• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.146-150
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• 2015

PURPOSE. This in vitro study aimed to compare the failure load and failure characteristics of two different zirconia framework designs of premolar crowns when subjected to static loading. MATERIALS AND METHODS. Two types of zirconia frameworks, conventional 0.5 mm even thickness framework design (EV) and 0.8 mm cutback of full contour crown anatomy design (CB), were made for 10 samples each. The veneer porcelain was added on under polycarbonate shell crown made by vacuum of full contour crown to obtain the same total thickness of the experiment crowns. The crowns were cemented onto the Cobalt-Chromium die. The dies were tilted 45 degrees from the vertical plane to obtain the shear force to the cusp when loading. All crowns were loaded at the lingual incline of the buccal cusp until fracture using a universal testing machine with cross-head speed 0.5 mm/min. The load to fracture values (N) was recorded and statistically analyzed by independent sample t-test. RESULTS. The mean and standard deviations of the failure load were $1,170.1{\pm}90.9$ N for EV design and $1,450.4{\pm}175.7$ N for CB design. A significant difference in the compressive failure load was found (P<.05). For the failure characteristic, the EV design was found only cohesive failures within veneering porcelain, while the CB design found more failures through the zirconia framework (8 from 10 samples). CONCLUSION. There was a significant difference in the failure load between two designs, and the design of the framework influences failure characteristic of zirconia crown.

• The Journal of the Korean dental association
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• v.23 no.9 s.196
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• pp.747-751
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• 1985

• Journal of the Korean Academy of Esthetic Dentistry
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• v.23 no.2
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• pp.70-76
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• 2014

After extraction of tooth, alveolar ridge resorption is inevitable in most cases. Clinicians confront with horizontal and vertical resorption of alveolar bone. Without massive amount of bone and soft tissue graft, dental implant will be placed apically to gain stability. In those cases, not only white esthetic part, but also pink esthetic part should be restored with pink porcelain. The margin of prosthesis should be located apically to reproduce natural look with adjacent teeth. However, when the margin is located apically, it is always hard to remove remaining cement, thus complications may arise. In this report, a novel design of implant prosthesis is introduced to solve those issues. The novel design is consisted of zirconia framework with pink porcelain and separate crowns on top of the framework. It eliminates the possibility of cement remnants by bringing the crown margin coronally. Pink esthetic part is incorporated in abutment part instead of crown part and the screw hole is covered with separate crowns.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.1
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• pp.20-27
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• 2024

As a high-performance polymer, Polyetherketoneketone (PEKK) has good biocompatibility and excellent physical properties and is used in several areas, including dentistry. Many successful cases of implant-supported fixed prostheses with a PEKK framework have been reported; however, a long-term observation of the reported cases and discussion of complications are not available. In this case report, we present three cases of implant-supported fixed prostheses with a PEKK framework veneered with composite resin, lithium disilicate crown, and high-impact polymethyl methacrylate (PMMA), and discuss their 6-year follow-up results.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.4
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• pp.454-464
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• 1999

The metal ceramic crown is currently the most popular complete veneer restoration in dentistry, but in many cases, the metal cervical collar at the facial margin is unesthetic and unacceptable. Facial porcelain margin has been used in place of it. But this dose not solve the problems, such as dark gingival discoloration and cervical opaque reflection of porcelain veneer. Recently, metal copings which were designed to terminate its labio-cervical end on the axial walls coronal to the shoulder have been clinically used to solve the esthetic problem of metal ceramic crown. But in this design, porcelain veneer of labio-cervical area which is not supported by metal may not be able to resist the stress during cementation and mastication. The purpose of this study was to evaluate fracture strength and fractured appearance of crowns according to different coping designs. A resin maxillary left central incisor analogue was prepared for a metal ceramic crown, and metal dies were made with duplication mold. Metal copings were made and assigned to one of four groups based on facial framework designs: group 1, coping with 0.5mm metal collar; group 2, metal extended to the shoulder; group 3, metal extended to 1mm coronal tn the shoulder: group 4, metal extended to 2mm coronal to the shoulder. Copings and crowns were adjusted to be same size and thickness, and cemented to metal dies with zinc phosphate cement by finger pressure. Fracture strength was measured with Instron Universal Testing Machine. Metal dies were anchored in Three-way-vice at 3mm below finish line and at $130^{\circ}$ inclined to the long axis of the crown. Load was directed lingually at 2mm below midincisal edge. Load value at initial crack and at catastrophic fracture was recorded. The results obtained were as follows : 1. Fracture strength values at initial crack were higher in groups 1, 2 than in groups 3, 4 but this difference was not statistically significant(P<0.05). 2. Conventional metal collared crown had greater catastrophic fracture strength than any other collarless crowns. 3. The greater the labial metal coping reduction, the lower the catastrophic fracture strength of crowns but when more than 1mm of labial metal reduction was done, the difference in strengths was not statistically significant(p<0.05). 4. The strongest collarless coping design was group 2.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.33-38
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• 2010

Maxillectomy is a treatment option for maxillary cancer, which leaves the patient with a palatal defect. It may cause problems with facial deformation, swallowing, mastication, and speech. These functional problems and changes in appearance may result in psychological problems. To control these deficits after maxillectomy, surgical reconstruction or prosthodontic treatment can be chosen as a treatment option. Obturator prosthesis has been used as a preferred method of rehabilitation for most maxillectomy patients. This case is a patient who was classified Aramany classification II hemi-maxillectomy patient with residual teeth from #11-25, whose teeth had substantial labioversion and clinically lengthened from alveolar bone involution, thus making it hard to select proper framework design and resist to the rotational dislodging force of the obturator. Therefore we selected swing-lock attachment design to remain pre-existing crown and bridges and obtain retention and stability of obturator. The swing-lock RPD is economical than the conventional RPD because we can remain pre-existing crown and bridges. And residual teeth which have mobility and poor prognosis can be successfully retained through properly designed swing-lock RPD as it is functioning as a removable splint on the teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.17-24
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• 2018

Lost wax technique of casting wax patterns has been used principally to make metal frameworks of removable partial dentures. Since the development of digital technology and CAD, metal frameworks can be built through digital surveying and framework designing. Many cases proved that resin patterns made by CAD printing method were well adapted to internal oral structure and final metal frameworks also showed good internal adaptation as well. The metal frameworks of a removable partial denture were made by both lost wax technique and CAD technique and were applied to a patient with severe alveolar bone loss. Using CAD data and fit checker, internal adaptation of both metal frameworks were evaluated by comparing the gap between surveyed crown and its structure. This study is to prove that metal frameworks by both techniques showed adaptation that can be applied in clinical field.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.92-97
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• 2013

PURPOSE. All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS. Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS. The mean fracture strengths were as follows: $54.9{\pm}15.6$ N for the Lava CAD/CAM zirconia crowns and $87.0{\pm}16.0$ N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION. The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.4
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• pp.367-378
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• 2023

With the recent development of computer-aided design-computer-aided manufacturing technology and 3D printing technology, and the introduction of various digital techniques, the accuracy and efficiency of top-down definitive prosthetic restoration are increasing. In this clinical case, stable occlusion support was obtained through the placement of a total of 9 maxillary and mandibular posterior implants in patient with anterior-posterior crossed occlusion. The edentulous area of the maxillary anterior teeth, which showed a tendency of high resorption of the residual alveolar bone, was restored with a Kennedy Class IV implant assisted removable partial denture to restore soft tissue esthetics. Computed tomography guided surgery was used to place implants in the planned position, double scan technique was used to reflect the stabilized occlusion in the interim restoration stage to the definitive prostheses, and metal 3D printing was used to manufacture the coping and framework. This clinical case reports that efficient and predictable top-down full mouth rehabilitation was achieved using various digital technologies and techniques.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.354-361
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• 2011

There are still many limitations on fabricating dentures using digital method while computerized production of fixed prostheses utilizing intraoral scanner and CAD/CAM technology has propagated rapidly. Recently the digital solution of fabricating removable partial denture by applying haptic input device, electronic surveying, and rapid prototyping was introduced. In this case presentation, five patients were treated with surveyed crown and removable partial dentures by this digital solution. Fit of dentures was excellent except for one case which showed morphological difference between the actual teeth and that of master cast by the erroneous impression process. There also was not any problem of stability and retention after adaptation in the clinical setting.