Even though a conventional metal ceramic restoration is widely in use, its laboratory procedure is still technique-sensitive, complex, and time-consuming. A ceramic-pressed-to-metal restoration (PTM) can be a reliable alternative. However, simplified laboratory procedure for a PTM is still necessary. The article is to propose a technique that reduces time and effort to fabricate a PTM with the aid of computer-aided design, computer-aided manufacturing and selective laser sintering technologies.
Ceramics ; Computer-Aided Design*

Since LINAC-based stereotactic radiosurgery uses multiple noncoplanar arcs, three-dimensional dose evaluation and many beam parameters, a lengthy computation time is required to optimize even the simplest case by a trial and error. The basic approach presented in this paper is to show promising methods using an experimental optimization and an analytic optimization. The purpose of this paper is not to describe the detailed methods, but introduce briefly, proceeding research done currently or in near future. A more detailed description will be shown in ongoing published papers. Experimental optimization is based on two approaches. One is shaping the target volumes through the use of multiple isocenters determined from dose experience and testing. The other method is conformal therapy using a beam's eye view technique and field shaping. The analytic approach is to adapt computer-aided design optimization in finding optimum irradiation parameters automatically.
Computer-Aided Design ; Radiosurgery*

PURPOSE: The purpose of this study was to investigate the fit and screw joint stability between Ready-made abutment and CAD-CAM custom-made abutment. MATERIALS AND METHODS: Osstem implant system was used. Ready-made abutment (Transfer abutment, Osstem Implant Co. Ltd, Busan, Korea), CAD-CAM custom-made abutment (CustomFit abutment, Osstem Implant Co. Ltd, Busan, Korea) and domestically manufactured CAD-CAM custom-made abutment (Myplant, Raphabio Co., Seoul, Korea) were fabricated five each and screws were provided by each company. Fixture and abutments were tightening with 30Ncm according to the manufacturer's instruction and then preloding reverse torque values were measured 3 times repeatedly. Kruskal-Wallis test was used for statistical analysis of the preloading reverse torque values (alpha=.05). After specimens were embedded into epoxy resin, wet cutting and polishing was performed and FE-SEM imaging was performed, on the contact interface. RESULTS: The pre-loading reverse torque values were 26.0 +/- 0.30 Ncm (ready-made abutment; Transfer abutment) and 26.3 +/- 0.32 Ncm (CAD-CAM custom-made abutment; CustomFit abutment) and 24.7 +/- 0.67 Ncm (CAD-CAM custom-made abutment; Myplant). The domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) presented lower pre-loading reverse torque value with statistically significant difference than that of the ready-made abutment (Transfer abutment) and CAD-CAM custom-made abutment (CustomFit abutment) manufactured from the same company (P=.027) and showed marginal gap in the fixture-abutment interface. CONCLUSION: Within the limitation of the present in-vitro study, in domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) showed lower screw joint stability and fitness between fixture and abutment.
Computer-Aided Design* ; Torque

Objective: To present our in-house 3D planning protocol utilizing open-source computer-aided design software and discuss specific applications in reconstruction of various craniomaxillofacial defects, demonstrating a free, accessible, efficient, accurate, and easily learnable alternative to expensive counterparts. Methods: Design: Case Series. Setting: Tertiary Private Training Hospital. Participants: Ten (10) patients who underwent CAD assisted reconstructive surgeries from February 2017 – May 2018. Results: A total of 10 patients were included; 7 mandibular reconstructions were surgically reconstructed using our 3D planning protocol and achieved symmetric mandibular contour, with good functional occlusion after surgery; 1 cranioplasty and 1 orbital trauma case also achieved good symmetry and adequate correction of enophthalmos respectively. However, inadequate soft tissue correction was seen in 1 case of maxillary reconstruction despite achieving symmetric bony contour. Conclusion Our 3D planning protocol using open-source CAD applications is a viable alternative to expensive professional counterparts. Additional prospective studies may better demonstrate benefits in terms of accuracy and decreasing intraoperative time in craniomaxillofacial and head and neck reconstruction.
Computer-Aided Design

Brachytherapy ; Computer-Aided Design ; Humans

Computer-Aided Design ; Denture Design ; Humans

PURPOSE: The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS: An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of +/-0.1 microm at 50 points. RESULTS: Initial detorque values of milled abutment were significantly higher than those of cast abutment (P<.05). Detorque values after one million dynamic cyclic loadings were not significantly different (P>.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading. CONCLUSION: In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.
Computer-Aided Design ; Joints ; Mastication ; Titanium* ; Torque

PURPOSE: The purpose of this study was to evaluate the influence of different coping thicknesses and veneer ceramic cooling rates on the failure load of zirconia-ceramic crowns. MATERIALS AND METHODS: Zirconia copings of two different thicknesses (0.5 mm or 1.5 mm; n=20 each) were fabricated from scanning 40 identical abutment models using a dental computer-aided design and computer-aided manufacturing system. Zirconia-ceramic crowns were completed by veneering feldspathic ceramics under different cooling rates (conventional or slow, n=20 each), resulting in 4 different groups (CONV05, SLOW05, CONV15, SLOW15; n=10 per group). Each crown was cemented on the abutment. 300,000 cycles of a 50-N load and thermocycling were applied on the crown, and then, a monotonic load was applied on each crown until failure. The mean failure loads were evaluated with two-way analysis of variance (P=.05). RESULTS: No cohesive or adhesive failure was observed after fatigue loading with thermocycling. Among the 4 groups, SLOW15 group (slow cooling and 1.5 mm chipping thickness) resulted in a significantly greater mean failure load than the other groups (P<.001). Coping fractures were only observed in SLOW15 group. CONCLUSION: The failure load of zirconia-ceramic crowns was significantly influenced by cooling rate as well as coping thickness. Under conventional cooling conditions, the mean failure load was not influenced by the coping thickness; however, under slow cooling conditions, the mean failure load was significantly influenced by the coping thickness.
Adhesives ; Ceramics ; Computer-Aided Design ; Crowns* ; Fatigue*

PURPOSE: The purpose of this study was to investigate screw joint stability and sagittal fit between internal connection implant fixtures of two different manufacturers and customized abutments. MATERIALS AND METHODS: Internal connection implant systems from two different manufacturers (Biomet 3i system, Astra Tech system) were selected for this study (n=24 for each implant system, total n=48). For 3i implant system, half of the implants were connected with Ti ready-made abutments and the other half implants were connected with Ti CAD-CAM custom ones of domestic-make (Myplant, Raphabio Co., Seoul, Korea) and were classified into Group 1 and Group 2 respectively. Astra implants were divided into Group 3 and Group 4 in the same way. Micro-CT sagittal imaging was performed for fit analysis of interfaces and preloading reverse torque values (RTV) were measured. RESULTS: In the contact length of fixture-abutment interface, there were no significant differences not only between Group 1 and Group 2 but also between Group 3 and Group 4 (Mann-Whitney test, P>.05). However, Group 2 and Group 4 showed higher contact length significantly than Group 1 and Group 3 in abutmentscrew interface as well as fixture-screw one (Mann-Whitney test, P<.05). In addition, RTV was lower in CAD-CAM custom abutments compared to ready-made ones (Student t-test, P<.05). CONCLUSION: It is considered that domestically manufactured CAD-CAM custom abutments have similar fit at the fixture abutment interface and it could be used clinically. However, RTV of CAD-CAM custom abutments should be improved for the increase of clinical application.
Computer-Aided Design* ; Joints ; Seoul ; Torque

Computer-Aided Design ; Craniofacial Abnormalities ; surgery ; Humans