• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.148-155
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• 2009

Statement of problem: The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems there is a need to evaluate the quality levels of these new fabrication techniques. Purpose: This study is to evaluate the crown fidelity(absolute marginal discrepancy and internal gap) of various zirconia-based all-ceramic crowns fabricated with different CAD/CAM(computer-assisted design/computer-assisted manufacturing) systems and conventional cast metal-ceramic crowns. Material and methods: A resin tooth of lower right second premolar was prepared. After an impression was taken, one metal master die was made. Then 40 impressions of metal master dies were taken for working dies. 10 crowns per each system were fabricated using 40 working dies. Metal-ceramic crowns were cast by using the conventional method, and Procera, Lava, and Cerec inLab crowns were fabricated with their own CAD/CAM manufactruing procedures. The vertical marginal discrepancies and internal gaps of each crown groups were measured on a metal master die without a luting agent. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test. Results: 1. Vertical marginal discrepancies were $50.6{\pm}13.9{\mu}m$ for metal-ceramic crowns, $62.3{\pm}15.7{\mu}m$ for Procera crowns, $45.3{\pm}7.9{\mu}m$ for Lava crowns, and $71.2{\pm}2.0{\mu}m$ for Cerec inLab crowns. 2. The Internal gaps were $52.6{\pm}10.1{\mu}m$ for metal-ceramic crowns, $161.7{\pm}18.5{\mu}m$ for Procera crowns, $63.0{\pm}10.2{\mu}m$ for Lava crowns, and $73.7{\pm}10.7{\mu}m$ for Cerec inLab crowns. Conclusion: 1. The vertical marginal discrepancies of, 4 crown groups were all within the clinically acceptable range($120{\mu}m$). 2. The internal gaps of LAVA, Cerec inlab, and metal-ceramic crowns were within clinically acceptable range except Procera crown($140{\mu}m$).

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.132.2-132
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• 2003

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4329-4335
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• 2014

This study examined the effects of the shear bond strength when the surface condition of the metal and zirconia, each being the lower structures, was different when determining the bond strength (metal group) of the metal lower structure with upper ceramics, and the shear bond strength (zirconia group) of zirconia lower structure with the upper ceramics in prosthetic appliances of metal-ceramic crown and zirconia-ceramic crowns. The metal groups were divided into a total of four groups: the group with no condition on the metal surface(NM), the group with sand-blasting(SM), the group with applied opaque ceramics(OM), and the group with applied opaque ceramics and sand-blasting(SOM). The zirconia groups were also separated into four groups: the group with no condition(NZ), the group with sand-blasting(SZ), the group treated with ZirLiner on the zirconia surface(LZ), and the group applied with ZirLiner along and sand-blasting(SLZ). To examine the effects on the shear bond strength according to the surface condition of each of the four metal and zirconia groups, SPSS was used to conduct one-way ANOVA. For metal-ceramic crowns, it would be best to apply opaque ceramics after sand-blasting on the surface of the metal, the lower structure. For zirconia-ceramic crowns, it is recommended to apply the ZirLiner after sand-blasting on the surface of zirconia, the lower structure.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.136-143
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• 2004

The purpose of this study was to investigate the relationship between morphology and position of deciduous double teeth, and the occurrence of other dental anomalies in the same subject. Four morphological types were indentified according to Ailing's classification: type I, bifid crown-single root; type II, large crown-large root; type III, two fused crowns-single root; type IV, two fused crowns-two fused roots. Fifty-four double teeth were found in a total of 1,803 children, who had visited Wonkwang university hospital for dental treatment from January 1, 2003 to September 30, 2003. All of these children were examined clinically and intra-oral radiographs were taken. The results were as follows; 1. 49 children(2.7%) had more than one double teeth, 5 of these children had two double teeth on the bilateral side. And one child showed triple teeth which has three crowns and three roots. 2. Double teeth were predominantly situated in the anterior region, with a preference for the mandible. The ratio of cases involving central incisor and lateral incisor was higher than other cases. 3. There were 25 cases(46.2%) of missing successors among 54 cases of the double teeth. And, prevalence of the missing teeth was highest in the cases involving maxillary central incisor and lateral incisor. 4. In the case of type II(large crown-large root) had more missing successors.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.3
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• pp.359-367
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• 1994

The number and the distribution of fixed restorations including crowns, fixed bridges, Maryland bridges, periodontal splints and cast cores were statistically investigated with two thousand seven hundred and thirty cases of crowns and bridges placed at the Department of Prosthodontics of Seoul National University Hospital, from January 4th to December 31st, 1988. The results were as follow : 1. Among the fixed restorarions, single crowns were 46.9% , fixed bridges were 41.9%, Maryland bridges were 5.0%, periodontal splints were 0.6% and cast cores were 5.6%. 2. Three thousand nine hundred and ninty two teeth were restored with the fixed restorations, among them cast gold restorations were 47.2% and metal-ceramic restorations were 52.8%. 3. Cast gold restorations of the maxillary posteriors occupied 98.5% of the maxillary cast gold restorations, and 99.7% of the mandibular cast gold restorations and metal-ceramic restoration of maxillary anteriors occupied 68.4% of the maxillary metal-ceramic restorations, and 38.7% of the mandibular metal- ceramic restorations. 4. It is recommended that the curriculum of the dental school for undergraduated students and graduated students should be changed to accomodate the relative importance of the restorations.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.4
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• pp.317-323
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• 2003

When making crown and bridges on anterior regions, many practitioners consider the esthetics the most. For this reason functional aspect are not considered as much as the esthetics. If the occlusion on the anterior region are not formed correctly, movement of the temporomandibular joint can be disturbed and excessive stress can be occur that pathologic condition can be under lied. On this case presentation will show the importance of the anterior guidance and suggest the appropriate protocol of using customized anterior guide table. A 45years old male had to remake both of the upper central and lateral PFM because of the porcelain fracture. The new PFM crowns were made conventional methods without considering the anterior guidance. After the temporary setting, the patient complained of discomfort and short looking upper anteriors. To solve these problems we had to restore the palatal contour and length of the new crowns by making customized anterior guide table using temporary crowns that contains patient's old anterior guidance. This procedure which is copying the pt's comfortable anterior guidance to the final prosthesis made them to be esthetic and patients to feel comfortable.

• The Journal of Advanced Prosthodontics
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• v.7 no.4
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• pp.329-337
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• 2015

PURPOSE. This retrospective study aims at the evaluation of implant-supported overdentures (IODs) supported by ceramo-galvanic double crowns (CGDCs: zirconia primary crowns + galvano-formed secondary crown). MATERIALS AND METHODS. In a private practice, 14 patients were restored with 18 IODs (mandible: 11, maxilla: 7) retained by CGDCs on 4 - 8 implants and annually evaluated for technical and/or biological failures/complications. RESULTS. One of the 86 inserted implants failed during the healing period (cumulative survival rate (CSR) implants: 98.8%). During the prosthetic functional period (mean: $5.9{\pm}2.2years$), 1 implant demonstrated an abutment fracture (CSR-abutments: 98.2%), and one case of peri-implantitis was detected. All IODs remained in function (CSR-denture: 100%). A total of 15 technical complications required interventions to maintain function (technical complication rate: 0.178 treatments/patients/year). CONCLUSION. Considering the small sample size, the use of CGDCs for the attachment of IODs is possible without an increased risk of technical complications. However, for a final evaluation, results from a larger cohort are required.

• The Journal of Advanced Prosthodontics
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• v.14 no.1
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• pp.56-62
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• 2022

PURPOSE. The aim of this study was to investigate shade changes in fully- and pre-crystalized CAD-CAM lithium disilicate crowns after the required and additional firing processes. MATERIALS AND METHODS. One hundred and five crowns of shade A1 with high translucency were milled out of CAD-CAM lithium disilicate blocks and categorized as follows (n = 15): (1) restorations fabricated from Straumann n!ce with no additional sintering process; (2) restorations fabricated from Straumann n!ce with one additional sintering process; (3) restorations fabricated from Straumann n!ce with two additional sintering processes; (4) restorations fabricated from Amber Mill with one sintering process; (5) restorations fabricated from Amber Mill with two sintering processes; (6) restorations fabricated from IPS e.max CAD with one sintering process; (7) restorations fabricated from IPS e.max CAD with two sintering processes. All restorations were evaluated with a color imaging spectrophotometer. RESULTS. All restorations presented some color alteration from the original shade both after a single and after two firing processes. CONCLUSION. The required and additional sintering processes for restorations fabricated with chairside CAD-CAM lithium disilicate blocks cause an alteration of the original shade selected. Shade A1 high translucency restorations tend to change to a more yellowish B1 shade after a sintering process.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.60-69
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• 2016

Complicated crown-root fracture of permanent incisors cause esthetic, functional, and psychological problems to patients. Therefore, treatment is important and multidisciplinary treatment is required. This case report describes the clinical procedures involved in the treatment of trauma-induced complicated crown-root fractures in the maxillary incisor of two young patients. Conventional root canal treatment and apexification were performed in each patient. To expose the fracture margins to the supragingival level and to reestablish the biologic width, orthodontic extrusions with fixed appliances were performed followed by a retention period. During the retention period, fiber-optic posts and cores were built up and provisional crowns were placed. Finally, ceramic crowns manufactured using a computer-aided design/computer-aided manufacturing (CAD/CAM) system were placed. In both patients, the teeth presented satisfactory functional and esthetic outcomes without relapse. The periodontal tissues were healthy.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.57-63
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• 2008

The purpose of this study was to ascertain the effect of different abutment height and different taper of abutment on retention force of cemented implant-supported prostheses. Test specimens consisted of different abutment height group(3mm, 4mm, 5mm, 6mm, 7mm) and different taper(degrees) abutment group($4^{\circ},\;5^{\circ},\;6^{\circ},\;7^{\circ},\;8^{\circ}$). The surfaces of abutments and crowns were manufactured and finished by automatic lathe(CNC). Luting cement(Tokuso Ionomer) was prepared according to the manufacturer's instruction. And the cylinders were sealed onto the abutments and loaded in compression at 5kg for 10minutes. Excess cement was removed from the abutment-cylinder junction and the specimens were stored at room temparature for 24 hours. Specimens were tested in tension using a universal testing machine. Within the limits of this study, the following conclusions were drawn: 1. The increase in abutment height result in improvement in retention strength(P<0.05). 2. The increase in taper of abutment result in decrease in retention strength(P<0.05). 3. The decrease in abutment height result in decrease in retention strength, besides has a significantly lower retention strength at 3mm abutment height. 4. The increase in taper of abutment result in decrease in retention strength, besides has a significantly lower retention strength at $7^{\circ}$ abutment.