• Journal of Technologic Dentistry
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• v.42 no.4
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• pp.326-333
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• 2020

Purpose: The purpose of this study was to evaluate the effects of various zirconia surface treatment methods on shear bond strength with resin cements. Methods: We prepared 120 cylindrical zirconia specimens (⌀10 mm×10 mm) using computer-aided design/computer-aided manufacturing (CAD/CAM). Each specimen was randomly subjected to one of four surface treatment conditions: (1) no treatment (control), (2) airborne-particle abrasion with 50 ㎛ of Al2O3 (A50), (3) airborne-particle abrasion with 125 ㎛ of Al2O3 (A125), and (4) ZrO2 slurry (ZA). Using a polytetrafluoroethylene mold (⌀6 mm×3 mm), we applied three resin cements (Panavia F 2.0, Super-Bond C&B, and Variolink N) to each specimen. The shear bond strength tests were performed in a universal testing machine. The surfaces of representative specimens of each group were evaluated under scanning electron microscope. We used one-way analysis of variance (ANOVA), two-way ANOVA, and post hoc Tukey honest significant difference test to analyze the data. Results: In the surface treatment method, the A50 group showed the highest bond strength, followed by A125, ZA, and control groups; however, no significant difference was observed between A50 and A125, A125 and ZA, and ZA and control (p>0.05). Among the resin cements, Super-Bond C&B showed the highest shear bond strength, followed by Panavia F 2.0 and Variolink N (p<0.05). Conclusion: Within the limitations of this study, application of airborne-particle abrasion and ZrO2 slurry improved the shear bond strength of resin cement on zirconia.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.291-297
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• 2016

Patients with $Sj{\ddot{o}}gren^{\prime}s$ syndrome usually suffer from teeth discoloration and attrition due to xerostomia. If the anterior teeth are badly worn, problems such as loss of anterior guidance, occlusal disharmony, and limited space for restoration may occur. However, ideal occlusion is obtained in both centric and eccentric relation by regaining the disocclusion of the posterior teeth through the anterior and lateral guidance using twin-stage method. In this case, rehabilitation was performed for a $Sj{\ddot{o}}gren^{\prime}s$ syndrome patient with maxillary and mandibular incisor's severe attrition and teeth discoloration by using twin-stage method.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.80-90
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• 2022

With the development of digital dentistry, it is being applied in various ways of dental treatment. This case report presents the definitive prosthesis designed in advance with a re-established vertical dimension and the digital technology, which determined the amount of tooth preparation, in order to preserve as much tooth structure as possible in a patient with pathological wear of the posterior teeth and loss of vertical dimension. For accurate tooth preparation, the guides of the occlusal and axial surfaces were digitally and additively manufactured. Then, aesthetics and anterior guidance were established at the provisional stage. The information of the provisional restoration was delivered to the definitive stage by double scanning. The digital technology, including the virtual planning and the guided tooth removal, produced the definitive restorations satisfactory to both the patient and clinician.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.166-172
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• 2018

In case of the treatment of maxillary anterior teeth, it should be taken into account the proper morphology, arrangement and color satisfying patient's esthetic demands. For this purpose, facial composition, dentofacial composition, dental composition and dentogingival composition should be considered making diagnosis and treatment plan in an esthetic point of view. In adjustable temporary crown state, careful evaluation and correction of the esthetic and functional aspect were performed, and the definite restoration was reproduced using double scan.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.341-349
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• 2021

The evaluation of occlusion using digital methods is easier and simpler in terms of recording, comparison, analysis, and objectivity compared to existing methods such as articulating paper and occlusion foil. The purpose of this case report was utilizing the digital method for evaluating occlusion. The occlusion of patient requiring full veneer crown restoration was evaluated using an intraoral scanner (i500, Medit, Seoul, Korea) at every visit. The occlusion was also assessed using conventional articulating paper and a digital occlusal analysis system (Dental prescale II, GC corp., Tokyo, Japan) for comparison. Throughout the treatment process, the intraoral scanner and the conventional articulating paper method showed similar outcomes. The results suggest that the use of digital evaluation system is highly probable in the near future.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.72-81
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• 2024

Purpose: This study aimed to assess the marginal and internal fit of 3-unit monolithic zirconia fixed partial dentures (FPDs) fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) from solid working casts and removable die system. Materials and Methods: The tooth preparation protocol for a zirconia crown was executed on the mandibular right first premolar and mandibular right first molar, with the creation of a reference cast featuring an absent mandibular right second premolar. The reference cast was duplicated using polyvinyl siloxane impression, from which 20 working casts were fabricated following typical dental laboratory procedures. For comparative analysis, 10 FPDs were produced from a removable die system (RD group) and the remaining 10 FPDs from the solid working casts (S group). The casts were digitized using a dental desktop scanner to establish virtual casts and design the FPDs using CAD. The definitive 3-unit monolithic zirconia FPDs were fabricated via a CAM milling process. The seated FPDs on the reference cast underwent digital evaluation for marginal and internal fit. The Mann-Whitney U test was applied for statistical comparison between the two groups (α = 0.05). Results: The RD group showed significantly higher discrepancies in fit for both premolars and molars compared to the S group (P < 0.05), particularly in terms of marginal and occlusal gaps. Color mapping also highlighted more significant deviations in the RD group, especially in the marginal and occlusal regions. Conclusion: The study found that the discrepancies in marginal and occlusal fits of 3-unit monolithic zirconia FPDs were primarily associated with those fabricated using the removable die system. This indicates the significant impact of the fabrication method on the accuracy of FPDs.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.469-477
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• 2021

For successful restoration of maxillary anterior implants, both pink esthetics and white esthetics must be satisfied. For pink esthetic part, the role of appropriate provisional prosthesis restoration is important, and for white esthetic part, the color and shape of the definitive prosthesis is important. Multilayer zirconia can be used for natural tooth appearance due to the higher transparency of the incisal area compared to the conventional monolithic zirconia. Therefore, in this case, white esthetic part was achieved through multilayer zirconia after recovering function and esthetics through appropriate provisional prosthesis in a patient who lost the maxillary anterior teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.1
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• pp.100-109
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• 2022

Installation of dental implants at optimal angles and positions is critical in long-term stable implant-supported restorations. Surgery and prosthodontic procedures should be performed accurately as the treatment is planned. In this clinical case, Computer aided design and manufacturing technology was used not only to establish a precise surgical plan, but also to fabricate both provisional and definitive fixed prostheses. A surgical guide was designed to install the implants at proper positions for the definitive prostheses. The patient's esthetic information, which was necessary for the new provisional and definitive fixed prostheses, was obtained from the existing temporary dentures. Finally, the complete mouth fixed implant-supported rehabilitation using monolithic zirconia provided the patient with functionally and esthetically satisfactory prostheses.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.210-217
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• 2016

Purpose: The aim of this study was to evaluate the marginal and internal adaptation of monolithic zirconia restoration made without physical model by digital intraoral scanner. Materials and methods: A prospective clinical trial was performed on 11 restorations as a pilot study. The monolithic zirconia restorations were fabricated after digital intraoral impression taking by intraoral scanner (TRIOS, 3shape, Copenhagen, Denmark), computer-aided designing, and milling manufacturing process. Completed zirconia crowns were tried in the patients' mouth and a replica technique was used to acquire the crown-abutment replica. The absolute marginal discrepancy, marginal gap, and internal gap of axial, line angle, and occlusal part were measured after sectioning the replica in the mesiodistal and buccolingual direction. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (${\alpha}=.05$). Results: From the adaptation analysis by replica, the statistically significant difference was not found between mesiodistal and buccolingual sections (P>.05), but there was significant difference among the measurement location (P<.01). The amount of absolute marginal discrepancy was larger than those of marginal gap and internal gap (P<.01). Conclusion: Within the limitations of this study, the adaptation accuracy of model-free monolithic zirconia restoration fabricated by intraoral scanner exhibited clinically acceptable result. However, the margin of zirconia crown showed tendency of overcontour and cautious clinical application and follow up is necessary.

• Journal of Korea Foundry Society
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• v.31 no.4
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• pp.218-223
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• 2011

Computer Aided Engineering (CAE) is very helpful field for every manufacturing industry including foundry. It covers CAD, CAM, and simulation technology also, and becomes as common sense in developing new products and processes. In South Korea, more than 600 foundries exist, and their average employee number is less than 40. Moreover, average age of them becomes higher. To break out these situations of foundry, software tools can be effective, and many commercial software tools had already been introduced. But their high costs and risks of investment act as difficulties in introducing the software tools to SMEs (Small and Medium size Enterprise). So we had developed cloud computing platform to propagate the CAE technologies to foundries. It includes HPC (High Performance Computing), platforms and software. So that users can try, enjoy, and utilize CAE software at cyber space without any investment. In addition, we also developed platform APIs (Application Programming Interface) to import not only our own CAE codes but also 3rd-party's packages to our cloud-computing platforms. As a result, CAE developers can upload their products on cloud platforms and distribute them through internet.