• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.235-242
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• 2012

Purpose: The purpose of this study was to compare the fracture behavior of Zironia, glass infiltrated Alumina and PFM full crown system. Materials and methods: Fifteen crowns for each of 3 experimental groups (Zironia, glass infiltrated Alumina and PFM full crown) were made by the conventional method. The crowns mounted on the testing jig were inclined in 30 degrees to the long axis of the tooth and the universal testing machine was used to measure the fracture strength. Results: 1. The mean fracture strengths were $588.3{\pm}49.6MPa$ for zirconia system, $569.1{\pm}61.8MPa$ for PFM system and $551.0{\pm}76.5MPa$ for glass-infiltrated alumina system (P>.05). 2. The mean shear bond strengths were $25.5{\pm}5.6MPa$ for zirconia system, $38.9{\pm}5.0MPa$ for Ni-Cr alloy system and $39.4{\pm}5.1MPa$ for glass-infiltrated alumina system. 3. The chemical bonding was observed at interfaces between PFM or glass-infiltrated alumina and veneering porcelain, however, no chemical bonding was observed at interface between zirconia and veneering porcelain. Conclusion: With the study, the fracture strengths of PFM crown system had a higher fracture strength than conventional zirconia system crown and glass-infiltrated alumina crowns. and than the shear bond strengths glass-infiltrated alumina system had a higher shear bond strength than conventional PFM system and zirconia system.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.5
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• pp.493-506
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• 2002

Recently as the esthetic concerns about dental prosthesis have been increased, the nonmetallic post and core systems have been introduced clinically to improve the color and the low optical transmittance of conventional casting metal post and core systems. The purpose of this study was to compare and analyze the optical transmittance and the shade changes of all-ceramic crowns with two nonmetallic post and core systems. The experimental groups were classified as follows : Total 27 specimens(9 samples in each group) were evaluated. Group I : Natural teeth as a control group Group II : CosmoPost and $Empress^{(R)}$ core (Ivoclar-Vivadent, Liechtenstein) Group III : $LIGHT-POST^{TM}$ and $LIGHT-CORE^{TM}$ (Bisco, U.S.A.) In all group, all-ceramic crowns were fabricated with the same shade of IPS $Empress^{(R)}$ II (Ivoclar-Vivadent, Liechtenstein) after abutment preparation, and then two kinds of spectrophotometers, UV 3101 PC (Shimadzu, Japan) and CM 503i (Minolta Co. Ltd. Japan), were used to measure the optical transmittance and the color value. The following results were obtained : 1. The optical transmittance of each group without all-ceramic crowns, was siginificantly decreased in order of Group III, I and II (p<0.05). 2. The optical transmittance of each group with all-ceramic crowns cemented, were siginificantly decreased in order of Group I, II and III (p<0.05). 3. In comparison with the shade of all-ceramic crowns, there were no significant differences between groups regardless of the cementation. 4. In comparison with the shade changes in each group after the cementation of all-ceramic crowns, there were no significant differences between groups. From the above results, it is thought that the selection among materials used in this study doesn't influence greatly the esthetic restoration, because the differences of optical transmittance were so small that those were clinically insignificant.

• Journal of Technologic Dentistry
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• v.45 no.1
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• pp.1-7
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• 2023

Purpose: To evaluate the marginal and internal fit of metal coping fabricated by a metal three-dimensional (3D) printer that uses selective laser melting (SLM). Methods: An extraoral scanner was used to scan a die of the prepared maxillary right first molar, and the coping was designed using computer-aided design software and saved as an stereo lithography (STL) file. Ten specimens were printed with an SLM-type metal 3D printer (SLM group), and 10 more specimens were fabricated by casting the castable patterns output generated by a digital light processing-type resin 3D printer (casting the 3D printed resin patterns [CRP] group). The fit was measured using the silicon replica technique, and 8 points (A to H) were set per specimen to measure the marginal (points A, H) and internal (points B~G) gaps. The differences among the groups were compared using the Mann-Whitney U-test (α=0.05). Results: The mean of marginal fit in the SLM group was 69.67±18.04 ㎛, while in the CRP group was 117.10±41.95 ㎛. The internal fit of the SLM group was 95.18±41.20 ㎛, and that of the CRP group was 86.35±32 ㎛. As a result of statistical analysis, there was a significant difference in marginal fit between the SLM and CRP groups (p<0.05); however, there was no significant difference in internal fit between the SLM group and the CRP group (p>0.05). Conclusion: The marginal and internal fit of SLM is within the clinically acceptable range, and it seems to be applicable in terms of fit.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.21-28
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• 2009

Purpose: The purpose of this study was to compare the wear characteristics of human enamel opposing 2 heat-pressed ceramics (e.max Press and Empress Esthetic), conventional feldspathic porcelain (Ceramco 3) and type III gold alloy. Material and methods: Intact cusps of extracted premolars were used for enamel specimens. Five disk samples were made for each of two heat-pressed ceramics groups, conventional feldspathic porcelain group and type III gold alloy group. Wear tests were conducted in distilled water using a pin-on-disk tribometer. The amount of enamel wear was determined by weighing the enamel specimens before and after wear tests, and the weight was converted to volumes by average density. The wear tracks were analyzed by scanning electron microscopy and surface profilometer to elucidate the wear characteristics. Results: 1. Ceramco 3 led to the greatest amount of enamel wear followed by Empress Esthetic, e.max Press and type III gold alloy. However, there was no significant difference between Ceramco 3 and Empress Esthetic (P>.05), and there were also no significant differences among Empress Esthetic, e.max Press and type III gold alloy (P>.05). 2. The average surface roughness of e.max Press after wear test was smallest followed by Empress Esthetic and Ceramco 3, but there was no significant difference between Empress Esthetic and Ceramco 3 (P>.05). 3. There were no significant differences among the depth of wear tracks of all the groups (P>.05). The group that showed the largest width of wear track was Ceramco 3 followed by Empress Esthetic, e.max Press and type III gold alloy. However, there was no significant difference between e.max Press and Empress Esthetic (P>.05), and there was also no significant difference between Empress Esthetic and Ceramco 3 (P>.05). Conclusion: Within the limits of this study, heat-pressed ceramics were not more abrasive than conventional feldspathic porcelain.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.1
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• pp.1-17
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• 2008

The purpose of this study were to report the reasons for removal of fixed prostheses and survival rate of abutment teeth. A total 192 fixed prostheses removed at Chosun university Dental Hospital and 308 abutment were investigated. The most frequent reason of removal was periodontal problem(30.7%), followed by caries(29.7%), then periapical problem(18.8%) and defective margins(14%). In metal ceramic crown, periodontal problem was the most frequent reason of removal. In complete cast crown, caries was the most frequent reason of removal. Periapical and periodontal problem was the most frequent reason people under forties and over fifties, respectively. Of the 308 abutment teeth, vital and non-vital teeth were 135(43.8%) and 173(56.2%), respectively. Of 135 vital abutment teeth, 39(28.9%) were extracted and of 173 non-vital abutment teeth, 85(49.1%) were extracted. Each risk factor for removal of fixed prostheses and extraction of abutment should be evaluated more clearly for prediction of prognosis of final prostheses and abutment teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.191-197
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• 2012

Esthetics is important in restoring maxillary anterior area. Alveolar bone resorption and loss of interdental papilla may be minimized by immediate implantation. Previous studies showed successful results with the immediate implantation in healthy extraction socket, while many of these studies objected the immediate implantation into extraction sites with periapical lesions. Recent studies, however, reported successful results of the immediate implantation into extraction sites with periapical lesions with careful debridement of extraction sockets and general medication of antibiotics prior to implantation. A 73-year-old female visited the department of Prosthodontics in ${\bigcirc}{\bigcirc}$ University Dental Hospital with the chief complaint of fallen post-core and crown on left maxillary incisor. Although the incisor was with vertical root fracture and periapical lesion, the immediate implantation following the extraction of tooth was planned. Thorough socket debridement, irrigation with chlorhexidine, and tetracycline soaking were followed by immediate implantation. The general medication of antibiotics (Moxicle Tab.$^{(R)}$, 375 mg) was prescribed before and after the surgery. Immediate provisional restoration was delivered two days after the surgery, and the definitive metal-ceramic restoration was placed about six months later after reproducing the emergence profile from the provisional restoration. This case presents satisfying result esthetically and functionally upto two years after the placement of prosthesis with the harmonious gingival line and no loss of marginal bone.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.47-51
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• 2013

With the introduction of dental implants, restoration of missing teeth with conventional fixed or removable partial dentures is being replaced with implants. Especially, with young patients, not only longevity but also esthetic factors need to be considered. Implant restorations provide long-term success functionally but, esthetic complications such as, marginal exposure due to gingival recession, loss of the papilla and dark color of metal abutments may occur. Recently, zirconia restorations with CAD/CAM technology provide functional, biocompatible and esthetic restorations possible. All-ceramic restorations using the pressed ceramic technique show better fracture toughness values than those of the conventional porcelain veneering technique. Pressed ceramic technique creates the veneer design in wax and the lost wax technique is used to create the restoration. The final contour of the restoration may be controlled during wax-up. A 22-year old female patient was restored with dental implants and zirconia restorations using the pressed ceramic technique presenting short-term but optimistic prognosis.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.215-226
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• 2023

Severe wear of the anterior teeth facilitates the loss of anterior guidance, which protects the posterior teeth from wear during excursive movement. Additionally, when treating patients with collapsed occlusion due to multiple tooth loss and tooth wear, it is important to determine the presence of vertical dimension loss through accurate clinical and radiographic examinations and diagnostic wax-up. The patient of this case is a 44-year-old female patient who complained of overall tooth wear and loss of posterior teeth due to bruxism and clenching habits, visited the hospital with the address of restoring masticatory function and improving aesthetic appearance through prosthetic treatment. Through model analysis and diagnostic wax-up, an increase in vertical dimension was determined, and full mouth restoration with fixed prostheses was planned. The degree of adaptation to the vertical dimension was confirmed step by step using an occlusal splint designed with CAD (Computer aided design) software and 3-D (3-Dimensional) printed, and then restored with provisional restoration and after a 4-month adaptation period, the entire dentition was restored with metal ceramic crowns and implants. Through this procedure, satisfactory treatment results were obtained in terms of function and aesthetics.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.33-38
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• 2013

Occlusal plane is a sagittal expression of dental arch form, and it composes the shape of occlusion, which is one of the most important elements of Maxillo-oral system. In this case, vertical, horizontal coordinates of bionic-median-sagittal plane was produced in articulator, and to achieve relation of left and right position of upper, lower teeth and deficits in alveola, Shilla system was used to reconstruct occlusal plane. In this case, a 41 year-old male patient visited for fracture of 10 unit metal-ceramic fixed partial denture of upper anterior teeth and for overall treatment. Clinical, radiographical, model examination was held, full mouth rehabilitation was achieved by placing dental implant. Maxillo-oral relation was recorded using Gothic arch Tracer complex and were mounted. And for the next step, we estimated original occlusal plane using Shilla system. After analysis we produced diagnosis wax pattern. On the basis of this, radiography stent was manufactured and dental implant was placed, and temporary prosthesis was made by using diagnosis wax pattern. Cross mounting and anterior guiding table were performed in order to reproduce temporary restoration morphology and bite pattern, followed by final restoration made of all ceramic crown with zirconia coping. As stated above, appropriately esthetic and functional results can be seen in using Shilla system in diagnosis and treatment procedure of full mouth rehabilitation patient.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.5
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• pp.477-491
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• 2001

The purpose of this study is to compare and analyze the shade changes(${\Delta}E^*$) about $In-Ceram^{(R)}$, $IPS-Empress^{(R)}$, $OPC^{(R)}$ by using of the spectrophotometer arising from inital status and before and after cementation of the resin cement mounted on the metal core. We used a couple of statistics such as 'One- Way ANOVA' and 'Multiple Range Test.' We could be able to verify significantly what is being discussed here up to 95%. The results drawn from our research are as follows : 1. At the time of our experiments regarding the initial shapes of all-ceramic and mounting status of all-ceramic on the metal crown(${\Delta}E^*1$), and a comparison of mounting of all ceramic on the metal crown with all-ceramic cemented on the metal core(${\Delta}E^*2$), at the time of shade change of initial shapes and after we cemented on the metal core. (1) no significant difference among all-ceramics was found. (2) no particular difference was found regarding the $In-Ceram^{(R)}$. (3) a significant difference between the ${\Delta}E^*1$ and ${\Delta}E^*2$ regarding the $IPS-Empress^{(R)}$ was found(P<0.05). (4) a significant difference between the ${\Delta}E^*1$ and ${\Delta}E^*2$ regarding the $OPC^{(R)}$ was found(P<0.05). 2. When we compared the shade changes(${\Delta}E^*$) resulted from before and after the cementation on each of the parts involved of some all-ceramic, we could be able to find shade change increase form incisal third, middle third. and cervical third in that order in $In-Ceram^{(R)}$(spinell), IPS $Empress^{(R)}$, and $OPC^{(R)}$ all. In addition. we could be able to find a significant difference between cervical third and incisal third, middle third. (P<0.05) From what we have just seen, we might conclude that there is a significant shade change difference before and after the cementation with respect to $IPS-Empress^{(R)}$ and $OPC^{(R)}$. In addition, we could also be able to find more shade change difference at the cervical third rather than incisal third and middle third depending on the parts involved.