• 대한치과기공학회지
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• 제40권2호
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• pp.73-82
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• 2018

Purpose: The purpose of this study was to investigate the production environment of crown prosthesis for National Health Insurance(NHI) benefit. Methods: This study carried out self-administered questionnaire survey from September 1, 2016 to October 31 by having research subjects as 261 dental technician. Except 100 copies with incomplete response, 161 copies were used as the materials of final analysis. Results: Unlike gold crowns, the material cost of metal crowns was paid at the dental laboratory(86.3%). Total material consumption for making metal crown was more than gold crown(63.4%), especially for the finishing and polishing processes(78.3%). The subjects responded that a routine dental laboratory fee of crown prosthesis is unreasonable, and it is necessary to adjust and improve it(metal crown 96.2%, gold crown 96.9%). NHI coverage dental prosthesis was not marked on the order form(46.0%), and the dental laboratory fee of that was nor received(64.0%). Conclusion : It is necessary to estimate the NHI cost level of the crown prosthesis by reflecting the production environment and engineering process in dental laboratories. In addition, institutional arrangement should be backed up so that dental laboratories can receive appropriate dental laboratory fee.

• 대한치과기공학회지
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• 제39권2호
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• pp.93-99
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• 2017

Purpose: With the development of digital dental technology, we are manufacturing prosthetic crown in various ways. However, the wax-up method that makes existing prosthetic crown is also used steadily. Thus, we will compare the shape of the crown designed with wax-up and the crown designed with CAD. Methods: Sculpt the crown with wax-up on the model to 10 dental technicians. The same model was used to design the crown CAD. Measure the size of the sculpted crown. The shapes were compared in three dimensions. Results: As a result, we could observe a difference in size and shape in crown designed with wax - up crown and crown. Conclusion: These results suggest that there are differences according to the method of carving crown and the method of processing.

• 대한치과기공학회지
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• 제25권1호
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• pp.29-40
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• 2003

This study was aimed to verify a comparison by dental alloys upon the marginal fitness of dental prosthesis. Firstly, we waxed up on 45 epoxy resin dies, pressed the margin with hands, and identified the marginal fitness with microscope. And we made a single direct spruing system type of sprue by 3 dental alloys - metal crown alloys, PFM crown alloys, and gold crown alloys - each 15, total 45 waxing up, adjusting W/P ratio and invested the cast ring. Then, we made the dental prosthesis using the electric casting machine. In these processes we followed the manufacturer's instructions, in order to maintain the other conditions from the inner and outer, which included investment and burning out. After we tried on the dental prosthesis on epoxy resin dies, we have got the means of marginal gap at 9 points with same distances, around the cervical line which was checked already, using microscope($\times$300). The results of this study were as follows : 1. Metal crown alloys showed 2.9% better in marginal fitness than PFM crown alloys, and the difference was not statistically significant(P=0.497). 2. Gold crown alloys showed 31.3% better in marginal fitness than Metal crown alloys, and the difference was statistically significant(P=0.004). 3. Gold crown alloys showed 32.4% better in marginal fitness than PFM crown alloys, and the difference was statistically significant(P=0.002). 4. We saw that Gold crown alloys was the best dental alloys in the marginal fitness among the three.(P=0.049).

• 대한치과의사협회지
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• 제54권7호
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• pp.492-500
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• 2016

Crown fractures are a common type of dental injuries and very frequently occurred on maxillary anterior teeth, area of requiring a rapid aesthetic recovery. Crown fragment reattachment is a simple and conservative method to restore the fractured teeth. The technique promotes esthetic outcomes as utilizing natural contour, shade, surface texture of teeth and gives mechanical similarity in terms of wear-resistance. Also it gives emotional positive responses to patients and requires less of chair time and costs. This case report presents two cases of crown fragment reattachments on maxillrary anterior teeth, including one complicated crown fracture and one uncomplicated crown fracture. If the fragment is available in cases of crown fractures, reattachment of fragment can be regarded as a predictable alternative. However, it is all the time important that a close conversation informing the patients about the limitations and prognoses of this treatment option.

• 대한치과기공학회지
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• 제23권2호
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• pp.9-15
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• 2002

A new kind of 'All Ceramic Crown' could be manufactured by making improvements in the manufacturing technique for the current 'All Ceramic Crown' which does not use a special ceramic but rather a general one as a substitute. If we use the manufacturing technique for the 'All Ceramic Crown', metal coping and core are not produced. The effects of the new manufacturing technique for the 'All Ceramic Crown' are as follows: First. We do not need to use new material or special machinery or tools. Second. We can use general machinery and tools. Third. Using the basic 'All Ceramic Technique', we anticipate improvement in learning in our students. Forth. We can save effort, materials and time. Fifth. The technique also has advantages for esthetic 'temporary crown'.

• 대한치과기공학회지
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• 제21권1호
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• pp.115-121
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• 1999

This investing was carried out to evaluate the alteration of stress distribution on teeth and esthetic crowns. Analyzing the stress distribution by the two-dimensional finite element methods, a model of lower 1st molar according to the porcelain fused metal crown an the porcelain fused glass ceramic core crown and the all glass ceramic crown. 1. The pattern of stress distribution showed no apparent differences. 2. The greatest von Mises values were concentrated around the central fossa of all esthetic crowns. The greatest Maximum principle value were concentrated around the interface between the base of esthetic crown and the abutment tooth. It was found that the apatite glass ceramic could be applicable for use in dental crown prosthesis.

• 대한치과기공학회지
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• 제16권1호
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• pp.57-77
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• 1994

The purpose of this study is to investigate the extent to which dental laboratories use proper materials, procedures, devices, and equipments to fabricate crown & bridge, PFM(Porcelain Fused to Metal) crown & bridge, partial denture, complete denture, and other prosteses. 100 laboratories in Seoul were selected for this investigation. Questionnaires were constructed focusing on five topocs:crown & bridge, PFM crown & bridge, partial denture, complete denture, and other prostheses. The results from this survey were as follows : 1. Most dental laboratories used old, inexpensive, and familiar materials rather than newly developed ones. 2. Most of the dental technicians did not stick to the standard procedures of handling materials, but to their own experiences. 3. Newly developed equipments to fabricate dental prostheses were possessed by nearly 30% dental laboratories. 4. About 80% of dental laboratories were using the procedures they had learned in the school : die trimming for accurate crown margin and softening heat treatment after RPD gold casting. But less than 30% of laboratories were shown to follow the boxing procedure to produce master cast and laboratory remounting in the process of complete denture. The findings show that dental laboratory procedures to fabricate dental prostheses are incomplete and inaccurate in some instances. So, further studies are neededs to clarify the causes of some inaccurate procedures, the better and more equipments should be supplied to produce the more accurate dental posthesis, and more efforts at enancing the appropriate use of dental materials and procedures should be made.

• 대한치과마취과학회지
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• 제10권1호
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• pp.54-57
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• 2010

Foreign body aspiration (FBA) into the tracheobronchial tree could be life threatening requiringprompt intervention. Any objects placed in the oral cavity put patients at a risk of aspirating or swallowing the objects slipped or broken by physical injuries. Here, we report a case of 30 yr old patient with FBA during gold crown replacement was successfully treated with the use of the flexible bronchoscope. Case: A 30 yr old woman was admitted to Seoul National Dental Hospitalfor an amalgam restoration. She was scheduled to gold crown restoration for replacement of the damaged amalgam at #37 site. After performing crown lengthening procedure, the aspiration of gold crown occurred during the cementation of the crown. After aspiration, the patients complained of the subjective distress of respiration. Chest radiograph revealed that gold crown was enlodged to the left bronchus. Flexible fiberoptics was inserted to the bronchus to remove the aspirated crown. Fiberoptic assisted removal of the aspiratedcrown was successfully performed. After removal, there was no radiopaque material in the left bronchus on follow-up chest radiograph. Discussion: When aspiration of dental materials occurs, flexible fiberoptic can be used in the treatment of FBA. It is also very useful to take preventive management such as rubber dam, application of dental floss in dental procedure where there is high likelihood of FBA.

• 대한치과의사협회지
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• 제54권6호
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• pp.414-428
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• 2016

Objectives: The aim of this study was to assess the morphologic characteristics of two types of stainless steel crowns (SSCs) for the first primary molar using a 3D scanner. Study design: Two types of SSCs, KIDS CROWN (KC) and 3M ESPE ND-96 (ND), for the first primary molars were scanned using a 3D scanner. The mesiodistal and buccolingual diameters at the height of the contour and the cervical margin, occlusocervical diameters on the mesial, distal, buccal, and lingual aspects were measured, and the crown shape ratio, the smooth surface crown height ratio, and the cervical convergence were calculated. Results: In the crown shape ratio of the mandibular SSC, KC was larger buccolingually compared with ND. In the smooth surface crown height ratio, ND was larger than KC in all of the maxilla and mesial, distal, and lingual aspects of the mandible. ND was more convergent to the cervical mesiodistally and buccolingually compared with KC. Conclusion: In the superimposed images of the maxillary SSC, the mesiolingual and distolingual line angles of KC were more prominent compared with ND. In the mandible, ND demonstrated higher cusps and more obvious buccal developmental lobes than KC. ND showed a larger cervical undercut than KC.

• Restorative Dentistry and Endodontics
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• 제37권4호
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• pp.240-244
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• 2012

Crown reattachment is the most conservative treatment which can be used to restore fractured tooth, presumably with sufficient strength, while maintaining original contour, incisal translucency, and reducing chair time and cost. However, in case of crown fracture with pin-point pulp exposure, we should cautiously minimize the irritation to the pulp and consider pre-treatment pulpal status, choice of pulp capping materials, choice of bonding system and treatment sequence during crown reattachment procedures. This case reports the considerations while crown reattachment with direct pulp capping using calcium hydroxide (Dycal, Dentsply Caulk).