共查询到20条相似文献，搜索用时 31 毫秒
1.
Statement of problem
Research of the ability of a cast mounted on an articulator on maintaining the identical position of a cast mounted on an articulator after repeated repositioning is lacking, despite the possible effects this may have on the occlusion of a mounted cast.Purpose
The purpose of this in vitro study was to verify and compare the vertical repositioning accuracy of 4 different, commercially available articulator magnetic mounting plate systems.Material and methods
Four articulators and their associated magnetic mounting plates were selected for the study. These were the Artex AR articulator (Amann Girrbach AG), the Denar Mark II articulator (Whip Mix Corp), the Kavo Protar Evo articulator (Kavo Dental GmbH), and the SAM3 articulator (SAM Präzisionstechnik GmbH). Three new magnetic mounting plates were prepared for each articulator system. The repositioning accuracy of each mounting plate was evaluated by comparing the standard deviation of the vertical distances measured between the mounting plate and a laser displacement sensor. The lower arm of the articulator was secured, and the vertical distance was measured by positioning the laser displacement sensor positioned vertically above the mounting plate. Once the vertical distance was measured, the mounting plate was detached from the articulator and reattached manually to prepare for the next measurement. This procedure was repeated 30 times for each of the 3 magnetic mounting plates. Data were analyzed by ANOVA for 2-stage nested design and the Levene test (α=.05).Results
Significant differences were detected among articulator systems and between magnetic mounting plates of the same type. The standard deviations of the measurements made with the Artex AR articulator, Denar Mark II articulator, Kavo Protar Evo articulator, and SAM3 articulator were 0.0027, 0.0308, 0.0214, and 0.0215 mm, respectively. Thus, the repositioning accuracy could be ranked in the order as follows: Artex AR, Kavo Protar Evo, SAM3, and Denar Mark II.Conclusions
The position of the magnetic mounting plate after repositioning did not maintain an identical position in the vertical dimension on any of the 4 articulator models tested. The repositioning accuracy of the mounting plates showed significant differences among the articulators tested in this study. 相似文献2.
Wonsup Lee Young-Jun Lim Myung-Joo Kim Ho-Beom Kwon 《The Journal of prosthetic dentistry》2017,117(4):532-538
Statement of problem
A simplified mounting technique that adopts an average condylar guidance has been advocated. Despite this, the experimental explanation of how average settings differ from individual condylar guidance remains unclear.Purpose
The purpose of this in vitro study was to examine potential occlusal error by using average condylar guidance settings during nonworking side movement of the articulator.Material and methods
Three-dimensional positions of the nonworking side maxillary first molar at various condylar and incisal settings were traced using a laser displacement sensor attached to the motorized stages with biaxial freedom of movement. To examine clinically relevant occlusal consequences of condylar guidance setting errors, the vertical occlusal error was defined as the vertical-axis positional difference between the average setting trace and the other condylar guidance setting trace. In addition, the respective contribution of the condylar and incisal guidance to the position of the maxillary first molar area was analyzed by multiple regression analysis using the resultant coordinate data.Results
Alteration from individual to average settings led to a positional difference in the maxillary first molar nonworking side movement. When the individual setting was lower than average, vertical occlusal error occurred, which might cause occlusal interference. The vertical occlusal error ranged from -2964 to 1711 μm. In addition, the occlusal effect of incisal guidance was measured as a partial regression coefficient of 0.882, which exceeded the effect of condylar guidance, 0.431.Conclusions
Potential occlusal error as a result of adopting an average condylar guidance setting was observed. The occlusal effect of incisal guidance doubled the effect of condylar guidance. 相似文献3.
Hyun-Ji Hwang Sang J. Lee Eun-Jin Park Hyung-In Yoon 《The Journal of prosthetic dentistry》2019,121(1):110-117
Statement of problem
Limited information is available evaluating the trueness and tissue surface adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) maxillary denture bases fabricated using digital light processing (DLP).Purpose
The purpose of this in vitro study was to evaluate the trueness of DLP-fabricated denture bases and to compare the tissue surface adaptation of DLP with milling (MIL) and pack and press (PAP).Material and methods
The maxillary denture bases were virtually designed on the reference cast and were fabricated using DLP and MIL. Their intaglio surfaces were scanned and superimposed on the reference computer-aided design denture base to evaluate the trueness. A total of 20 denture bases (10 per technique) were also fabricated on the duplicated master casts using DLP and MIL. Ten denture bases were additionally made using PAP. The intaglio surfaces of the dentures were scanned and superimposed on the corresponding casts to compare the degree of tissue surface adaptation among the 3 techniques. The Mann-Whitney test and Kruskal-Wallis ANOVA were used for statistical analyses (α=.05).Results
The trueness of the DLP denture base was significantly better than that of the MIL denture base (P<.001). Statistically significant differences were detected with respect to tissue surface adaptation of the denture base among the groups (P<.001). The DLP denture base showed the best denture base fit among the 3 techniques with a small interquartile range.Conclusions
Within the limitations of this in vitro study, the DLP maxillary denture base showed better trueness and tissue surface adaptation of ≤100 μm of the 3-dimensional surface deviation than the MIL and PAP denture bases. 相似文献4.
Statement of problem
The long-term color stability of precolored monolithic zirconia has not been thoroughly investigated.Purpose
The purpose of this in vitro study was to evaluate the effect of hydrothermal aging on the optical properties, phase transformation, and surface topography of precolored monolithic zirconia ceramics.Material and methods
Precolored monolithic zirconia specimens (17.0×17.0×1.5 mm, n=50) and lithium disilicate glass-ceramic specimens (16.0×16.0×1.5 mm, n=50) were artificially aged in an autoclave at 134°C under 0.2 MPa for 0, 1, 3, 5, or 10 hours (n=10). CIELab color parameters were obtained from spectral measurements. The translucency parameter (TP) and CIEDE2000 color differences (ΔE00) were calculated. The microstructural and surface properties were analyzed by X-ray diffraction (XRD), atomic force microscope (AFM), and scanning electron microscope (SEM). Data were analyzed with 2-way ANOVA and pairwise comparison (α=.05).Results
Significant interactions were found between aging time and ceramic material on L*, a*, b*, and TP (P<.001) as follows: b* partial eta squared [ηp2]=0.689; L* ηp2=0.186; a* ηp2=0.176; and TP ηp2=0.137. The b* values significantly decreased after aging for zirconia (P<.001), whereas TP increased after aging for zirconia (P<.014) except at 10 hours (P=.389) and for lithium disilicate (P<.001). The ΔE00 values relative to baseline ranged from 2.03 to 2.52 for aged zirconia and from 0.07 to 0.23 for aged lithium disilicate. XRD analysis revealed that hydrothermal aging promoted an increase in m-phase contents. AFM and SEM demonstrated surface alterations after aging.Conclusions
Optical properties and microstructures of precolored monolithic zirconia ceramics were affected by hydrothermal aging, and translucency increased slightly with aging time. 相似文献5.
Hong-Keun Hyun Soojung Kim Changmin Lee Teo Jeon Shin Young-Jae Kim 《The Journal of prosthetic dentistry》2017,117(2):294-302
Statement of problem
Few studies have investigated the colorimetric distribution of gingival color, including the posterior area and alveolar mucosa.Purpose
The purpose of this in vivo study was to investigate the distribution of colorimetric values in different areas of gingiva and to determine its relationship to colorimetric findings of the tooth and skin in a young Korean population.Material and methods
Participants included 40 periodontally healthy adults (22 men and 18 women) 25 to 36 years of age. Commission Internationale de l'Eclairage values (CIELab: L* lightness, a* green-red, and b* blue-yellow) were measured using a colorimeter at a total of 23 sites for each participant, including attached gingiva (AG) and alveolar mucosa (AM) in the maxillary and mandibular and incisor and molar regions, maxillary central incisor, and skin points of the glabella, cheek, and inner upper arm.Results
AG showed higher L* and lower a* values than AM. AG demonstrated higher L* and lower a* values in the maxillary region than in the mandibular region and higher b* values in the incisor region than in the molar region. AM revealed higher L* and lower a* and b* values in the incisor region than in the molar region. Positive significant correlations were found for L* between the skin area and AM and for b* between the skin area and AG.Conclusions
The colorimetric values of AG and AM differ according to the area, possibly as a result of differences in anatomic and histologic distribution that influence optical properties. 相似文献6.
Eun-Ha Kim Du-Hyeong Lee Sung-Min Kwon Tae-Yub Kwon 《The Journal of prosthetic dentistry》2017,117(3):393-399
Statement of problem
Although new digital manufacturing techniques are attracting interest in dentistry, few studies have comprehensively investigated the marginal fit of fixed dental prostheses fabricated with such techniques.Purpose
The purpose of this in vitro microcomputed tomography (μCT) study was to evaluate the marginal fit of cobalt-chromium (Co-Cr) alloy copings fabricated by casting and 3 different computer-aided design and computer-aided manufacturing (CAD-CAM)-based processing techniques and alloy systems.Material and methods
Single Co-Cr metal crowns were fabricated using 4 different manufacturing techniques: casting (control), milling, selective laser melting, and milling/sintering. Two different commercial alloy systems were used for each fabrication technique (a total of 8 groups; n=10 for each group). The marginal discrepancy and absolute marginal discrepancy of the crowns were determined with μCT. For each specimen, the values were determined from 4 different regions (sagittal buccal, sagittal lingual, coronal mesial, and coronal distal) by using imaging software and recorded as the average of the 4 readings. For each parameter, the results were statistically compared with 2-way analysis of variance and appropriate post hoc analysis (using Tukey or Student t test) (α=.05).Results
The milling and selective laser melting groups showed significantly larger marginal discrepancies than the control groups (70.4 ±12.0 and 65.3 ±10.1 μm, respectively; P<.001), whereas the milling/sintering groups exhibited significantly smaller values than the controls (P=.004). The milling groups showed significantly larger absolute marginal discrepancy than the control groups (137.4 ±29.0 and 139.2 ±18.9 μm, respectively; P<.05). In the selective laser melting and milling/sintering groups, the absolute marginal discrepancy values were material-specific (P<.05). Nonetheless, the milling/sintering groups yielded statistically comparable (P=.935) or smaller (P<.001) absolute marginal discrepancies to the control groups.Conclusions
The findings of this in vitro μCT study showed that the marginal fit values of the Co-Cr alloy greatly depended on the fabrication methods and, occasionally, the alloy systems. Fixed dental prostheses produced by using the milling/sintering technique can be considered clinically acceptable in terms of marginal fit. 相似文献7.
Joon-Soo Kim Ji-Hyeon Bae Mi-Jung Yun Jung-Bo Huh 《The Journal of prosthetic dentistry》2017,117(6):775-783
Statement of problem
Recently, zirconia removal diamond rotary instruments have become commercially available for efficient cutting of zirconia. However, research of cutting efficiency and the cutting characteristics of zirconia removal diamond rotary instruments is limited.Purpose
The purpose of this in vitro study was to assess and compare the cutting efficiency, durability, and diamond rotary instrument wear pattern of zirconia diamond removal rotary instruments with those of conventional diamond rotary instruments. In addition, the surface characteristics of the cut zirconia were assessed.Material and methods
Block specimens of 3 mol% yttrium cation-doped tetragonal zirconia polycrystal were machined 10 times for 1 minute each using a high-speed handpiece with 6 types of diamond rotary instrument from 2 manufacturers at a constant force of 2 N (n=5). An electronic scale was used to measure the lost weight after each cut in order to evaluate the cutting efficiency. Field emission scanning electron microscopy was used to evaluate diamond rotary instrument wear patterns and machined zirconia block surface characteristics. Data were statistically analyzed using the Kruskal-Wallis test, followed by the Mann-Whitney U test (α=.05).Results
Zirconia removal fine grit diamond rotary instruments showed cutting efficiency that was reduced compared with conventional fine grit diamond rotary instruments. Diamond grit fracture was the most dominant diamond rotary instrument wear pattern in all groups. All machined zirconia surfaces were primarily subjected to plastic deformation, which is evidence of ductile cutting. Zirconia blocks machined with zirconia removal fine grit diamond rotary instruments showed the least incidence of surface flaws.Conclusions
Although zirconia removal diamond rotary instruments did not show improved cutting efficiency compared with conventional diamond rotary instruments, the machined zirconia surface showed smoother furrows of plastic deformation and fewer surface flaws. 相似文献8.
Jong-Eun Kim Joo Hyun Kwon Jee-Hwan Kim June-Sung Shim 《The Journal of prosthetic dentistry》2017,117(5):597-600
Various attempts have been made to transfer the transverse hinge axis and mandibular movement pattern to the mechanical articulator and to fabricate dental prostheses with the fewest errors. However, the occlusal adjustment of a dental prosthesis is always necessary to ensure a precise intraoral fit even when the facebow transfer technique is used in the cast mounting procedure. This is because the true hinge axis is not obtained when the facebow is applied to a patient who exhibits a variable mandible movement pattern rather than a single rotational axis. This technique merges facial scanning data and digital data obtained from a diagnostic cast based on measurements of several landmarks of the anterior teeth and makes it possible to design a dental prosthesis while considering the mandibular opening and closing movements of the patient. This technique could be used to design prosthetic restorations, occlusal splints, and intermediate splints for orthognathic surgery and for complete mouth rehabilitation when changes in vertical dimensions are needed. 相似文献
9.
Jong-Eun Kim Ami Amelya Yooseok Shin June-Sung Shim 《The Journal of prosthetic dentistry》2017,117(6):755-761
Statement of problem
Intraoral scanners have been reported to have limited accuracy in edentulous areas. Large amounts of mobile tissue and the lack of obvious anatomic landmarks make it difficult to acquire a precise digital impression of an edentulous area with an intraoral scanner.Purpose
The purpose of this in vitro study was to determine the effect of an artificial landmark on a long edentulous space on the accuracy outcomes of intraoral digital impressions.Material and methods
A mandibular model containing 4 prepared teeth and an edentulous space of 26 mm in length was used. A blue-light light-emitting diode tabletop scanner was used as a control scanner, and 3 intraoral scanners were used as experimental groups. Five scans were made using each intraoral scanner without an artificial landmark, and another 5 scans were performed after application of an artificial landmark (a 4×3 mm alumina material) on the edentulous area. The obtained datasets were used to evaluate trueness and precision.Results
Without an artificial landmark on the edentulous area, the mean trueness for the intraoral scanner ranged from 36.1 to 38.8 μm and the mean precision ranged from 13.0 to 43.6 μm. With an artificial landmark on the edentulous area, accuracy was improved significantly: the mean trueness was 26.7 to 31.8 μm, and the mean precision was 9.2 to 12.4 μm.Conclusions
The use of an alumina artificial landmark in an edentulous space improved the trueness and precision of the intraoral scanners tested. 相似文献10.
Jae-Won Choi Ji-Hyeon Bae Chang-Mo Jeong Jung-Bo Huh 《The Journal of prosthetic dentistry》2017,117(5):628-635
Statement of problem
Implant angulation should be considered when selecting an attachment. Some in vitro studies have investigated the relationship between implant angulation and changes in the retention force of the stud attachment, but few studies have evaluated the effect of cyclic loading and repeated cycles of insertion and removal on the stud attachment.Purpose
The purpose of this in vitro study was to evaluate the effects of implant angulation on the retentive characteristics of overdentures with 2 different stud attachments, an experimental system and O-rings in red and orange, after cyclic loading and repeated insertion and removal cycles.Material and methods
The canine region of a mandibular experimental model was fitted with 2 implant fixtures with 2 different stud attachment systems at implant angulations of 0, 15, or 30 degrees. A mastication simulator was used to simulate cyclic loading, and a universal testing machine was used to evaluate retentive force changes after repeated insertion and removal cycles. To simulate the numbers of mastication and insertion and removal cycles per annum, 400 000 cyclic loadings and 1080 insertion and removal cycles were performed. Wear patterns and attachment surface deformations were evaluated by scanning electron microscopy. Data were analyzed using the Kruskal-Wallis test, Mann-Whitney U test with Bonferroni correction (α=.05/3=.017), and the paired-sample Student t test (α=.05).Results
When retentive forces before and after testing were compared, O-ring showed significant retention loss at all implant angulations (P<.001). In contrast, the experimental system showed little retention loss in the 0- and 15-degree models (P>.05), whereas the 30-degree model showed a significant increase in retentive force (P=.001). At all implant angulations, retention loss increased significantly for the orange O-ring, followed by the red O-ring, and the experimental system (P<.001). Scanning electron microscopy analysis showed more intense wear in the matrix than the patrix (abutment that matches to matrix) and more severe wear and deformation of the O-ring rubber matrix than of the experimental zirconia ball.Conclusions
Upon completion of the experiment, wear and deformation were found for all attachment systems. Even when implants are not installed in parallel, the experimental system can be used without involving great loss of retention. 相似文献11.
This clinical report describes the management of a patient who had an excessively tight reconstructed lip because of oral cancer surgery and postoperative radiotherapy. The presented technique used an intraoral scanner for a preliminary impression and computer-aided design and computer-aided manufacturing (CAD-CAM) technology for preliminary laboratory procedures. This digital impression technique may reduce patient discomfort. 相似文献
12.
Christin Arnold Jeremias Hey Ramona Schweyen Jürgen M. Setz 《The Journal of prosthetic dentistry》2018,119(4):586-592
Statement of problem
The conventional fabrication of removable partial dentures (RPDs) is a complex, error-prone, time-consuming, and expensive process. The use of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, especially rapid prototyping, promises a more effective method for fabricating RPD frameworks.Purpose
The purpose of this in vitro study was to evaluate the fit of RPD clasps fabricated by means of 4 different CAD-CAM-systems and to compare those fittings with that of the conventional lost-wax casting technique (LWT).Material and methods
A master model of a partially edentulous maxilla with the canines and second molars as the remaining teeth was fabricated. After the model was optically scanned, we designed a quadrangularly supported RPD with 4 clasps and a palatal strap major connector. A standard tessellation language data set was used to fabricate 12 identical RPDs by using 4 different CAD-CAM techniques: indirect rapid prototyping (wax inject printing combined with LWT), direct rapid prototyping (selective laser melting), indirect milling (wax milling with LWT), and direct milling (resin milling [polyetheretherketone]). Three conventionally cast RPDs (LWT) served as the control group. The fit accuracy of the clasps (n=12 for each group) was determined in both the horizontal and vertical dimensions by using light microscopy.Results
Indirectly milled RPDs (117 ±34 μm horizontal and 45 ±21 μm vertical) and directly milled RPDs (43 ±23 μm horizontal, and 38 ±21 μm vertical) showed significantly better (P<.05) fit than did conventionally fabricated LWT RPDs (133 ±59 μm horizontal; 73 ±25 μm vertical). The worst fit was found for RPDs fabricated using indirect rapid prototyping (323 ±188 μm horizontal and 112 ±60 μm vertical) or direct rapid prototyping (365 ±205 μm horizontal and 363 ±133 μm vertical), which were unstable on the master model, making them unsuitable for clinical use. Most RPDs exhibited smaller vertical measuring distances.Conclusions
Compared with the LWT, milling techniques enabled fabrication of RPDs with comparable or better fit. However, RPDs fabricated with rapid prototyping techniques showed distinct fitting irregularities. 相似文献13.
14.
Statement of problem
The introduction of intraoral scanners has increased the use of digital technology in dental procedures. However, research on the extent of clinically recommended scans is lacking.Purpose
The purpose of this in vitro study was to compare 3D arch distortion according to the distance from the tooth at the beginning of a complete-arch scan made using an intraoral scanner.Material and methods
An industrial scanner was used to digitize a master model for a computer-aided design (CAD) reference model. In addition, the master model was digitized using 4 intraoral scanners (TRIOS2, TRIOS3, CS3500, and CS3600) and 1 dental laboratory scanner (FREEDOM HD) to make the CAD test model (N=20). The scanned teeth were divided using an inspection software program (Geomagic control X), and overlapping and 3D analyses of the CAD reference model and CAD test model were performed. The presence or absence of normal distribution in the root mean square (RMS) values of all divided teeth was assessed and evaluated with the Kruskal-Wallis test (α=.05), and post hoc comparison was performed using the Mann-Whitney U-test and Bonferroni correction method (α=.005).Results
The overall RMS value was significantly different for all scanners (P<.001). The dental laboratory scanner showed the lowest value (47.5 ±1.6 μm), whereas TRIOS2 showed the highest value (343.4 ±56.4 μm). TRIOS3 (9.6 ±1.2 μm) showed the best trueness in those teeth where the scan started. However, the larger the scan range, the lower the RMS value difference between TRIOS3 and CS3500. The RMS values of the dental laboratory scanners were higher than those of the intraoral scanners in the narrow scan range. CS3600 showed an RMS value less than or equal to that of the dental laboratory scanner at 5 teeth scan ranges. However, the wider the scan range, the lower the RMS values of all the intraoral scanners.Conclusions
Current complete-arch scanning is not sufficiently accurate for fabricating fixed prostheses. However, intraoral scanners are useful for short scans, such as those for single (TRIOS2, TRIOS3, and CS3500) or short-span prostheses (CS3600). 相似文献15.
Statement of problem
Because of their relatively small scanning area, intraoral scanners may result in less accurate fixed dental prostheses (FDPs) than do laboratory scanners.Purpose
The purpose of this in vitro study was to evaluate the accuracy of monolithic zirconia FDPs with different numbers of pontics fabricated with different impression techniques.Material and methods
The mandibular right premolars and molars of an acrylic resin model were prepared to receive 4-unit FDPs. Three master models were fabricated with epoxy resin: model NP, no pontic; model 1P, 1 pontic; and model 2P, 2 pontics. Each master model was scanned by using direct (DD) and indirect digitalization (ID). Four-unit monolithic zirconia FDPs were fabricated and divided into 3 groups (groups NP, 1P, and 2P) and then subdivided according to the digitalization technique (group DD and ID; n=10). The FDPs were also evaluated based on the presence (Po) or absence (NPo) of an adjacent pontic. The marginal, axial, and occlusal gap widths of each FDP were measured, and statistical analyses were performed to evaluate and compare the amount of gap present (α=.05).Results
For direct digitalization, group 2P had significantly greater marginal (69.4 μm versus 60.9 μm or 62.3 μm; P<.001) and axial gap widths (127.1 μm versus 108.9 μm or 110.4 μm; P<.001) than group NP or 1P. Group DD resulted in significantly smaller gaps compared with group ID at marginal (64.8 μm versus 73.6 μm), axial (114.8 μm versus 124.3 μm), and occlusal (172.6 μm versus 184.1 μm) measurement locations (P<.001). Greater marginal and axial gaps were noted in group Po than NPo (P<.001).Conclusions
The length of the edentulous area significantly influenced the extent of the marginal and internal gap with the use of direct digitalization. Direct digitalization resulted in significantly smaller gap widths in all measurement areas than indirect digitalization; however, the mean differences were less than 12 μm, which is considered clinically insignificant. The presence of an adjacent pontic had a significant effect on the adjacent marginal and axial gap widths. 相似文献16.
Chan Park Mong-Sook Vang Sang-Won Park Hyun-Pil Lim 《The Journal of prosthetic dentistry》2017,117(3):430-437
Statement of problem
Although many systems are used to polish zirconia, a comparison of the performance of zirconia and feldspathic porcelain polishing systems is lacking.Purpose
The purpose of this in vitro study was to compare the effects of 3 polishing systems on surface roughness, zirconia phase transformation, and durability of the polishing systems when applied to zirconia and feldspathic porcelain.Material and methods
Three polishing systems were evaluated: Z1, a zirconia polishing system; Z2, a zirconia polishing system, and F1, a feldspathic porcelain polishing system. Three ceramic systems were evaluated: PR and ZM zirconia specimens (diameter 15 mm, height 2 mm; 23 specimens each) and CB feldspathic porcelain specimens of the same size (15 specimens). A rough surface was created on the 3 types of specimens (15 specimens each) to model an occlusal adjustment under the same conditions. Polishing was carried out with the 3 polishing systems for 2 minutes each. Surface roughness was measured with a 3-dimensional (3D) optical profiler. The surface was also observed with a scanning electron microscopy. X-ray diffraction analysis was performed for 8 PR or ZM zirconia specimens polished by using the Z1 and Z2 systems for 8 minutes to evaluate the phase transformation of zirconia before, during, and after polishing. These specimens were compared and analyzed for phase transformation that might have occurred during the polishing of the specimens. After finishing the surface roughness experiment and the phase transformation experiment, the volumes of the polishers were measured with a 3D volume scanner and compared with those before the experiments to evaluate the durability of the polishing system. A statistical analysis of all data was performed using 2-way ANOVA and the Tukey honest significant difference test (α=.05).Results
The 2 zirconia polishing systems (Z1, Z2) created a significantly (P<.001) smoother surface, regardless of the type of specimens used for polishing, than the feldspathic porcelain polishing system (F1). When polishing treatment was carried out on zirconia specimens for 8 minutes, the maximum percentages of monoclinic phase increased by 0.03% in the Z1 system and by 0.09% in the Z2 system. The volume change for the durability evaluation of the polishing system was 13.35 and 29.37% in the Z1 system, 2.05 and 5.92% in the Z2 system, and 3.60 and 4.95% in the F1 system, respectively.Conclusions
Zirconia polishing systems created a smoother surface on zirconia than the feldspathic porcelain polishing system. No significant changes in the phase transformation of zirconia were found before and after polishing. Each polishing system showed different levels of wear resistance. 相似文献17.
Statement of problem
Dental clinical procedures are being replaced by digital workflows. Therefore, the time necessary to learn dental computer-aided design (CAD) software to achieve a change in the digital workflow should be evaluated.Purpose
The purpose of this study was to predict the learning curve according to the type of dental CAD software with the Wright model and to determine the rate of improvement in the learner’s working time with iterative learning.Material and methods
A total of 40 participants with various degrees of experience with dental computer-aided design and computer-aided manufacturing (CAD-CAM) systems were recruited. The 4 specified steps of a custom abutment design were performed with 3DSystem CAD software (Daesung) and exocad DentalCAD (exocad GmbH) software and were repeated 3 times in stages. The times were analyzed with repeated-measures 1-factor and 2-factor analyses. The learning time for 300 design iterations was estimated by applying the Wright model formula, and the 300-repetition times were analyzed with the Mann-Whitney U test (α=.05).Results
exocad had a longer mean learning time than the 3DSystem. The overall change with repeated learning was significantly different (P<.001), and all differences were found in the first to third iterations. Software-dependent differences were also observed (P=.005). The Mann-Whitney U test also revealed a significant difference between the 2 software programs (P=.015), but no significant difference was found after the 56th iteration (57th iteration: P=.051).Conclusions
As the time reduction patterns for iterative learning differ depending on the type of CAD software, the learning curves may differ according to the type of software. As the operator’s skill increased through iterative learning, the differences in learning times between the software programs gradually disappeared. 相似文献18.
Jong-Eun Kim Dong-Ho Kwon Jee-Hwan Kim June-Sung Shim 《The Journal of prosthetic dentistry》2019,121(4):566-570
The technique described allowed an implant custom tray to be fabricated referencing the location of connected impression copings. The technique uses dental computer-aided design (CAD) software and 3D printing technology. The method controls the thickness of the impression material around the impression copings, improving the impression-making process. 相似文献
19.
Converting a conventional removable partial dental prosthesis (RPDP) into an implant-assisted removable partial dental prosthesis (IARPDP) may be facilitated by using data from the intaglio surface of the RPDP for proper implant placement. This procedure can be done by connecting the data from the intaglio surface of the RPDP to the residual ridge data of the cone beam computed tomography scan with implant planning software. However, although a misplaced implant under an RPDP can cause various complications, as yet, no technique has connected the information on a patient’s existing RPDP to the implant planning software. This article presents computer-guided implant planning, using a patient’s existing RPDP. 相似文献
20.
Jong-Eun Kim Ji-Hyun Park Jee-Hwan Kim June-Sung Shim 《The Journal of prosthetic dentistry》2019,121(3):373-377
The purpose of this technical report was to describe a method for the fabrication of a custom tray with landmark structures to coordinate cone beam computed tomography and scan data for use in guided implant surgery in patients with numerous artifact-causing metal prostheses. The fabricated custom tray can be used to coordinate cone beam computed tomography data and scan data from the dentition, as well as to fabricate the prostheses. 相似文献