• The Journal of Advanced Prosthodontics
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• v.10 no.3
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• pp.197-204
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• 2018

PURPOSE. To determine the extent of treatment traces, the roughness depth, and the quantity of titanium nitride (TiN) removed from the surface of CAD/CAM abutments after treatment with various instruments. MATERIALS AND METHODS. Twelve TiN coated CAD/CAM abutments were investigated for an in vitro study. In the test group (9), each abutment surface was subjected twice (150 g vs. 200 g pressure) to standardized treatment in a simulated prophylaxis measure with the following instruments: acrylic scaler, titanium curette, and ultrasonic scaler with steel tip. Three abutments were used as control group. Average surface roughness (Sa) and developed interfacial area ratio (Sdr) of treated and untreated surfaces were measured with a profilometer. The extent of treatment traces were analyzed by scanning electron microscopy. RESULTS. Manipulation with ultrasonic scalers resulted in a significant increase of average surface roughness (Sa, P<.05) and developed interfacial area ratio (Sdr, P<.018). Variable contact pressure did not yield any statistically significant difference on Sa-values for all instruments (P=.8). Ultrasonic treatment resulted in pronounced surface traces and partially detachment of the TiN coating. While titanium curettes caused predominantly moderate treatment traces, no traces or detectable substance removal has been determined after manipulation with acrylic curettes. CONCLUSION. Inappropriate instruments during regular plaque control may have an adverse effect on the integrity of the TiN coating of CAD/CAM abutments. To prevent defects and an increased surface roughness at the transmucosal zone of TiN abutments, only acrylic scaling instruments can be recommended for regular maintenance care.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.444-450
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• 2017

Prosthetic decision-making is complex because of various factors, and involves a combination of the individual dentist's interpretation of the objective clinical data and his or her interaction with the patient. Increasing therapeutic options and emerging outcome data demand the constant re-evaluation of our decision-making process. In this case, fixed prosthetic restorations were selected as a treatment method to reconstruct the occlusal plane of a patient with disharmonious occlusal plane. And the occlusal plane was re-established by establishing a treatment plan through diagnostic wax-up. Provisional restorations obtained by continuous re-evaluation for a sufficient period of time was replicated to definitive restorations using CAD/CAM technology. The results were satisfactory when they were observed through clinical follow-up for 3 months after the end of treatment.

• 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.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.243-253
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• 2009

This report described a technique utilizing a computer-aided design (CAD) /computer-aided machining (CAM) - guided surgical implant placement and prefabricated fixed complete denture for an immediately loaded restoration. A patient with an edentulous maxilla and mandible received 6 implants in maxilla and 6 implants in the mandible using CAD/CAM surgical templates. Prefabricated provisional maxillary and mandibular implant supported fixed prostheses were connected immediately after implant installation. Provisional prostheses were evaluated for aesthetics, function during 6 months. Definitive prostheses were fabricated.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.271-278
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• 2018

PURPOSE. The purpose of this in vitro study was to evaluate the effect of abrasive toothbrushing on the surface properties of monolithic computer-assisted design and computer-assisted manufacturing (CAD/CAM) materials stored in food-simulating liquids (FSLs). MATERIALS AND METHODS. Fourty-eight disk-shaped test specimens of each material (Paradigm MZ100/PMZ, Lava Ultimate/LU, Vita Enamic/VE, and Vita Mark II/VMII) with a diameter of 10.0 mm and a thickness of $3.0{\pm}0.05mm$ were prepared. Specimens were divided into 4 subgroups (n=12) and stored in air, distilled water, 0.02 M citric acid, or 75% ethanol/water solution for 7 days at $36.5^{\circ}C$. Then, the specimens were brushed in a multi-station brushing machine under a vertical load of 2.0 N for 3 hours. Surface gloss (GU), roughness (Ra), and hardness (Vickers [VHN]) were measured after storage and brushing simulation. The data sets were statistically analyzed with 2 and 3-way ANOVAs followed by the Tukey's post-hoc comparisons (${\alpha}=.05$). RESULTS. Statistically significant difference was found among the materials concerning the results of surface properties. VMII showed the highest VHN, while PMZ produced the lowest. Storage in FSLs significantly affected the VHN of PMZ and LU. VMII showed the lowest Ra and highest GU irrespective of FSLs and of abrasive toothbrushing. VE, LU, and PMZ produced significant decrease in GU and increase in Ra after toothbrushing. CONCLUSION. Surface properties of monolithic CAD/CAM restorative materials were differently affected by the storage media and abrasive toothbrushing.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.317-325
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• 2010

Purpose: The aim of this study is to make some basic materials to find retention force difference based on the total height of CAD/CAM zirconia abutment used for implant, retention force difference based on how to regulate the height of the abutment, retention force difference based on the size and retention force difference based on the design group. Methods: The retention force was measured by being pulled at the speed of 1mm/min after being combined with zirconia block and abutment using Temp-BOND of Kerr. The experiment was done at the research lab of OSTEM in Busan by useing UNIVERSAL TESTING MACHINE on March 3rd, 2010. Results: After analysing the total height and the retention force, p-value had minor difference by 0.01 statistically. Namely, 3mm, 4mm, 5mm had the retention force difference and we could see retention force difference on 3mm and 5mm at the post test. After analyzing how to regulate the height and retention force, p-value had minor difference by 0.000 statistically. Namely, 1mm and 2mm had the retention difference and we could see that 1mm and 2mm with the total height had retention difference. After analyzing the retention force based on the size, p-value had minor retention force difference by 0.000 statistically. Namely, 7 different size had retention force difference and we could see the size 21.9mm, 32.9mm, 32.9mm, 38.4mm, 48.9mm and 54.9mm had retention force difference. Conclusion: Namely 9 different design group had retention difference and we could see that 9 design group with 5.6.7.8 design group and 9 design group with 1.2.3.4. design group had retention force.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.335-339
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• 2018

PURPOSE. The purpose of the present study was to compare scanning trueness and precision between an abutment impression and a stone model according to dental computer-aided design/computer-aided manufacturing (CAD/CAM) evaluation standards. MATERIALS AND METHODS. To evaluate trueness, the abutment impression and stone model were scanned to obtain the first 3-dimensional (3-D) stereolithography (STL) file. Next, the abutment impression or stone model was removed from the scanner and re-fixed on the table; scanning was then repeated so that 11 files were obtained for each scan type. To evaluate precision, the abutment impression or stone model was scanned to obtain the first 3-D STL file. Without moving it, scanning was performed 10 more times, so that 11 files were obtained for each scan type. By superimposing the first scanned STL file onto the other STL files one by one, 10 color-difference maps and reports were obtained; i.e., 10 experimental scans per type. The independent t-test was used to compare root mean square (RMS) data between the groups (${\alpha}=.05$). RESULTS. The $RMS{\pm}SD$ values of scanning trueness of the abutment impression and stone model were $22.4{\pm}4.4$ and $17.4{\pm}3.5{\mu}m$, respectively (P<.012). The $RMS{\pm}SD$ values of scanning precision of the abutment impression and stone model were $16.4{\pm}2.9$ and $14.6{\pm}1.6{\mu}m$, respectively (P=.108). CONCLUSION. There was a significant difference in scanning trueness between the abutment impression and stone model, as evaluated according to dental CAD/CAM standards. However, all scans showed high trueness and precision.

• 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.

• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.46-52
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• 2014

PURPOSE. The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS. An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of ${\pm}0.1{\mu}m$ at 50 points. RESULTS. Initial detorque values of milled abutment were significantly higher than those of cast abutment (P<.05). Detorque values after one million dynamic cyclic loadings were not significantly different (P>.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading. CONCLUSION. In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.434-443
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.