• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• Journal of Technologic Dentistry
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• v.33 no.3
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• pp.203-210
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• 2011

Purpose: The purpose of this study was to compare color correspondence of different sizes of Vita Mark II$^{(R)}$ and TriLuxe$^{(R)}$ Feldspar blocks. Methods: The three commercially available shades(1M2, 2M2, 3M2) of Mark II & TriLuxe blocks for the CEREC$^{(R)}$ CAD/CAM system were examined. For each of three colors, three different sizes were tested, 5 blocks each. The measurements were made using a spectrophotometer equipped with an integrating sphere using the CIE $L^*$, $a^*$, $b^*$ colorimetric system. Results: The $L^*$, $a^*$, $b^*$ value of Vita Mark II$^{(R)}$ ceramic block showed significantly higher than TriLuxe$^{(R)}$ ceramic block(p<0.05). In comparing the Vita Mark II$^{(R)}$ specimen of the three different shade, color differences between materials(${\Delta}E^*$) showed the lowest value of 2.09, and the highest was 2.24. ${\Delta}E^*$ values of the materials of Vita Mark II$^{(R)}$ were higher than 2. As the size of ceramic block differed, the color correspondence of Vita Mark II$^{(R)}$ showed statistically significant difference but, this result is clinically acceptable. Conclusion: All the different sizes of the different shades of Vita TriLuxe$^{(R)}$ blocks for the CEREC$^{(R)}$ system showed the high degree of color correspondence necessary in industrially prefabricated CAD/CAM blocks. The results of the present study suggested that it would be necessary to establish the reproducible and constant color specification system for an esthetic restoration.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.134-140
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• 2013

Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.269-279
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• 2008

STATEMENT OF PROBLEM: Recently, various all-ceramic crowns fabricated with CAD/CAM systems have come into wide use in dental clinic. However, there are only few domestic studies on CAD/CAM restorations. PURPOSE: Purpose of this study was to compare the fidelity (absolute marginal discrepancy and internal gap) between various cores fabricated with different CAD/CAM systems (Procera system, Lava system, Cerec inLab system) and conventional metal cast core. MATERIALS AND METHODS: 10 cores per each system were fabricated. The absolute marginal discrepancies were measured using measuring microscope and digital counter. The internal gaps were calculated using a silicone paste. The results were statistically analyzed using the one-way ANOVA test and Tukey's HSD test. RESULTS: Within the limits of this study the results were as follows. 1. The absolute marginal discrepancies were $32.5{\pm}3.7\;{\mu}m$ for metal cast core, $72.2{\pm}7.0\;{\mu}m$ for Procera core, $40.8{\pm}5.4\;{\mu}m$ for Lava core, and $55.3{\pm}8.7\;{\mu}m$ for Cerec inLab core. The internal gaps were $38.4{\pm}5.7\;{\mu}m$ for metal cast core, $71.4{\pm}5.3\;{\mu}m$ for Procera core, $45.9{\pm}7.3\;{\mu}m$ for Lava core, and $51.8{\pm}6.2\;{\mu}m$ for Cerec inLab core. 2. The fidelity of metal cast core showed the smallest gaps, followed by Lava core, Cerec inLab core, and Procera core. CONCLUSION: The fidelities of 4 core groups were all within the clinically acceptable range ($120\;{\mu}m$).

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.3
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• pp.263-269
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• 2011

The digital impression technique has been developed for more precise restorations and convenient procedures in prosthodontic treatment compared to the conventional impression technique. Along with the utilization of CAD/CAM, the introduction of digital impression technique actualizes the digitalization of dental treatments. This case is to compare two different prostheses introducing each procedure in detail; one from CAD/CAM after taking digital impression and the other from the conventional technique. A 22-year-old female visited the clinic with the chief complaint of correction of discoloration and shape on maxillary right central incisor. Due to the trauma 8 years ago, the tooth was endodontically treated with post and resin core. The treatment was planned and the procedures were conducted under the patient's consent to treat the tooth with all ceramic crowns in two different ways for comparison. In conclusion, both prostheses presented clinically acceptable results with comparing the internal fitness of two all ceramic crowns. The prosthesis from digital impression, however, showed more errors in respect of internal fitness.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.53-60
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• 2009

Statement of problem: At present, as the esthetic demands are on the increase, there are many ongoing studies for tooth-colored post and cores. Most of them are about fiber post and prefabricated zirconia post, but few about one-piece milled zirconia post and core using CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Purpose: The objective of this study was to compare microleakage of endodontically treated teeth restored with three different tooth-colored post and cores. Material and methods: Extracted 27 human maxillary incisors were cut at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 3 groups (n=9); restored with fiber post and resin core, prefabricated zirconia post and heat-pressed ceramic core, and CAD/CAM milled zirconia post and core. After the preparation of post space, each post was cemented with dual-polymerized resin cement (Variolink II). Teeth were thermocycled for 1000 cycles between $5-55^{\circ}C$ and dyed in 2% methylene blue at $37^{\circ}C$ for 24 hours. Teeth were sectioned (bucco-lingual), kept the record of microleakage and then image-analyzed using a microscope and computer program. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: All groups showed microleakage and there were no significant differences among the groups (P>.05). Prefabricated zirconia post and heat-pressed ceramic core showed more leakage in dye penetration at the post-tooth margin, but there was little microleakage at the end of the post. Fiber post and resin core group and CAD/CAM milled zirconia post and core group indicated similar microleakage score in each stage. Conclusion: Prefabricated zirconia post and heat-pressed ceramic core group demonstrated better resistance to leakage, and fiber post and resin core group and CAD/CAM milled zirconia post and core group showed the similar patterns. The ANOVA test didn't indicate significant differences in microleakage among test groups. (P>.05)

• The Journal of the Korean dental association
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• v.50 no.3
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• pp.126-139
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• 2012

Loss of dentition can lead to not only compromised esthetics and functions of the patient, but also alveolar bone resorption. Bone grafting with prosthetic reconstruction of the gingiva can be selected for the treatment, and it provides many benefits as prosthetic gingival reconstruction does not require a complicated surgical process and is available within a short period of time, with stable clinical results. However, conventional porcelain fused to metal prosthesis has certain limits due to its size, and deformation after several firing procedures. In this clinical report, the author would like to introduce a patient with severe alveolar resorption who was treated with gingiva-shaped zirconia/titanium CAD/CAM implant fixed prosthesis for esthetic and functional rehabilitation. Clinical reports Clinical report 1, 2 : A case of loss of anterior dentition with atrophied alveolar bone. Implant retained zirconia bridge applied with Procera implant bridge system to simulate the gingiva. Upper structure was fabricated with zirconia all ceramic crown. Clinical report 3, 4 : A case of atrophied maxillary alveolus was reconstructed with fixed implant prosthesis, a CAD/CAM designed titanium structure covered wi th resin on its surface. Anterior dentition was reconstructed with zirconia crown. Conclusion and clinical uses. All patients were satisfied with the outcome, and maintained good oral hygiene. Zirconia/titanium implant fixed prosthesis fabricated by CAD/CAM system was highly accurate and showed adequate histological response. No critical failure was seen on the implant fixture and abutment overall. Sites of severe alveolar bone loss can be rehabilitated by implant fixed prosthesis with CAD/CAM system. This type of prosthesis can offer artificial gingival structure and can give more satisfying esthetics and functions, and as a result the patients were able to accept the outcome more fondly, which makes us less than hard to think that it can be a more convenient treatment for the practitioners.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.140-149
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• 2020

PURPOSE. This study evaluated the color stabilities of two computer-aided design and computer-aided manufacturing (CAD/CAM) blocks and a nanofill composite resin and the microtensile bond strength (µTBS) between the materials. MATERIALS AND METHODS. Twelve specimens of 4 mm height were prepared for both Lava Ultimate (L) and Vita Enamic (E) CAD/CAM blocks. Half of the specimens were thermocycled (10,000 cycle, 5° to 55℃) for each material. Both thermocycled and non-thermocycled specimens were surface treated with one of the three different methods (Er,Cr:YSGG laser, bur, or control). For each surface treatment group, one of the thermocycled and one of non-thermocycled specimens were restored using silane (Ceramic Primer II), universal adhesive (Single Bond Universal), and nanofill composite resin of 4-mm height (Filtek Ultimate). The other specimens were restored with the same procedure without using silane. For each group, 1 × 1 × 8 mm bar specimens were prepared using a microcutting device. Bar specimens were thermocycled (10,000 cycle, 5° to 55℃) and microtensile tests were performed. Staining of the materials in coffee solution was also compared using a spectrophotometer. Data were analyzed using one-way ANOVA, t-test and post-hoc Scheffe tests. RESULTS. µTBS were found similar between the thermocycled and non-thermocycled groups (P>.05). The highest µTBS (20.818 MPa) was found in the non-thermocycled, bur-ground, silane-applied E group. Silane increased µTBS at some E groups (P<.05). Composite resin specimens showed more staining than CAD/CAM blocks (P<.05). CONCLUSION. CAD/CAM blocks can be repaired with composite resins after proper surface treatments. Using silane is recommended in repair process. Color differences may be shown between CAD/CAM blocks and the nanofill composite after a certain time period.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.111-123
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• 2006

A Study on the Fracture Strength of All-Ceramic Crown according to the Zirconia Coping Design using CAD/CAM System L. Bulgan, In-Ho Cho, Soo-Yeon Shin Department of Prosthodontics, Graduate School, Dankook University The fracture strength of prosthesis is important, because it affects the function, and long term success of prosthesis and teeth. The purpose of this study was to compare the fracture strength of zirconia coping designs. Experimental test group were classified into three designs according to coping design, Modified design: Zirconia coping margin was located at 1mm above the axiogingival line angle. Collarless design: The coping margin terminated at the axiogingival line angle Butt design: The coping margin was extended to the finishing line of prepared margin. A $Cercon^{(R)}$(Degussa, Germany) CAD/CAM system was used to make the zirconia coping. Fracture strength was measured using loading machine at a cross head speed of 1mm/min. The results were statistically analyzed using the one-way ANOVA and multiple comparison test. Statistical significance was set in advance at the probability level of less than 0.05. The result : I. Collarless($738N{\pm}155N$) and Modified($755N{\pm}185N$) groups showed significantly a lower fracture strength than Butt($1057N{\pm}262N$) group(p<0.05). II. There were no statistical differences of the fracture strength between Modified($755N{\pm}185N$) and Collarless($738N{\pm}155N$) groups. III. When comparing the fractured surface, all the group showed porcelain fracture, which were fractured at the labial surface of baked porcelain The butt design of the zirconia coping has higher fracture strength than modified and collarless design.

• The Journal of Advanced Prosthodontics
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• v.4 no.3
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• pp.162-169
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• 2012

PURPOSE. Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques. MATERIALS AND METHODS. A 1.2 mm, $360^{\circ}$ chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely $X^{TM}$ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (${\alpha}$= 0.05). Scanning electron microscope was used to investigate the fractured interface. RESULTS. Mean fracture load and standard deviation was $4263.8{\pm}1110.8$ N for Group LT, $5070.8{\pm}1016.4$ for Group HT and $6242.0{\pm}1759.5$ N for Group ST. The values of Group ST were significantly higher than those of the other groups. CONCLUSION. Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength.