• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.446-460
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• 2000

All-ceramic restorations have had a more limited life expectancy than metal ceramic crowns be-cause of their lower strength. The relatively lower strength has limited the use of all-ceramic crowns to the areas where occlusal loads are lower Therefore many researches have been done to increase the strength of all-ceramic crowns. IPS Empress 2 is a new type of lithium disilicate glass-ceramic with enhanced physical characteristics which has been in use clinically since 1998. Previous researches reported that the flexural strength of all-ceramic material was greater than 300 MPa, and all-ceramic crowns can be used in staining or layering technique. The objective of this study was to investigate the influence of the thickness of IPS Empress 2 ceramic on fracture strength. Both staining technique and layering technique was investigated. Vita VMK was used as control. For all three groups, five specimens each of 0.8mm, 1.0mm, 1.4mm, 1.8mm, and 2.2mm thick-ness (a total of 75 specimens) were prepared. Control group : Vita VMK Porcelain specimens were prepared with dentine ceramic and liquid glazing was done. Group I : IPS Empress 2 were prepared with staining technique and stained twice and glazed once. Group II : IPS Empress 2 were prepared with layering technique and glazed after wash firing. The thickness and diameter of the specimen were measured and controlled after specimen preparation. Biaxial Flexure Test (ASTM Standard F394-78) was adopted as this test method produces results least affected by the edge condition of the specimens. Fracture strength was measured with Instron Universal Testing Machine. Conclusions are as follow : 1. The fracture strength was increase in order of control group, test group I, test group II. 2. Fracture strength of the group I (Empress 2 Staining) was 65.54 N in 0.8mm, 155.2 N in 1.0mm, 233.5 N in 1.4mm, 434.5 N in 1.8mm, and 600.1 N in 2.2mm. 3. Fracture strength of the group II (Empress 2 Layering) was 190.0 N in 0.8mm, 283.5 N in 1.0mm. 437.2 N in 1.4mm, 732.0 N in 1.8mm, and 1115.0 N in 2.2mm. 4. No statistical difference was found in flexural strengths according to thickness in a specified group(p>0.05).

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.4
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• pp.423-439
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• 2012

This case report described a technique utilizing a computer-aided design (CAD)/computer-aided machining (CAM) - guided surgical implant placement and prefabricated temporary fixed prosthesis for an immediately loaded restoration. The advantages of CAD/CAM guided implant procedures are flapless, minimally invasive surgery and shorter surgery time. With this technique, less postoperative morbidity and delivery of prosthesis for immediate function would be possible. A patient with an edentulous maxilla received 8 implants in maxilla using CAD/CAM surgical templates. Prefabricated provisional maxillary implant supported fixed prosthesis were connected immediately after implant installation. Provisional prosthesis was evaluated for aesthetics, function during 6 months. Definitive implant supported fixed porcelain fused metal bridges were fabricated.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.319-332
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• 2021

With the rapid development of aesthetic ceramic materials and resin adhesives, the transition from metal ceramic crown to all-ceramic restoration is being actively carried out. When making porcelain restorations, the advantages can be maximized only when appropriate forms and techniques are used. Recently, an esthetic partial-coverage restoration method with supra-gingival margins was introduced by applying a minimally invasive tooth removal method that preserves enamel as much as possible and enhances adhesion efficiency. Through this, various advantages such as minimization of tooth structure removal and ease of excess cement removal can be obtained. In addition, since this manufacturing method does not require cord packing, it is possible to save time for impression taking and reduce patient discomfort. Furthermore, the margins can be clearly obtained without the intervention of gingival fluid or blood, making it possible to manufacture more accurate restorations. In the following cases of patients with partial tooth defects, esthetic ceramic partial-coverage restorations with supra-gingival margin was applied using minimally invasive tooth preparation method according to the concept of adhesive dentistry. Therefore, unnecessary tooth abutment preparation was prevented and residual tooth structure could be preserved as much as possible. After delivery of the ceramic partial-coverage restorations, favorable outcome was obtained.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.175-186
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• 2022

A crossed occlusion resulting from the presence of posterior teeth in one arch but no opposing teeth in the opposite arch results in collapse of the vertical dimension. In this case, the patient has a class III malocclusion with crossed occlusion and anterior crossbite. In order to evaluate the proper vertical dimension, provisional denture was used to stabilize the vertical occlusal dimension for 3 months. After, provisional fixed restoration was used for the stabilizing occlusal relationship and aesthetic improvement for lip support. Definitive prosthesis in implants in the mandible and abutments in the maxillary were using Porcelain-fused-to-metal crown (PFM) crown and the maxillary unilateral edentulous area was treated with removable partial dentures. Through this, proper support of the posterior region and normal anterior occlusal relationship were formed, and the patient was able to obtain aesthetically and functionally satisfactory treatment results.