• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.342-348
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• 2020

Anatomical changes in the facial and alveolar bones occur after multiple teeth are extracted. In the maxilla, the alveolar bone is absorbed in the direction and inclination of the root, and the remaining alveolar bone becomes shorter, reducing the diameter of the arch. In addition, as the nasolabial angle increases, the support of the lips and the aesthetics of the face are lost. This case reports a functional and aesthetically satisfactory results of full mouth rehabilitation with the implant-supported fixed prosthesis using a zirconia framework.

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.346-350
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• 2014

PURPOSE. Impact forces in implant supported FDP (fixed dental prosthesis) are higher than that of tooth supported FDPs and the compositions used in frameworks also has a paramount role for biomechanical reasons. The aim of this study was to evaluate the flexural strength of two different zirconia frameworks. MATERIALS AND METHODS. Two implant abutments with 3.8 mm and 4.5 mm platform were used as premolar and molar. They were mounted vertically in an acrylic resin block. A model with steel retainers and removable abutments was fabricated by milling machine; and 10 FDP frameworks were fabricated for each Biodenta and Cercon systems. All samples were thermo-cycled for 2000 times in $5-55^{\circ}C$ temperature and embedded in $37^{\circ}C$ artificial saliva for one week. The flexural test was done by a rod with 2 mm ending diameter which was applied to the multi-electromechanical machine. The force was inserted until observing fracture. The collected data were analyzed with SPSS software ver.15, using Weibull modulus and independent t-test with the level of significance at ${\alpha}=.05$. RESULTS. The mean load bearing capacity values were higher in Biodenta but with no significant differences (P>.05). The Biodenta frameworks showed higher load bearing capacity ($F_0=1700$) than Cercon frameworks ($F_0=1520$) but the reliability (m) was higher in Cercon (m=7.5). CONCLUSION. There was no significant difference between flexural strengths of both zirconia based framework systems; and both Biodenta and Cercon systems are capable to withstand biting force (even parafunctions) in posterior implant-supported bridges with no significant differences.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.71-80
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• 2014

Full-mouth reconstruction of a patient using dental implants is a challenge if there is vertical and horizontal bone resorption. Therefore, it is should be cautious in making the fixed prostheses that restore the function and the esthetics of the gingiva and teeth. In full mouth rehabilitation, CAD/CAM system makes it possible to fabricate restorations with high precision, regardless of span of the restoration. Recently, Palladium-silver (Pd-Ag) alloy which is highly biocompatible and millingable has been developed to compensate for the shortcomings of the titanium or zirconia. This clinical report presents the reconstruction of a maxillary arch with a cement retained implant supported fixed prosthesis using a Pd-Ag alloy generated by CAD/CAM system on eleven osseointegrated implants. The occluding surfaces were made of Pd-Ag alloy, to decrease the risk of chipping or fracture. The prostheses were esthetically pleasing, and no clinical complications have been reported after two years.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.29-39
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• 2006

Statements of problem: Zirconia core is used for posterior fixed partial dentures because it's good mechanical properties. Stress is concentrated on connectors in fixed partial dentures, so the proper design of connector areas is needed for adequate mechanical long-term properties of any prosthesis. The area of connector is critical, but tooth size and surrounding soft tissue limit the connector design. Purpose: The purpose of this study is to compare fracture strengths between different connector designs of zirconia core for posterior fixed partial dentures manufactured with CAD/CAM system and determining the optimal connector design satisfying strength and hygiene. Material and method: The following four groups of 40 posterior fixed partial denture specimens(each group 10) were fabricated as followed; group 1 vertical height of connector is 3mm (control group, all groups have the same condition); group 2, lingual vertical 1mm reinforcement on connector; group 3, lingual vertical 2mm reinforcing on connector and group 4, lingual vertical 3mm reinforcing on connector. Specimens were subjected to compressive loading on the central fossa of pontic by instron. SEM was used to identify the initial crack and characterize the fracture mode. Results: The results were as follows: 1. The mean fracture load of the non-lingual reinforcing group was 1212N and the lingual vertical 1mm reinforcing group was 1510N, the lingual vertical 2mm reinforcing group was 1882N, the lingual vertical 3mm reinforcing group was 1980N. 2. The reinforcing groups were statistically significant compared to non-reinforcing groups(P<0.001). 3. There were 2, 3mm reinforcing groups that were statistically significant compared to 1mm reinforcing groups(P<0.001), and the 3mm reinforcing group was not statistically significant compared to 2mm reinforcing groups(P>0.05) 4. Fractures were initiated in gingival embrasures of connectors and processed to the loading site. Conclusion: In this study, lingual reinforcement of connector for improved strength of zirconia based fixed partial denture is nessasary. And long-term study for clinical application is required

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.3
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• pp.196-207
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• 2018

An accurate implant placement with ideal location is significant for long-term success of the implant. An exact evaluation of nearby anatomic structures such as quality of residual bone, an inferior alveolar bone and a maxillary sinus is required. For a prosthetic-driven treatment, planned surgery, precise prosthesis and communication with the patient are significant requisites especially for full-mouth rehabilitation. In this case, the patient with severe alveolar bone resorption had a CT guided surgery supported by CT data and the data from scanning diagnostic wax-up. Afterward, edentulous area was restored by full mouth implant-supported prosthesis by using monolithic zirconia and CAD/CAM technique. This paper reports the outcome of the procedure which was remarkable both esthetically and functionally.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.233-238
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• 2020

PURPOSE. This study aims to compare the marginal fitness of two types of implant-supported fixed dental prosthesis, i.e., cementless fixation (CL.F) system and cement-retained type. MATERIALS AND METHODS. In each group, ten specimens were assessed. Each specimen comprised implant lab analog, titanium abutment fabricated with a 2-degree tapered axial wall, and zirconia crown. The crown of the CL.F system was retained by frictional force between abutment and relined composite resin. In the cement-retained type, zinc oxide eugenol cement was used to set crown and abutment. All specimens were sterilized with ethylene oxide, immersed in Prevotella intermedia culture in a 50 mL tube, and incubated with rotation. After 48 h, the specimens were washed thoroughly before separating the crown and abutment. The bacteria that penetrated into the crown-abutment interface were collected by washing with 500 µL of sterile saline. The bacterial cell number was quantified using the agar plate count technique. The BacTiter-Glo Microbial Cell Viability Assay Kit was used to measure bacterial adenosine triphosphate (ATP)-bioluminescence, which reflects the bacterial viability. The t-test was performed, and the significance level was set at 5%. RESULTS. The number of penetrating bacterial cells assessed by colony-forming units was approximately 33% lower in the CL.F system than in the cement-retained type (P<.05). ATP-bioluminescence was approximately 41% lower in the CL.F system than in the cement-retained type (P<.05). CONCLUSION. The CL.F system is more resistant to bacterial penetration into the abutment-crown interface than the cement-retained type, thereby indicating a precise marginal fit.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.136-142
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• 2014

Nowadays, dental zirconia is widely used as a framework material for a fixed dental prosthesis as well as a single restoration. However, clinical studies have reported high incidence of veneer chipping of zirconia-ceramic restorations compared to that of metal-ceramics. Several factors were raised as the possible causes of veneer ceramic chipping, however, it is still in debate. Recently, residual stresses in the veneer ceramics after cooling process gathers attention as one possible cause of chipping and many studies reported that the rate of cooling significantly influenced the types and the amount of residual stress. The purpose of current review was to briefly describe the effect of cooling rate on the residual stress in zirconia-ceramics. It was also described that the different behavior of residual stress between zirconia-ceramics and metal-ceramics following different cooling rate.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.237-249
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• 2023

Orofacial dystonia is a neuromotor disorder that causes irregular or repetitive movements of the face, lips, tongue, and jaw involuntarily, also called tic disorder. Edentulous patients with these symptoms experience functional and aesthetic problems, including difficulty using complete dentures, speech and swallowing difficulties, and orofacial pain. In this case, for a patient with orofacial dystonia who experienced complete edentulism at a relatively young age, restorative treatment was performed with a maxillary complete denture with bilateral posterior zirconia occlusal surfaces and a mandibular implant-supported fixed prosthesis, and continuous smile training was performed. The aim was to improve the aesthetics of facial muscles. As a result of the treatment, the patient was very satisfied with not only improved chewing function and aesthetics, but also regained psychological stability and was able to lead a normal daily life, so we would like to report this.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.51-57
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• 2015

When an implant-supported maxillary full-arch fixed prosthesis is planned for patients with the horizontal and vertical bone resorption induced by periodontal disease, it is necessary to consider the masticatory function, esthetics and phonetics when placing implants. For this reason, thorough clinical and radiological diagnosis is necessary. Extensive bone and soft tissue grafting may be required as well. Since there is no clear guideline for proper number of implants, segment or splinting of substructure and method of retaining prosthesis, these should be considered during diagnostic process. This clinical report describes a patient who has experienced several tooth extractions and periodontal treatment due to severe periodontitis on maxilla and mandible. With bone and soft tissue graft before dental implant placement, the patient have satisfactory result in esthetic and functional aspect with the implant-supported maxillary full-arch fixed prosthesis opposing mandibular natural dentition.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.1
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• pp.100-100
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• 2023