• Journal of the Korean Academy of Esthetic Dentistry
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• v.13 no.1
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• pp.31-39
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• 2004

For the prosthodontic results which are compatible with esthetics to be fulfilled, the first prerequisite would be periodontal intervention and stability, the second one may be functional competency and the ultimate goal should be ascribed to esthetic considerations. Other words, esthetic dentistry is a whole entity which encompasses the biological stability of the periodontium, physical accuracy of the prosthodontic structure and finally, the beauty which can be found in natural dentition. It also implies the harmonized lip line which reveals the well-balanced tooth morphology and health gum profiles (Red-White Esthetics). Largely, there lie some differences in the input system of the 3-dimentional data from the prepared abutments between respective computer-assisted systems available now. But the manufacturing systems (CAM) are very similar between them, to say, comprise numeric control systems with whole 3-dimensional milling units according to the restorations to be made. Now the author is going to present CAD/CAM Zirconia All Ceramic Restoration on the topics for the Red-White Esthetics, periodontal control and maintenance, treatment for the discolored teeth, post & core build-up works for the devitalized teeth, characteristics of the Zirconium oxide All Ceramics, fabrication procedures, clinical considerations and its application to diverse clinical situations.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.75-81
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• 2003

Pocket machining is metal removal operation commonly used for creating depressions in machined parts. Numerically controlled milling is the primary means for machining complex die surface. These complex surfaces are generated by a milling cutter which removes material as it traces out pre-specified tool paths. To machine, a component on a CNC machine, part programs which define the cutting tool path are needed. This tool path is usually planned from CAD, and converted to a CAM machine input format. In this paper I proposed a new method for generating NC tool paths. This method generates automatically NC tool paths with dynamic elimination of machining errors in 2$\frac{1}{2}$ arbitrary shaped pockets. This paper generates a spiral-like tool path by dynamic computing optimal pocket of the pocket boundary contour based on the type and size of the milling cutter, the geometry of the pocket contour and surface finish tolerance requirements. This part programming system is PC based and simultaneously generates a G-code file.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.2
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• pp.114-125
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• 1993

In the present study the newly developed CAD/CAM system is applied to the process of the molding design, machining for mini-sized and precise processive die, and the production of press-stamped parts. When the design of a die was completed by means of CAD, wire cut NC data were generated with the aid of a design drawing in the CAD system and then inputed into the wire cut machine, and with the aid of a hole chart which had been made for this purpose, all the data were classified into the categories of CNC milling, jig boring, jig grinding, and machine center, and then developing a program of generating NC data, errors in process were reduced and programming time was shortened. The program was developed by using Autolisp language which was built-in the CAD, and realizing the intergation of designing a die, generating and processing NC data directly by a designer, designing time and machinery processing time were shorted. And the traditionally required working time for design. NC program required 6 days of work becomes 4 days of work by using the developed CAD/CAM system so that the efficiency shows 150% of the reduction working time. The prpgram of the design of the automation a progressive die mold was developed in the PC-Class Autocad system, therefore development expense could be reduced, and the integration of the CAD/CAM of the progressive die mold with the standard DB being built could be realized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.944-947
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• 2000

Sculptured surface machining plays a vital role in the process of bring new products to the market place. A great variety of products rely on this technology for the production of the dies and moulds used in manufacturing. And, the use of CNC machines and CAD/CAM system has become a vital parts of product development process. The propose of this study is to investigate the effect of cutting parameters on the machinability such as surface roughness and cusp generated in the machining of sculptured surface on a three-axis CNC machining center using the CAD/CAM system. Experimental result showed that: In step down cutting, as the inclined angle of surface became smaller, the cusp height appeared higher. On the other hand, in step over cutting, as the inclined angle of surface became larger, the cusp height appeared higher. In the point of precision machining, step over cutting was more effective. For the minimization of cusp height, step down cutting was effective in larger inclined surface, but step over cutting in smaller inclined surface.

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.55-64
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• 2019

PURPOSE. The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method. MATERIALS AND METHODS. The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at ${\alpha}=.05$. RESULTS. No statistically significant differences in distances among four notches (P>.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly (P<.05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods (P<.05). CONCLUSION. The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.

• The Journal of Advanced Prosthodontics
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• v.12 no.6
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• pp.329-337
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• 2020

PURPOSE. To verify the influence of computer-aided design/computer-aided manufacturing (CAD/CAM) implant-supported prostheses manufactured with cobalt-chromium (Co-Cr) and zirconia (Zr), and whether ceramic application, spark erosion, and simulation of masticatory cycles modify biomechanical parameters (marginal fit, screw-loosening torque, and strain) on the implant-supported system. MATERIALS AND METHODS. Ten full-arch fixed frameworks were manufactured by a CAD/CAM milling system with Co-Cr and Zr (n=5/group). The marginal fit between the abutment and frameworks was measured as stated by single-screw test. Screw-loosening torque evaluated screw stability, and strain analysis was explored on the implant-supported system. All analyses were performed at 3 distinct times: after framework manufacturing; after ceramic application in both materials' frameworks; and after the spark erosion in Co-Cr frameworks. Afterward, stability analysis was re-evaluated after 106 mechanical cycles (2 Hz/150-N) for both materials. Statistical analyses were performed by Kruskal-Wallis and Dunn tests (α=.05). RESULTS. No difference between the two materials was found for marginal fit, screwloosening torque, and strain after framework manufacturing (P>.05). Ceramic application did not affect the variables (P>.05). Spark erosion optimized marginal fit and strain medians for Co-Cr frameworks (P<.05). Screw-loosening torque was significantly reduced by masticatory simulation (P<.05) regardless of the framework materials. CONCLUSION. Co-Cr and Zr frameworks presented similar biomechanical behavior. Ceramic application had no effect on the biomechanical behavior of either material. Spark erosion was an effective technique to improve Co-Cr biomechanical behavior on the implant-supported system. Screw-loosening torque was reduced for both materials after masticatory simulation.

• Restorative Dentistry and Endodontics
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• v.44 no.3
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• pp.27.1-27.12
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• 2019

This case report describes a technique in which endodontic treatment and permanent indirect restoration were completed in the same clinical appointment with the aid of a computer-aided design/computer-aided manufacturing (CAD/CAM) system. Two patients were diagnosed with irreversible pulpitis of the mandibular first molar. After access preparation, root canals were located, irrigation was performed until bleeding ceased, and the coronal tooth structure was prepared for indirect restoration. Then, utilizing an interim 3-mm build-up of the endodontic access cavity, a hemi-arch digital scan was performed with an intraoral scanner. Subsequent to digital scanning, restoration design was performed simultaneously with the endodontic procedure. The root canals were shaped using the Race system under irrigation with 2.5% sodium hypochlorite followed by root canal filling. The pulp chamber was subsequently filled with a 3-mm-thick composite resin restoration mimicking the interim build-up previously utilized to facilitate block milling in the CAD/CAM system. Clinical try-in of the permanent onlay restoration was followed by acid etching, application of a 5th generation adhesive, and cementation of the indirect restoration. Once the restoration was cemented, rubber dam isolation was removed, followed by occlusal adjustment and polishing. After 2 years of follow-up, the restorations were esthetically and functionally satisfactory, without complications.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.161-167
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• 1993

This paper deals with a new method for the machining of a die cavity defined by sculptured surfaces. In machining die cavities or pockets, process planners have been faced with some troulbes. One of the troubles ius to rebove a great deal of material within a given boundary while avoiding cutter interference. Cutter interference is a ciritical problem in NC machining of a die cavity. Even though this cavity machining has been implemented in many CAM systems, most of them can handle limited shapes of cavities or pockets. In this paper, a procedure has been developed to machine die cavity or pocket of a sculptured surface. The offset surfaces of the part surfaces and boundary surfaces are determined to calculate the intersection curves. These intersection curves form a FACE on the part surface, and the interference free tool pathe is generated by eliminating the points outside the FACE when computing the cutter contact (CC) data. Additionally, the cutter location (CL) data obtained from the CC data convert to an NC data. The NC data generated through this algorithm are verified on the CINCINNATI milling machine. A propotype die cavity machining system has been implemented in FORTRAN language and FIGARO graphics library on IRIS workstation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.75-84
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• 2000

The main goal of our research is to compensate the milled surface errors induced by the tool deflection effects, which occur during the milling process. First, we predict cutting forces and tool deflection amount. Based on predicted deflection effects, we model milled surface shapes. We present a compensation methodology , which can generate a new tool trajectory, which is determined so as to compensate the milled surface errors. By considering manufacturing tolerance, tool path compensation is generalized. To validate the approaches proposed in this paper, we treat an illustrative example of profile milling process by using flat end mill. Simulation and experimental results are shown.

• Journal of Technologic Dentistry
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• v.39 no.4
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• pp.235-242
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• 2017

Purpose: The aim of this study was to evaluate the marginal and internal gap of zirconia copings fabricated by CAD/CAM system and to research the effect of cement space on the fit of zirconia prosthesis. Methods: Zirconia copings were designed using 3shape software and then milled from presintered zirconia blocks by Kavo dental milling machine. The cement space was set at $0{\mu}m$ around the margins for all groups, and additional cement space appling 1 mm above the finish lines of tooth. The samples were classified into 4 groups according to the cement space setting(Cs-0, Cs-40, Cs-80, Cs-120). Replica technique used to investigate marginal and internal gap. The silicone film thickness was recorded using a optical microscope with image software analysis system at 75${\times}$magnification. The assessment performed on the six points in bucco-lingual and mesio-distal sections(4 groups, 10 copings per group, 12 measuring points per coping). The data were statistically analyzed with one-way ANOVA followed by pair-wise Tukey's post hoc tests(${\alpha}$<0.05). Results: Better marginal and internal fit values were exhibited by $80{\mu}m$ cement space. The results showed that different cement space values had statistically significant effect on the marginal and internal gap of zirconia copings(p<0.001). The gap of margin and axial wall area was smaller than that the gap of occlusal area in all groups(p<0.001). Conclusion : Effect of different cement spaces on the marginal and internal gap of zirconia copings.