cusp tip to lingual cusp tip into mesial and distal halves. The copings were examined under electron microscope at ${\times}200$ magnification and the measurements were recorded at 9 predetermined areas in micrometers. RESULTS. Overall mean gap values for the three groups was found to be $155.93{\pm}33.98{\mu}m$ with Anatomical Occlusal preparation design having the least gap value of $139.23{\pm}30.85{\mu}m$ showing the best adaptation among the groups. Post Hoc Tukey's test showed a statistically significant difference (P=.007) between the means of gap for A & NA preparation designs. Measurements recorded at 9 predetermined points showed variations for the three groups. CONCLUSION. Anatomical occlusal preparation designs resulted in better marginal and internal adaptation of Zr copings. There is a considerable variation between the measured marginal and internal gap values for the Zr copings fabricated by the (CAD4DENT-CAD/CAM). This variation may be associated with the lack of standardization of the preparation of teeth, computerized designing of the coping for each tooth, cement used, uniform pressure application during the cementation of the copings, sectioning of the copings and the microscopic measurements.

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.197-204
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• 1993

This study was conducted to evaluate and compare the apical leakage in the following retrofilling techniques after apical resection; No apical cavity preparation and no retrofilling(control group), Amalgam(group I) or silver glass ionomer cement(group II) retrofilling after apical cavity preparation with mini contra-angle and bur, Amalgam(group III) or silver glass ionomer cement(group N) retrofilling after apical cavity preparation with ultrasonic micro endo tip. Extracted ninety upper anterior and lower canine teeth were fixed in skull simulators and root canals were prepared with step-back method and obturated with gutta-percha and zinc oxide eugenol sealer. Obturated roots were resected 2mm from apical ends and apical cavities of 1mm width and 2mm depth were prepared and retrofilled by above mentioned methods. After application of nail varnish on all surface except resected surface, apical 1/3 of the roots were placed in 1% methylene blue solution for 3 days. After longutudinal sectioning to expose central parts of filled materials, depths of penetrated dye were measured by measuring microscope and were analyzed statistically. The results were as follows. 1. Having no relation with instruments used in apical cavity preparation, amalgam retrofilling groups(group I and II) showed less apical leakage which was not significant statistically than no retrofilling group(control group) (P<0.05), but silver glass ionomer cement retrofilling gruoups(group II and IV) showed significantly less apical leakage than no retrofilling group(control group) (P<0.01). 2. In the groups retrofilled with the same material, the apical leakage in cavities prepared with ultrasonic micro endo tip (group III and IV) was less than that in cavities prepared with mini contra-angle and bur(group I and II), but not significant statistically(P>0.05). 3. When apical cavities were prepared with same instrument. the egroups retrofilled with silver glass ionomer cement(group II and IV) showed significantly less apical leakage than the groups retrofilled with amalgam(group I and III)(<0.01).