scholarly journals Evaluation of Dimensional Changes According to Aging Period and Postcuring Time of 3D-Printed Denture Base Prostheses: An In Vitro Study

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6185
Author(s):  
Seung-Ho Shin ◽  
Re-Mee Doh ◽  
Jung-Hwa Lim ◽  
Jae-Sung Kwon ◽  
June-Sung Shim ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Denture Base ◽  
Dimensional Changes ◽  
Aging Period ◽  
Stability Change ◽  
3D Printed ◽  
The Stability

During the three-dimensional (3D) printing process of a dental prosthesis, using photopolymer resin, partially polymerized resin is further cured through the postcuring process that proceeds after the printing, which improves the stability of the printed product. The mechanical properties of the end product are known to be poor if the postcuring time is insufficient. Therefore, this study evaluated the effect of the postcuring time of the 3D-printed denture base on its dimensional stability, according to the aging period. The 3D prints were processed after designing maxillary and mandibular denture bases, and after the following postcuring times were applied: no postcuring, and 5, 15, 30, and 60 min. The dimensional stability change of the denture base was evaluated and analyzed for 28 days after the postcuring process. The trueness analysis indicated that the mandibular denture base had lower output accuracy than the maxillary denture base, and the dimensional stability change increased as postcuring progressed. In the no postcuring group for the mandible, the error value was 201.1 ± 5.5 µm (mean ± standard deviation) after 28 days, whereas it was 125.7 ± 13.0 µm in the 60 min postcuring group. For both the maxilla and the mandible, shorter postcuring times induced larger dimensional stability changes during the aging process. These findings indicate that in order to manufacture a denture base with dimensional stability, a sufficient postcuring process is required during the processing stage.

scholarly journals Evaluation of the 3D Printing Accuracy of a Dental Model According to Its Internal Structure and Cross-Arch Plate Design: An In Vitro Study

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5433
Author(s):  
Seung-Ho Shin ◽  
Jung-Hwa Lim ◽  
You-Jung Kang ◽  
Jee-Hwan Kim ◽  
June-Sung Shim ◽  
...  
Keyword(s):  
3D Printing ◽  
Internal Structure ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Thick Shell ◽  
Plate Design ◽  
Dental Model ◽  
3D Printed ◽  
Modeling Data

The amount of photopolymer material consumed during the three-dimensional (3D) printing of a dental model varies with the volume and internal structure of the modeling data. This study analyzed how the internal structure and the presence of a cross-arch plate influence the accuracy of a 3D printed dental model. The model was designed with a U-shaped arch and the palate removed (Group U) or a cross-arch plate attached to the palate area (Group P), and the internal structure was divided into five types. The trueness and precision were analyzed for accuracy comparisons of the 3D printed models. Two-way ANOVA of the trueness revealed that the accuracy was 135.2 ± 26.3 µm (mean ± SD) in Group U and 85.6 ± 13.1 µm in Group P. Regarding the internal structure, the accuracy was 143.1 ± 46.8 µm in the 1.5 mm-thick shell group, which improved to 111.1 ± 31.9 µm and 106.7 ± 26.3 µm in the roughly filled and fully filled models, respectively. The precision was 70.3 ± 19.1 µm in Group U and 65.0 ± 8.8 µm in Group P. The results of this study suggest that a cross-arch plate is necessary for the accurate production of a model using 3D printing regardless of its internal structure. In Group U, the error during the printing process was higher for the hollowed models.

scholarly journals Surface Characteristics of Milled and 3D Printed Denture Base Materials Following Polishing and Coating: An In-Vitro Study

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3305
Author(s):  
Pablo Kraemer Fernandez ◽  
Alexey Unkovskiy ◽  
Viola Benkendorff ◽  
Andrea Klink ◽  
Sebastian Spintzyk
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
In Vitro Study ◽  
Surface Characteristics ◽  
Denture Base ◽  
Liquid Resin ◽  
Base Materials ◽  
Superior Surface ◽  
3D Printed

(1) Background: To date, no information on the polishability of milled and 3D-printed complete denture bases has been provided, which is relevant in terms of plaque accumulation. (2) Methods: three groups (n = 30) were manufactured using the cold-polymerization polymethilmethacrilate, milling (SM) and 3D printing (AM). 10 specimens of each group were left untreated (reference). 10 more specimens were pre-polished (intermediate polishing) and 10 final specimens were highgloss polished. An additional 20 specimens were 3D printed and coated with the liquid resin (coated), 10 of which were additionally polished (coated + polished). For each group Ra and Rz values, gloss value and REM images were obtained. (3). The “highgloss-polished” specimens showed statistically lower Ra and Rz values in the SM, followed by AM and conventional groups. In the AM group statistically lower surfaces roughness was revealed for highgloss-polished, “coated + polished”, and “coated” specimens, respectively. (4) Conclusions: The milled specimens demonstrated superiors surface characteristics than 3D printed and conventionally produced after polishing. The polished specimens demonstrated superior surface characteristics over coated specimens. However, the surface roughness by both polished and coated specimens was within the clinically relevant threshold of 0.2 µm.

scholarly journals Comparison of the Accuracy of Three-Dimensional Printed Casts, Digital, and Conventional Casts: An In Vitro Study

2020 ◽  
Vol 14 (02) ◽  
pp. 189-193 ◽  
Author(s):  
Passent Aly ◽  
Cherif Mohsen
Keyword(s):  
Treatment Planning ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
In Vitro Study ◽  
Vitro Study ◽  
The Other ◽  
Intraoral Scanner ◽  
Linear Measurements ◽  
3D Printed

Abstract Objectives The integration of computer-aided design and manufacturing technologies in diagnosis, treatment planning, and fabrication of prosthetic restoration is changing the way in which prosthodontic treatment is provided to patients. The aim of this study was to compare the accuracy of three-dimensional (3D) printed casts produced from the intraoral scanner using stereolithographic (SLA) 3D printing technique, their digital replicas, and conventional stone casts. Materials and Methods In this in vitro study, a typodont of maxillary and mandibular arches with full dentate ivory teeth was used as a reference cast. The typodont was digitized using Trios 3Shape intraoral scanner to create digital casts. The digital files were converted into 3D printed physical casts using a prototyping machine that utilizes the stereolithography printing technology and photocurable polymer as printing material. Linear measurements (mesiodistal and occlusocervical) and interarch measurements (intercanine and intermolar) were made for digital and prototyped models and were compared with the original stone casts. The reference teeth were canines, first premolars and second premolars in the maxillary and mandibular arches on the right and left sides. The measurements on printed and conventional casts were done by digital caliper while on digital casts; Geomagic Qualify software was used. Statistical Analysis One-way analysis of variance (ANOVA) was used to compare measurements among groups. Results Digital casts showed significantly higher error than the other two groups in all linear and interarch measurements. The mean errors of the digital cast in occlusocervical (OC) and mesiodistal (MD) measurements (0.016 and 0.006, respectively) were higher compared with those in the other two groups (OC, 0.004 and 0.007 and MD, 0.003 and 0.005 [p < 0.0001 and p = 0.02, respectively]). Also, digital mean error in intermolar width (IMW) and intercanine width (ICW) (0.142 and 0.113, respectively) were greater than the other two groups (IMW, 0.019 and 0.008 and ICW, 0.021 and 0.011 [p < 0.0001]). However, the errors were within the acceptable clinical range. Conclusion The 3D printed casts may be considered as a substitute for stone casts with clinically acceptable accuracy that can be used in diagnosis, treatment planning, and fabrication of prosthetic restorations.

scholarly journals A Proposed In Vitro Methodology for Assessing the Accuracy of Three-Dimensionally Printed Dental Models and the Impact of Storage on Dimensional Stability

2021 ◽  
Vol 11 (13) ◽  
pp. 5994
Author(s):  
Li Hsin Lin ◽  
Joshua Granatelli ◽  
Frank Alifui-Segbaya ◽  
Laura Drake ◽  
Derek Smith ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Reference Model ◽  
Three Dimensional ◽  
Posterior Region ◽  
Digital Light Processing ◽  
Dental Models ◽  
3D Printed ◽  
T1 And T2 ◽  
The Impact

The objective of this study was to propose a standardised methodology for assessing the accuracy of three-dimensional printed (3DP) full-arch dental models and the impact of storage using two printing technologies. A reference model (RM) comprising seven spheres was 3D-printed using digital light processing (MAX UV, MAX) and stereolithography (Form 2, F2) five times per printer. The diameter of the spheres (n = 35) represented the dimensional trueness (DT), while twenty-one vectors (n = 105) extending between the sphere centres represented the full-arch trueness (FT). Samples were measured at two (T1) and six (T2) weeks using a commercial profilometer to assess their dimensional stability. Significant (p < 0.05) contraction in DT occurred at T1 and T2 with a medium deviation of 108 µm and 99 µm for MAX, and 117 µm and 118 µm for F2, respectively. No significant (p > 0.05) deviations were detected for FT. The detected median deviations were evenly distributed across the arch for MAX at <50 µm versus F2, where the greatest error of 278 µm was in the posterior region. Storage did not significantly impact the model’s DT in contrast to FT (p < 0.05). The proposed methodology was able to assess the accuracy of 3DP. Storage significantly impacted the full-arch accuracy of the models up to 6 weeks post-printing.

scholarly journals Shape fidelity and sterility assessment of 3D printed polycaprolactone and hydroxyapatite scaffolds

2021 ◽  
Vol 28 (9) ◽  
Author(s):  
Franca Scocozza ◽  
Mirena Sakaj ◽  
Ferdinando Auricchio ◽  
Stefania Marconi ◽  
Pietro Riello ◽  
...  
Keyword(s):  
Thermal Analyses ◽  
Three Dimensional ◽  
The United States ◽  
United States Pharmacopoeia ◽  
3D Printed ◽  
The Fourier Transform ◽  
The Stability ◽  
In Vitro Cell Cultures ◽  
3D Printing Technique

AbstractPolycaprolactone (PCL) and hydroxyapatite (HA) composite are widely used in tissue engineering (TE). They are fit to being processed with three-dimensional (3D) printing technique to create scaffolds with verifiable porosity. The current challenge is to guarantee the reliability and reproducibility of 3D printed scaffolds and to create sterile scaffolds which can be used for in vitro cell cultures. In this context it is important for successful cell culture, to have a protocol in order to evaluate the sterility of the printed scaffolds. We proposed a systematic approach to sterilise 90%PCL-10%HA pellets using a 3D bioprinter before starting the printing process. We evaluated the printability of PCL-HA composite and the shape fidelity of scaffolds printed with and without sterilised pellets varying infill pattern, and the sterility of 3D printed scaffolds following the method established by the United States Pharmacopoeia. Finally, the thermal analyses supported by the Fourier Transform Infrared Spectroscopy were useful to verify the stability of the sterilisation process in the PCL solid state with and without HA. The results show that the use of the 3D printer, according to the proposed protocol, allows to obtain sterile 3D PCL-HA scaffolds suitable for TE applications such as bone or cartilage repair.

Reverse torque values of abutment screws after dynamic loading: The effects of sealant agents and the taper of conical connections

2020 ◽  
Author(s):  
Arda Ozdiler ◽  
suleyman dayan ◽  
Burc Gencel ◽  
Gulbahar Isık-Ozkol
Keyword(s):  
Dynamic Loading ◽  
Antibacterial Agent ◽  
In Vitro Study ◽  
Control Group ◽  
Silicone Sealant ◽  
Reverse Torque ◽  
The Stability ◽  
Torque Values ◽  
Chlorhexidine Gel

This in vitro study evaluated the influence of taper angles on the internal conical connections of implant systems and of the application of chlorhexidine gel as an antibacterial agent or a polyvinyl siloxane (PVS) sealant on the reverse torque values of abutment screws after dynamic loading. The current study tested four implant systems with different taper angles (5.4°, 12°, 45°, and 60°). Specimens were divided into three groups: control (neither chlorhexidine gel filled nor silicone sealed), 2% chlorhexidine gel-filled or silicone-sealed group, and group subjected to a dynamic load of 50 N at 1 Hz for 500,000 cycles prior to reverse torque measurements. Quantitative positive correlation was observed between the taper angle degree and the percentage of tightening torque loss. However, this correlation was significant only for the 60° connection groups except in the group in which a sealant was applied ( p = 0.013 for the control group, p = 0.007 for the chlorhexidine group). Percentages of decrease in the torque values of the specimens with silicone sealant application were significantly higher compared with both the control and chlorhexidine groups ( p = 0.001, p = 0.002, p = 0.001, and p = 0.002, respectively, according to the increasing taper angles); the percentage of decrease in torque values due to chlorhexidine application was statistically insignificant when compared with the control group. The application of gel-form chlorhexidine as an antibacterial agent does not significantly affect the stability of the implant–abutment connection under dynamic loads. PVS sealants may cause screw loosening under functional loads.

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