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Browsing by Author "Yang, Chao-Chieh"
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Item The effects of additive manufacturing technologies and finish line designs on the trueness and dimensional stability of 3D-printed dies(Wiley, 2023) Lai, Yi-Cheng; Yang, Chao-Chieh; Levon, John A.; Chu, Tien-Min G.; Morton, Dean; Lin, Wei-Shao; Prosthodontics, School of DentistryPurpose To evaluate the effects of 5 manufacturing technologies and 2 finish line designs on the trueness and dimensional stability of 3D-printed definitive dies at finish line regions under different storage conditions and time. Material and methods Preparation of light chamfer and round shoulder finish lines were adopted individually on two mandibular first molar typodont teeth and digitalized as standard tessellation language (STL) files. A total of 240 samples (192 AM definitive dies and 48 definitive conventional stone dies) in 20 groups (n = 12) were manufactured based on 2 finishing line designs (chamfer and shoulder), 5 manufacturing technologies (4 additively manufactured technologies and conventional stone die), and 2 storage conditions (light exposure and dark). The 4 additively manufactured (AM) technologies include a DLP 3D-printer, an economic LED 3D-printer, a CLIP 3D-printer, and an SLA 3D-printer. All the study samples were distributed into two storage conditions. Subsequently, samples were digitalized to STL files at 3 different time points (within 36 hours, 1-month, and 3-months). A surface matching software was used to superimpose the sample STL files onto the corresponding original STL files with the best-fit alignment function. The trueness of each printed and stone definitive dies and their dimensional stabilities were measured by the root mean square (RMS, in mm). A linear mixed-effects model was used to test the effects of the finish line design, manufacturing technology, storage condition, and storage time on RMS values (α = 0.05). Results While finish line designs had no significant effects [F(1, 220) = 0.85, p < 0.358], the manufacturing technologies [F(3, 220) = 33.02, p < 0.001], storage condition [F(1, 220) = 4.11, p = 0.044], and storage time F(2, 440) = 10.37, p < 0.001] affected the trueness and dimensional stability of 3D-printed dies at finish line regions. No significant interactions were found among the 4 factors. For the manufacturing technologies, Type IV stone groups and LCD 3D-printer groups had significantly higher RMS values than the other 3 printers (p < 0.001) with no significant differences between Type IV stone and LCD 3D-printer groups (p = 0.577). DLP 3D-printer groups had higher RMS values than both SLA 3D-printer groups and CLIP 3D-printer groups (p < 0.001). There were no significant differences between SLA 3D-printer groups and CLIP 3D-printer groups, p = 0.671. For the effects of storage conditions, RMS values were significantly higher in the groups stored with the direct light exposure than the ones stored in the dark, p = 0.044. In terms of the effects of storage time, the RMS values were significantly higher after 1-month storage, p = 0.002; and 3-month storage, p < 0.001, than the ones at the immediate postmanufacturing stage. However, the RMS values after 1-month and 3-month storage were not significantly different from each other (p = 0.169). Conclusions Manufacturing technologies, storage conditions, and storage time significantly affected the trueness and dimensional stability of 3D-printed dies at finish line regions, while finish line designs had no significant effects. Among the AM technologies tested, all have produced either comparable or truer 3D-printed dies than the Type IV dental stone dies, and the CLIP and SLA 3D-printers produced the best outcomes. 3D-printed dies showed significant distortion after 1-month and 3-months storage, especially under light exposure storage conditions. These findings may negate the clinical need to preserve 3D-printed dies, and digital data should be preserved instead.Item Influence of coloring techniques and cement opacity on the optical properties of high translucent monolithic zirconia(2017) Yang, Chao-Chieh; Phasuk, Kamolphob; Chu, Tien-Min Gabriel; Brown, David; Levon, John A.Background: With the improvement of CAD/CAM technology and translucency of zirconia material, the full contour zirconia crown was introduced to offer dentists a metal free, high strength, and acceptable esthetic prosthesis option. In addition, it is claimed that it is possible to make a full contour high translucent zirconia crown close to natural tooth color by using coloring liquid. However, there is little information in the literature regarding the effect of coloring techniques and cement color on the optical properties of high translucent zirconia. Objective :1) To evaluate the effect of the coloring liquid technique on the resulting optical properties of a monolithic high translucent zirconia 2) To evaluate the cumulative effect of the cement color on the resulting optical properties of a monolithic high translucent zirconia. Alternative hypothesis: There is a significant difference in optical properties between the high translucent monolithic zirconia ceramics with different color staining technique. In addition, the use of shaded resin cement has an effect on the final optical properties of high translucent monolithic zirconia ceramics. Materials and methods: 35 specimens of high translucent zirconia (11mm x11mm) with thickness 1mm was divided into 5 groups according coloring technique, as follows: no color, submerge, two layers of painting, four layers of painting, and six layers of painting. All specimens were measured for the Δ E, transparent parameter (TP), and opalescence parameter(OP) by spectrophotometer (CM-2600D) after firing. Forty-two specimens of high translucent zirconia (11mm x11mm) with thickness 1mm were divided into three groups according to cement color, as follows: clear, opaque, and A2. After firing and cementing with ND4 resin Block. The Δ E, TP and OP will be measured by spectrophotometer. Statistics: The data were analyzed with significant level set at 0.05 one way ANOVA followed by pair-wise group comparisons using Fisher’s Protected Least Significant Differences. Result: 1) The shade of cement significantly affected the mean value of ΔE of E-max CAD and BruxZir high translucent zirconia restoration. Using opaque cement combined with E-max CAD resulted in color difference that was above the clinically perceptible level (ΔE> 3.7). 2) With more layers of staining liquid application, the ΔE and value decreased. The six-layered group showed lowest mean delta ΔE value of 22 (0.78). ΔE was significantly different among groups (p<0.0001). The submerged group showed higher ΔE than the all painting groups. Conclusions: Based on the results of the study, the colors of BruxZir high translucent zirconia and E-max CAD restorations were affected by the shade of cement, whereas white opaque resin cement resulted in BruxZir high translucent zirconia more yellowish. The results of the study demonstrated that the staining technique has an influence on value and final color of Lava-Plus high translucent. Therefore, it is recommended to consider staining technique as one of the influential factors on the final color of zirconia crowns.Item Marginal Fit, Mechanical Properties, and Esthetic Outcomes of CAD/CAM Interim Fixed Dental Prostheses (FDPs): A Systematic Review(MDPI, 2023-02-28) Al-humood, Hussain; Alfaraj, Amal; Yang, Chao-Chieh; Levon, John; Chu, Tien-Min Gabriel; Lin, Wei-Shao; Prosthodontics, School of DentistryThis systematic review aimed to study the outcomes of CAD-CAM (milled and 3D-printed) interim dental prostheses when compared to conventional ones. The focused question of "In natural teeth, what are the outcomes of CAD-CAM interim FDPs compared to the conventionally-manufactured ones regarding marginal fit, mechanical properties, esthetics, and color stability" was formulated. The systematic search was conducted electronically in the PubMed/MEDLINE, CENTRAL, EMBASE, Web of Science, New York Academy of Medicine Grey Literature Report, and Google Scholar databases by using the MeSH keywords and keywords associated with the focused question and limiting articles to those published between 2000 and 2022. A manual search was conducted in selected dental journals. The results were analyzed qualitatively and are presented in table format. Of the included studies, 18 studies were in vitro and 1 was a randomized clinical trial. Of the eight studies analyzing the mechanical properties, five studies favored the milled interim restorations, one study favored both 3D-printed and milled interim restorations, and two studies reported better mechanical properties in conventional interim restorations. Among four studies evaluating the marginal discrepancies, two studies favored the marginal fit in milled interim restorations, one study reported a better marginal fit in both milled and 3D-printed interim restorations, and one study found conventional interim restorations have a better marginal fit and smaller marginal discrepancy when compared to both milled and 3D-printed restorations. Among five studies that evaluated both the mechanical properties and marginal fit, 1 study favored 3D-printed interim restorations and four studies favored milled interim restorations over the conventional ones. Two studies analyzing the esthetics outcomes demonstrated better results with milled interim restorations compared to conventional and 3D-printed interim restorations in terms of their color stabilities. The risk of bias was low for all the studies reviewed. The high level of heterogeneity within the studies excluded meta-analysis. Most of the studies favored the milled interim restorations over the 3D-printed and conventional restorations. The results suggested that milled interim restorations offer a better marginal fit, higher mechanical properties, and better esthetic outcomes in terms of color stabilities.Item The Trueness of Obturator Prosthesis Base Manufactured by Conventional and 3D Printing Techniques(Wiley, 2021) Alfaraj, Amal; Yang, Chao-Chieh; Levon, John A.; Chu, Tien-Min G.; Morton, Dean; Lin, Wei-Shao; Prosthodontics, School of DentistryPurpose : To compare the intaglio surface trueness of obturator prosthesis bases manufactured by traditional compression molding, injection molding, and 3D printing techniques. Materials and Methods : A complete edentulous master cast with Aramany Class I maxillary defect was selected for this in vitro study. Four study groups (n = 10/group) were included in this study, Group A: Compression Molding, Group B: Injection Molding, and Group C: Cara Print 3D DLP Printer, and Group D: Carbon 3D DLS Printer. All obturator prostheses' intaglio surfaces were scanned with a laboratory scanner (E4; 3Shape Inc, New Providence, NJ) and the dimensional differences between study samples and their corresponding casts were calculated as the root mean square (measured in mm, absolute value) using a surface matching software (Geomagic design X; 3D Systems, Rock Hill, SC). One-way Analysis of variance (ANOVA) and Fisher's least significant difference (LSD) test were used to compare groups differences in RMS (α = .05). Results There was a significant effect of manufacturing technique on the RMS values for the 4 conditions [F(3,36) = 5.743, p = .003]. Injection Molding (0.070 mm) and Compression Molding groups (0.076 mm) had a lower interquartile range, and the Cara Print 3D-Printer group (0.427 mm) and Carbon 3D-Printer (0.149 mm) groups had a higher interquartile range. The Injection Molding group showed the best and uniform surface matching with the most area in green in the color maps. The Injection Molding group (0.139 ±0.049 mm) had significantly lower RMS than all other groups (p<.001 for all comparisons). Compression Molding (0.269 ±0.057 mm), Cara Print 3D-Printer (0.409 ±0.270 mm), and Carbon 3D-Printer (0.291 ±0.082 mm) groups were not significantly different from each other (Compression Molding versus Carbon 3D-Printer, p = .59; Compression Molding versus Cara Print 3D-Printer, p = .25; Cara Print 3D-Printer versus Carbon 3D-Printer, p = .40). Conclusion : Obturator prosthesis bases manufactured with injection molding technique showed better intaglio surface trueness than ones made by the compression molding technique and 3D printers. Although obturator prosthesis bases manufactured from different 3D printers showed similar trueness, a DLP 3D printer produced less consistent outcome than a DLS 3D printer.Item Virtual Facial Simulation of Prosthetic Outcome for Static Computer-Aided Implant Surgery and CAD-CAM Prostheses(Allen Press, 2022-02) Harris, Bryan T.; Yang, Chao-Chieh; Morton, Dean; Lin, Wei-Shao; Prosthodontics, School of Dentistry