• Journal of Technologic Dentistry
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• v.41 no.1
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• pp.9-19
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• 2019

Purpose: This study was conducted to comparative evaluate the marginal and internal gap of three-unit metal frameworks(Co-Cr) fabricated by wax milling method and digital light projection method of CAD/CAM systems. Methods: All the specimens were fabricated by three different fabrication methods: conventional wax up with casting(CWC), milled wax block with casting(MWC), digital light projection with casting(DLPC) (n=10 each). The marginal and internal fits of specimens were examined using a replica technique. The light-body silicone thickness was measured at 8 reference points(each abutment: 16 measurements). All measurements were conducted by a stereomicroscope. Digital photo were taken at $150{\times}$ magnification and then analyzed using a measurement software. The Mann-Whitney test was used for analyzing the results. Results: Statistically significant differences were found between the fabrication methods(p<0.001). The mean(SD) is ${\mu}m$ for fabrication methods, the mean marginal fit were recorded respectively, CWC 63(38), MWC group 50(33), DLPC 103(54) and the mean internal fit CWC 96(47), MWC group 116(41), DLPC 138(66). Conclusion : The marginal and internal fit were statistically different according to the fabrication methods(p<0.001). In all fabrication methods, the greatest misfit was found the occlusal area of all specimens.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.72-81
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• 2024

Purpose: This study aimed to assess the marginal and internal fit of 3-unit monolithic zirconia fixed partial dentures (FPDs) fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) from solid working casts and removable die system. Materials and Methods: The tooth preparation protocol for a zirconia crown was executed on the mandibular right first premolar and mandibular right first molar, with the creation of a reference cast featuring an absent mandibular right second premolar. The reference cast was duplicated using polyvinyl siloxane impression, from which 20 working casts were fabricated following typical dental laboratory procedures. For comparative analysis, 10 FPDs were produced from a removable die system (RD group) and the remaining 10 FPDs from the solid working casts (S group). The casts were digitized using a dental desktop scanner to establish virtual casts and design the FPDs using CAD. The definitive 3-unit monolithic zirconia FPDs were fabricated via a CAM milling process. The seated FPDs on the reference cast underwent digital evaluation for marginal and internal fit. The Mann-Whitney U test was applied for statistical comparison between the two groups (α = 0.05). Results: The RD group showed significantly higher discrepancies in fit for both premolars and molars compared to the S group (P < 0.05), particularly in terms of marginal and occlusal gaps. Color mapping also highlighted more significant deviations in the RD group, especially in the marginal and occlusal regions. Conclusion: The study found that the discrepancies in marginal and occlusal fits of 3-unit monolithic zirconia FPDs were primarily associated with those fabricated using the removable die system. This indicates the significant impact of the fabrication method on the accuracy of FPDs.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.193-202
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• 2016

Purpose: This study was performed in order to assess the effect of the surface treatment methods and the use of bonding agent on the shear bond strength (SBS) between the aged CAD-CAM (computer aided design-computer aided manufacturing) hybrid materials and added composite resin. Materials and methods: LAVA Ultimate (LU) and VITA ENAMIC (VE) specimens were age treated by submerging in a $37^{\circ}C$ water bath filled with artificial saliva (Xerova solution) for 30 days. The surface was ground with #220 SiC paper then the specimens were divided into 9 groups according to the combination of the surface treatment (no treatment, grinding, air abrasion with aluminum oxide, HF acid) and bonding agents (no bonding, Adper Single Bond 2, Single Bond Universal). Each group had 10 specimens. Specimens were repaired (added) using composite resin (Filtek Z250), then all the specimens were stored for 7 days in room temperature distilled water. SBS was measured and the fractured surfaces were observed with a scanning electron microscope (SEM). One-way ANOVA and Scheffe test were used for statistical analysis (${\alpha}=.05$). Results: Mostly groups with bonding agent treatment showed higher SBS than groups without bonding agent. Among the groups without bonding agent the groups with aluminum oxide treatment showed higher SBS. However there was no significant difference between groups except two subgroups within LU group, which revealed a significant increase of SBS when Single Bond Universal was used on the ground LU specimen. Conclusion: The use of bonding agent when repairing an aged LAVA Ultimate restoration is recommended.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.124-130
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• 2020

PURPOSE. The aim of this in vitro study was to evaluate the effect of sintering procedures on marginal discrepancies of fixed partial metal frameworks fabricated using different sintering-based computer-aided design and computer/aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS. Forty resin die models of prepared premolar and molar abutment teeth were fabricated using a three-dimensional (3D) printer and divided into four groups (n = 10) according to the fabrication method of metal frameworks used: HM (via hard milling), SM (via soft metal milling), L25 (via direct metal laser melting [DMLM] with a 25 ㎛ layer thickness), and L50 (via direct DMLM with a 50 ㎛ layer thickness). After the metal frameworks were fabricated and cemented, five vertical marginal discrepancy measurements were recorded in each site (i.e., buccal, facing the pontic, lingual, and facing away from the pontic) of both abutment teeth under a stereomicroscope (×40). Data were statistically analyzed at a significance level of 0.05. RESULTS. No statistically significant differences (P>.05) were found among the four axial sites of metal frameworks fabricated by sintering-based CAD/CAM techniques. The HM and L25 groups showed significantly (P<.001) lower marginal discrepancy values than the SM and L50 groups. CONCLUSION. Marginal discrepancy in the sites facing the pontic was not influenced by the type of sintering procedure. All fabrication methods exhibited clinically acceptable results in terms of marginal discrepancies.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.257-264
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• 2017

PURPOSE. To evaluate the adhesion to CAD/CAM feldspathic blocks by failure analysis and shear bond strength test (SBSt) of different restorative systems and different surface treatments, for purpose of moderate chipping repair. MATERIALS AND METHODS. A self-adhering flowable composite (Vertise Flow, Kerr) containing bi-functional phosphate monomers and a conventional flowable resin composite (Premise Flow, Kerr) applied with and without adhesive system (Optibond Solo Plus, Kerr) were combined with three different surface treatments (Hydrofluoric Acid Etching, Sandblasting, combination of both) for repairing feldspathic ceramics. Two commercial systems for ceramic repairing were tested as controls (Porcelain Repair Kit, Ultradent, and CoJet System, 3M). SBSt was performed and failure mode was evaluated using a digital microscope. A One-Way ANOVA (Tukey test for post hoc) was applied to the SBSt data and the Fisher's Exact Test was applied to the failure analysis data. RESULTS. The use of resin systems containing bi-functional phosphate monomers combined with hydrofluoric acid etching of the ceramic surface gave the highest values in terms of bond strength and of more favorable failure modalities. CONCLUSION. The simplified repairing method based on self-adhering flowable resin combined with the use of hydrofluoric acid etching showed high bond strength values and a favorable failure mode. Repairing of ceramic chipping with a self-adhering flowable resin associated with hydrofluoric acid etching showed high bond strength with a less time consuming and technique-sensitive procedure compared to standard procedure.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.46-55
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• 2018

Oral rehabilitation of a patient having severe periodontitis with alveolar bone resorption and periodontal inflammation presents a challenge to clinicians. However, if appropriate implant placement according to the bone shape is selected, unnecessary bone grafting or soft tissue surgery can be minimized. In recent years, using cone beam CT and software, it has become possible to operate the planned position with the surgical guide made with 3D printing technology. This case was a 70 years old female patient who required total extraction of teeth due to severe periodontitis and performed a full-mouth rehabilitation with an implant - supported fixed prosthesis. During the surgery, the implant was placed in a flapless manner through a surgical guide. Immediate loading of the temporary prosthesis made by CAD/CAM method before surgery was done. Since then, we have produced customized abutments and zirconia prostheses, and have reported satisfactory aesthetic and functional recovery.

• The Journal of Advanced Prosthodontics
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• v.11 no.1
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• pp.55-64
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• 2019

PURPOSE. The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method. MATERIALS AND METHODS. The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at ${\alpha}=.05$. RESULTS. No statistically significant differences in distances among four notches (P>.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly (P<.05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods (P<.05). CONCLUSION. The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.1
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• pp.16-22
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• 2021

Purpose: The purpose of this study is to investigate the effect of surface polishing and fabrication method on the flexural strength of temporary restorative resin. Materials and Methods: Each of four fabrication methods was used to make 30 temporary restorative resin specimens and the specimens were divided into two groups depending on whether they were polished by mechanical polishing. Specimens were stored in 37℃ thermostat for 24 hours. Flexural strength was measured using a universal testing machine (UTM). The data obtained through the experiment were analyzed with Two-way ANOVA, Tukey's HSD test and Paired t-test. Results: CAD/CAM milling group showed the highest flexural strength regardless of surface polishing. In decreasing order, the flexural strength of the other fabrication method group was as follows SLA 3D printing, DLP 3D printing, and Conventional method group. Conclusion: Surface polishing did not affect flexural strength of the temporary restorative resin (P > 0.05). However, there were statistically significant differences in flexural strength depending on fabrication method (P < 0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.243-249
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• 2001

Statement of the 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 or Copy-milling systems there is a need for evaluating the quality levels of these new fabrication techniques. Purpose. This study was to evaluate the fitting accuracy of machined all-ceramic crowns made out of an industrially prefabricated feldspathic porcelain. Material and Methods. Three master models with different cutting depth (0.8mm/1.0mm/1.2mm)were produced using a palladium-silver alloy. A total of 36 working dies, 12 of each form, was used for the modellation of prototype resin copings and 36 additional crowns, 12 of each cutting depth, were produced by using the $CEREC^{(R)}2$ system for all crowns. The maginal fit of all 72 crowns was then evaluated on their respective master die at 54 circularly staggered points of measurement per crown under a fixation pressure of 30 N by using a computerized video image system. Results. The medians of the copy-milled $CELAY^{(R)}$ crowns ranged from 29 to $36{\mu}m$. The highest value for the marginal gap was found in group B (cutting depth 1.0mm) at $107{\mu}m$. The median for the $CEREC^{(R)}2$ crowns was found between 43.5 and $70{\mu}m$. The maximum values for all three groups ranged from $181{\mu}m$ to $286{\mu}m$. With $286{\mu}m$ the highest value for marginal gap was found in group C. the Kruskal-Wallis test and multiple comparisons analysis procedure revealed a significant influence of the production technique on the marginal fit in all three groups (p<0,02). Conclusion. 1. The $CELAY^{(R)}$ system is capable to produce all-ceramic crowns with a significantly better marginal fit than the $CEREC^{(R)}2$ system. 2. As far as premolar crowns produced with the $CEREC^{(R)}2$ system are concerned, the cutting depth has a significant influence on fitting accuracy. 3. The production of crowns with an acceptable marginal fit is possible with both systems. However, adhesive luting is recommended for milled feldspathic porcelain crowns.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.362-373
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• 2022

For a full-mouth fixed prosthetic treatment of the edentulous patient, it is essential to confirm the proper tooth position and thorough evaluation of the remaining alveolar bone and soft tissue before surgery. CAD-CAM dentistry and guided implant surgery have such advantages of providing simultaneous planning of surgery and prosthetic treatment to ensure pre-knowledge of the treatment. In this clinical case, using the digital technology, digital temporary denture fabrication, esthetic evaluation before fixed prostheses treatment, and guided surgery planning was possible. After the surgery, previously obtained data was used for fabricating fixed temporary prostheses. Definitive zirconia prostheses transferred from the provisional prostheses were fabricated and functionally and esthetically satisfying results were obtained.